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April 29

Albert Einstein

Who is the next genius, i meant the smartest person, after Albert Einstein's Death?75.168.119.109 (talk) 00:04, 29 April 2010 (UTC)

Tricky: My vote goes to Richard Feynman - but there are a lot of other possibilities. The problem is that the word "smart" is hard to pin down - the concept of "intelligence" and even "IQ tests" is very fuzzy - and the most intelligent people of all sometimes do very badly at those kinds of tests because they are so much smarter than the people who designed them. If you read biographies of Einstein, you tend to come away with the idea that aside from his abilities in the areas of theoretical physics - he was a complete idiot and a general pain in the ass. I don't think I would have liked him - or found him particularly interesting to talk to. Similar complaints may be raised against other possibilities such as Stephen HawkinsStephen Hawking. Personally, I respect Feynman precisely because he was brilliant (and funny and talented) in absolutely everything he approached - the sheer breadth of his talent was impressive. But I'm sure we'll have a lot of alternatives put forward. SteveBaker (talk) 00:19, 29 April 2010 (UTC)

I'm not convinced that Steve meant to link Stephen Hawkins (an Australian rower) in the above comment. Perhaps he meant Stephen Hawking (the physicist). Astronaut (talk) 01:51, 29 April 2010 (UTC)

No, no! I'm in awe of australian rowers! sorry SteveBaker (talk) 02:48, 29 April 2010 (UTC)

You mean nobody is the smartest person? I would agree with that because nobody know everything. I'm sure Albert Einstein didn't know much about other areas beside science and physic like art, genetic, biology...75.73.152.238 (talk) 00:32, 29 April 2010 (UTC)

The problem is that Einstein is not the "smartest person," he's just an icon, a popular hero. He was a smart guy and did smart things, to be sure (Many of his "big ideas" were clever; a few were downright brilliant and have stood the test of time; a few did not pan out at all and we now think he was wrong). But the popular representation of him is simultaneously exaggerated and misunderstood. (He was not doddering and out of touch with the world. He was intensely political and controversial and pushed the envelope on things like war, race, and democracy to the point that he accrued a large FBI file.) Einstein is a singular icon... there is almost nobody else like him in the 20th century, from the point of view of being the living embodiment of what it means to be a "scientist" in the popular mind. Stephen Hawkings is something of a comparison (his "iconic" status is derived in a large way from his disability in a fairly obvious way). Newton, Galileo, and Darwin served the role for earlier generations (and our own, of course). Anyway, SteveBaker's point is not that "nobody is the smartest person" but that "smartest person" is an ill-defined concept—it makes it sound like you can measure all-around smartness with one number. Nobody thinks that is case, at least not on the level of pitting individual geniuses against each other (which is not, for example, what IQ tests do). --Mr.98 (talk) 01:02, 29 April 2010 (UTC)

Right. If we had a really solid definition of "smart" we'd have a "smartest person". So maybe: "The person who is able to memorize and recite the most digits of PI" is the smartest - and currently that is a guy called Lu Chao who memorized 100,000 digits and was able to recite 65,000 digits before he mis-spoke and screwed up one digit. If you say it is the person with the highest recorded score on an IQ test then the answer is Marilyn vos Savant (who always strikes me as kinda stupid and annoying...but that's just my opinion). If it's "the person with the most Nobel prizes" then John Bardeen, Marie Curie, Linus Pauling and Frederick Sanger each have two - but Fred Sanger is the only one of them who is still alive. But which of those (or a gazillion other things I could come up with) should count? It's entirely a matter of opinion. My opinion is that being 'smart' at just one thing isn't so impressive as being good at a wide range of things - and that's why Richard Feynman gets the prize as far as I'm concerned. He only had one Nobel prize - but he also became an expert bongo player, he learned to write the Tuvan language by reading an English-Russian and a Russian-Tuvan dictionary, he was a working theoretical physicist - who became a biologist as a 'vacation', he was a self-taught safe cracker, he taught himself how to 'lucid dream', he figured out the cause of the Challenger disaster and demonstrated the problem live on TV with a $2 clamp and a glass of iced water, he learned how to pretend to be drunk and to pick up women in bars using scientific principles!...he had a life that was filled to bursting with intellectual pursuits. I think he was the "all-round" smartest guy ever...but that's just my opinion - yours will undoubtedly be different. SteveBaker (talk) 01:29, 29 April 2010 (UTC)

See, and I would actually vote for Linus Pauling. His contributions to Chemistry are as important and wide reaching as Einstein or Feynman's were to Physics. He's as close to a Chemistry Polymath as there can be; his work stretches to nearly all aspects of chemistry. Pauling's rules are central to X-ray crystalography. He formalized the concept of electronegativity and used it to explain the ionic - covalent bond continuum. He invented the concept of resonance and of delocalized electrons. He worked in biochemistry, being the among the first people to explain how hemoglobin binds oxygen. He explained the main secondary structure in proteins, the so-called "alpha helix" and "beta-pleated-sheet" models. He helped explain the molecular causes of sickle-cell anemia. He also worked on nuclear mechanics, devising his own "spheron model of the nucleus". Oh, and he also won the Nobel Peace Prize for his anti-nuclear weapons activism. I've always placed him as second after Einstein in terms of overall importance to the general scientific world. --Jayron32 01:55, 29 April 2010 (UTC)

Sure - Pauling was a god in Chemistry - but what did he do outside of that? This isn't a question about what someone achieved - it's a question about how smart they were. Knowing absolutely everything there is to know about Chemistry requires you to be pretty smart - but that's not the limit on smartness...how smart was he in his daily life? Einstein really wasn't very smart when you took away his physics. Did Pauling do smart things in his spare time? What about on vacation? What did he do for fun? Did he use all of those 'smarts' in lots of other ways? Those are all rather important to me.

My "hero" (for want of a better word) has to be good at everything he/she does - and has to do a huge variety of things - inside and outside of some narrow career path. I could come up with a long list of theoretical physics stuff that Feynman did - but he also worked to improve science and math textbooks in schools, he worked on the Manhatten project but worked to subtly subvert the military - to mock their censorship rules by doing things like writing letters to his wife in codes that they couldn't break so they had to sheepishly ask him to please tell them how to decode the letters! He achieved many breakthroughs in computing algorithms...before there were actual electromechanical computers and "computers" were people. He trained his small army of "computers" to do impressive military-style drill with their pencils on command in order to impress the generals when they came around to visit!

Pauling's biographies are mostly stuff about chemistry - a bit about his anti-nuke activisim and a bit about the sad loss of his wife and subsequent bringing up of his daughters. He's a completely two-dimensional character. Chemistry - activism - kids...the end.

SteveBaker (talk) 03:17, 29 April 2010 (UTC)

Feynman's awesomeness comes mostly from being a character. I will not attempt to diminish his awesomeness, but most of his intrigue comes from his quirky personality and his expressions thereof. I would not attempt to compare the intelligence of Feynman vs. Pauling, except that Feynman's expressions of his intelligence come off as far more entertaining which is why he gets better pub. Surely You're Joking, Mr. Feynman! is a far more entertaining read than any biography of Pauling, and much of our impressions of Feynman come from that and other books about him. I will grant you that Feynman is a far more interesting person than Pauling, but that doesn't necessarily mean he was either smarter or more important to his field or to the general advancement of knowledge. I will grant you a "tie" with Pauling on anything except "entertainment factor" which Feynman wins hands down. --Jayron32 05:14, 29 April 2010 (UTC)

Linus Pauling was of course also known for his controversial work in and advocacy of orthomolecular medicine and megavitamin therapy, particularly vitamin C, in his later years. Nil Einne (talk) 09:00, 29 April 2010 (UTC)

I nominate Raquel Welch for contributions to Paleontology and medicine. Cuddlyable3 (talk) 09:40, 29 April 2010 (UTC)

Well if you're talking about people with major achievements in more than one field, then a modern candidate would be Professor Brian Cox (physicist), who had a Number One hit in the UK in the 1990s with D:Ream (Things can only get better), went on to become an astrophysicist and work at CERN, and now is a bit of a celeb. (oh and he's a bit dishy too!) --TammyMoet (talk) 10:56, 29 April 2010 (UTC)

Brian May. --Phil Holmes (talk) 13:28, 29 April 2010 (UTC)

Intelligence is task-specific. Einstein was great at physics and math and taking a high-level view of humanity. If you want to ask about who may be exceedingly learned in some regard, you will have to specify which regard. And if you don't want to be bothered with that, if you just want some names thrown out there, I will offer singer-songwriter Mark Knopfler. An account of his humanism, and ability to express it in majestic fashion. Vranak (talk) 14:23, 29 April 2010 (UTC)

more
Why Mark Knopfler, and not for example Johnny Cash? 76.103.104.108 (talk) 06:18, 30 April 2010 (UTC) Good question! I think it comes down to lyrical and melodic elegance. Vranak (talk) So you take those things to be indications of less intelligence? --Trovatore (talk) 00:22, 1 May 2010 (UTC) This is getting silly. i.e. No. Vranak (talk)

I think we've had a good demonstration on why it's so hard to define intelligence. I can think of at least three kinds of outliers - the genius that's virtually the best in the world at a certain thing (think: Albert Einstein), the polymath that's exceptionally good at a wide array of things (think: Leonardo Da Vinci), and the teacher that can seemingly understand virtually everything and relate it to laypeople understandably (think: Isaac Asimov). Now take the first kind and multiply it by however many branches of study have ever existed. Is Stephen Hawking smarter than, say, Bach or Mozart? How could you even compare them meaningfully? Or take guys from a millennium ago like Abu Rayhan Biruni and Avicenna. How could you compare their staggering accomplishments in virtually everything to a polymath of today? Do they get credit for figuring out huge swaths of the sciences during a time when getting eaten by a bear was a realistic cause of death for people - or does someone from today get credit for reaching even further, after the "easy" stuff has been done? Matt Deres (talk) 16:42, 29 April 2010 (UTC)

Cell

I knew all cells come from cell then where the first cell come from?75.168.119.109 (talk) 00:04, 29 April 2010 (UTC)

You should read our article Abiogenesis. The short, honest answer is that we don't know for sure - but we suspect that chemicals that can copy themselves (like, maybe RNA) could come about spontaneously from random chemical reactions in the soil or the oceans - then for such molecules to become trapped inside a lipid bubble and thereby form primitive cells. But we don't know for sure. We're pretty certain it wasn't magic though. SteveBaker (talk) 00:10, 29 April 2010 (UTC)

Evolution can't explain it. --Chemicalinterest (talk) 14:55, 29 April 2010 (UTC)

Evolution doesn't attempt to explain it: evolutionary theories aim to explain how existing forms of life change over time, not how life came to exist in the first place. 87.81.230.195 (talk) 21:14, 29 April 2010 (UTC)

Aliens

I have heard and read many resources show that aliens are really exist or do not exist. Is alien really exist?75.168.119.109 (talk) 00:07, 29 April 2010 (UTC)

You're aiming for all of the difficult questions today! See our article on the Drake equation which estimates the probability that there is intelligent life on other planets - and comes to the conclusion: "Yes, there probably is". But we haven't found life anywhere - so the answer can only be "probably". On the other hand, aliens visiting Earth...No - that doesn't seem either likely or possible from the evidence we have available. SteveBaker (talk) 00:12, 29 April 2010 (UTC)

I think the aliens have came to Earth before at least one time. If not then how could you explain all the UFO we have seen from the ancient time until today.75.168.119.109 (talk) 00:23, 29 April 2010 (UTC)

I don't explain "all of the UFO's" - there is not one single reliable sighting of such a thing. The ideas put around by "UFOlogists" are just typical 'nut job' stuff - packed full of unlikely conspiracy theories and unreliable "eye witness" testimony. The idea that a small craft could cross hundreds of lightyears and somehow hide from us for 60 years while still revealing itself in conveniently unconvincing ways to individual humans in the numbers they claim...it's not remotely credible. The idea that governments are 'covering up' the evidence is crazy - the government are completely inept at covering things up. Go to a UFO conference sometime (I did...once!) and the people there who claim to have been visited or abducted are the least convincing people you'll ever meet - their stories fall apart once you start asking careful questions - they are liars, one and all - mostly, they seem to be people who have had nothing interesting happen in their lives who have come up with this story to make themselves seem different, interesting, important. It's just sad. SteveBaker (talk) 01:54, 29 April 2010 (UTC)

Actually, Steve, UFO's really do exist on Earth -- just not the alien kind. See List of experimental aircraft, Skunk Works, Nellis Air Force Base, and Edwards Air Force Base for more details. :-) 76.103.104.108 (talk) 02:33, 29 April 2010 (UTC)

I don't think all of the people who said they have seen the aliens are all liars. There must be at least one of them say the truth. And also in ancient time there are some UFO were written by historian, i don't think their purpose is lying to us.75.168.119.109 (talk) 22:46, 29 April 2010 (UTC)

I expect very few UFO sightings are lies. Most of them are simply mistakes. --Tango (talk) 06:15, 30 April 2010 (UTC)

Those probably aren't the kind of UFO spotters that travel the country telling their story. "I Saw a mysterious red dot in the sky." just isn't interesting or special enough. APL (talk) 04:07, 1 May 2010 (UTC)

Yea I agree but there must be one is the real aliens. Maybe by some reasons the aliens didn't want to contact us yet. I think there are some aliens visited us on 20th century after maybe a hundred years travel in the space and they have some kind of machine to make them not getting older so as long as they sleep in that machine they will not die. I think they didn't try to contact us yet because they saw the World War 2 were happening and they also want to come back their planet to inform to their planet that they found alien, us, and to prepare the next travel to Earth. If this is right then we have to wait like about 100 more years to see aliens come back to Earth again.75.168.119.109 (talk) 22:17, 30 April 2010 (UTC)

I wonder why aliens never try to contact us. Does anyone know?75.73.152.238 (talk) 00:32, 29 April 2010 (UTC)

Most aliens keep a low profile, because even if they are here legitimately, the Arizona police will stop them and demand their papers. Nimur (talk) 08:26, 29 April 2010 (UTC)

I agree with Steve! Just because YOU can't explain something, doesn't mean Aliens did it. As to why they haven't tried to contact us, well maybe they have but we missed it? One of the difficulties is the vast amount of empty space and time involved. I believe it is extremely likely there would be intelligent life somewhere else in the universe, but it might be a million years ago, or a million light years away, or billion, or any combination of the two. In any case, there's no real way to know, let alone communicate anything meaningful. Vespine (talk) 01:44, 29 April 2010 (UTC)

The universe is very, very empty, but it is also very very big. There are billions of galaxies, each containing billions of stars. A large proportion of those stars probably have planets. Using the Drake Equation it is easy to calculate there are probably other planets with intelligent life - quite possibly millions of planets. Because eveything is so far away that even light takes years to travel between the stars, it is unlikely that aliens would be able to make the journey to visit Earth, or for us to make the journey to visit them. Using current technology, it would take many thousands of years to travel to the nearest stars (see Voyager 2#Escaping the solar system and Voyager 1#Current activities for estimates of when these NASA probes could reach interstellar distances). Astronaut (talk) 01:46, 29 April 2010 (UTC)

Perhaps they do - but if they are out there - they are hundreds of light-years away. If you put the most powerful radio transmitter mankind has ever made on a planet orbiting the nearest star to us - then our most sensitive radio telescope would be unable to detect it. So unless these aliens have vastly more powerful transmitters than we do (or unless they know that we're here and can use a laser or something) - then we stand no chance of hearing them. Because the only way they could "know we're here" is if they can detect the signs of civilization in our atmosphere or something - and those changes only proceed outwards at the speed of light - they would have to be pretty close to us in order to have time to notice that we're here. Furthermore - their idea of "clear communications" might be very different from ours. We're expecting something like a sequence of prime numbers, transmitted in binary on a frequency near the "hydrogen hole" - but it might come in the form of choreography instructions for interpretive dance steps designed for creatures with eleven hooves and nine tentacles transmitted using 'spread spectrum' techniques. They might well be blasting us with copies of "The Encyclopedia Galactica" and "Welcome to the space-faring species club!" messages - and we'd never know it. SteveBaker (talk) 01:54, 29 April 2010 (UTC)

Also, aliens may not use electromagnetic radiation to communicate. For some alternative possibilities, see here and here. Count Iblis (talk) 02:05, 29 April 2010 (UTC)

There are many more possibilities - how about aliens who live long lives - but who's brains work v-e-r-y s-l-o-w-l-y. Suppose they sent their messages by radio or light at a rate of one bit per month or something. Would we notice such incredibly low frequency messages? Or suppose they were incredibly patient and sent messages by changing the chemical composition of immense gas clouds around some star or other - expecting us to decode the spectral characteristics resulting from that? If you consider all of the ways we could imagine they might communicate - and then realise that there are just about guaranteed to be a bunch of other ways we couldn't imagine...it's easy to see how we haven't heard anything as a result of the SETI work. A darker possibility is that there are dangerous races of aliens out there and all of the others realize that the risk of broadcasting their position is simply too great. Maybe they just aren't particularly talkative - it could easily be that this desire to communicate is a uniquely human characteristic. Maybe their technology just took off in a different direction and they never bothered much with astronomy or even physics in general? Until or unless we find something 'out there' we simply cannot know why we aren't. SteveBaker (talk) 03:33, 29 April 2010 (UTC)

The Fermi paradox discusses these reasons. CS Miller (talk) 12:49, 29 April 2010 (UTC)

You know, if I were an alien species with super-duper technology, and I wanted to make other intelligent beings know I existed, then I would make a star blink. Create a giant movable star-shade and send out ultra low-frequency bits (showing primes or whatever). That would give you enormous power, a broadband signal, and a wide viewing angle. And of course, a flickering star would be easily noticed with even the level of technology available to stupid apes like us. Dragons flight (talk) 07:08, 29 April 2010 (UTC)

"Create a giant star-shade" Hmm?!! —Preceding unsigned comment added by 86.4.186.107 (talk) 07:48, 29 April 2010 (UTC)

Very good, and there's me thinking we were discovering hundreds of exoplanets, and all it was was some alien race putting on a light show with morse-code. How disheartening.... :) --KägeTorä - (影虎) (TALK) 12:11, 29 April 2010 (UTC)

That's not a bad idea. It is probably centuries beyond our technology, though (the usual caveats about any technological prediction beyond 25 years apply). The shade would have to be planet sized to result in a noticeable dimming to our best current telescopes. It would have to be star sized to noticeable to the naked eye. --Tango (talk) 14:10, 29 April 2010 (UTC)

I think if an alien intelligence wants to send a detailed message then some kind of mathematical signal sent using EM is by far the most likely. The aliens will go through the same thought process as us and try to work out what is likely to be in common between technological species and they are likely to come to the same conclusion we did - mathematics. If they are intelligent enough to be sending messages to other species then they are likely to be intelligent enough not to assume all intelligent species have the same number of legs they do. EM is the most likely medium because the only other option is gravity and that is much harder work (due to elementary particles having much greater charges than they do masses, in natural units). One thing we should keep in mind is that they may not be trying to send a detailed message but just something that unambiguously says "We are here". In that case they don't need mathematics, just anything unnatural. Changing the spectra of nebulae could do that. They may think it is easier to do something like that and look for responses so they can send their detailed messages to a specific target. --Tango (talk) 14:10, 29 April 2010 (UTC)

One possible explanation for the lack of alien contact may be that aliens don't think it is worth it. Travelling between stars takes a long time (aliens could have longer lifespans than us, but they aren't likely to be much longer since that would tend to slow down evolution, so they wouldn't have reached intelligence yet - of course, I'm extrapolating from a single data point, so the margin of error is rather large!), so they may well assume they will never actually meet any aliens and will just be communicating with a round-trip time of decades or centuries. Such slow communication won't allow for much information to be exchanged, so the practical benefit is likely to be minimal. --Tango (talk) 14:10, 29 April 2010 (UTC)

They could be completely different from humans in a way that no one ever dreamed of. There is no evidence either way. --Chemicalinterest (talk) 15:06, 29 April 2010 (UTC)

I agree, but we can still make educated guesses based on the basic principle that a notion of "technologically more advanced" should correpond to "being able to utilize resources to achieve more objectives". Then I think that since we are all machines, but that in biological form we don't have much control over our lives, more advanced civilizations will be machine civilizations. Space travel is far more practicical if you are an electronic machine because then you can just upload yourself to a machine on the place of destination via radio communications.

You can then also imagine that civilizations repeatedly transmit radio messages that contain details on how to build their hardware, followed by messages containing their software. Such messages can be picked up long after the civilization is gone, billions of years later, by another civilization who could decide to build the machines and then download the aliens into the machines. Count Iblis (talk) 15:55, 29 April 2010 (UTC)

If we have absolutely nothing in common with them, then we'll never be able to communicate with them (or perhaps even recognise them) anyway, so we might as well assume we do have something in common with them. The something is the technology necessary to send and receive messages between stars. There are different ways of doing that, but it doesn't seem likely (and I'm only talking about likelihoods, I'm not ruling out anything as impossible) that they could be built without mathematics. --Tango (talk) 16:18, 29 April 2010 (UTC)

The Drake equation makes sense, it is just that for most of the variables going into this equation we could be off by orders of magnitude and not realize it since our observations of extrasolar items smaller then stars is extremely limited and prone to observation bias. Googlemeister (talk) 20:03, 29 April 2010 (UTC)

I don't think all of the people who said they have seen the aliens are all liars. There must be at least one of them say the truth. And also in ancient time there are some UFO were written by historian, i don't think their purpose is lying to us.75.168.119.109 (talk) 22:46, 29 April 2010 (UTC)

You're assuming that all speakers have perfect knowledge. Far more likely that some are lying, whereas others are mistaken and telling the truth about their subjective experience. Since we do know of phenomena which lead to exactly the experiences reported by the majority of 'abductees', see particularly parasomnia, it would be odd to assume they were, instead, abducted by aliens of which we have no other evidence. Alien abduction has a good overview of the basics. 86.178.225.111 (talk) 18:54, 1 May 2010 (UTC)

Hmm, sorry I see the parasomnia article is somewhat lacking. Try sleep paralysis for more detail. 86.178.225.111 (talk) 19:04, 1 May 2010 (UTC)

A couple thoughts on why, if aliens exist and are able to communicate with us, they might choose not to:

1) The noninterference directive. That is, they want our civilization to develop (or maybe destroy itself), without influence from them. This could either be because they think it's immoral to interfere or because they view our development as a science experiment, and they don't want to bias the results.

2) There may have been a vicious galactic war, and the few survivors only manage to stay alive by keeping hidden/quiet. Perhaps reruns of Gilligan's Island are headed to the evil aliens even now, who will then find us and wipe us out as a potential future threat. (Somehow I always knew that show would bring about our destruction. :-) ) StuRat (talk) 19:17, 1 May 2010 (UTC)

Personally, StuRat, I think you've been reading too much H.G. Wells. :-) 67.170.215.166 (talk) 03:45, 2 May 2010 (UTC)

God

There are many religions in the world. Is god really exist? Or big bang.75.73.152.238 (talk) 00:35, 29 April 2010 (UTC)

If god does exist then who create god? —Preceding unsigned comment added by 75.73.152.238 (talk) 00:42, 29 April 2010 (UTC)

Start with God and then move onto Big bang. People here might tell you that science does not deal with questions regarding God, but there are people who would disagree. For a scientific treatment of God you could try reading God: The Failed Hypothesis by Victor Stenger, I've just started reading it myself. No prizes for guessing Vic's stance on the subject ;) . Vespine (talk) 01:19, 29 April 2010 (UTC)

You have to take it on faith that (the christian interpretation of) god has always existed and was therefore never created. On the other hand, there is reasonably compelling scientific evidence that the big bang occurred around 13.7 billion years ago. Astronaut (talk) 01:18, 29 April 2010 (UTC)

God and the Big Bang are not mutually exclusive concepts; there is nothing that prevents a person from understanding the implications of the Big Bang and also believing in God. To understand how philosphers have long tried to reconcile these ideas in a more formal way, you may want to read Primum movens and Unmoved mover and Cosmological argument. The notion of a God who exists before creation (whatever the nature of that creation may be) has been pondered since the time of Aristotle. --Jayron32 01:43, 29 April 2010 (UTC)

And these concepts have been disproven long ago. At the end of the day the unmoved mover cannot be questioned, because there's no answer there. Imagine Reason (talk) 13:52, 29 April 2010 (UTC)

Where did the material from the Big Bang come from? It requires just as much faith to believe that it came from nothing as to believe that God created it. --Chemicalinterest (talk) 15:30, 29 April 2010 (UTC)

It takes no faith, but perhaps some courage, to say simply: "I don't know." Dragons flight (talk) 18:39, 29 April 2010 (UTC)

But it is simpler to say "The universe appeared from nowhere." than "God appeared from nowhere and created the universe". They both require the same amount of unexplained appearance, but one involves an extra entity. (See Occam's razor.) --Tango (talk) 19:05, 29 April 2010 (UTC)

One does not involve an extra entity; both require that something was there already. In science, things cannot appear. That's why origins is not science; its philosophy, regardless whether somebody doesn't like philosophers. I believe that God was always there, even though it is difficult to comprehend. --Chemicalinterest (talk) 19:15, 29 April 2010 (UTC)

One involves the universe. The other involves the universe and god. That is an extra entity that is not required, which is why it is not included in scientific theories. --Tango (talk) 18:48, 1 May 2010 (UTC)

'Where did the material from the Big Bang come from?' (Supposedly,) A singularity - a zero dimensional object with infinite density and zero volume. --Joe^Talk_Work 13:36, 3 May 2010 (UTC)

We have pretty good evidence for the Big bang now (See: Cosmic microwave background radiation, for example) - so it's pretty much certain that it happened. God is the opposite. Zero proof - zip, nada. Worse still, the descriptions of god (or gods, plural) that people come up with seem carefully thought out so as to make the hypothesis that god(s) exist "unfalsifiable". This is a serious matter in science - if a hypothesis cannot (even in principle) be proven to be false - then we generally discount it. The proponents of gods claim that god can do absolutely anything and has no restrictions on his/her/its' behavior whatever - and (worse still) that he actively works to deceive us (in order to "test our loyalty"). So scientists say "Hey - look at all those fossil dinosaurs! We can test them with radioactive dating techniques they are a bazillion years old! We must be right about evolution and that whole Noah's ark and Garden of Eden story is definitely false!"...and the religious folks say "No, the Earth is 6000 years old. God put the fossils in there - and deliberately created the right amount of radioactivity in them to 'test your faith'...you have no faith! Hahahahaha!". If you're happy to take that shit on trust - then there is nothing science can do to 'falsify' that. There is no possible experiment we could do that the religious nuts can't just turn around and say "Gotcha! Proved you don't have faith!". It all seems kinda childish actually - but that's how it is.

Some atheists have created 'fake' religions - The Invisible Pink Unicorn (mhhbb) is a popular one. The point being that there is quite literally nothing to say that the god of the christians or the jews or the muslims is any more or less real than the IPU (pbuh). Anything that suggests that the IPU (whans) isn't real or shouldn't be worshipped (for example, by eating ham & pineapple pizza - She is not a particularly demanding God) can easily be dismissed by using the exact same arguments that the 'real' religions use. They'll say "but our religion has been around for two thousand years - God has been worshipped for millennia" - and the response is that the universe was created last Thursday and all those old churches and gorgeous pieces of music were created by Her to test the faith of the righteous. They don't have a leg to stand on.

The scientific answer is: "There is nothing whatever out there that even hints at the possibility that there are gods out there."...the hypothesis that there is some kind of divine presence is unfalsifiable and Occam's razor says we should ignore all of that stuff. Russell's teapot bears reading.

SteveBaker (talk) 02:42, 29 April 2010 (UTC)

There is evidence for a God; it just depends on one's prejudice, whether they ignore the facts or not. --Chemicalinterest (talk) 19:19, 29 April 2010 (UTC)

It's a category error to try to apply science to things that don't admit direct observation. (Now, it is possible to just reject all things that can't be scientifically observed; logical positivism does that. It's a very simple philosophy that rejects the existence of all of the fun things philosophers talk about: ethics, qualia, souls, God, etc. Our article explains why most philosophers don't do that.)

This all is to say that the science reference desk can't help you with this question. Since a metaphysics reference desk doesn't (and can't) exist, all we can do is point you to the Existence of God article. Paul (Stansifer) 03:10, 29 April 2010 (UTC)

Oh nonsense! Science is successfully applied to all sorts of things that we can only deduce indirectly - quantum theory, string theory, dark matter, dark energy, neutrinos...many, MANY things! Religious types wish science would just leave them alone and decide that religion is outside the scope of study - but that's not gonna happen. (Besides, philosophers are a waste of quarks! Their function in the universe is to hasten its end by accelerating entropy - taking in ordered information and producing hot air.) SteveBaker (talk) 03:53, 29 April 2010 (UTC)

False religion, which as I said in Cheminterest's talk page, is just another method of controlling people (as are dictatorships). True religion accepts science, knowing that it will never contradict God's word. False religion is disproved by science; true religion is supported. --Chemicalinterest (talk) 19:21, 29 April 2010 (UTC)

Steve the first bit is right but the second an absurd generalisation. Sure Stupid types wish science would just leave them alone and decide that they could hang on to any superstitious or religious beliefs (tried telling an old lady she is silly to believe her horoscope?) but I see no evidence that more stupid people are religious than are not. It may be true of course especially in the US where the default belief set might be religious it does not seem to be in most of Western Europe, where the no thought>>no religion (not the converse, of course). But I think there should be an absolute prohibition on people discussing the existence of God before they can demonstrating their grasp of the much more straightforward question of whether a scientific test can be devised for the existence of people, will science ever see beyond the atoms and cells? --BozMo talk 07:42, 29 April 2010 (UTC)

There is evidence that less intelligent people are more religious. See Religiosity and intelligence. Whether the evidence is conclusive or not, I will leave to you to decide (the main difficulty is quantifying intelligence in a meaningful way). --Tango (talk) 14:22, 29 April 2010 (UTC)

It does not mean that more intelligent people are less religious; it is just that people who think themselves more intelligent are less religious. --Chemicalinterest (talk) 19:17, 29 April 2010 (UTC)

Not seen that before but as you can imagine it is pretty weak, First, "religiosity" not religiousness(the former apparently means superstitiousness) and of course the fact it is all tgs data (which as I mentioned is the obvious case). There are good reasons to believe less intelligent people are less likely to question the prevaling beliefs where they are. But no visible evidence beyond that, and some counter data (e.g. religious expression by Mensa members if ever you wanted a contrived selection of clever people... --BozMo talk 18:21, 29 April 2010 (UTC)

There was a US study published this year (I think) claiming to find a statistically significant difference of ~7 IQ points between Americans who attend church weekly and those who attend never or only a few times a year. Of course, even if the difference is statistically significant, 7 points is too small to be of any practical impact with individual cases. Undoubtedly there are nonetheless many smart religious people and many dumb atheists. Dragons flight (talk) 18:33, 29 April 2010 (UTC)

The true God wants man to use his full brain power. Some people may think otherwise, but God isn't a crutch (to lean on instead of using your God-given abilities), he is an assistance (to enhance your abilities and help you when you try to think over some problem). --Chemicalinterest (talk) 19:25, 29 April 2010 (UTC)

Neutrinos are observable; it's just that the experiments that you need to run on them are very expensive and long. We can't experiment on goodness at all. (You can experiment on what people think about goodness, but that's not nearly as important a problem.) The only way to approach it is through philosophy. It may not be that rigorous, but it's the only thing we've got! Paul (Stansifer) 09:45, 29 April 2010 (UTC)

Careful there... It's a common mistake, but people very commonly misunderstand the concept of religion, and assume that we all blindly reject science for our religions. It is my belief, as a Christian (and I am NOT trying to tell people what to believe, this is only my belief as a supporting example) that God created the Universe the way it is, along with all of the science. I believe that it is billions of years old, and that humans are evolved. I am unabashedly Christian, a "proponent of God", and I can certainly say that Steve Baker's understanding of religion only applies to certain groups. Religion and science are not inherently exclusive. I already accept science without any hesitation, but some scientists seem incapable of allowing for the unknown, which makes me question their motives of even positing theories. Falconus^{p t c} 12:02, 29 April 2010 (UTC)

Humans don't need redemption or salvation in the theory of evolution. Imagine Reason (talk) 14:01, 29 April 2010 (UTC)

Falcon, if you accept the laws of physics then the God you speak of is a God of the gaps. We don't need to use the god-hypothesis to explain any phenomena that we've observed because the laws of physics explain everything. In this case, all outcomes are simply the result of previous outcomes (plus a bit of randomness perhaps) so all God did was to press the big red button that says "start big bang" and then he just walked away - in this belief system, prayer is futile. 196.38.62.178 (talk) 15:14, 29 April 2010 (UTC)

That;s not necessarily so. The "God of the Gaps" explanation purports that people assume that all unexplained phenomena are proscribed to God, and that when the unexplained becomes explainable, God is somehow "removed" from the equation. Falcon's philosophy seems to mirror mine very closely, and I can tell you its a very different understanding of God (at least for me, I won't speak for him). I have no doubt that God exists, and yet I also have no desire to explain the as-yet-unexplained phenomenon as "miraculous" or "from God". I fully expect that all observable events and the basic laws of how the universe works are perfectly describably by science. I don't expect to find God in any of the gaps. Instead, I find that God serves a purpose in human experience in that God helps define those things, such as purpose and morality and the like, which science is incapable of describing. Science can describe how I got here, but it does a terrible job of describing for what purpose am I here. For many people, "we are here for absolutely no purpose" is a fine conclusion, but that conclusion is as unsupported by anything scientific. It is equally as valid as "We are here for God's purposes, he gives us our purpose" insofar as neither statement has any evidence which supports or refutes it. Another way to look at it: No matter how detailed we get in describing God's creation, such detail in no way denies the Creator. I can study the details of my TV and know exactly how every component came to be and the chemical composition and organization of every single bit in it; I can understand the processes that brought it into being, but none of that denies that my TV was made by something. The TV was built by someone for a purpose, and did not become a TV by random chance. Describing the laws of the universe is much the same for religious scientists. No aspect of understanding God's creation is off-limits, but no level of detail in describing that creation denies the existance of the creator. I am not so arrogant that I think I should tell God how he should work. If he works through the laws of physics so be it. If his plan to create me was evolution than so be it. I accept God as he is, insofar as my observational skills can understand him. --Jayron32 18:26, 29 April 2010 (UTC)

Wow, Jayron. We both posted very similar perspectives, about 3 minutes apart (see below). Well done, sir. Kingsfold (talk) 18:35, 29 April 2010 (UTC)

IP 196 logged in Jayron, two quick comments. If you expect that all observable events are described (or describable) by science, how can God perform miracles (i.e. answer prayers)? Surely He would have to violate the laws of physics if he were to intervene on Earth - i.e. all events are a function of previous events and the laws of physics (assuming determinism, but this argument still applies if things are non-deterministic) so either A)God will have to break the laws of physics to change things, or B)God set out his grand plan at the begining and everything is unfolding exactly as he wanted including people worshipping and praying to Him. There is no point to praying under B and A can't be true if things are describable by science. Second comment: Occam's razor says "We are here for no purpose" is preferable to "We are here for God's purposes". Zain Ebrahim (talk) 21:41, 29 April 2010 (UTC)

First comment: That's not necessarily true -- many miracles described in the Bible would not actually require God to break the laws of physics, but only to apply a sufficiently large amount of energy, of the right kind, in the right place, at the right time. To illustrate what I mean: Suppose there is some person on some big battlefield somewhere, hunkering down in his foxhole under intense artillery bombardment, and praying for God to protect him. Suppose further that God has some special reason to protect that particular doughboy from harm, because this person plays some important role in His plan. Further suppose that God sees that the enemy has just fired, or about to fire, a big shell that will kill the aforementioned doughboy if allowed to follow its own ballistic trajectory. Finally suppose that He decides to protect this special doughboy by subtly altering (directly or indirectly) the atmospheric pressure/temperature distribution of the atmosphere in the immediate area of the battlefield in order to set up a high-altitude wind shear that would cause the shell to miss its target point and explode harmlessly in an empty area of the battlefield. What laws of physics can you name that would categorically prevent the scenario I just described?

Second comment: "We are here for no purpose" is a thoroughly despicable position from an ethical and sociological point of view, because it encourages apathy (thus discouraging people from working for the betterment of their nation) and moral laxity (which abets all kinds of self-destructive tendencies within society, like drug abuse, unchecked promiscuity, etc.) For this reason, "We are here for God's purposes" is preferable to "We are here for no purpose", absolutely regardless of Occam's razor or any such philosophical shenanigans. Occam's razor (and the scientific process in general) is intended to explain how the world around us works, and NOT what our own purpose in this world is. The first is the proper domain of science, the second is the proper domain of philosophy, ethics and (in some philosophical systems) religion. 76.103.104.108 (talk) 06:57, 30 April 2010 (UTC)

We make our own purpose. Imagine Daniel Dennett's survival machine, which is made to keep us alive under stasis for centuries. If the machine becomes self-conscious, it will make its own purpose, regardless of what we programmed into it. Thus even if the bible is correct, we humans, once self-conscious, do not serve the god's purpose anymore. 67.243.7.245 (talk) 14:00, 30 April 2010 (UTC)

That is, unless He has already foreseen the purpose that each one of us chooses to serve (and personally, I don't see no reason why He wouldn't have that ability).76.103.104.108 (talk) 01:39, 1 May 2010 (UTC)

76, First comment: the laws of physics don't allow for a God to change things as He pleases. Initial conditions plus physical laws determine future events - so if God wants to change future events, he'll have to change the physical laws (assuming determinism). Second comment: Maybe I should have been clear about what I meant by "preferable" - I meant "a more likely statement". Ethics, apathy, laxity and whatnot are irrelevant to the discussion of whether we have a purpose or not. All of those things say that it might be nice if we had a purpose but they don't provide any evidence that we do. 196.38.62.178 (talk) 14:23, 30 April 2010 (UTC)

"Initial conditions + physical laws determine future events", you say? That would mean that every future event is already predetermined by initial conditions and can't be changed by anyone's free will, and this makes absolutely no sense. If this was true, then it would mean, for example, that if you were driving on the turnpike and you saw someone in the middle of the road, you would have no control over whether or not you hit that person -- which is demonstrably false from everyday experience. (Incidentally, it actually supports the idea that some theologians support [but I strongly reject] that when God created the world, He predetermined all future events by determining the world's initial conditions; but this is beside the point.) The truth is, each one of us can influence future events through our own free will, by applying the right amount of energy in the right manner at the right time (for example, in the scenario I just mentioned, by applying about 10 pounds-force of kinetic energy to your car's brake pedal); and if each one of us has the ability to influence future events by applying energy to objects around us, why wouldn't God have the same ability on a bigger scale? 76.103.104.108 (talk) 01:55, 1 May 2010 (UTC)

Most every assertion about God that you could come across tends to unravel into ribbons of illogic flapping silently in the breeze, once put under close scrutiny. But logical rigour is not what religion is about. It is about social control. I will admit that it is not a bad ideology under some circumstances. So to answer your question -- yes God has substance and reality, insomuch as there are definite and concrete forms that the concept takes within the human psyche. Apart from that though, no, plainly God does not manifest itself in the world. God is the world, a theologian might tell you. Vranak (talk) 14:19, 29 April 2010 (UTC)

Please allow me to offer another perspective. Please also understand that I write not to preach or to assert, but to simply provide what I feel is a sufficient explanation for my belief system. I realize and completely understand that for many people, belief in a higher power is illogical and unproveable. However, my belief isn't founded in intellectual logic or proof-- it's founded in faith.

It has been stated above that there is absolutely no evidence that God exists, but depending on where you lie on the continuum of what to accept as proof, from as little as the beautiful and complex perfection of the Charonia tritonis to as much as God Himself descending from a sky accompanied by concourses of angels; anything and everything could be accepted as proof. I would also suggest that the most steadfast non-believers would probably not accept even a personal visit as proof… In other words, “absence of evidence is not evidence of absence.”

I feel like I can both accept science AND believe in God because for me, science answers the “what,” while my beliefs answer the “why.” For me, science can’t begin to answer the reasons for our existence, or where our spirits go when we die. Admittedly, those that don’t believe will assert that there is no greater reason for our existence, and we aren’t headed anywhere. That’s OK for them, but I suppose I need to understand for myself.

For me, God actually knew the science of what he was creating, used it, and doesn’t go around saying, “Hey—I’m God! I did that!” (Would we believe Him if He did? Probably not.) I believe that He initiated the Big Bang, wistfully aware that many of his children would not see his omniscience behind the science. I’ll probably draw fire from both sides on this one, but I don’t believe either the ex nihilo principle, or the literalist principle that the Earth was created around 6000 years ago. In my belief set, the dinosaur question can be answered by the principle that God organized already-existing materials into the earth that we live on. As such, this could mean either that dinosaurs existed on older planets and were within fragments used to create this earth, or that God can manipulate our understanding and measure of time, and the dinosaurs existed here on this earth but were extinct before Adam was created. It may just be remotely possible that God knew that our imperfect civilizations would one day rely (for better or worse) on fossil fuels, and made them available for just that purpose.

I also am not compelled to believe that God, as we know Him, has always existed. Realizing that this is somewhat “deep water,” spiritually speaking, I would suggest that God learned to do what he is now doing in a process of self-perfection. He, then, was created by His God, who was created by His God, who was created by His God, etc., etc., etc. For many, this will smack of blasphemy and polytheism; neither of which I intend. I worship my God, or in other words, the God that corresponds to my sphere of existence. This may kind of boggle the mind a little bit, but I simply keep the First Commandment… or at least I try to.

I also don’t believe, as was asserted, that God can do absolutely anything and has no restrictions. He operates under natural laws, many of which we may just be unaware of. He also has the so-called “restriction,” of not being able to suspend free will. He cannot force me to believe in Him or obey His commandments. I act as my own agent, but I am also bound to accept the eternal consequences of those actions.4

So to sum up—while I believe in God, I hope that I don’t come across as an illogical religious zealot, because I’m not. I just feel like I’ve found a system that accommodates both science and religion, and that offers the best explanations on the reasons for them. Thanks much! Kingsfold (talk) 18:29, 29 April 2010 (UTC)

That's pretty much what I said (which is what you said). Also consider the following analogy. Lets say you are an engineer designing some system to do something. A big machine that does something really important. Who's the better engineer: The one that designs a machine that needs constant maintaince, such that the engineer has to show up every few days to make it work; that requires constant input to get the right results, or the one that designs a machine that just needs to be turned on and runs smoothly and does what it is supposed to do with very little tending. Seems to me that the better engineer is the one that designs a well-made machine that needs very little interference. Which kind of engineer is God? To me, its OK for God to be a good engineer, who designs a system that runs smoothly in His absence. I don't need him to be a bad engineer whose system needs constant maintenance. He can still show up once in a while to make sure everything does run smoothly. But he doesn't have to... --Jayron32 19:01, 29 April 2010 (UTC)

God enjoys watching what he makes. He likes to communicate and be friends with people on earth. --Chemicalinterest (talk) 19:52, 29 April 2010 (UTC)

@Jayron32 and Kingsfold. You've both mentioned (explicitly or implicitly) that science answers the hows, while religion has provided answers to the whys for you. As a very firm non-believer, I'm curious which "why" questions religion has answered for you and what the answers were. Again speaking only for myself, as you have done, I wouldn't see any reason to accept why answers from a source that's gotten virtually every single how question wrong it's ever tried to answer, so I suppose my third question would be why would you make the decision to do that. Matt Deres (talk) 20:30, 29 April 2010 (UTC)

Sure Matt Deres. Here are some of the questions religion has answered for me, that science has been unable to:

• What is expected of me as a human, in terms of how I am to interact with other humans.
• What is expected of me in relation to my creator; that is having created me, how does he expect to relate with me
• The expectation that life has a purpose, even if I may never know that purpose. For me, living a meaningful life means that I am here for a reason, knowing that the creator has a reason, even if I am incapable of understanding it.
• Knowing that there is more to my existance than the short time I am "alive", and also knowing that my time being alive is special and not to be wasted, since it will effect what happens after death.
• Knowing that there is a path to atone for all of the mistakes I have made, and that there is an end to the cycle of guilt for those mistakes.

I actually find it quite suprising that many people don't, at some point, think about the purpose of their lives. I have been an athiest for a sizable part of my life, and I found that the greater sense of purpose, and the sense of well-being knowing that there is a plan, was what was missing from my life at the time. --Jayron32 21:07, 29 April 2010 (UTC)

True religion and science complement each other. One helps the other. False religion may prevent scientific discoveries. Life is purposeless without God. As the Bible puts it, "We may eat, drink, and be merry; for tomorrow we die." When people know God in their lives, it gives them a purpose. They are here to bring others on the right path. BTW, some people find their atheist beliefs comforting because they can understand science. People cannot always understand God, which makes them uncomfortable because of their pride. That is why true religion humbles you. You are not infallible. --Chemicalinterest (talk) 00:13, 30 April 2010 (UTC)

I'm not surprised you find such beliefs comforting. Many people take comfort and strength from religion. However, I am curious that you say you were an atheist for many years. If you don't mind my imposing on you further, I wonder if you could explain what changed to make a scientifically inclined atheist believe in God, and an afterlife, and a divine plan, etc.? Dragons flight

(talk) 21:42, 29 April 2010 (UTC)

What makes atheism science, and God religion? Both are religions, one glorifying man's reason, and the other glorifying a Supreme Being. --Chemicalinterest (talk) 00:15, 30 April 2010 (UTC)

Don't want to be a party pooper, not that I don't find this kind of stuff personally interesting, but this has long ago ceased being a ref desk topic and turned into a general opinion debate. If you want to continue maybe you can take it to aa user page or something? Vespine (talk) 22:22, 29 April 2010 (UTC)

The problem is: people make many more opinions about God and religion than they do about mercury I and II ions, which will necessarily make the discussion much bigger. As I said earlier, feel free to use my talk page too. --Chemicalinterest (talk) 00:22, 30 April 2010 (UTC)

No Vespine, you're not being a part pooper; you're correct (though I guess that doesn't preclude to also being a party pooper!). Anyway, my apologies for my part in the shift away from references. Jayron, I've learned quite a bit about various topics from you on these pages over the years. If you'd care to continue the conversation off-board, my email works. If not, then I thank you for your indulgence here. Matt Deres (talk) 22:36, 29 April 2010 (UTC)

This conversation seems is not going to end. you could argue forever whether god is exist or not because nobody could prove god is exist. Same as big bang. I think the big bang theory is make more sense because god could not just come from no where and has superpower to create Earth. Perhaps big bang is the one who create god then god create us. Conclusion: Nobody knows for sure what actually happen at the beginning of the universe whether god or big bang create the universe. By the way, just for you guys know English is my second language and I'm not fluent on it yet. Therefore my English grammar is bad.75.168.119.109 (talk) 22:31, 29 April 2010 (UTC)

The Big Bang could just as easily have come from nowhere and created the world as God came from nowhere and created the world. Time seems to make the ludicrous seem more scientific. If someone said that an explosion happened and H2 and O2 changed into amoebas in one second, fish in another, horses in another, and man in four seconds, people would laugh you away. But eons of time makes it seem much more appealing to others. Its a subtle strategy. --Chemicalinterest (talk) 00:22, 30 April 2010 (UTC)

Actually, whether god exist or not. It doesn't matter. we, humans, still humans whether god exist or not. God doesn't do anything impact to us anyway. But we, humans, alway curious about everything around us. We alway want the correct and make sense answer. I believe one day someone will find out the true but at least several more hundreds years.75.168.119.109 (talk) 23:07, 29 April 2010 (UTC)

How do you know that God does not do anything to impact you? You might have just never experienced life without God (e.g. in hell). --Chemicalinterest (talk) 00:22, 30 April 2010 (UTC)

Because i don't see anything that god impact human.75.168.119.109 (talk) 01:35, 30 April 2010 (UTC)

I also think as humans become more advance technology the less people believe in god. An example: Before 18th century most people believe in god because they could not explain anything in the life. The only thing they could think is someone has superpower do all of them. In 20th century, as we become much more advance the people believe in god continue to reduce more. At my parents time, in school, they teach about evolution and the creation of god but today, they get rid of the creation of god already.75.168.119.109 (talk) 23:36, 29 April 2010 (UTC)

Actually they used to attribute more things to spooks, magic, ghosts, and the devil than God, like St. Elmo's fire and lightning. --Chemicalinterest (talk) 11:37, 30 April 2010 (UTC)

They trust in their technology rather than in God. That does not mean that God is not real; it is just that people are becoming proud of their achievements and would rather be independent. Thinking that they are responsible for all of their actions to someone who created them is too restricting. --Chemicalinterest (talk) 00:22, 30 April 2010 (UTC)

LOL! Less people believe in god because the more we are advance the more we find out that a lot of things aren't doing by god as we thought.75.168.119.109 (talk) 01:23, 30 April 2010 (UTC)

A lot of great responses here. I have a lot I could say, but I don't really feel the need to, because others have covered my sentiments well. Falconus^{p t c} 04:44, 30 April 2010 (UTC)

Which way do they lie? Everyone has their own subtle differences. --Chemicalinterest (talk) 11:37, 30 April 2010 (UTC)

That both faith and science can exist together without issues. Indeed faith and science compliment each other. Falconus^{p t c} 12:36, 30 April 2010 (UTC)

Yes. They never contradict each other, if the faith is true. --Chemicalinterest (talk) 16:41, 30 April 2010 (UTC)

Science has found that humans die like other animals, and nothing but molecules live on. It has also found that humans evolved for no particular reason but that we tend to have survived better. We are not special, and this troubles religious people. You can continue to claim the god of the gaps, but that is not one of the bible. 67.243.7.245 (talk) 14:02, 30 April 2010 (UTC)

Consider these points, from a friend who is a biologist and is religious:

1. Regarding dinosaur bones being faked by God to test faith: "God does not deceive."

2. Regarding evolution: "Evolution is how God works."

My additional thought: Substitute "Nature" for "God" and that covers it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:50, 30 April 2010 (UTC)

religion and science could never be friend because their belief is always arguing to each other. There must be one right whether it is science or religion. We just don't know yet but i think as our tech. keep getting better. One day we will find out the answer for this junk of mystery. The only reason religion still exist is it already made root in many people minds for thousands of years. And unexplainable things because whenever scientist could not explain anything the religious people will say: god did it. By the way, i want to ask some question about god.

If god is a creator of the universe then he could do whatever he wants to the universe like we could do whatever we want to our stuffs, which are created by us. Then why didn't him show up his power to humans then we, humans, will believe in god. He didn't do anything to make people to believe. All i saw is there are some extreme religious people claimed themselves as the prophets sent by god and come to show us their faith by being the martyrs, if someone ask: why would they die for their faith, that's probably god's power. Maybe they are just crazy and extremely believe in what they have learned from their parents, religion teachers... He could send people to make humans believe in god why didn't he do it by himself. Isn't god too lazy? I think Jesus is a man who knows a lot of tricks and miracle, as a lot of people called god's power, and he wants to be famous and becomes god. His death is great right but could not compare to how many people have die to follow religion. Many people have die even more painful way than the way god die. I think at some point in human history, there must be something has happened to started to make humans to believe in god. Maybe gods are actually aliens. If i could come back 2000 years ago and bring all the technology we have now. It's just easy to make people think i'm god. This book would be an good example to who actually god is: behold the man. I think another possible way to explain about god is. In future when we invented time machine and when scientist found out and prove there is no god. More and more people deny to believe in god. In the despair of losing faith, there is a man who extremely believe in god. He tries to come back in time and bring real Jesus to this time so Jesus could save his religion. But after he traveled back to time, he stuck here then he thought god want him to play a role of Jesus to started Christianity then he did it. I hope those who are religious people don't get mad at me.75.168.119.109 (talk) 22:51, 30 April 2010 (UTC)

What do you mean, "he didn't do anything to make people believe"? Don't the Ten Plagues of Egypt count as "doing something"? 76.103.104.108 (talk) 02:00, 1 May 2010 (UTC)

A reference? On the reference desk? Since I got bored reading people insist that other people didn't really think what they said they thought, endlessly cycling without listening to the replies. 86.178.225.111 (talk) 18:33, 1 May 2010 (UTC)

Black hole

What inside the black hole?75.73.152.238 (talk) 00:42, 29 April 2010 (UTC)

Gravitational singularity, you might also find our Black hole article interesting. Vespine (talk) 01:13, 29 April 2010 (UTC)

"The black hole?" Which black hole do you mean? Astronaut (talk) 01:11, 29 April 2010 (UTC)

It is (technically) impossible to ever know what's inside a black hole because nothing (not even information) can escape from the hole. All we know about it is its mass, it's electrical charge and whether it's spinning or not...but what's inside the 'black' event horizon is literally impossible to know. Because the black hole is made of ordinary matter that's gotten so massive that the very atoms that it's made of are crushed by the pressure - it seems likely that the material keeps collapsing until it's an infinitesimal 'dot'. This dot would soon have literally zero size - a "singularity". But because we can't examine the physics of what happens to matter when it's crushed to that crazy extent, we can't EVER know for sure. SteveBaker (talk) 02:04, 29 April 2010 (UTC)

It's not actually known if information can escape a black hole, see Thorne–Hawking–Preskill bet. Ariel. (talk) 05:01, 29 April 2010 (UTC)

We know is that there is a ball of great mass in the center of the black hole with a radius less then the event horizon. I do not think there is a way to definitively determine whether the ball is an infinitesimally sized sphere, or a house sized sphere, or for large black holes, even a planet sized sphere, but we do know that it is incredibly dense. Googlemeister (talk) 19:07, 29 April 2010 (UTC)

To be a bit snarky, it isn't clear whether it is possible to find out what's inside a black hole (many physicists don't believe there would really be a singularity), but whatever the answer is, you wouldn't be able to tell anybody outside about it. Looie496 (talk) 21:12, 29 April 2010 (UTC)

Wormhole

Have we found any of wormhole? does wormhole really allow time travel?75.73.152.238 (talk) 00:46, 29 April 2010 (UTC)

No. Wormholes are theorised to exist, but none have yet been discovered. Parts of the same theory predict that an object falling into a wormhole might travel in time, as well as in space. Astronaut (talk) 01:06, 29 April 2010 (UTC)

Wormholes are just theoretical - we've never found one - we might never find one. However, that was true about black holes until we started finding them - and now they've gone from "unlikely theory" to "definite fact", to "found in the center of every galaxy" and now to "fundamentally important to the formation of galaxies"...so there is still hope for wormholes! However, the time-travel thing is MUCH more tricky. It's not really enough for wormholes to exist - we'd need to be able to create them, move them around - enlarge them - and even then, the odds are very good that the whole thing would turn out to have a horrible snag. So I'd put the odds of Wormholes existing at maybe one in ten (gut feel) - and the chances of them being usable for time-travel as one in a trillion...I strongly believe that the laws of physics will conspire to make time travel (into the past) impossible. SteveBaker (talk) 02:16, 29 April 2010 (UTC)

About blackholes found in the center of galaxies - do they know it's a black hole specifically, or just a super massive object? But not necessarily a black hole with all it's strange properties. Ariel. (talk) 02:45, 29 April 2010 (UTC)

Well, the one at the centre of the Milky Way is the mass of 3.7 million Suns and occupies a small volume. See Supermassive black hole and Schwarzschild radius#Supermassive black hole for more info. Astronaut (talk) 03:01, 29 April 2010 (UTC)

Yep we know it's a black hole. Anything with that much mass and that little volume has enough density to crush itself down to a singularity - it's way too big to become a neutron star - so yep, it's the real McCoy alright. Schwarzschild radius, Event horizon, Devourer of Worlds, singularity, australian-rower-radiation, spaghettification, The Whole Shebang. SteveBaker (talk) 03:42, 29 April 2010 (UTC)

That's actually circular reasoning. The assumption is that a large mass will become a black hole (due to the math). Then you find a large mass, assume it's a black hole, and prove the theory is correct. Perhaps there is something currently unknown that prevents the mass from fully collapsing? That's basically what I was asking, is there evidence that the mass actually collapsed? Because until there is such evidence I would hold off on saying black holes were found. To flesh out what I was saying, let's assume (for no reason at all) that quark degeneracy pressure is infinite. Could our current observations distinguish such an object from a true black hole? Ariel. (talk) 04:52, 29 April 2010 (UTC)

That assumption violates causality, but I get your point. It's just not a very good one. Everything we observe is interpreted within theoretical understanding. Dauto (talk) 04:56, 29 April 2010 (UTC)

I know everything is interpreted within theoretical understanding, I just wanted to know if there was evidence for a black hole, or if we are still working with theoretical models. Why would it violate causality? Ariel. (talk) 05:04, 29 April 2010 (UTC)

Even before the discovery of real life black holes, no theoretician worth their salt would have placed black holes and worm holes in the same bag of goods. the former is an almost unavoidable consequence of the collapse of very massive objects while the later is more of a theoretical chimera that likely doesn't exist at all. Dauto (talk) 04:56, 29 April 2010 (UTC)

Titration curve: help!

Let's say we have a solution of HCl of known volume and concentration, being titrated by NaOH of known concentration. I want to know what the pH is after x mL of NaOH have been added. According to my book, we can assume that all the OH in NaOH react completely with all the H+ in HCl and neutralize. The obvious problem is, what happens near the equilibrium point? Following the textbook's logic, all the H+ in the solution would eventually react with OH- and disappear, which is obviously impossible because that would make the equilibrium point have a pH of infinity instead of 7. So, how would I calculate pH's near the equilibrium point? --99.237.234.104 (talk) 00:48, 29 April 2010 (UTC)

It hardly "disappears". It turns into H2O, which has a pH of 7. 69.210.129.248 (talk) 01:17, 29 April 2010 (UTC)

H2O doesn't have a pH of seven; pure H2O self-ionizes into H+ and OH-, and the H+ cause the water to have a pH of 7. --99.237.234.104 (talk) 01:27, 29 April 2010 (UTC)

It does have a pH of 7; the ionization does not affect the pH because the OH- causes the water to have a pH just as much as the H+. --Chemicalinterest (talk) 19:29, 29 April 2010 (UTC)

(edit conflict)To explain a bit better. Under all conditions, all water solution obey the equilbrium of the autoionization of water. In all conditions, the equilibrium constant for this reaction, Kw = [H3O¹⁺] * [OH^1-] = 1.00 x 10^-14. That is because at 25^oC, the reaction goes to the point where [H3O¹⁺] = [OH^1-] = 1.00 x 10^-7 M . Since pH = -log [H3O¹⁺], pH of neutral water = 7. Now, since the expression Kw = [H3O¹⁺] * [OH^1-] must always be true, if we change the value of either [H3O¹⁺] or [OH^1-], the value of the other one must change in the opposite direction. So, if you add [OH^1-], the [H3O¹⁺] drops by however much is needed to keep [H3O¹⁺] * [OH^1-] = 1.00 x 10^-14. The article pH also discusses this some. --Jayron32 01:33, 29 April 2010 (UTC)

I know the basics, so although I'm grateful that you tried to help, your post wasn't very useful. I was asking how you find the pH of a solution that's being titrated when the solution is near, but not at, the equilibrium point. --99.237.234.104 (talk) 02:24, 29 April 2010 (UTC)

pH meter? --Jayron32 02:34, 29 April 2010 (UTC)

He's trying to find it theoretically. You would assume that your acid and base react completely, and then use whatever you have left (either a small amount of acid or a small amount of base) as the starting concentrations in an ICE table for the autoionization of water: H₂O → H⁺ + OH^-.

That's exactly the method suggested by the textbook. As I noted in the question, this doesn't work if the amount of NaOH added is exactly the same as the quantity of HCl in the beaker. In that case, your method would suggest there would be no H+ left in the solution, which is not possible. Intuitively I suspect your method breaks down close to the equilibrium point, not just exactly at the equilibrium point, but I'm not sure about that. --99.237.234.104 (talk) 03:04, 29 April 2010 (UTC)

The ICE table works fine. Use the expression Kw = [H+] * [OH-]. If there is zero added H+ or OH-, this still works fine, since 1 x 10^-14 = Kw, and if there is no added H+ or OH-, you know that, because of the autoionization of water reaction, you can use the stoichiometric relationships in that reaction to prove that [H+] = [OH-]. If that is the case then [H+] = [OH-] = SQRT (Kw) = 1 x 10^-7. If you have a SMALL amount of added H+ (i.e. within an order of magnitude of the amount in neutral water), then you can assume that [H+](eq) = [H+](Init) + [H+](added) and simply recalculate [OH-] from the Kw expression; and visa versa. --Jayron32 03:12, 29 April 2010 (UTC)

You have to know the number of moles per liter of H+ and OH- ions. Subtract the OH- from the H+ because a certain amount of OH- was added, and calculate the pH using the negative logarithm of the moles per liter of H+ to find the pH. --Chemicalinterest (talk) 19:31, 29 April 2010 (UTC)

conductivity of crumpled aluminum foil

I seem to have forgotten my basic MSE ... does work hardening increase or decrease the conductivity of a material? I know you dope semiconductors with foreign atoms ... but this is effectively a form of hardening by encouraging defects, right? John Riemann Soong (talk) 04:50, 29 April 2010 (UTC)

I think it decreases slightly due to dislocations impeding the flow of electrons, but this effect is negligible compared to other factors like temperature. FWiW 76.103.104.108 (talk) 05:29, 29 April 2010 (UTC)

Wrong. See Doping (semiconductor). Doping increases the number of available carriers, and therefore reduces the resisitivity. Putting defects into a semiconductor typically increases resisitivity. --Phil Holmes (talk) 13:20, 29 April 2010 (UTC)

Oh hmm... now I remember... there is a tradeoff right? Doping increases hardening, so if you dope too much you end up decreasing conductivity overall, so there is an "optimum". John Riemann Soong (talk) 15:03, 29 April 2010 (UTC)

Broadly speaking, doping a semiconductor has no effect on its hardness. In the normal range of dopant concentrations (which are in between very low and low in everyday terms) doping has a linear relationship with resistivity - see http://cleanroom.byu.edu/ResistivityCal.phtml for example. At very high levels of dopant, it's possible that the semiconductor becomes degenerate and so adding extra dopant adds no further carriers. However, the extra impurities would reduce the carrier mobility so the resistivity would increase. I can't currently find a reference for this actually happening, though. --Phil Holmes (talk) 16:12, 29 April 2010 (UTC)

I'm pretty sure I remember seeing a graph for that in my MSE class. Conductivity increases then decreases with increasing dopant concentration. John Riemann Soong (talk) 05:08, 30 April 2010 (UTC)

As I said - if this does happen, it would only be at very high dopant levels - higher than are normally employed in semiconductor manufacture. --Phil Holmes (talk) 08:22, 30 April 2010 (UTC)

Hmm, yes, now that I remember, the x-axis (dopant concentration) was plotted logarithmically... but it seems someone did experiment with this (rather than this being based on any industrial data). Perhaps the dopant levels in industry are set this way precisely to avoid conductivity issues? John Riemann Soong (talk) 12:51, 30 April 2010 (UTC)

I can't remember well off the top of my head, but I believe the dopant was a p-type and conductivity started decreasing around 10^-6 to 10^-5 molar... if I remember correctly. John Riemann Soong (talk) 13:51, 30 April 2010 (UTC)

No. That's roughly 1e17cm-3, which is pretty low doping. I think you may be thinking of mobility, not conductivity. This decreases with increasing doping owing to carrier scattering at the dopant sites. Conductivity is a function of mobility and carrier concentration, but since carrier concentration increases way faster than mobility decreases, conductivity still decreases with increasing dopant levels at this dopant level. Boron is the only commercially used p-dopant with silicon. --Phil Holmes (talk) 14:40, 30 April 2010 (UTC)

Reactivity series for anions

I know the Reactivity series for metals, but is there any such list for anions (such as NO₃^-, SO₄^2-, Cl^-, etc.)? Thanks in advance, --The High Fin Sperm Whale 05:16, 29 April 2010 (UTC)

Exactly what kind of reactivity are you talking about? 76.103.104.108 (talk) 05:31, 29 April 2010 (UTC)

If you meant reactivity in redox reactions, then yes, there is such a list, but it's called a table of standard reduction potentials. Clear skies to you 76.103.104.108 (talk) 05:36, 29 April 2010 (UTC)

See Standard electrode potential (data page) for a complete list. The activity series is basically derived from the Standard reduction potential data; you get it by pulling the metals out of the list, and ignoring the numbers. Before chemistry students are introduced to electrochemistry and redox it is a way to predict the likelyhood of a single replacement reaction occuring, as identifying the products of basic chemical reactions is taught several months before electrochemistry is. Once you have learned basic redox stuff, the activity series is moot. --Jayron32 18:13, 29 April 2010 (UTC)

I also was looking for the activity series for anions, but I didn't come up with very reliable results. One thing I have found is that metal ions lower on the activity series tend to take the conjugate base of the weaker acid. In other words, the metal ions higher on the activity series take the anions that come from stronger acids. HCl is stronger than H₂O. OH^- is the conjugate base of H₂O, and Cl^- is the conjugate base of HCl. NaOH will react with CuCl₂ to take the stronger acid's conjugate base Cl^-, giving CuCl₂ the weaker acid's conjugate base OH^-. This may vary, though. --Chemicalinterest (talk) 19:36, 29 April 2010 (UTC)

Actually, you are completely mistaken about the NaOH and CuCl₂ reaction. The reaction is a simple precipitation reaction. Neither "NaOH" nor "CuCl₂" exist in solution. Both are strong electrolytes, meaning that they dissociate 100% in water. So if you have a solution of NaOH, you actually have a solution that has equal parts Na¹⁺ and OH^1- ions. Likewise, a solution of CuCl₂ has one part Cu²⁺ ions and two parts Cl^1- ions. When you mix the solutions, the Cu²⁺ ions from the second solution clump together with the OH^1- ions from the first solution (they are now in the same batch of water) and the clumps stick together and sink to the bottom. The reason the clumps form can be explained electrostatically or thermodynamically, but solubility rules provide a nice list of how to predict what sorts of ions are incompatibile in solution with each other. The Na¹⁺ and Cl^1- ions don't do a darned thing. They are floating in water before the reaction, and they are floating in the water after the reaction. The net reaction when you mix sodium hydroxide and copper(II) chloride is:

• Cu²⁺ + 2 OH^1- --> Cu(OH)₂

There are further reactions that can occur if the OH^1- is in enough excess. Complex ions like Cu(OH)₄^2- can form as well. The reaction between copper and hydroxide, to form both the precipitate and the complex ion, is best explained by Lewis acid-base theory. --Jayron32 20:53, 29 April 2010 (UTC)

What makes the Cu++ and the OH- ions bond? The forces between the anions and cations. I measure those forces by my rule: Ions of a more reactive metal tend to react with anions of stronger acids. The NaCl does theoretically form, because the other ions are evacuated.--Chemicalinterest (talk) 00:04, 30 April 2010 (UTC)

NaCl does not form. There are no discrete particles of NaCl in the solution. There are only sodium ions and chloride ions. Saying it exists does not make it so. It just doesn't exist as discrete particles. You cannot find a single "NaCl" moety in the water solution, so its a pointless distinction. There is no reaction, they are spectator ions pure and simple. The Cu++ and OH- form bonds because the ion-ion interaction is more favorable from a gibbs free energy standpoint than the ion-water interaction. --Jayron32 02:59, 30 April 2010 (UTC)

dietary fiber supplements such as methycellulose and inulin. What is each of these, and what is the difference between the two?

Having bought both, I called the makers, who explained they were fiber derived from plants/vegetables but they were unable to tell me what the difference between them is or why one might be easier to digest then the other. The labels indicate, however, that you need to take a lesser quantity of inulin than methylcellulose for same result. Can you explain the difference? —Preceding unsigned comment added by 71.51.75.185 (talk) 06:21, 29 April 2010 (UTC)

Do you mean Methyl cellulose? We have an article about Methyl cellulose as well as about inulin. I am not personally familiar with those dietary supplements, and I cannot offer any help or advice. Sorry. --Dr Dima (talk) 07:25, 29 April 2010 (UTC)

Neither can be digested, by you, that is. Inulin and methylcellulose are both dietary fibres, and as such, are not metabolized by the human body. Inulin, however, can be metabolized by intestinal flora and promotes their growth. It can also have positive affects on kidney function. Which one is better for you is something you could discuss with your doctor or nutritionist. Someguy1221 (talk) 07:37, 29 April 2010 (UTC)

Eagles and their Wings

Eagles unlike other birds do not flap its wings often (mostly). How do they fly so high and for a longer time? I presume that it flies higher flapping the wings and just descends down with no wing movement, searching for a prey. Let me be clarified. - anandh, chennai —Preceding unsigned comment added by 125.21.50.214 (talk) 06:45, 29 April 2010 (UTC)

We have an article on Bird flight. If you still have questions after reading it and following links, please ask. --Dr Dima (talk) 07:10, 29 April 2010 (UTC)

Thanks. gliding (flight) is also informative. Do all predators (birds) show flight movements like eagles? —Preceding unsigned comment added by 125.21.50.214 (talk) 09:12, 29 April 2010

It's not just the predators. Few things are more beautiful than watching a kettle of turkey vultures soaring a thermal. --jpgordon^{::==( o )} 16:08, 29 April 2010 (UTC)

Turkey vultures? They aren't normally considered beautiful. Should I edit your comment???... --Chemicalinterest (talk) 19:37, 29 April 2010 (UTC)

If you can watch what I've just described and not find beauty, I feel deeply sorry for you. --jpgordon^{::==( o )} 01:04, 30 April 2010 (UTC)

Turkey vultures are very graceful in flight, indeed. Quite common, too, so easy to observe. --Dr Dima (talk) 07:49, 30 April 2010 (UTC)

Living and Non-living

How are we (creatures) differentiated from inanimate objects when everything in this world is of chemicals (elements, atoms, molecules or compounds)? Is that like we have active components, being recycled in search of stability, supporting the entropy of the universe, reactions with delta E negative etc., etc.,? If so, why don't inanimate objects have this sort of happenings (nevertheless, the entropy of the universe is positive anyways)? I am not sure if am clear, hope you get the question(s). - anandh, chennai. —Preceding unsigned comment added by 125.21.50.214 (talk) 06:59, 29 April 2010 (UTC)

Life#Biology is a good place to start reading. --Dr Dima (talk) 07:19, 29 April 2010 (UTC)

Cogito ergo sum. How about you? Cuddlyable3 (talk) 09:18, 29 April 2010 (UTC)

Would that work for AI? 67.243.7.245 (talk) 13:55, 30 April 2010 (UTC)

How do I know you aren't just an artificial intelligence with an IP address? See Turing test. Cuddlyable3 (talk) 22:07, 1 May 2010 (UTC)

I think therefore I am. The question is why can't inanimate objects think? (they don't think and therefore they are not?, but WHY "they don't" and what in us makes us to "think" is what i wish to know) - anandh, chennai —Preceding unsigned comment added by 125.21.50.214 (talk) 09:42, 29 April 2010 (UTC)

Keep in mind that it's cogito ergo sum, not cogito igitur sum. That is, my cognition proves my existence, because nothing that does not exist can think. There is no suggestion that my thought is the cause of my existence, or a necessary condition for my existence. (Actually I'm not sure at all that ergo and igitur are used distinctively in this way, but I am sure that this is what Descartes meant.) --Trovatore (talk) 18:13, 29 April 2010 (UTC)

How do you know they don't think? --TammyMoet (talk) 10:50, 29 April 2010 (UTC)

As a sidebar from a humanities person, this is sometimes taken as evidence of a higher being. I am not endorsing or refuting this view on this reference desk, and I don't particularly want to start a massive debate; since it is a fairly common explanation even to today among large groups of people, I felt it worth mentioning, despite the lack of scientific evidence. That is all, Falconus^{p t c} 11:49, 29 April 2010 (UTC)

I think you should avoid the cogito ergo sum approach. That barely works with humans (if it does) and certainly can't be extrapolated to all living creatures (and not even to all humans). The article Dr Dima linked to has a more generalizable description of how we define things and why it gets tricky in border cases.

As for understanding why animate objects exist: if you start with very complicated organisms (humans, for example), it looks endlessly miraculous. Start small and build up. Bacteria and viruses are a bit more easy to understand, and what makes them "alive" or "dead" or "neither" (in the case of viruses) is easier to see. Then realize that every cell of in a multi-cellular organism meets the criteria for "life", and that we are a very complicated amalgamation of many types of specialized cells all working together. (Then wonder where our sense of consciousness and individuality comes from out of all of this mass of cells.) --Mr.98 (talk) 12:55, 29 April 2010 (UTC)

The border between living and nonliving isn't a bright line. It gets quite fuzzy. You first have to consider whether you are talking about individual living things or about Life as a system (i.e. the entirety of the biosphere or all of living things taken together) Consider things like viruses and prions. Are they alive? Depends on how you define life. Is a virus alive when it is isolated on a petri dish? What about when it is actively infecting a cell? Could viruses exist outside of Life as a system? Could viruses have come to exist outside of Life as a system? Do viruses do anything we expect an organism to do? There's some stuff which is unquestionably alive (like me). There's other stuff which is unquestionably not (like say, a chunk of granite). Things just get a bit fuzzy at some of the border conditions. --Jayron32 18:56, 29 April 2010 (UTC)

Ancient pagan religions considered everything to be alive, i.e. to have a "spirit" associated with it, yes? And even now we anthropomorphize storms, bodies of water, the earth itself. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:39, 30 April 2010 (UTC)

Gas and Gravity

Why are not gases influenced by gravity? - anandh, chennai. —Preceding unsigned comment added by 125.21.50.214 (talk) 07:07, 29 April 2010 (UTC)

They are influenced by gravity, of course. If they were not, the atmosphere of the Earth would have escaped into space almost immediately. --Dr Dima (talk) 07:15, 29 April 2010 (UTC)

Perhaps you are asking, "If gas is influenced by gravity, why doesn't it all fall to the surface of the Earth?" Mm? It's a good question. And I can answer it with another question: "Why don't your feet sink into the ground?" Obviously, because the ground is solid, and it pushes back on your feet. Now, we all know that gas is not solid. But have you ever tried squeezing a balloon? Even though gas is not solid, it does push back when you try to compress it. And that's why air stays "up". Earth's gravity does pull it down, but air resists from being compressed infinitely. Someguy1221 (talk) 07:22, 29 April 2010 (UTC)

Atmospheric escape might be a good article to read in order to understand the role of gravity. A Balloon (aircraft) also, requires the action of gravity on gases in order to obtain its buoyancy.--Aspro (talk) 07:58, 29 April 2010 (UTC)

Thanks. But i think the explanation with gas compression is paradoxical when degree of randomness is considered. —Preceding unsigned comment added by 125.21.50.214 (talk) 08:09, 29 April 2010 (UTC)

OK, how about this. Let's go to extremes, the gas Sulphur Hexafluoride is heavy enough to float a boat (sort of), as can be seen here in this demo. [1]. Just think about how much you could support with Uranium Hexafluoride! --Aspro (talk) 08:35, 29 April 2010 (UTC)

Gas molecules do fall to the surface of the Earth, but then they bounce up again. The reason they never lose all their energy to friction and settle down is that the surface of the Earth is vibrating (because it's warm). It's not obvious to us but it's very obvious to the gas molecules with their very tiny masses. There's a nice mechanical model of this at the Exploratorium in San Francisco—here's a photo of it. The molecules also bounce off of each other, but that's not essential. You can pretend that each molecule moves independently, bouncing off the ground over and over, and get basically the right physical predictions (this is the ideal gas approximation). -- BenRG (talk) 09:14, 29 April 2010 (UTC)

Thanks. Warm air (or hot land surface in this case) expands gases and so it is above. Obviously because of warm air, gases raise and tend to be in a region where it is not influenced (means, concentrated there) but below that region, the concentration is less. Fine, to what extent the effectiveness of warm air is...to keep the gases from moving to a region with lower concentration? —Preceding unsigned comment added by 125.21.50.214 (talk) 09:31, 29 April 2010 (UTC)

Each parcel of gas is attracted to the Earth's gravity, but it is also repelled by the pressure of the gas below (which is minutely greater than the pressure of the gas above.) The end result is that the forces on each parcel of air are in equilibrium. (If we imagine too much gas moving closer to the Earth we must also imagine the pressure gradient increasing too, and that would drive the excess gas upwards again, to restore the equilibrium.) Dolphin (t) 13:15, 29 April 2010 (UTC)

See hydrostatic equilibrium. You can actually model this using a computer program. Model a bunch of bouncing balls under a constant force of gravity, but make all the collisions elastic (i.e. flip all the vector components the opposite sign when it hits a wall or another ball). You'll get a distribution of balls heaviest near the bottom and light near the top. Interestingly, that's what the atmosphere behaves like...

The reason why we don't behave like air molecules is that generally our collisions with the ground are not so elastic. But if every time we jumped we didn't lose any kinetic energy, we would behave like gas molecules. John Riemann Soong (talk) 15:10, 29 April 2010 (UTC)

Alarm clock

My wife and I each have an alarm clock on our nightstands. They are not identical, but both are of the common type that has a red LED display, plugs into the wall outlet, and has a 9 volt battery for backup during power failures. They're probably both 10–15 years old. Yesterday there was a power failure while we were at work. I don't know how long it lasted, but no more than ~8 hours and probably less. After the power failure, both alarm clocks were ahead of the correct time by 10–20 minutes. This is, of course, horrible accuracy compared to even the cheapest wristwatch. Why are these alarm clocks so inaccurate when running on battery? -- Coneslayer (talk) 11:05, 29 April 2010 (UTC)

When running on alternating current, the frequency of the supply provides an accurate source of information, and the clock is designed to make use of that information. When running on battery the clock has an alternative mechanism for keeping track of time, probably some sort of resonant circuit. It seems the mechanism for time-keeping on battery is simple and inexpensive, and remarkably inaccurate. The designer of the clock was presumably of the view that the battery would only be required for relatively short periods, and designed the resonant circuit accordingly. Dolphin (t) 13:09, 29 April 2010 (UTC)

I knew that analog wall clocks often used the AC frequency for timekeeping, but didn't realize that digital clocks did as well. Is it possible that the frequency of the DC circuit has a dependence on the battery voltage? After all, the voltage of an alkaline battery varies considerably over its useful life. -- Coneslayer (talk) 13:25, 29 April 2010 (UTC)

I had one which allowed you to switch between 50hz and 60hz before. Have you ever looked closely at your clock and/or the manual if you still have it do see if yours does? Nil Einne (talk) 06:57, 30 April 2010 (UTC)

Very intersting. I would've expected the clocks to be BEHIND the real time. --Kvasir (talk) 16:24, 29 April 2010 (UTC)

Since I didn't notice the discrepancy until I was early for work this morning, I'm glad they were ahead. -- Coneslayer (talk) 16:28, 29 April 2010 (UTC)

Maybe the quartz crystals were defective. --Chemicalinterest (talk) 19:39, 29 April 2010 (UTC)

It may be by design. If you know the backup you're designing is generally going to be inaccurate it makes sense to make it so it's normally faster rather then slower when one of the likely intentions is to keep an alarm, for obvious reasons. Nil Einne (talk) 06:55, 30 April 2010 (UTC)

Since even a $5 wristwatch runs much more accurately than that, it's probably just that the manufacturer used the cheapest timing circuit they could find, figuring that it would very rarely come into play. Looie496 (talk) 21:05, 29 April 2010 (UTC)

$5? I actually saw a wristwatch for $1 plus tax in a dollar store. Everything in it was a dollar. --Chemicalinterest (talk) 00:40, 30 April 2010 (UTC)

Just as a point of information, this is something that varies (or has varied) from one brand so another. There are three alarm-clock-radios in my house with digital time displays and battery backup: a Toshiba, an Optimus, and a Sony Dream Machine. The first two behave in the way the original poster describes. But the Sony's designer evidently felt differently about this issue. When the power goes off and comes back on, the display starts flashing so you're warned it might not be accurate. And, ironically, it's also much more accurate than the other two in this situation. Of course, that might not apply to this year's equivalent model. --Anonymous, <blink>01:02</> UTC, April 30, 20, 10.

These refs [2] [3] suggests it a common issue, they usually use a cheap and crap RC oscillator for the purpose. Nil Einne (talk) 06:50, 30 April 2010 (UTC)

Quartz crystal oscillators usually have a Q factor on the order of 10 x 10⁶, or one part in ten million error (this one is 10 parts in 1 million, but still darned good). So, if the clock is losing or gaining minutes on the day, it's clearly not using a quartz oscillator; I'd assume such a clock keeps time with a poorly tuned RC oscillator whose accuracy is under-engineered for cost-reduction. It's probable that it uses a separate clock for its backup than it does for its powered, normal operation - probably because "backup" was tacked on as a feature. Again, the OP's assertion is totally correct - it could be designed to operate entirely on battery and use the power only to drive the LED lights and alarm speaker, and therefore the accuracy would not change when power goes out. It probably uses a "sloppy" design to save costs or use up stock components in a manufacturer's warehouse. Nimur (talk) 14:50, 30 April 2010 (UTC)

Nimur, when talking about the frequency accuracy of clock oscillators you should not call that their Q factor. Q factor as the article explains defines the resonator damping, not its long-term accuracy. Cuddlyable3 (talk) 22:02, 1 May 2010 (UTC)

What? Crystal_oscillator#Electrical_oscillators. Damping is directly related to frequency stability. Undamped oscillators have infinite Q and would be an ideal simple harmonic oscillator. Real oscillators have a frequency spread because they are dissipating energy. Crystal oscillators are normally characterized by their Q and their center-frequency. If our articles aren't sufficient, I can point you to about 29,000 Google Scholar hits for quartz oscillator q factor. It is standard engineering parlance to use Q factors to describe frequency stability. Nimur (talk) 06:38, 2 May 2010 (UTC)

How to Identify nylon 6 from nylon 6,6?

I was wondering if anyone knew of a way to tell the difference between nylon 6 and nylon 6,6? This information would be useful to help me recycle the nylon with more efficiency. Thank-you for your time. —Preceding unsigned comment added by 70.229.42.54 (talk) 12:46, 29 April 2010 (UTC)

In the lab one can use a rather large spectroscope machine and look for their respective signatures. On that basis, I did a search and found there is now a hand-held Fourier transform infra-red spectroscopy unit that will do the same thing. No idea how much it is though. No doubt the same technique could be used to automatically sort wast on a conveyor belt. Here's the instrument[4] and here is a PDF in which the claims that it can do these two Nylons is specifically made [5] --Aspro (talk) 13:47, 29 April 2010 (UTC)

I actually already have an IR machine unfortunately this only lets you know that you are dealing with nylon and not what kind of nylon. are there any other tests that can be done? —Preceding unsigned comment added by 70.229.42.54 (talk) 16:31, 30 April 2010 (UTC)

Forget your IR machine for a minute. Above it says: I was wondering if anyone knew of a way to tell the difference between nylon 6 and nylon 6,6?and on page two of this [6] the text reads For this market, the PHAZIR is programmed with a chemometric analysis program that not only identifies major fiber groups (wool, nylon, polyester, cotton), but can distinguish accurately between Nylon 6 and Nylon 6-6. Are you saying you have the same model with the same caperbilities or just some other IR machine? --Aspro (talk) 18:17, 30 April 2010 (UTC)

animal government

I know we talk about "queen ants" but do any animals actually have any government? 82.113.106.110 (talk) 14:32, 29 April 2010 (UTC)

Depends on definitions. Wikipedia defines "Government" as:

"A government is the organization, machinery, or agency through which a political unit exercises its authority, controls and administers public policy, and directs and controls the actions of its members or subjects"

Animals are known to exert some kind of "authority" (again, this needs to be defined) over other animals. But as for controling/administering policy, nope. I think you need to tell us what definition you're using. 196.38.62.178 (talk) 14:40, 29 April 2010 (UTC)

(ec) It depends how you define "government." Certain animals do cooperate and have extremely intricate social hierarchies (meerkats, mole rats, wolf packs) that we sometimes call "clans" or "colonies" or things of that nature. They look not dissimilar from certain "primitive" forms of human government. Ants are eusocial, and are maybe best understood as superorganisms, which may or may not be similarly to your definition of "government." --Mr.98 (talk) 14:43, 29 April 2010 (UTC)

Rooks and owls have parliaments [7].--Shantavira|^{feed me} 15:01, 29 April 2010 (UTC)

Do you mean do any animals have leaderships made up of more than one individual? Some species have groups with an alpha pair - a breeding pair that are in charge, rather than just an alpha male (or alpha female) in charge. There are also species where the group will have a detailed order of precedence, but I don't think any individuals other than the one (or two) at the top play a significant leadership role. --Tango (talk) 15:09, 29 April 2010 (UTC)

If we take government to be equivalent to 'social hierarchy', then plainly yes. You could probably even discern 'taxation systems' and 'public infrastructure projects' if you looked closely. Vranak (talk) 15:51, 29 April 2010 (UTC)

BTW, queen ants are only egg-laying machines; they don't govern. --Chemicalinterest (talk) 19:40, 29 April 2010 (UTC)

See http://multilingualbible.com/proverbs/30-27.htm. -- Wavelength (talk) 23:12, 29 April 2010 (UTC)

Not sure what you're trying to do here. The biblical proverb is "The locusts have no king yet they go forth in bands" and it looks like it means that a group of people don't need a leader to be united (or something like that). This really doesn't help our questioner. 196.38.62.178 (talk) 14:30, 30 April 2010 (UTC)

Most animals appear to be in favor of anarchy, though it is common to refer to those making up the lower levels of membership in the major US parties as sheep. Googlemeister (talk) 20:32, 30 April 2010 (UTC)

I realize that that is a counterexample to what the original poster mentioned, but that proverb might suggest that they are ruled by instinct. I did not intend it to be interpreted as a model for humans to imitate, as in the case of ants

(http://multilingualbible.com/proverbs/6-6.htm; http://multilingualbible.com/proverbs/6-7.htm; http://multilingualbible.com/proverbs/6-8.htm; http://multilingualbible.com/proverbs/6-9.htm; http://multilingualbible.com/proverbs/6-10.htm; http://multilingualbible.com/proverbs/6-11.htm). -- Wavelength (talk) 21:12, 1 May 2010 (UTC)

[For clarity, I am revising "I realize that this is" to "I realize that that is". -- Wavelength (talk) 22:43, 1 May 2010 (UTC)]

See Dominance hierarchy. -- Wavelength (talk) 00:18, 1 May 2010 (UTC)

Biological Classification

I was thinking about biological classification and I came across this picture. How does man fit into it? Could someone please list my labels in this list. For example, my species is human, my genus (I think) is primate, etc... THANKS! •• Fly by Night (talk) 15:03, 29 April 2010 (UTC)

See species:Homo_sapiens_sapiens. CS Miller (talk) 15:12, 29 April 2010 (UTC)

...and note that primate is an order, not a genus. Gandalf61 (talk) 15:16, 29 April 2010 (UTC)

A somewhat less daunting list, with all the relevant entries from kingdom on down, is in the taxobox at the top of Human. Deor (talk) 19:07, 29 April 2010 (UTC)

Fact checking from Fight Club

I found some parts from the novel Fight Club extremely suspicious (for not saying, outright false). I pasted them below. Is there any truth in them? Mr.K. (talk) 15:18, 29 April 2010 (UTC)

1. "they used their urine and the urine of their dogs to wash their clothes and hair because of the uric acid and ammonia."
2. "Spiders," (...) "could lay their eggs and larva could tunnel, under your skin."
3. "It doesn't matter," Tyler says. "If the applicant is young, we tell him he's too young. If he's fat, he's too fat. If he's old, he's too old. Thin, he's too thin. White, he's too white. Black, he's too black." This is how Buddhist temples have tested applicants going back for bahzillion years, Tyler says.
4. "The three ways to make napalm: "One, you can mix equal parts of gasoline and frozen orange juice concentrate," the space monkey in the basement reads. "Two, you can mix equal parts of gasoline and diet cola. Three, you can dissolve crumbled cat litter in gasoline until the mixture is thick."
5. "A cathode ray tube can hold 300 volts of passive electrical storage, so use a hefty screwdriver across the main power supply capacitor, first. If you're dead at this point, you didn't use an insulated screwdriver."
6. "A sort of fun explosive is potassium permanganate mixed with powdered sugar. The idea is to mix one ingredient that will burn very fast with a second ingredient that will supply enough oxygen for that burning. This burns so fast, it's an explosion. Barium peroxide and zinc dust. Ammonium nitrate and powdered aluminum. Barium nitrate in a sauce of sulfur and garnished with charcoal. That's your basic gunpowder."
7. "You take a 98-percent concentration of fuming nitric acid and add the acid to three times that amount of sulfuric acid. You have nitroglycerin. Mix the vitro with sawdust, and you have a nice plastic explosive. A lot of the space monkeys mix their vitro with cotton and add Epsom salts as a sulfate. This works, too. Some monkeys, they use paraffin mixed with vitro. Paraffin has never, ever worked for me."

1. You don't think Wikipedia would over look that particular use of urine do you.--Aspro (talk) 15:36, 29 April 2010 (UTC)
2. No larva, no burrowing under the skin. The Burk Museum of Natural History and Culture has a myth busting site: [8]--Aspro (talk) 20:11, 29 April 2010 (UTC)
3. *
4. It would be a bit irresponsible for the publisher to allow the author to be too precise about these things -don't you think?--Aspro (talk) 15:48, 29 April 2010 (UTC)
5. Yes, the output capacitor and tube can hold a charge. See Wikipedia:Reference_desk/Archives/Science/2010_April_12#Old_television_smoky_exploding_madness.21. --Aspro (talk) 15:55, 29 April 2010 (UTC)
6. Potassium permanganate reacts with glycerin; it probably does with sugar, belching clouds of water vapor, carbon dioxide gas, spattering black manganese dioxide smoke; messy, messy, messy... Zinc dust will react with barium peroxide to produce barium oxide and zinc oxide smoke. It might not make a good explosive since there are no gaseous products. Ammonium nitrate and aluminum would make aluminum oxide, nitrogen gas, and probably water vapor. Potassium nitrate is normally used instead of barium nitrate in gunpowder. Caution: Barium fumes and compounds are toxic.--Chemicalinterest (talk) 19:48, 29 April 2010 (UTC)
7. Where is the glycerin? Nitric acid reacts with glycerin according to the nitroglycerin article using sulfuric acid as a catalyst to produce nitroglycerin. Extremely dangerous, may detonate when created. --Chemicalinterest (talk) 19:48, 29 April 2010 (UTC)

Wikipedia contains details on nitroglycerin and napalm and gunpowder among other dangerous things. I'm not sure it makes any sense to assume that just because the work is fiction, the author couldn't—or wouldn't—have looked into these things and published them accurately. There is no law against it. --Mr.98 (talk) 16:07, 29 April 2010 (UTC)

According to an interview with Palahniuk, his explosive recipes in the book are correct, but the ones in the movie are not. --Mr.98 (talk) 16:04, 29 April 2010 (UTC)

I've uncollapsed and numbered the questions, so they're easier to respond to. Buddy431 (talk) 19:39, 29 April 2010 (UTC)

6. I think permanganate (a strong oxidizer) and powdered sugar would likely deflagrate quickly in an explosion like manner. He's essentially right in his assertion: pretty much any pyrotechnic is a fuel (sugar, charcoal, metals like zinc or aluminum will work) along with a strong oxidizer (permanganates, nitrates, peroxides all fit the bill). And he's right about gunpowder: a nitrate, charcoal, and a bit of sulfur. Usually potassium nitrate is used because it's more widely availiable than Barium nitrate, but it's only the nitrate that's important.

7. I think you're missing an ingredient in nitroglycerine: you need a source of glycerol! But yes, nitroglycerine is made by adding glycerol to a solution of concentrated nitric and sulfuric acids. This mix generates Nitronium ions, a strong electrophile that attacks the oxygens on glycerol. As in the previous question, the nitrates are acting as an oxidizing agent. I suspect that all of the mixes listed would at least burn, though maybe not explode like you want them to (sawdust, cotton, and paraffin can all act as a fuel). However, 98% nitric acid is quite expensive. It's much cheaper to buy nitrates and make some of the gun-powder like substances that are mentioned in your question number six.Buddy431 (talk) 19:58, 29 April 2010 (UTC)

And please don't try making any of this. Apart from the obvious explosion/fire risk, concentrated nitric acid and sulfuric acid are uber nasty. Buddy431 (talk) 19:57, 29 April 2010 (UTC)

Plus, playing around with these kinds of things could easily land you in jail with no parole (either for attempted murder/terrorism with weapons of mass destruction for an extra 20-years-to-life tacked on, or at the very least for criminal endangerment of others). Definitely not a good idea. 76.103.104.108 (talk) 07:11, 30 April 2010 (UTC)

2. While not a spider, the Botfly will lay eggs under the skin of the host. Icky. Buddy431 (talk) 20:01, 29 April 2010 (UTC)

Fuming nitric acid is probably restricted because of the ease by which explosives may be made from it. --Chemicalinterest (talk) 20:07, 29 April 2010 (UTC)

1) Urine was used in Ancient Rome to wash clothes (at least by those Romans who couldn't afford soap -- which was at the time damnably expensive).

4) Of these three recipes, only the one with the cat litter would produce a useful grade of napalm. A better recipe, though, would be to dissolve rubber or Styrofoam instead of cat litter.

5) Capacitors can indeed store enough charge to zap you very badly (in extreme cases, they could even deliver a lethal shock). Don't screw around with high-voltage components unless you really know what you're doing.

6) KMnO₄ + C₆H₁₂O₆ → MnO₂ + CO₂ + H₂O (gunpowder-like deflagration). BaO₂ + Zn → BaO + ZnO (will burn with green flame and white smoke, but will not explode). NH₄NO₃ + Al → NH₃ + Al(NO₃)₃ (will also deflagrate, but with less explosive force than plain ammonium nitrate, and will release toxic ammonia gas). Ba(NO₃)₂ + S + C → BaO (highly toxic) + N₂ + SO₂ + CO₂ (explosively deflagrates just like gunpowder). Actual gunpowder uses KNO₃ or NaNO₃ because they're more readily available and contain more oxygen (as nitrate) per unit weight. Don't try any of this at home if you don't want to risk your own life and those of your family.

7) A mixture of fuming nitric and sulfuric acid will react with glycerin to make nitroglycerin; mixing this with sawdust will produce a form of dynamite. Nitroglycerin is EXTREMELY unstable and liable to blow up in your face upon the slightest shock, like if you sneeze on it; and when it does blow up, it can explode with enough force to turn a good-sized apartment building to a pile of rubble (with you at the bottom of the pile). In summary: DON'T TRY ANY OF THIS AT HOME!!! 76.103.104.108 (talk) 07:47, 30 April 2010 (UTC)

Notes to 76.103.104.108: When KMnO4 oxidizes sugar, it produces potassium hydroxide, a strong base. When NH4NO3 reacts with aluminum, nitrogen is produced. You can never get your equation balanced because the aluminum is being oxidized and the nitrate isn't being reduced. The reaction is: 3 NH₄NO₃ + 2 Al → Al₂O₃ + 6 H₂O + 3 N₂ SO₂ isn't normally produced in gunpowder exhaust. It would be a form of BaS. --Chemicalinterest (talk) 16:24, 30 April 2010 (UTC)

I stand corrected on the gunpowder question. 76.103.104.108 (talk) 02:14, 1 May 2010 (UTC)

Superconductivity and gravity

What are the latest news regarding superconductivity and gravity? Are there any hopes to levitate objects as done with magnetic field? If so, then how is the object's response to this force cancellation; is it just apparent on the surface or in every point?--Email4mobile (talk) 18:15, 29 April 2010 (UTC)

Lots of things are levitated via magnetic field. And you don't even need a superconductor to do it. See Maglev train. --Jayron32 18:43, 29 April 2010 (UTC)

Some maglevs are using superconductors now, though. There now exist "High Temperature" superconductors that operate at the balmy temperature of -196 C. This may seem very cold (and it is), but that's the temperature of liquid nitrogen, a relatively cheap and easily handled coolant. Buddy431 (talk) 19:30, 29 April 2010 (UTC)

I meant something like this.--Email4mobile (talk) 02:12, 30 April 2010 (UTC)

I don't have the physics background to evaluate any of those claims, but a lot of it looks pretty fishy. Wikipedia has articles on a number of the characters mentioned: Ning Li (physicist), Martin Tajmar, Eugene Podkletnov. They seem a bit shady. Our Antigravity article covers some of the claims by these characters, i.e. here, and indicates that as of yet, none of their claims have been verified by any independent experiments. Buddy431 (talk) 05:53, 30 April 2010 (UTC)

The PDF rang loud bells for me too as it mentions Eugene Podkletnov more than once. Don't bother trying to get your head around anything he says, nor to even finish reading anything that mentions his name. It's all nonsense, based on some odd measurements in physics . Cold fusion is a piece of cake in comparison and far more likely to succeed.--Aspro (talk) 15:12, 30 April 2010 (UTC)

Edge of the Universe

I understand current models of the universe establish there is no boundary in three dimensions as we may live within a 4-sphere. If that's the case though then if you consider the universe in 5 dimensions there will still be an edge. So what's over THAT edge? TheFutureAwaits (talk) 18:34, 29 April 2010 (UTC)

Think about a 2-sphere in 3-space. There's no edge. If you lived in 2-dimension land on that sphere, every point in your world would look the same to you. Rckrone (talk) 18:45, 29 April 2010 (UTC)

See shape of the universe for more details on this issue. --Jayron32 18:50, 29 April 2010 (UTC)

While it can help to think about the universe embedded in higher-dimensional space, it is inadvisable to do so. It's just a way of getting your head around it, it doesn't actually represent anything in reality. (There is the theory of Brane cosmology that includes something similar, but that's not important.) Most likely, there is no edge to the universe in anything meaningful sense. --Tango (talk) 18:51, 29 April 2010 (UTC)

I agree. This is the way I often see it: the laws of physics exist within the universe only. There is no existence without these laws. Therefore there can be no boundary with something that has no existence, because it does not even have dimensions which would be needed in order to say where it is. There is just the universe.--Aspro (talk) 19:09, 29 April 2010 (UTC)

If there is no edge then what if we just continue to go then where are we going to?75.168.119.109 (talk) 22:36, 29 April 2010 (UTC)

There are two possibilities. Either the universe is infinite in extent and you just keep on going for ever and nothing interesting happens or the universe is closed and if you keep going far enough you end up going around in a big circle and end up back where you started. --Tango (talk) 22:48, 29 April 2010 (UTC)

This is no sense how could we go that far then end up going around and back where we started. I think there must be a boundary but you could not go anymore when you get to the boundary or it, the boundary, destroys everything touch it.75.168.119.109 (talk) 22:58, 29 April 2010 (UTC)

That is simply not true. A universe in which you can go all the way round and get back to where you started is possible within mainstream cosmological theories. It is like the surface of the Earth - if you go far enough, you'll get back to where you started. There is no "end of the world" where you fall off into oblivion. The (spacial part of the) universe could be a 3-sphere, so very much like the surface of the Earth, just a dimension higher, or it could be a 3-torus (the 3D equivalent of the surface of a ring doughnut), which still allows you to go all the way around the universe, but the universe would be flat (which fits with observations). (There are more complicated shapes, but 3-spheres and 3-tori are the simple ones worth considering in this discussion.) --Tango (talk) 23:25, 29 April 2010 (UTC)

How could you compare the universe same as Earth? Earth shape is a circle and that's how you could go around it but not the universe. I still think that's nonsense to go around the universe.75.168.119.109 (talk) 23:43, 29 April 2010 (UTC)

Well, you are wrong. That's all there is to say about it (Jayron gave a link to our article which has references to back up my statement). --Tango (talk) 23:44, 29 April 2010 (UTC)

There are two ways that the universe works. One is that it is finite, but with no edges. Sounds crazy, but it does work. Imagine that you are an 2-D ant living on (technically within, but w/e) the surface of a sphere. You can go anywhere you want as far as you want, but you end up where you started eventually. It is a finite surface, but no edge. The sphere is a 2-D surface, just curved. Now scale that up to three dimensions. You get a curved, finite, 3-D space, but with no edges. The other option is that the universe is infinite, but that is a much easier concept to grasp. KyuubiSeal (talk) 02:28, 30 April 2010 (UTC)

Healing of cut

How long (typically) after a minor cut (such as a paper cut) does the skin become impermeable to viruses? Thanks. —Preceding unsigned comment added by 160.109.98.44 (talk) 19:40, 29 April 2010 (UTC)

After a good scab (don't pick it) is developed. If no viruses have gotten in, you should be safe. --Chemicalinterest (talk) 19:49, 29 April 2010 (UTC)

But even if viruses do get in does not mean the end of the world. The human body has a great immune system for dealing with the average virus. It works best though if you let a few viruses in now and again so that it can form and/or maintain immunity against them. Richard Avery (talk) 06:24, 30 April 2010 (UTC)

Unless that virus is Human Immunodeficiency Virus, in which case you can kiss your immune system goodbye. If you're working in a situation where dangerous viruses are likely to be transferred, you should take safety precautions dictated by an authority on the matter, and not take advice from random people on the internet, regardless of whether you have a paper cut or not. Buddy431 (talk) 15:36, 30 April 2010 (UTC)

Dissolution of Metals

Would dissolving of metals necessarily mean the metal was oxidized? For example, Ta dissolves in KOH. Is is being oxidized. --Chemicalinterest (talk) 20:29, 29 April 2010 (UTC)

Yes. Metals do not dissolve as neutral atoms or molecules the way that most nonmetals do (for example, gasseous O₂ dissolves in oxygen as O₂ molecules, neutrally charged). Instead, metals only dissolve if they are oxidized. So when, say, Magnesium metal dissolves in an acidic solution, the magnesium is oxidized from the metal to the Mg²⁺ ion. In such cases, there has to be a corresponding reduction reaction. In the case of magnsium dissolve it will be the formation of H₂ gas from H₃O¹⁺ ions in the acid solution. --Jayron32 20:40, 29 April 2010 (UTC)

If you dissolve the metal in mercury it does not oxidise in that process. The same would be try of metal dissolving in other molten metals. There could be some other solvents that take up metals as complexed neutral atoms. may be liquid ammonia. Graeme Bartlett (talk) 22:44, 29 April 2010 (UTC)

Potassium is sometimes dissolved in liquid ammonia and used as a strong reducing agent. However, people think that the extra electron is removed from the potassium and solvated in the ammonia, so really it's still the potassium ion that's dissolved. Buddy431 (talk) 23:34, 29 April 2010 (UTC)

Here's the appropriate articles: Ammonia#Solutions_of_metals as well as solvated electron. Mr. Bartlett mentioned mercury solutions: those are generally known as Amalgams. Buddy431 (talk) 23:38, 29 April 2010 (UTC)

You can certainly have zero-valent metals (i.e., not "ions") in solution...Tetrakis(triphenylphosphine)palladium(0) is just one example of many hundreds of soluble organometallic compounds. It's just "just atoms" (those ligands are bound to it), but "solvent having specific affinity to solute particles" is how most dissolving works. So all you need is an organic liquid that can serve as a Lewis-base ligand for a metal atom, and you have the same idea as water serving as a Lewis-base coordinating to a cation. One thing I don't know is if you can literally "dissolve the metal". All the organometallics I know are formed by reducing the dissolved metal cation back to zero. DMacks (talk) 01:03, 30 April 2010 (UTC)

I quite accept that it is possible to have a zero-oxidation-state metal, properly coordinated with the right ligands, which is then soluble. The question is can you take a chunk of metal and put it into something, and have it dissolve without any oxidation occuring. I am sure there are some exotic cases (nothing is impossible, per se), but under normal circumstances, for any normal definition of "metal" and "dissolve" then probably not. --Jayron32 02:54, 30 April 2010 (UTC)

Gold in mercury does this. Graeme Bartlett (talk) 09:09, 30 April 2010 (UTC)

See Amalgam (chemistry) Googlemeister (talk) 20:30, 30 April 2010 (UTC)

Death

After we died then where are we going to? Is reborn one of the possible way?75.168.119.109 (talk) 22:38, 29 April 2010 (UTC)

This is a topic explored by all religions, philosophies, and sciences as long as human has existed. See our articles on Death and Afterlife. Specifically, see reincarnation for the topic on "rebirth". --Kvasir (talk) 22:45, 29 April 2010 (UTC)

Since you have asked on the science desk, I'll give a scientific answer: Once you die, that is it. Your conciousness ceases to exist and your body decays. Pretty much every religions involves some kind of life-after-death, but they are very different in different religions. --Tango (talk) 22:50, 29 April 2010 (UTC)

You mean once we die then that's it. That's mean once we die then we are same as if we are not exist. It is hard to imagine how could that be like.75.168.119.109 (talk) 22:53, 29 April 2010 (UTC)

Your consciousness relies on the electrical signals among the cells in your brain. When you die, those signals stop and your consciousness ceases to exist, as Tango said. 196.38.62.178 (talk) 09:45, 30 April 2010 (UTC)

See http://multilingualbible.com/ecclesiastes/9-5.htm; http://multilingualbible.com/ecclesiastes/9-10.htm.

-- Wavelength (talk) 23:08, 29 April 2010 (UTC)

Remember what it was like to be you before you were born? No? Well, that's what it's like when you are dead.--Eriastrum (talk) 23:11, 29 April 2010 (UTC)

If you are going to give a religious answer on the science desk, please at least give a summary of the various different religious viewpoints. --Tango (talk) 23:16, 29 April 2010 (UTC)

I suggest that the question probably should have been moved to the Humanities desk from the get-go. Kingsfold (talk) 11:47, 30 April 2010 (UTC)

Is what really happen to us after we die?75.168.119.109 (talk) 23:18, 29 April 2010 (UTC)

What is scientific about just saying that the soul goes nowhere when one dies? It is just what people who don't believe in God believe. I believe (an unpopular belief) that people who are saved (believe that you are a sinner, that God can pay for your sins, that you cannot pay for your sins, to trust in God for redemption) go to heaven, and people who are not saved go to hell. Simple. --Chemicalinterest (talk) 23:20, 29 April 2010 (UTC)

You are misrepresenting the scientific view - science doesn't involve a concept of souls at all. It is scientific because it is the simplest answer that is consistent with observations - that is how science works. --Tango (talk) 23:29, 29 April 2010 (UTC)

You are true when you said that science does not involve a concept of souls. It, like origins, is relegated to the realm of philosophy. --Chemicalinterest (talk) 00:38, 30 April 2010 (UTC)

Before you were born you did not exist. But even though your body goes away, your soul never dies. --Chemicalinterest (talk) 23:27, 29 April 2010 (UTC)

That's not necessarily a scientific view or a religious one. References such as Job 38:7, Eccl 12:7, and Jeremiah 1:5 indicate that there was an antemortal existence, or (if you read those scriptures differently) at least that one is possible. Kingsfold (talk) 11:27, 30 April 2010 (UTC)

I disagree. Science has found the answer. People just won't accept it. 67.243.7.245 (talk) 11:49, 2 May 2010 (UTC)

I could see nobody actually knows the answer for this. But I hope after we die we would not be like never exist, is better to be reborn and become a human again.75.168.119.109 (talk) 23:25, 29 April 2010 (UTC)

If your soul has lived through 100,000 generations of life which was a period miserable brutish suffering, loneliness and torture, and all that is waiting is 1,000,000,000 more generations just as miserable, with no prospect of one bit of improvement, then an end might be preferable to more reincarnations. Going to some Heaven and living happily foreverafter would be a better prospect, as would being reincarnated into some happier state leading to greater enlightenment. Edison (talk) 20:46, 30 April 2010 (UTC)

Unfortunately, the universe tends not to work in the way that makes us happiest. --Tango (talk) 23:29, 29 April 2010 (UTC)

Well if you hope that, that's fine. This is a question to which there is no scientific answer beyond either "it cannot be known" or "your body decays", depending on whether you consider 'you' to be your consciousness or your physical body. If you had asked on the humanities desk, you would have got versions of Kvansir's excellent answer (the first answer you got here). Being reborn is certainly an option proposed by several religions, and you are free to hope for that. If you find that's what you really believe will happen, that's fine too. But nobody here can tell you which afterlife to believe in. 86.178.225.111 (talk) 23:53, 29 April 2010 (UTC)

I disagree. There is a scientific answer: your conciousness ceases to be. It can't be proven any more than anything else in can in science, but it is still be most reasonable theory. --Tango (talk) 23:58, 29 April 2010 (UTC)

If you are saved, even better. By the way, what is atheism? Just another religion that denies there is a God. --Chemicalinterest (talk) 23:28, 29 April 2010 (UTC)

Strong atheism can be described as another religion, but weak atheism (which is what the vast majority of atheists are - I don't think I've ever knowingly met, online or in real life, a strong atheist) can't. A key (and I would say, defining) feature of religion is that it claims to know absolute truth. Weak atheism doesn't do that. --Tango (talk) 23:32, 29 April 2010 (UTC)

Strong atheism makes sense when people care to define the term god. 67.243.7.245 (talk) 11:51, 2 May 2010 (UTC)

Some might claim to know absolute truth by arguing for evolution in cases where creation clearly has the upper hand. --Chemicalinterest (talk) 00:36, 30 April 2010 (UTC)

First, "arguing for" != "absolute truths", and secondly, you are speaking about the vacuous case here... --Stephan Schulz (talk) 08:17, 30 April 2010 (UTC)

It is folly to presume anything about the unknowable, e.g. post-death realities. Vranak (talk) 00:02, 30 April 2010 (UTC)

Physical body stops working and decays. Spirit/soul/conciousness, nobody knows. People have been working on it for millennia, and we still haven't found an answer yet. KyuubiSeal (talk) 00:32, 30 April 2010 (UTC)

I believe that scientists in the past have actually conducted experiments to look for human souls leaving the body upon death (it's been mentioned here before). Some positive results were indeed reported (see Duncan MacDougall (doctor), for example) but nothing that could be unambiguously reproduced/confirmed beyond reasonable doubt by others. --Kurt Shaped Box (talk) 07:07, 30 April 2010 (UTC)

Yet more evidence that people of faith are desperate for evidence. 67.243.7.245 (talk) 13:35, 1 May 2010 (UTC)

Its a one-way street. Once you die, you cannot know with human knowledge what is after death. --Chemicalinterest (talk) 00:36, 30 April 2010 (UTC)

I don't believe it's unknowable. A spirit, the afterlife or reincarnation relies on mind /body or Consciousness /Matter dualism. We have been investigating it for millennia and so far there is so far no good evidence to suggest the mind is separate from the brain, but good evidence just keeps piling up that the mind and brain are not separate. I think it can and will be conclusively proved that the mind is a result of the brain, maybe it will take 50 or 100 years until we download someone's mind into a computer brain or something, but it will happen eventually. We're not that far off achieving the raw power, but there'll obviously be a lot more to it then just that.. However, even then I don't believe religion will disappear, they will justify it away just like they have every time science has proved them many times wrong in the past. 203.110.235.1 (talk) 00:45, 30 April 2010 (UTC)

Basically, we have no clue. This isn't a religious debate, and I'm not sure how we got there. Nothing to do with evolution, atheism, God, or religion. We have no evidence for the soul existing in this world after death. Maybe we go to heaven, maybe our soul goes nowhere, we really don't know. On a more humorous note: http://xkcd.com/659/ KyuubiSeal (talk) 01:36, 30 April 2010 (UTC)

Here on the Science desk, you're going to get the science answer, and science demands evidence. Since there hasn't been any evidence there is an afterlife, the presumption is that there isn't one. Comet Tuttle (talk) 03:48, 30 April 2010 (UTC)

Absence of evidence is not evidence of absence. Since there is no evidence for or against, science can have no opinion. There is nothing wrong with having undecidables in a discipline. Ariel. (talk) 05:55, 30 April 2010 (UTC)

Science usually uses Occam's razor as a tiebreaker in these situations, which comes down on the side of no afterlife. As far as science is concerned, there is no problem to solve here. There is no reason to question what happens after death - the answer is obvious. It is just that humans don't like that answer, so choose to believe a different one despite the lack of evidence. --Tango (talk) 06:26, 30 April 2010 (UTC)

I would dispute that there's been no evidence. We're lacking proof, not evidence. Kingsfold (talk) 11:39, 30 April 2010 (UTC)

I would be very interested in seeing any evidence you have for an afterlife. --Tango (talk) 17:28, 30 April 2010 (UTC)

For something that is sometimes interpreted as evidence, see Near Death Experience. It's not a question that they regularly occur, but the explanation for these experiences is hotly debated. Some people will tell you that it's just a scientifically explained brain phenomenon on the verge of death, and others will claim to have evidence to support the claim that it proves that conciousness is not tied with the brain as previously thought. Either way, it is extremely fascinating (at least to me). Falconus^{p t c} 04:30, 30 April 2010 (UTC)

I too find it interesting. By the way, (not really science, per se - but seems like an appropriate thread as any in which to ask) what is the name for the theory that sapience is the result of the presence of a soul? I read someone's take on this a while back and found it good 'food for thought'. --Kurt Shaped Box (talk) 07:13, 30 April 2010 (UTC)

It doesn't solve your problem, but only adds one more thing to what you're trying to answer. Like the creation problem, you're not only not answering how exactly this came to be, but you're adding one more thing to the problem you have trouble explaining. 67.243.7.245 (talk) 13:35, 1 May 2010 (UTC)

Many scientists think they know the answer. Many laypeople don't want to hear it. 67.243.7.245 (talk) 13:49, 30 April 2010 (UTC)

We cannot take serious any reasoning based on concepts and assumptions that are not well defined/supported. Not only can't we invoke some undefined afterlife, Heaven, Soul, etc. etc. but we shouldn't make other hidden assumptions e.g. about the nature of time, about whether or not information is exactly conserved by the laws of physics. Any assumptions should be made explicit.

So, if I assume that time does not really exist, in the sense that there is no physical pointer that points out the present moment relative to the past and the future, which makes that only the present moment really exists, then you don't really die. All the past states in which you "were" alive simply exist. One has to note that this idea of time is far better motivated than the naive interpretation in which only the present moment really exists. In fact, the naive notion of time violates special relativity, see e.g. the Andromeda paradox article for a clear illustration of why the physical status of yesterday should be the same as the status of today.

Another assumption one could make is that information is exactly conserved in the universe. Both in classical physics and in quantum physics information does not get lost. However, in the Copenhagen interpretation of quantum mechanics, this is only true in a probabilistic sense, while in the Many Worlds interpretation this is true in a more exact sense. So, this assumption is quite well motivated.

So, even if time were to somehow exist in the naive interpretation, the past would still exist in the present moment, albeit in a scrambled form. Yesterday then exists inside today in a sphere of one light day diameter. But to see it, you would have to apply the exact time evolution operator to it. If you belive in the strong artificial intelligence assumption, the way you are are implemented does not affect your consciousness. So, the fact that the copy of you in yesterday's state is scrambled within that one light day sphere, should not be relevant to his consciousness. Of course, his entire physical world is scrambled with him in it, so he subjectively experiences being alive in yesterday world. But the point is that it all exists within today's world. Count Iblis (talk) 15:03, 30 April 2010 (UTC)

(ec) Just like the ghost question asked by the same OP, the answer to this one is pretty much that there is an overwhelming scientific consensus that counter-indicates the presence of rebirth, afterlife, and so on. If the religious folks want to weasel up some contorted definition about the afterlife, and play like it's not subject to scientific reason, then ... by the same logic, those religious people are all pink aardvarks who are not subject to rational, scientific reason. The instant you make a claim about some kind of tangible, extant soul - or afterlife - we can start questioning the logical consequences that would follow from such a claim. If there is a heaven, then where is it? If there is a soul, what is it made of? If the answers to these are "nowhere" and "nothing", then we have a resounding victory for the "sorry, OP, there is no afterlife" camp. If the religious folks want to start digging their hole deeper, they can make shit up to explain the soul and the afterlife. Every single detail they explain will be subject to the same demands for observational evidence as any other scientific claim. If the soul is made of some luminiferous ether, we have already shown that to be inconsistent with our observations of the universe. If heaven is located above the clouds, I have some bad news for you, because we've been there, and it's pretty drab and empty (though it sure does excite the plasma physicists). As the technologies and thought processes available to humans expand, we become better able to explain all of the things we are experiencing without the need for vague and hand-wavey answers. And as for User:Chemicalinterest - while I respect your right to hold your beliefs, I have no qualms telling you that your beliefs are simply moronic, and do not stand up to even the slightest scientific inquiry. The Resurrection of Christ could be explained by an ascent to heaven - or the body might have been eaten by coyotes or jackals. Which is the scientific explanation? If you want to stick to your guns and tell me about heavenly ascent, I have some very simple questions about how a body can levitate, pass through solid rock, and then fly to a place above the clouds, and so on. Do you really feel that there is a scientific ANY explanation for those details, or do you want us to just resign to the idea that "a pink aardvark did it for the lulz"? Nimur (talk) 15:18, 30 April 2010 (UTC)

Coyotes, to my knowledge, did not even live in Palestine during Roman times, so they must be ruled out as a scientific explanation for the disappearance of the body. We should not introduce explanations that are inconsistent with known historical fact. Nimur (talk) 15:20, 30 April 2010 (UTC)

Would I call your immense faith that there is no greater purpose, and that life ends after death "moronic"? Absolutely not, that would be very closed-minded of me. Truth is that neither of us have a clue, scientifically speaking, as both of us have the distinction of being alive, and have to date found no way to test hypotheses dealing with the afterlife (well, that is, test them and then record the results). Falconus^{p t c} 19:01, 30 April 2010 (UTC)

The concept of an afterlife is based on faith, not proof. If you could prove it, there wouldn't be any debate about it. Science demands scientific evidence, and there isn't any. That doesn't mean there's no afterlife, it simply means science has not figured out a way to detect and/or measure it. So anything science says about it is also based on "faith". ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:33, 30 April 2010 (UTC)

The concept of an afterlife is not needed to explain any observed phenomena - so there is no need to test for it. It's also not falsifiable - so we couldn't if we wanted to. The only reason anyone would want to test for it would be to shut everyone up. All the evidence as well as common sense says that when we die our brains shut off permanently and our consciousness ends - I don't know why anyone would want more than that. Zain Ebrahim (talk) 17:02, 30 April 2010 (UTC)

It's the faith, or hope, that there's something more than just this. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:44, 30 April 2010 (UTC)

Reduction of Iodate

What is the half equation for the reduction of iodate $({IO_{3}}^{-})$?--115.178.29.142 (talk) 23:06, 29 April 2010 (UTC) Reduction to what? I₂? I^-? HIO?

Reduction to HIO is: IO3− + 5 H+ + 4 e− ⇄ HIO(aq) + 2 H2O (+1.13V)

Reduction to I2: 2 IO3− + 12 H+ + 10 e− ⇄ I2(s) + 6 H2O (+1.20V) --Chemicalinterest (talk) 23:24, 29 April 2010 (UTC)

(edit conflict) Reduction to what? At Standard electrode potential (data page) we have two reactions where iodate is reduced, one to HIO and one to I₂ (+1.13 V and +1.20 V, respectively). The half reactions are given on that page (I see I've been beaten... must still post) Buddy431 (talk) 23:29, 29 April 2010 (UTC)

I had it on my computer, so I had easier access. --Chemicalinterest (talk) 00:24, 30 April 2010 (UTC)

Why do birches grow in clumps

I've often seen 2-5 birch trees growing out of one compact spot like in the image at right. Other trees like oaks and pine trees I usually see growing individually. Is there a term for this clumping? Does it stem (pun intended) from birches being considered shrubs, like the Birch article states in the first section? Why does this not happen with other trees? Or is this all observation bias on my part? Dismas|^(talk) 23:50, 29 April 2010 (UTC)

Well, it can be the result of coppicing (there may be a single very short trunk that all the other trunks come out of, but it can be cut so low that it ends up getting covered with soil). It could also be a natural occurrence similar to coppicing - a tree may have died back to a stump and then had many shoots regrow. Our article does mention birch as one of the trees that can be coppiced. If it is intentional coppicing, then you'll probably see lots of clumps like that nearby. --Tango (talk) 00:04, 30 April 2010 (UTC)

I've used this memory crutch for decades, to help tell the difference between Aspens and Birches:

Aspens alone, Birches in bunches.

Ergo, it has to be more than just an accident. DaHorsesMouth (talk) 00:32, 30 April 2010 (UTC)

A good way to tell the difference between aspens and birches is by their bark -- birch bark is white and has a papery texture to it (the ancient Russians even used it as a paper substitute), while aspen bark is brown and glossy. 76.103.104.108 (talk) 02:21, 1 May 2010 (UTC)

Well, since aspens can form into clonal colonies some consider the largest organisms on earth, you're either very right (the aspen is alone because it's the whole freaking forest) or you're very, very wrong. Matt Deres (talk) 00:50, 30 April 2010 (UTC)

Just from personal observation, birches will seed even in deep shade so their seedlings will become a forest. It is possible that aspens need more daylight for their seeds to sprout, which means they will only be single specimens. --TammyMoet (talk) 15:00, 30 April 2010 (UTC)

April 30

Rust metal quickly.

I'm trying to make a chess set of nuts and bolts, and one side needs to be rusted. How would you rust steel quickly? There is a zinc coating that needs to be removed. I'm thinking of using a strong acid or base to remove it, and I'd prefer not go out and buy it, so are there any good household chemicals that react well with zinc? I can leave it in a safe area, so toxic gases shouldn't be much of a problem. As for rusting the steel, I know that salt water works, but are there any other factors I can manipulate to make it rust faster? Also, should I spritz the solution on or soak it in a bath? Cost is the main worry here, time isn't as important. KyuubiSeal (talk) 00:14, 30 April 2010 (UTC)

If you have some lye, it is a fairly strong base (NaOH) assuming it hasn't been diluted too much. If you have some (applied and pure) chemistry knowledge, you could try battery acid, but that is kind of very dangerous so don't mess with it unless you know what you're doing! The fastest way to oxidize something is to burn it, though the temperatures needed to burn steel probably are outside your price range. 76.229.165.96 (talk) 00:28, 30 April 2010 (UTC)

Dissolve some baking soda in water. Find a power supply (6-18V, do not go higher electrocution hazard). Attach all of your components to the positive electrode of the power supply. Use either stainless steel clips that would not be dissolved, or use junky ones. Attach any piece of metal to the negative electrode. Turn on the power supply. Hydrogen will be emmitted at the negative electrode. If the zinc plating is thick, you will see a white film coming off the positive electrode. After that, ferrous hydroxide (green rust) will be formed. If you let it sit it will be oxidized by air to ferric oxide (brown rust). Let it go for about 10-120 minutes (the higher the voltage, the shorter the time) and take it out. It will be rough and unshiny. If you keep it moist, it should rust in a couple of days. If you want it faster, you can place it in sodium hypochlorite solution to turn it brown. Keep it in there for a day. Remove it and it should be nice and rusty. --Chemicalinterest (talk) 00:30, 30 April 2010 (UTC)

BTW, battery acid isn't very dangerous. If you get some on your skin, you will feel a burning sensation. Quickly pour baking soda on it and wash it thoroughly in water. NaOH is not as dangerous unless it is concentrated (more than 10 molar). It won't dissolve zinc, though. --Chemicalinterest (talk) 00:31, 30 April 2010 (UTC)

So after it forms green rust, does it need to be in contact with air, or can it be left in a bucket of water? KyuubiSeal (talk) 00:39, 30 April 2010 (UTC)

Either. It just needs water vapor, which is present in small quantities in the air, and oxygen, which is present in small quantities in the water, to rust. You could leave it in salt water (probably the fastest), under moist cloths, or in humid air. --Chemicalinterest (talk) 00:47, 30 April 2010 (UTC)

I wonder if you could set up a basic Cathodic protection system and make the parts you want to rust into Sacrificial anodes? The article says they use zinc for sacrificial anodes on steel pipes.. No idea off the top of my head how you'd set it up, you'd need to work out how to attach the components and what kind of current and how to run it, but it might be a fun project if you are into that kind of thing. Vespine (talk) 00:59, 30 April 2010 (UTC)

Yes you could but it wouldn't rust much faster than ordinary corrosion. Ordinary iron contains areas of more stress, which are eaten away and function as anode, and areas of less stress, where oxygen is reduced and functions as cathode. --Chemicalinterest (talk) 11:17, 30 April 2010 (UTC)

Would there be any effects on the glue used to hold the pieces together? KyuubiSeal (talk) 01:49, 30 April 2010 (UTC)

If the glue is made to bond to metal, it might behave differently with the metal oxide. Just experiment on a few before making your set. --Chemicalinterest (talk) 11:17, 30 April 2010 (UTC)

I don't know about the zinc coating, but bleach is very effective at rusting iron and steel. Dragons flight (talk) 01:59, 30 April 2010 (UTC)

Bleach does sounds like a good idea, it is a strong oxidizer, such as Hydrogen peroxide. As for glue, you need a good electrical connection between the components so glue probably isn't the best solution, maybe clamping them between two pieces of steel would work, but the contact surfaces would probably not rust.. Thinking about it, might be more complicated then it is worth, I'd try the bleach idea first. ;) Vespine (talk) 02:17, 30 April 2010 (UTC)

3% hydrogen peroxide rusts too slow. Bleach, as I scientifically called it sodium hypochlorite, does rust iron (and zinc). --Chemicalinterest (talk) 11:17, 30 April 2010 (UTC)

If you want it to rust fast, spray it with water, then dry it on low heat in an oven (as close to, but under 212f). It'll fully rust in no time. I learned that the hard way when foolishly thinking I should quickly dry water from a brake rotor by heating it. To remove zinc I would just sand it. The hotter the metal the faster it rusts. Don't soak it in water - it needs lots of air. Just spray water on it. Ariel. (talk) 06:02, 30 April 2010 (UTC)

Another idea for you: Zinc likes to react with sulfur. Buy some sulfur at a [compounding] drug store (or online), sulfur is pretty cheap. Shake some sulfur all over the metal parts, add ... Actually I'm not sure what the next step would be. I would experiment with heating it, with and without water, and trying to ignite it with a blowtorch. I'm also not sure if the result will stick to the underlying metal. But it should be cheap to experiment. Ariel. (talk) 06:13, 30 April 2010 (UTC)

I tried it, but it didn't affect it. The iron tends to carry heat away too fast. --Chemicalinterest (talk) 11:17, 30 April 2010 (UTC)

right|thumb|Your call Death -what colour!

An easy to obtain acid that will dissolve off zinc and help it to go rusty, is commonly sold in stores as 'Spirit of Salt' better known as hydrochloric acid and used domestically for cleaning drains. When you are ready to make the pieces rusty, use a 10% solution of hydrochloric to remove your 'invisible' but greasy finger prints! That way, you will achieve a more even oxide coat in less time. As mentioned above: a moist warm atmosphere is excellent for rust formation. Be advised though: This form of natural rust is very loose. It will come of as soon as you start playing with them and may make the board feel gritty(you are not the first to think of rusty chest pieces). The acid in sweat and friction will make the metal edges shiny again. It might be better to oxidise the surface to form a Iron(II,III) oxide. This is much more durable. The colour can be adjusted from a grey to a nice black , through brown to a somewhat reddish tone. This coating is often used as a durable finish on military equipment. A professional sculpture would probably choose to send it away and get it done by a sub-contractor. As an example, here is one such firm in Canada.[9]. Another option, very attractive, (only not quite so durable) is Bluing which can be toned all the way down to black. Often used on guns, in order to avoid signalling to the enemy on sunny days “Hay, I 'm over here - hiding in the bushes!”. The bluing solution can be bought from your local gun emporium, for you to do at home. These sort of coating will make it a more practical chess set. After all, you never know who may come to be your opponent !--Aspro (talk) 09:06, 30 April 2010 (UTC)

Yes, if you heat it until it is red-hot, it will form iron(II,III) oxide. --Chemicalinterest (talk) 11:17, 30 April 2010 (UTC)

I'm testing the baking soda bath with a few spare parts right now. I didn't have alligator clips, so I wrapped the copper wire around the screw. Hope the exposed copper doesn't affect it. Hydrogen is bubbling off the negative electrode, and the zinc coating disappeared, so it seems like it's working. Thank you! EDIT: It worked great! KyuubiSeal (talk) 22:40, 30 April 2010 (UTC) If the copper is underwater, blue green copper(II) hydroxide will be formed. If not, it will not have any affect. Do not run it too long or you will completely dissolve the entire screw. --Chemicalinterest (talk) 12:02, 3 May 2010 (UTC)

noble barrier

What is meant by a "noble" barrier, as in a coating to protect iron?--115.178.29.142 (talk) 00:51, 30 April 2010 (UTC)

"Unreactive" or "inert" (like the noble-gas elements). DMacks (talk) 00:57, 30 April 2010 (UTC)

There is a patent covering the idea here. Perhaps that would be of some help? SteveBaker (talk) 00:58, 30 April 2010 (UTC)

It is typically an unreactive oxide coating which prevents further corrosion, such as the one aluminum forms. Another term is passivation. --Chemicalinterest (talk) 01:00, 30 April 2010 (UTC)

Noble gases (like argon) by definition cannot form coatings on metals. Noble metals (like gold or platinum) could be used, though, but they would be prohibitively expensive (although gold coatings are sometimes used on electronic components). FWiW 76.103.104.108 (talk) 07:54, 30 April 2010 (UTC)

Passivation layer may be of interest. Nimur (talk) 15:25, 30 April 2010 (UTC)

Solar sail

How fast would a spaceship propelled by a solar sail go? --75.33.219.230 (talk) 01:34, 30 April 2010 (UTC)

If the sail was powered by a laser, in theory, it could come close to the speed of light. However, to do this, A sail several kilometers across and about 0.001 mm thick would be needed to push a probe the size of the lunar capsule, and micrometeorites would be a major problem. I don't think it's possible. --The High Fin Sperm Whale 02:23, 30 April 2010 (UTC)

Our solar sail article is pertinent, with the first proposal having been to use batteries of Earthbound lasers powered at gigawatt strength for years or decades. I must mention, as always, The Mote in God's Eye as a science fiction novel in which this occurs. Comet Tuttle (talk) 03:13, 30 April 2010 (UTC)

Spaceship propulsion

Would this method for propelling a spaceship work?

1. Uranium is fissioned, releasing energy to power the spaceship.
2. At the same time, an equal amount of anti-uranium is fissioned in a separate chamber, also releasing energy.
3. The two fission chambers are separated by a barrier with holes slightly smaller than a uranium atom. The uranium and anti-uranium atoms can't pass through, but the fission products can, and they annihilate with one another, releasing even more energy to power the spaceship.

In step 3, the same amount of energy is released as if that mass of antimatter had been annihilated immediately, but the preceding fission releases more energy. --75.33.219.230 (talk) 01:34, 30 April 2010 (UTC)

Energy is a conserved quantity. You can't convert a given amount of matter into energy in two different ways and get different amounts of energy. The amount of energy you get by fission will be lost when you collide the fission products, in comparison to colliding the original uranium and anti-uranium. Looie496 (talk) 01:49, 30 April 2010 (UTC)

(ec) I'll leave aside the obvious technical hurdles which prevent such an engine being built, and address what I presume is your central question — do you get more energy out of fissioning the uranium nuclei and then annihilating their fission products than you would from pre-fission annihilation? Instead of giving you the answer outright, I'll ask you a question of my own — Are the products of nuclear fission equal in mass to the original uranium nuclei? Answer that, and you'll be able to answer your question. TenOfAllTrades(talk) 01:54, 30 April 2010 (UTC)

(also ec seems we were on the same page) I'm not a physicist but I suspect that the energy you gain in your fission reaction (and hence the mass you lose) would be the same as the energy you lose by reducing the amount of mass in your matter/anti-matter annihilation. In other words, skip the fission and just annihilate the whole anti-uranium. That's just a guess ;) Vespine (talk) 01:55, 30 April 2010 (UTC)

There are two other points missed by the OP besides the obvious conservation of energy

• Uranium atoms are not smaller than their fission products
• The anti-uranium atoms would annihilate with the container walls.

Dauto (talk) 02:34, 30 April 2010 (UTC)

Ignoring all of the OTHER problems with this scenario, your second problem can be ameliorated with either magnetic or electric fields. For example, if the anti-uranium was ionized, electrically charged walls could repel the anti-uranium atoms... --Jayron32 02:46, 30 April 2010 (UTC)

U-235 + n -> U-236 -> Kr-92 + Ba-141 + 3n

Both sides have a total mass of 236 AMU, so where's the mass loss to correspond with the energy released? --75.33.219.230 (talk) 12:01, 30 April 2010 (UTC)

The AMU is not a sufficiently precise measure of mass here - see binding energy. Gandalf61 (talk) 13:58, 30 April 2010 (UTC)

As gandalf pointed out, you need to be more precise than that. For instance, the mass of Uranium-235 is M²³⁵U=235.0439299 u. Dauto (talk) 14:16, 30 April 2010 (UTC)

OK, here are the values you will need

• M²³⁵U=235.0439299 u
• M¹n=1.0086649156 u
• M⁹²Kr=91.926156 u
• M¹⁴¹Ba=140.914411 u

So, the masses of the left side of your equation add to 236.0526 u and the right side adds to 235.8666 u. Not exactly the same thing.

Dauto (talk) 14:31, 30 April 2010 (UTC)

Using E=mc², we can rearrange the equation to give us an energy-mass equivalence of 9.0 × 10¹³ J/g. Combine that with the value of 0.186 g/mole converted to energy (see above) we get a value of 1.7 x 10¹³ J/mol for the fission of Uranium. In scientific circles, that's what we call a "shitload of energy". --Jayron32 00:39, 1 May 2010 (UTC)

Or put in very basic terms, it's about 200 MeV per atom per fission. Which is enough energy to disturb, say, a bit of dust. Which is pretty impressive for a single atom—I did the mass comparison at some point, and it's along the lines of an ant kicking an ocean liner and having it tip a bit. --Mr.98 (talk) 13:00, 1 May 2010 (UTC)

chrome plating

is there a way to tell if the layer underneath chrome plating is nickel or brass? —Preceding unsigned comment added by Tom12350 (talk • contribs) 02:19, April 30, 2010

Try using a magnet, nickel is magnetic, brass is not. If you have the tools to do it, you can also try measuring the density of the metal. Ariel. (talk) 06:54, 30 April 2010 (UTC)

would the chrome plating interfere with the magnet? —Preceding unsigned comment added by Tom12350 (talk • contribs) 03:29, April 30, 2010

No, chrome is non-magnetic (not under normal conditions, anyway). FWiW 76.103.104.108 (talk) 07:56, 30 April 2010 (UTC)

does it have to be any special type of magnet? —Preceding unsigned comment added by Tom12350 (talk • contribs) 06:44, April 30, 2010

Tom12350, please sign your posts with ~~~~. Just a regular magnet, a stronger one is better I guess. Flexible fridge magnets are pretty weak. Ariel. (talk) 11:48, 30 April 2010 (UTC)

If it is something you do not care about ruining, squirt some concentrated hydrochloric acid on it. If it is nickel, it will slowly fizz hydrogen gas and form a green-blue solution. If it is brass, it will barely fizz at all. --Chemicalinterest (talk) 11:19, 30 April 2010 (UTC)

Even through the chrome coating? Ariel. (talk) 11:48, 30 April 2010 (UTC)

No. --Chemicalinterest (talk) 14:03, 30 April 2010 (UTC)

this item has some greenish rust on it does that tell if it is nickel or brass? —Preceding unsigned comment added by Tom12350 (talk • contribs) 12:18, 30 April 2010 (UTC)

The greenish rust could be patina, not ferrous hydroxide. It would be a copper-containing alloy such as brass, copper, or bronze. Ferrous hydroxide would spontaneously oxidize to brown ferric oxide. --Chemicalinterest (talk) 14:03, 30 April 2010 (UTC)

How to remember names?

I could easily identify people's faces but it's hard for me to remember their names. Any tips on improving name recall?--121.54.2.188 (talk) 07:56, 30 April 2010 (UTC)

Saying their name out-loud whilst looking at them helps. E.g. if someone says "Hello i'm Trevor" you say "Hi trevor" whilst looking at them (similarly if you use their name to start with when referring to them it helps). 194.221.133.226 (talk) 08:15, 30 April 2010 (UTC)

Those that attended the Open University will all know of Tony Buzan. He gave really good advice on how to study effectivly. See Speed Memory – Remembering names and face. Chapter 9 page 59 [10].--Aspro (talk) 09:57, 30 April 2010 (UTC)

How do you learn best? Reading? Hearing? Doing? Whichever it is, do that with the name. Are you good at songs? Make a small ditty out of the name. Or imagine a dance. Or write it down. Or repeat it to yourself a few times. Whichever works best for you. What kinds of things are you good at remembering? Lets say you are good at remembering trees, then in your mind 'link' a kind of tree with the face and then the name. Just think of all three at once. Then you'll see the face, think of the tree, and then think of the name. Ariel. (talk) 11:49, 30 April 2010 (UTC)

I know a teacher, he is amazing with names. I don't know if that's because he's a teacher or that helped him to become a teacher. --Kvasir (talk) 18:35, 30 April 2010 (UTC)

I'm a teacher. I am terrible with names. So it isn't necessarily a related skill. --Jayron32 00:46, 1 May 2010 (UTC)

One thing that works for me is to associate the person with somebody you know who has the same name. Stanstaple (talk) 19:56, 4 May 2010 (UTC)

amines and hydroxide ions

I have reacted amines with hydroxide-sensitive electrophiles quite a few times now, most of the time due to solubility reasons I used an aprotic organic solvent anyway. But funny enough I haven't really thought of this ... if I had water-soluble reactants, if I dissolved bunch of amine (say a good Nu: like a secondary or primary amine) into water with my electrophile (not terribly sensitive to neutral water but sensitive to OH- on paper), would amine or hydroxide have the preference in adding to my electrophile? (Let's say, use a Michael acceptor as a convenient example.) John Riemann Soong (talk) 12:47, 30 April 2010 (UTC)

Can you provide any links where I can understand your terminology? --Chemicalinterest (talk) 16:42, 30 April 2010 (UTC)

Updated! John Riemann Soong (talk) 16:34, 2 May 2010 (UTC)

Our article on ammonium hydroxide notes that only 0.4% of a 1M solution of ammonia in water is in the form of [NH₄]⁺ + [OH]⁻. If this is also the case in the reactions you've been doing, then the concentration of free amine will far exceed that of hydroxide, so [OH]⁻ is unlikely to compete effectively with your intended nucleophile, the amine.

Am I right?

Ben (talk) 12:09, 2 May 2010 (UTC)

Hmm, thanks. Which is a better nucleophile, OH- or NH3? I think OH- is a little better overall, right? Will the comparative effectiveness depend on the mechanism (SN1 versus SN2, etc.)? What about Michael addition? John Riemann Soong (talk) 16:34, 2 May 2010 (UTC)

See nucleophilicity for some quantitative nucleophilicity scales. The rate of reaction of nucleophile and electrophile depends on the identity of both. Hydroxide will react faster with some electrophiles, ammonia (or amines) with others.

Hydroxide should be better at S_N1 than S_N2 because it is a hard nucleophile. NH₃ is (I think) borderline hard/soft, so should be OK at both. Both are bases, hydroxide being the stronger base, so you might get elimination reactions competing with nucleophilic substitution. For example, in S_N1 reactions, the carbocation can undergo E1 elimination to an alkene instead of accepting a nucleophile.

As you probably know, Michael addition favours soft nucleophiles because Michael acceptors are soft electrophiles, dominated by HOMO-LUMO interactions more than electrostatic interactions — basic HSAB theory. S_N2 also prefers soft nucleophiles because the carbon-leaving group σ* orbital is a soft electrophilic centre. I believe S_N1 works with almost any nucleophile, hard or soft, because most carbocations are very strong electrophiles. Where the nucleophile is soft enough and the electrophile can do both, S_N1 and S_N2 will compete.

Ben (talk) 18:38, 3 May 2010 (UTC)

magnetic question

If nickel is magnetic, why is a US 5 cent coin, made of 75% nickel, 25% copper not magnetic? Googlemeister (talk) 14:08, 30 April 2010 (UTC)

An alloy is not "pieces of one metal and pieces of another", but rather a single material with its own material properties not necessarily preserving all electronic and physical properties of each component. Our ferromagnetism article talks about the magnetic issue. DMacks (talk) 14:28, 30 April 2010 (UTC)

You have it backward, it's 75% copper, 25% nickel. Ariel. (talk) 14:28, 30 April 2010 (UTC)

Yes, rare earth metals aren't ferromagnetic, but alloys of them are. --Chemicalinterest (talk) 14:38, 30 April 2010 (UTC)

Neither nickel nor copper are rare earth elements. Every alloy has its own properties; it is invalid to say that "alloys of rare earth metals are ferromagnetic", because it depends on the particular alloy. Every part of you answer is wrong, Chemicalinterest. Please do not make things up before posting them to the reference desk. Nimur (talk) 15:28, 30 April 2010 (UTC)

I did not say that copper and nickel are rare earth metals. I was using that as an example that alloys are sometimes magnetic while the individual metals are not magnetic (or vice versa). Sorry if I confused anyone. --Chemicalinterest (talk) 16:27, 30 April 2010 (UTC)

Samarium-cobalt magnets are very strong, while samarium is nonmagnetic at normal temperatures and cobalt is much weaker. --Chemicalinterest (talk) 16:35, 30 April 2010 (UTC)

If you start adding copper to cobalt, that will start losing its magnetism as well. The copper electron will upset its magnetic moment, just as in nickel.--Aspro (talk) 19:09, 30 April 2010 (UTC)

Why the "niger" in Sciurus niger ?

Hello all,

Not sure if it should go here or on the language desk, but...

I was wondering why the scientific name of the Eastern Fox Squirrel is Sciurus Niger. Niger, both in Latin and in scientific nomenclature usage, has to do with the color black (cf. Niger_(disambiguation)#Species). But the Eastern Fox Squirrel is in fact not black at all, with the exception of some melanistic individuals, as with black panthers). So... why does their scientific name translate as "black squirrels" ?

Thanks, --Alþykkr (talk) 15:55, 30 April 2010 (UTC)

Some names are misnomers. -- Wavelength (talk) 16:26, 30 April 2010 (UTC)

Rattus rattus

This is the sort of question that is bound to come up again. The Type specimen ( the poor critter that ended up picked in a jar and sits on the shelf of some institution) which was used to first describe the species was – black!. As simple as that. Thinking you might not believe such an answer here is a PDF describing Sciurus niger niger.[11] Likewise if you look at the very broad range of Rattus rattus you can probably guess how that came to be the first type specimen as well.--Aspro (talk) 16:43, 30 April 2010 (UTC)

Thanks to you both. Aspro, I had thought of that, but somehow I thought that before naming a species and establishing a "type", you'd take more of a sample than just one individual. Oh well, guess hard sciences are not that hard. --Alþykkr (talk) 17:02, 30 April 2010 (UTC)

I imagine Charles Darwin and others look for a good 'typical' specimen but it's 'that' unique individual, the actual critter in the jar that is the reference specimen that zoologist always return to for comparison. I don't know if anyone can elaborate further on that? If they can, I'll add it to the WP article.--Aspro (talk) 17:13, 30 April 2010 (UTC)

In the 19th century it was pretty much the goal to find the "first" one and get it designated the holotype. Often this led to disputes and later redefinitions (if I recall Harvard has a triceratops skull that they claimed was a holotype, and Yale later proved it was just a variation on an already-identified species—which results in the skull being worth less, having less prestige, etc.). I don't know if that is the case here, but it is not uncommon in that particular era of taxonomy (I don't know if it still is or not, but I would imagine that things like DNA bar coding would make this a bit more unambiguous). --Mr.98 (talk) 02:39, 1 May 2010 (UTC)

transformer

when a transformer is on load its starting current is 12 times of its full load current called inrush current.then what is the starting current of a no load transformer and how. —Preceding unsigned comment added by Dvutukuri (talk • contribs) 16:34, 30 April 2010 (UTC)

The amount of current that passes through the coils of a no load transformer? None on the secondary side. --Chemicalinterest (talk) 16:37, 30 April 2010 (UTC)

Yeah this question is pretty bizarre even by our standards. A transformer typically will inrush some multiple of it's stated max current, like you said (and depending on the transformer's design). If there is no load then ipso facto there is no current on the output, and the input will only draw current according to the inrush characteristics as you already described. --Jmeden2000 (talk) 17:54, 30 April 2010 (UTC)

Per "Protective Relaying" by Blackburn and Domin, page 292-294 if a power utility transformer has no load on the secondary side, then the current drawn by the primary side is called the "exciting current" and its steady state value is typically 2% to 5% of the rated full load current. The transformer core of an unenergized transformer which has previously been energized may have residual flux, either positive or negative. Depending on this residual flux, the point in the voltage waveform at which the winding is energized, and the transformer design, an unloaded transformer might draw little more than the normal exciting current, or it might draw 8 to 30 times the full load current. It is not always 12 times as the OP stated. It may take 10 cycles to one minute for the inrush current on energizing to decay to the steady state exciting current value. In the case of high inrush, the transformer may make a large "Bong!" sound which decreases over a second or so, with dust flying off it. There may be a noticeable voltage dip if it is a very large utility transformer. Protective differential relays may see it as in internal transformer fault and trip the breaker, unless they are properly set to discount harmonic currents. This in itself is pretty "exciting" for those tasked with getting it in service. Edison (talk) 20:39, 30 April 2010 (UTC)

Expansion of the universe

Has it ever been hypothesized that the expansion of the universe is within each subatomic particles' growth from one instant to the next. in other words if you compared an object with mass = X at time = t to that same object with mass = X at time = t + y, it could actually be mass = 2X at time = t (in the past)? —Preceding unsigned comment added by 165.212.189.187 (talk) 16:57, 30 April 2010 (UTC)

No, it hasn't been hypothesized, since it doesn't make sense. If the mass at time t is X, then the mass at time t is X. It can't both be X and 2X (unless it is massless). --Tango (talk) 17:30, 30 April 2010 (UTC)

No let me rephrase: the mass of an object at two different times is two different masses: if you could go back in time and compare the future object to the past object. In other words we are all expanding through spacetime at the exact same rate so relative to each other we are not expanding but relative to our past selves we are. —Preceding unsigned comment added by 165.212.189.187 (talk) 17:45, 30 April 2010 (UTC)

The expansion isn't a mystery that needs to be solved, at least not in the sense you're talking about. It's already perfectly well modeled by general relativity. The idea that physical constants (like masses) might have been different in the past has been tested experimentally in various ways (by looking for variation in atomic spectral lines, for example). The experiments rule out anything more than a minuscule variation in physical constants over the age of the universe. -- BenRG (talk) 18:51, 30 April 2010 (UTC)

Isnt' General relativity is being put to the test everyday with quantum physics?Why couldn't those spectral lines be expanding also? A miniscule variation times all the atoms in the universe equals what ??? And BTW - What, pray tell, exactly is the sense that I am talking about? —Preceding unsigned comment added by 165.212.189.187 (talk) 19:13, 30 April 2010 (UTC)

General relativity makes very good predictions about this on large scales and quantum mechanics makes very good predictions about small scales. It is only when the two situations merge (eg. a large amount of mass in a very small space, like in a black hole or at the big bang) that our theories are inadequate and the expansion of the universe isn't purely within the realms of general relativity. I'm afraid you aren't making any sense at all. --Tango (talk) 21:29, 30 April 2010 (UTC)

I don't recall where I saw it, but there was a comic where a character postulated that he and everything in the universe was about to double in size. The next panels don't show any difference since all the reference points expand as well. If this is the situation the OP is asking about, then it would be an absurd and unfalsifiable proposal that doesn't seem to explain anything. — Ƶ§œš¹ _{[aɪm ˈfɹ̠ˤʷɛ̃ɾ̃ˡi]} 21:51, 30 April 2010 (UTC)

It's not a mystery in the sense that we already have a good model. There's always the mystery of "why that model?", but that's different from having no working model in the first place. "Why couldn't those spectral lines be expanding also?" Well, they could, but it turns out (experimentally) that they aren't. I'm talking about spectral lines of distant astronomical objects here, where the light has been in flight for a long time. -- BenRG (talk) 21:50, 30 April 2010 (UTC)

Doesn't seem to explain anything except why the universe is "expanding" . and do spectral lines have mass? Tango says that when the two situations merge that current theories are inadequate and then says that I! don't make any sense?! for all we know those "two situations" are not only merged all around us but completely inseperable! 98.221.254.154 (talk) 04:13, 2 May 2010 (UTC)kgb

So the universe is expanding because the universe is expanding? If the space between atoms is expanding and it's unobservable, then it's something different from the expansion of the universe that we can observe. — Ƶ§œš¹ _{[aɪm ˈfɹ̠ˤʷɛ̃ɾ̃ˡi]} 19:20, 4 May 2010 (UTC)

Not the space between atoms, the space INSIDE atoms, between subatomic particles, especially the electron cloud and the nucleus, and empty space itself. we can only observe it on the largest scales. Like when you put a marshmallow in a vacuum canister and it expands. That is whats happening to us and everything else at the same time. like the tidal force of the big bang pulling us in all directions equally.

increase the likelihood of having dreams

I asked a question here about dream recall, and someone suggested that eating lobsters would "increase the likelihood of having dreams". Is this true? What chemicals or substances do lobsters contain that might induce dreams? I must add I have no intention of ever eating lobsters myself because I'm a vegetarian. 82.43.89.71 (talk) 18:15, 30 April 2010 (UTC)

Seems like strange advice. I think that with a good night's sleep the likelihood of having dreams is pretty near 1 anyway. (REM Sleep is certainly almost 100% likely.) It's question of whether or not you remember them. (This usually requires waking up before it ends.) APL (talk) 18:46, 30 April 2010 (UTC)

Some foods, like lobster and cheese-an-onion sandwiches for supper, are 'reported' to give some people nightmares, but there is no proof of this -that I know of. Drugs on the other hand can, so its possible that a meal could send someone's brain messenger chemicals up dramatical. Antidepressants such as SSRI's can definitely give people nightmares and bright vivid dreams, as can St Johns Wort. Generally, I would say that if someone can't remember their dreams, then that is an indication that their brains are working normally. I get the very strong impression at times, from people who can remember their dreams in great detail, that their half way to being loopy – but that's just my impression and not a diagnosis of anyone. --Aspro (talk) 18:54, 30 April 2010 (UTC)

Did you mean to type THEY'RE half way to being loopy ? Cuddlyable3 (talk) 18:50, 1 May 2010 (UTC)

You can get advice about anything here. Sometimes it's worth exactly what we charge. alteripse (talk) 20:59, 30 April 2010 (UTC)

Well, theoretically very heavy meals can put you into a quick, deep sleep (think Thanksgiving - it's the amount of food and alcohol). This is an absurd stretch, but since eating lobster requires more energy than the average meal (cutting, cracking, etc.) and everything is essentially dripped in butter, then I suppose one could make the argument that it's more likely to knock you out than your average other meal. Especially since, lobster being (somewhat of) a delicacy, other things like wine and desert are probably being served as well. ~ Amory (u • t • c) 00:34, 1 May 2010 (UTC)

Quite possibly tryptophan. Cheese contains this, and some page I found on the internet [12] ranks a lot of crustaceans highly for tryptophan content. It ought to just make you relaxed, though, rather than inspire nightmares, as mentioned at Cheese#Effect_on_sleep. There is also cheese syndrome, mentioned at List of foods containing tyramine, and the whole cheese/dimethyltryptamine incompatibility thing, but I guess that has no bearing on lobster. Unless it's fermented lobster. 86.21.204.137 (talk) 11:33, 1 May 2010 (UTC)

It's nothing to do with diet. This probably falls under original research but I once did a course relating to dreams. It seems everyone dreams but many people don't remember them. The thing to do is write down anything you remember, even vague impressions, as soon as you wake up. After a few weeks you will be amazed how much detail you are writing down. It worked for me anyway.--Shantavira|^{feed me} 11:45, 1 May 2010 (UTC)

Jeez - what a lot of terrible answers have been given here! The idea that what you eat causes dreams is pure old-wifes-tale. How about we offer an actual scientific answer with some value to it instead of propagating bullshit?

Vivid dreams happen during REM sleep. As you will notice if you read that article, there has been considerable research into the subject - and not ONE of the linked articles describe evidence for food-related issues with REM sleep. So let's stop talking crap about lobster, onions, tryprophan and cheese - that's complete nonsense.

When you sleep for long enough to achieve REM sleep, you will dream - that's how it works. Typically, you'll enter REM sleep a few times each night - for a total of maybe an hour and a half. However, you won't remember those dreams unless you happen to wake up during REM. So of the half dozen ~15 minute dreams you have every night - you are unlikely to remember most of them. So the only way to remember more dreams (or to even know that they happened) is to somehow be awoken during REM sleep.

However, that's not easy to achieve - if you had something or someone wake you up frequently - you might never enter REM sleep (which would ultimately be bad for your health - people have become mentally deranged from prolonged lack of REM sleep). If you had something wake you up just once at a random time during the night, then the odds are about one in five that it would wake you during REM and produce a dream that you could remember. What you'd really need is someone (or some cunning machine) look for the 'rapid eye movement' that characterizes REM sleep and to wake you up maybe 10 minutes after it starts. However, if you have an alarm clock set to wake you in the morning before you'd naturally wake up by yourself - then that has just as much chance of waking you during REM than at any other time. But because you only spend 20% in REM - waking up with an alarm clock has about a one-in-five chance of waking you in the middle of a dream. But even if you do wake in the middle of a dream - the memory of it usually fades within minutes, so you need to keep a 'dream diary' and make a point of writing down as much of the dream as you can remember, the moment you wake up. So you are almost certainly having several dreams per night - and waking up with the memory of a dream once or twice a week - but simply failing to retain them in long-term memory. SteveBaker (talk) 15:17, 1 May 2010 (UTC)

Tryptophan does send you to sleep, which is a necessary prerequisite for having a dream. My answer may have been terrible and nonsense, but I don't think it was terrible in bold and italics, or complete nonsense. Perhaps lobster gained a reputation by making people more likely to have plesant naps and daydreams at the dinner table, or causing their minds to wander more in the early stages of sleep, possibly followed by waking up again due to indigestion from all the rich food. 86.21.204.137 (talk) 16:10, 1 May 2010 (UTC)

Great - so your advice for dreaming more is to sleep more. Profound. Thanks. Please, at least read REM sleep before you answer any more. SteveBaker (talk) 19:07, 1 May 2010 (UTC)

Your answer was technically correct if you define dreams narrowly, mine was about lobster and I suggested a psychoactive substance in it, and I was quite pleased with myself until you started implying that I'm Mystic Meg or something. I know what REM sleep is. Stop being insulting. 86.21.204.137 (talk) 20:05, 1 May 2010 (UTC)

External stimuli are definitely misinterpreted in dream scenarios. This is dramatised in countless movies where a character is woken out of a dream by a touch or a sound. Indigestion following something one ate the previous evening can also affect one's dream content, usually unpleasantly. This is common experience. BTW SteveBaker, old wives can be reliable sources. Cuddlyable3 (talk) 19:03, 1 May 2010 (UTC)

When old wives write for peer-reviewed scientific journals or other WP:RS...yes. Otherwise, not so much so. SteveBaker (talk) 19:10, 1 May 2010 (UTC)

Would Marie Curie fit the bill? 67.170.215.166 (talk) 05:36, 2 May 2010 (UTC)

Oddly enough, the best answer I can come up with is to get depressed. Antidepressants actually have the opposite effect: they reduce the amount of REM sleep, sometimes to the point of eliminating it altogether. There is a lot of evidence that many people with severe depression have altered sleep patterns that cause them to miss slow-wave sleep and go into the dream state much earlier at night that healthy people do. I doubt that this is the sort of solution the OP was looking for, but it's the only one that comes to me. Looie496 (talk) 23:21, 1 May 2010 (UTC)

Question about gun-type fission weapon

According to gun-type fission weapon the bomb fires U-235 at another U-235 target, and then that achieves critical mass, and fission occurs due to neutrons splitting the atom. Ok, but where are the neutrons coming from? ScienceApe (talk) 19:33, 30 April 2010 (UTC)

Uranium (as with all radioactive elements) is intrinsically unstable and spontaneously undergoes nuclear decay (fission in the case of uranium). So there are constantly neutrons being produced by this natural process. And some of them happen to hit other atoms nearby, causing them to decay. But many/most of them escape without causing anything from happening. In a critical mass, there are enough fissionable atoms nearby that the neutrons from one fission event hit several others rather than generally not hitting anything. The result is an exponential increase in the rate of reaction rather than a constant slow reaction. The "Little Boy" section of the gun-design article you were reading has all this information and more. DMacks (talk) 19:50, 30 April 2010 (UTC)

U-235 and U-238 undergo spontaneous fission with a low probability and this produces a few neutrons (as well as ambient neutrons from other sources like cosmic rays). According to Gun-type fission weapon, the 20% U-238 in Little Boy had 70 spontaneous fission events per second. Once a supercritical mass is assembled, any of these events could trigger a detonation. Dragons flight (talk) 20:00, 30 April 2010 (UTC)

Spontaneous fission is far too unreliable. It was on the article once but I think people are removing things. Around the tops of the uranium pieces were polonium and beryllium rings. When the uranium comes together, the polonium and beryllium are physically intermixed and emit neutrons of about the right energy to initiate a chain reaction and at the right time. There is about a two microsecond window for this to happen.--Aspro (talk) 20:09, 30 April 2010 (UTC)

You could rely on spontaneous fission alone, and Gun-type fission weapon says "An initiator is not strictly necessary for an effective gun design". But in practice Little Boy did use an initiator (that article says "Initiators were only added to Little Boy late in its design), as do implosion bombs. Modulated neutron initiator is the relevant article. -- Finlay McWalter • Talk 20:11, 30 April 2010 (UTC)

In the case of Little Boy, the 20% U-238 in the uranium had 70 spontaneous fissions per second. With the fissional material in a supercritical state, each gave a large probability of detonation: each fission creates on average 2.52 neutrons, which each have a probability of more than 1:2.52 of creating another fission. During the 1.35 ms of supercriticality prior to full assembly, there was a 10% probability of a fission, with somewhat less probability of pre-detonation. Think about it, the figures are naff! They might as well have trained a chimp to bang two lumps together with his hands and it would have been just as 'efective'. This is Wikipedia after all.--Aspro (talk) 20:27, 30 April 2010 (UTC)

I don't know what that means, but see demon core. Comet Tuttle (talk) 22:21, 30 April 2010 (UTC)

If you combined two lumps of the right amount of U-235 in, say, a bucket, you'd definitely get a reaction. But the difference between something carefully controlled and something haphazard would be significant. The first is probably in the neighborhood of 500 tons of TNT (which is still a pretty big explosion by human standards!), whereas the latter is in the neighborhood of 15,000 tons of TNT. If you are really good about controlling it (as they would be in later weapons) you can get more yield from the same amount of material (say, 40kt out of the same original amount), or use less material for the same yield (e.g. you get a "Little Boy" sized explosion out of something that can fit into an artillery shell). --Mr.98 (talk) 23:45, 30 April 2010 (UTC)

Yes, they wanted an overwhelming number of neutrons. The problem is not that a fission reaction would not begin (it would) but that the result would have been a fizzle (if you don't get a very good reaction started, it will blow itself apart before it is really destructive). So they used initiators. Not strictly necessary, but for a totally untested weapon, they provided a pretty good measure of certainty that you'd not only get a reaction, but a big one. --Mr.98 (talk) 23:42, 30 April 2010 (UTC)

the thermodynamics of an ideal air conditioner

Say the temperature of the environment around the exhaust port is at some absolute temperature T3 (it is a heat sink and remains at a constant temperature). You start with room some temperature T2 and cool it to T1.

Under standard atmospheric pressure (constant P and V) of regular old air in the room, how much free energy per mole of air molecules (on average) do I need to expend to effect this temperature change, as a function of the three given temperatures T1, T2 and T3? How would I begin to attack this problem? What thermodynamic relationships should I use?

Some assumptions: heat capacity of air is mostly constant with temperature, especially at the range we're considering (cooling from say, 310K to 290K). And I am curious about the two cases: initial room temperature starts BELOW exhaust temperature, initial room temp == exhaust temp, initial temp > exhaust temp. Btw, the exhaust temp is just the temperature of the heat sink, assume perfect/instaneous heat dissipation from the exhaust to the "outside" so it's not like we have to worry about energy expenditure on fans. And obviously exhaust temperature is always higher than final room temperature (or else the air conditioner would have no purpose -- we'd just go outside!). And of course, assume no heat/mass transfer between the room and the "outside" other than through the air conditioner exhaust.

I'm just curious say, when an air conditioner operates at 1000W, how much of that is used to perform thermodynamic work and how much of that is lost through inefficiency of the machine. How much is also lost due to the inefficiency of the room (on average, assuming a shut door and closed windows)? Rough proportions, of course. John Riemann Soong (talk) 19:52, 30 April 2010 (UTC)

Wikipedia has an article on heat pumps Heat_pump#Efficiency --Aspro (talk) 20:18, 30 April 2010 (UTC)

This seems to be based on the COP definition though. Which is sort of weird. Is there any relation I can get where I can solve for free energy? John Riemann Soong (talk) 22:00, 30 April 2010 (UTC)

Gun with balloon

Attach an inflated balloon to the muzzle of a pistol. Let's say the balloon has a diameter of 20 cm and will burst when its diameter reaches 30 cm. If you shoot the gun, would the balloon be pierced by the bullet or would it burst before that because of the expanding gases from the exploding gun powder? --InfoCan (talk) 20:24, 30 April 2010 (UTC)

After the bullet comes out, the air comes out at the same speed. Probably both will happen at the same time because the bullet and the air are travelling at the same speed. --Chemicalinterest (talk) 20:33, 30 April 2010 (UTC)

The gases will actually decelerate much faster than the bullet will because of fluid drag and turbulence. Furthermore, I am not sure the volume of the expended gases would be enough to pop the balloon by itself. A 20-30 cm diameter increase would represent 1.33*(3.14)*(15*15*15 - 10*10*10) = 522 cc increase, or roughly 1/2 a liter. At STP, this would be .522/22.4 = .0233 mol of expended gas. Even owing to the increase in volume due to the temperature of gas, I am not sure that that much gas is released by the cartridge in the conflagration that expells the bullet. I think its the bullet, and not the gas, that would burst the balloon. If the balloon were exactly at the breaking point, then maybe the gas would break it first. But given the parameters above, I doubt the gas would break the balloon before the bullet would. --Jayron32 21:10, 30 April 2010 (UTC)

Here's my idea: In order for the expanding air to break the balloon, it must first expand from where it is formed (the gunpowder) out to the edge of the balloon. Is it reasonable to assume that the wavefront of the expanding air spreads at the speed of sound? If so, and the bullet moves faster than the speed of sound then it will pierce the balloon before the balloon even feels the force of the expanding air. Thoughts??24.150.18.30 (talk) 02:07, 1 May 2010 (UTC)

Most pistols fire subsonic ammunition (that's a lousy redirect: our ammo article doesn't even talk about subsonic/supersonic bullets. Our cartridge article at least mentions the terms, but only in passing). So the shock wave would hit the rubber first. Would the shock wave to enough to pop a balloon? I have no idea. Buddy431 (talk) 04:57, 1 May 2010 (UTC)

That's because most pistol ammunition actually is supersonic; subsonic ammunition is used in situations where you need less damage potential or you want it to be quieter if the gun itself has a suppressor. The other thing I would point out is that while conventionally you would think that a shock wave in air would travel at the speed of sound, don't forget that the pressure behind the wave is significantly high thus essentially raising the speed of sound for air at that pressure. Given enough pressure the shock wave can easily travel much faster than the speed of sound at sea level. So, to venture a conclusion to the question, there are several variables such as the tension in the balloon (i.e. how much pressure already exists inside it) and the type of bullet and length of gun barrel being used. In most cases I bet that the bullet would puncture the balloon first. --Jmeden2000 (talk) 14:46, 1 May 2010 (UTC)

When the bullet emerges from the muzzle, it is riding in front of a jet of gas molecules produced from the explosion. So the answer to the question lies partly in how quickly the new gas molecules randomize their trajectories and distribute themselves evenly inside the ballon, so as to be able to push the wall of the balloon rather than the back of the bullet. --InfoCan (talk) 04:51, 2 May 2010 (UTC)

Telescope

If we could look far as a billion years light from Earth then why couldn't us look inside in the other planets so we could figure out aliens exist or not. Another question, as i knew if we look at the planet 5 years light ago from Earth what we saw is what happened on the planet 5 years ago not at current time right? Have we prove it?75.168.119.109 (talk) 22:58, 30 April 2010 (UTC)

1. Yes, we can use our telescopes to look at exoplanets circling other stars and try to figure out whether there are advanced alien races living there, probably by looking for a surprisingly large amount of electromagnetic energy coming from the planet (as in the movie Contact). Unfortunately, our telescopes aren't able to resolve sharp detail at many light years' distance, so most exoplanets we have detected so far have been gas giants like Jupiter, which can't sustain life as we know it. As we invent better telescopes, we'll be able to detect smaller and smaller planets around other stars, which may help.

2. That's correct; as our speed of light article discusses, light does not travel instantaneously, but moves at a speed of exactly 299,792,458 meters per second. The term "light year" means "the distance that light travels in a vacuum in 1 year", so, yes, when we look at a star that's 5 light years away from us, we are seeing light that was emitted 5 years ago. The star might have exploded 2 years ago and we're still not going to be able to see that it exploded for another 3 years.

3. Yes, the speed of light has been measured; see speed of light. Comet Tuttle (talk) 23:26, 30 April 2010 (UTC)

Nice answer! But can we look at inside the planets, like look at it's surface? If there are aliens in there, could we see them? Or we only could see the outside of the planets.

It is kind off weird. If we discovered some aliens but they are billion years light from us that's mean those aliens we saw were exist billion years ago, that shows it is hopeless to contact aliens because what we saw is not what actually happening. How far we could look into space, how many billion years light could we look at now? Why don't we invent a big telescope to look at 14 billions years light from us then we could see what happen 14 billion years ago. We may see BIG BANG.75.168.119.109 (talk) 23:53, 30 April 2010 (UTC)

In theory we could see a planet's surface, if we had a powerful enough telescope. However, such a planet probably would not have the atmospheric gases (such as water vapour) Earth does, and would be unlikely to support life. A larger telescope does not necessarily mean more powerful. Furthermore your final assertion assumes that the Big Bang occurred 14 billion light years away, which would put Earth at the edge of the Universe. Intelligentsium 00:01, 1 May 2010 (UTC)

We do not have telescopes powerful enough to show the surface of any exoplanets. But see betelgeuse to see a picture of the surface of a star. Note that betelgeuse is just a few light-years away and still we can barely distinguish any of its surface features at all. The idea of seeing a civilization billions of years away is completely hopeless. The Hubble telescope has allowed us to see pictures of galaxies many billions of years into the past and learn a lot about the beginnings of the universe. Unfortunately, it is not possible to see the big bang because the young universe was opaque. Dauto (talk) 00:13, 1 May 2010 (UTC)

Part of the problem is that light tends to spread out from a source. So, not only do objects which are farther away take longer for the light to reach us; we receive less light from those objects. Now, imagine bouncing a tiny portion of that light off a dark object and trying to catch THAT. Astronomical distances are huge, and relative to stars, planets are pretty small, and in order to support life, planets need to be a considerable distance from stars. In order to improve the resolution of a telescope, you need to collect more photons of light; well, with some of these exoplanets, we may only receive a total of a few photons at a time; far too few to resolve anything. In other words, even if we could catch EVERY photon of light hitting the earth from those planets (a telescope with infinite resolution, lets say) we still could not resolve the surface of the planet to any accuracy. --Jayron32 00:26, 1 May 2010 (UTC)

Most of our telescopes cannot resolve the Apollo landers on the Moon. I doubt that any would be able to resolve surface detail on exoplanets, let alone aliens. ~AH1^(TCU) 01:44, 1 May 2010 (UTC)

We just recently were able to directly see any exoplanet, at all, with any telescope. That's Fomalhaut b. Fomalhaut b is pretty much right in our faces, in star terms, at only 25 light years away. It's a gas giant, probably about the same size as Jupiter, though it's further away from its star than Neptune: that is, it's hard to imagine an alien civilization developing there. However, even with probably the best visible light telescope in the world for this sort of thing (Hubble), it appears to take up about four pixels in the photograph, and no surface detail whatsoever is visible. Now, our resolving power is certainly going to get better with new telescopes; if the Advanced Technology Large-Aperture Space Telescope ever gets built and launched, we might actually get some differentiation across the surface of very near and very large exoplanets. But even that probably couldn't even see a rocky planet closer to its star, let alone resolve surface detail. In short, we aren't going to detect an alien civilization anytime soon by seeing their cities from Earth, regardless of whether they're on the surface of underground. Buddy431 (talk) 04:50, 1 May 2010 (UTC)

I understand the question to be: since we have all kinds of tremendously powerful telescopes, can we look literally inside the planets in our own solar system? That is to say, under the surface of Mars? And I don't know, but I think not. 86.21.204.137 (talk) 11:59, 1 May 2010 (UTC)

Short answer: Yes, we can see below the surface of Mars.

Long answer: It depends on how you define the word "telescope" - but if you think of it as a thing for capturing visible light - then "No" - the solid surface of the planet is opaque to visible light - and you can't see more than a millimeter or two into that kind of object even with a super-bright light source and super-sensitive detector. But if you think more in terms of "radio telescope" and widen your definition of "telescope" to "a thing for capturing electromagnetic radiation" - then you could look at ground penetrating radar as a kind of "telescope"...and we have certainly scanned the surface of Mars with ground penetrating radar (see SHARAD and MARSIS). People don't normally describe these things as "telescopes" because they have to emit the radio waves and read back the reflection from the sub-surface layers of the planet. But this is how we examine the subsurface layers and "look inside" both Earth - and other planets. Obviously though, we can't do that with exoplanets because we have no way to get close enough. SteveBaker (talk) 14:44, 1 May 2010 (UTC)

That's mean our telescope is not advance enough. I think the important thing now is to developed an advance telescope to search for living thing. We only need to see them and take a picture of them. It is easier to contact them than to see them. How many years light could we look from Earth now?75.168.119.109 (talk) 05:38, 2 May 2010 (UTC)

I still don't understand why we could not see the big bang if we could look at 14 billion years light away from Earth, which is the time big bang occurred?75.168.119.109 (talk) 05:44, 2 May 2010 (UTC)

We can't see the big bang because the young universe was hot and dense which made it opaque. So, we cannot see all the way back to the big bang because there is no light coming to us from that far back since it was opaque. That's the same reason why we cannot see the center of the sun. The sun is hot and dense which makes it opaque, therefore there is no light coming to us from the center of the sun. Dauto (talk) 16:48, 2 May 2010 (UTC)

Habeñero pepper safety

Could a healthy person with no underlying medical conditions be hurt by eating an excess of Habeñero peppers? If so, what would be the safe limit for eating them? MMS2013 23:23, 30 April 2010 (UTC)

Capsaicin#Effects_of_dietary_consumption, perhaps. 90.195.179.138 (talk) 23:30, 30 April 2010 (UTC)

Also see Chili pepper#Possible health risks and precautions. Comet Tuttle (talk) 23:32, 30 April 2010 (UTC)

I strongly recommend reading this: http://www.habanero-hamburger.com/index.shtml - it's the website of a recently closed pub in San Mateo who regularly served Habanero Hamburgers - one pepper, lightly grilled, in a regular burger. There are some very detailed - vivid - literally "gut-wrenching" - descriptions about the consequences of eating one of these burgers (and one especially detailed blow-by-blow account here). The consensus is that if you can eat it in 60 seconds and no more than 5 bites - you'll get it down, then be in horrible pain for the next 12 to 20 hours as the stuff makes it's way through your digestive system...and there are many descriptions of "the ring of fire" and "exit wounds"! Having said that, there are people who have eaten them on as many as 20 separate occasions - and others who simply couldn't manage more than a single bite of the stuff. Our local NPR radio station interviewed the owner of the pub just before it closed - he said that he made people sign a waiver and present a doctor's note to prove they had no heart conditions before he would serve them - and despite that had several occasions when people had to be rushed to hospital before finishing their meals! There are a few people who ate two of them at one sitting. So, healthy people can certainly survive eating a couple of these toxic veggies - but it is most certainly not recommended. SteveBaker (talk) 02:10, 1 May 2010 (UTC)

I wonder if Johnny Cash had visited that place when he wrote his hit song "Ring of Fire"... ;-) 76.103.104.108 (talk) 02:27, 1 May 2010 (UTC)

(edit conflict) In college, I had a Hindi-Malaysian roomate who could literally eat them like strawberries. He'd comment that they were very hot, but not unbearably so. I managed to eat one, but didn't relish the experience. Oddly enough, I like the flavor of Habeneros a lot, so long as they are used right. Used sparingly, I find that they have a good "sweet" flavor under the heat, not unlike a Tabasco pepper, I like them better than the milder, but more common, Jalepenos, which I find to be bitter and grassy flavored. --Jayron32 02:39, 1 May 2010 (UTC)

Yes, habaneros are very tasty. I have built up a certain tolerance to the heat, and I agree that they have a lot of flavor beyond the heat. I like to use them to start a tomato sauce (sautee them along with the garlic, before putting in the tomatoes and wine), or sliced thinly on a toasted sandwich of sharp cheddar, black olives, maybe some tomato and avocado. Or I sautee them in the butter that I then use to fry an omelette.

I had to threaten my local supermarket that I'd stop shopping there if they stopped carrying them. They tell me that not many other customers buy them, which seems strange to me — it's not like I'm in the middle of Iowa or something.

There's a pepper I like even better, the Scotch bonnet. I can't find it around here anywhere. It was easily available when I lived in Texas and in Canada. --Trovatore (talk) 09:21, 1 May 2010 (UTC)

An aside here — the pepper's name is simply habanero, no eñe. It means "from Havana" (Havana is La Habana in Spanish; again, no eñe). This is one of my mild peeve spellings, though it doesn't bother me quite as much as latté, which is an error of a similar provenance. --Trovatore (talk) 02:15, 1 May 2010 (UTC)

Just to take the question literal: For most people, "hurt" starts at microscopic amounts of a habanero. "Injured" is much further down that path.... --Stephan Schulz (talk) 09:56, 1 May 2010 (UTC)

I have searched without avail for a BBC news article I read maybe two years ago in which a man died from eating ludicrously hot chilli peppers. What I remember is that they were served to him by a man who grew his own, and either it was a for a dare or there was a mix-up over hotness (perhaps both). What might have happened, of course, is that he turned out to have an allergy; but then you wouldn't think he'd be eating chilli peppers at all. If anybody can find this article, I'd be very grateful, since it's the kind of question that comes up in conversation often. 86.21.204.137 (talk) 12:29, 1 May 2010 (UTC)

If you frequently eat very spicy food, you become insensitive to it. But then normal food will become tasteless. I know someone who cannot eat normal food like bread anymore because of this. Count Iblis (talk) 15:29, 1 May 2010 (UTC)

This is not my experience. I still enjoy non-hot food. It's true that I don't get much satisfaction out of food that's supposed to be hot, but isn't; that strikes me as different from what you're talking about.

My supposition is that the tolerance is specific to the heat-inducing chemical, capsaicin. I can't see any reason that tolerance would reduce your sensitivity to other tastes. --Trovatore (talk) 17:52, 1 May 2010 (UTC)

The stories of people eating these things without the resulting pain reported by others often derives from the fact that there is a huge range of hotness in the same species of pepper. In particular, here in Texas you can buy specially bred 'mild habaneros' that - while still pretty spicy compared to a jalapeno - don't have the gut-wrenching effects of the habaneros at the top end of the scale, yet retain the interesting flavor. I've eaten those - and they don't compare with "the real thing". Our habanero article says that growth environment and and other factors can also have a large effect on the heat of the pepper. The San Mateo pub I linked to above used only Panamanian Habaneros - which are the most notorious kind. SteveBaker (talk) 16:28, 1 May 2010 (UTC)

May 1

Persistent odor

(Note to everyone: This is NOT a request for medical advice)

Just a couple days ago, while testing a sample of refinery wastewater for heavy metals, I accidentally took a whiff of some 5% aqueous ammonia solution (for those who'd never had that happen to them, it feels like a pair of burning matches up your nose). My mucous membranes were burned to a crisp in less than a second, and I had the most horrible itching and sneezing all day long, followed the next day by the worst runny/stuffy nose I've ever had (I've gone through more than two boxes of Kleenex in just one day). All this was stuff that one would expect when one gets ammonia poisoning. What really surprised me, though, was that even after I left the lab, I kept perceiving the stench of ammonia all day long; everything around me -- my hands, my clothes, soap, toothpaste, the food I ate, even the flowers in my yard -- positively reeked of ammonia. (And no, I hadn't spilled any ammonia on myself or my belongings, so the most obvious explanation is out of the question.) Can anyone come up with an explanation for this lingering odor? 76.103.104.108 (talk) 02:45, 1 May 2010 (UTC)

See Sensitization. You could have become rapidly sensitized to the odor of ammonia after your experience. Ammonia is present in LOTS of things. Normally, our brains may not be able to pick the ammonia out of a bunch of compounds that make up the smell profile of something, but given your experience, you may now be hyper-sensistive to ammonia, and can "pick it out" of otherwise complex mixtures of smells, even if it is only present in trace ammounts. Just an idea. --Jayron32 02:52, 1 May 2010 (UTC)

...or you just got a whole lot of it up your nose! 64.69.33.87 (talk) 02:57, 1 May 2010 (UTC)

When you burn your hand, doesn't it kind of feel like you hand is burning constantly until the wound begins to heal? Or when you cut yourself, as if your hand is cut? If there are nerves in your body that know that the smell of ammonia is a hurt smell, I don't see why those nerves wouldn't "throb" after your "injury", thus making you think that you were smelling ammonia. 219.102.220.42 (talk) 03:13, 1 May 2010 (UTC)

Thanks for your answers, everyone. 219 IP, I think your explanation is the most likely, 'cause the smell gradually decreased in intensity through the day, until it finally disappeared the next morning. (And yes, I did get a whole lot of it up my nose, which would explain the intensity and persistence of the smell.) So I can easily see how the nerve endings could continue to tingle for hours afterward, and how this could be perceived as an ammonia smell. As for any possible sensitization, Jayron, maybe I forgot to mention that I've handled ammonia (and smelled it -- it stinks so bad you could smell it from half a mile away) many times in the past -- we use it for a quick-and-dirty test of refinery wastewater for iron, chrome, manganese and vanadium (none of which we're supposed to dump in the river because of toxicity concerns) -- and I've never had a problem until I got a little careless and inhaled the concentrated vapors. Had I become sensitized, it would've happened when I first handled ammonia, wouldn't it? Also, how do you explain the sensitization going away gradually within about 24 hours? 67.170.215.166 (talk) 05:55, 2 May 2010 (UTC)

Sleeping in a chair

I frequently take overnight bus trips and I can never get to sleep on the chair, and I always end up feeling like crap for the rest of the day. Even in bed I can't sleep on my back for some reason, I have to start on my front or else my body never seems to realize that I'm trying to get to sleep. I'm looking for some tips on how to get to sleep sitting in a reclining bus/plane seat, short of taking heavy sleeping pills. I already taken some off-the-counter light pills, but I'm more asking about why I may be having trouble sleeping, and how I can counteract that naturally.

To be honest, I often have the choice to take a bus that will give me two seats, or one that has a fully reclining chair so that I can actually get on my side, but I'm just curious as to why it's so hard for front-sleepers like me to fall asleep on our backs! I guess I also might want to mention that I'm 6'3 (188) so that's also a frequent problem!! 219.102.220.42 (talk) 03:08, 1 May 2010 (UTC)

Part of your answer is sleep hygiene. Much like creating a bedtime routine for children helps them go to sleep, adults often find they need certain 'cues' to get them to sleep. As you say, it is like your body (or brain) doesn't realise you're trying to sleep. People vary in how much this applies to them, but the way you find it easier to sleep is strongly the product of habit. There are also things like sleep apnea, but if you can't even drop off it seems more likely it's just because you don't associate those situations with sleeping. 86.178.225.111 (talk) 16:45, 1 May 2010 (UTC)

Hmmm... practice makes perfect? 210.254.117.185 (talk) 01:27, 2 May 2010 (UTC)

That's actually true when it comes to sleeping in strange places. --Ouro (blah blah) 06:17, 3 May 2010 (UTC)

Lens-less imaging

I may be misunderstanding some of the fundamentals of optics here, but I was just wondering: if the angle each photon approaches at can be calculated by passing it through a non-focusing surface, would it be possible to resolve an accurate image using those calculations? It seems illogical to me that you could get a "focused" image without a lens, but I don't know why. 219.102.220.42 (talk) 03:36, 1 May 2010 (UTC)

See pinhole camera. Its possible to use diffraction instead of refraction to focus light. Thus, one can make images with tiny holes instead of lenses. --Jayron32 03:58, 1 May 2010 (UTC)

It sounds like you're saying that pinhole cameras work by diffraction. They don't, though you can focus light with a zone plate. -- BenRG (talk) 06:49, 1 May 2010 (UTC)

Sorry, I know what a pinhole camera is, I meant to clump in the pinhole camera with lensed cameras due to the fact it "focuses" the light. I'm asking if it is possible to resolve an image without any directing of the light by calculating the trajectories of individual photons. 210.254.117.185 (talk) 05:28, 1 May 2010 (UTC)

No, photons as particles obey the Heisenberg uncertainty principle, and as such, you cannot know the position AND momentum of a photon simultaneously. In other words, if you can locate a photon's position, you can't tell where it came from before it got there. So it is impossible to assign "trajectories" to photons. Since photons are merely the convenient term we use for the collection of properties that make light kinda-sorta behave like particles, however they are still light; and as such they still obey wave-like properties too, under the right conditions. See Double-slit experiment for a discussion over what happens when you try to assume that a photon is only a particle, and ignore its wave behavior as well. --Jayron32 06:30, 1 May 2010 (UTC)

That's a poor assessment. Heisenberg doesn't say that you can't know them both - it places a limit on the precision with which you can know them both. Since the momentum of the light relates to the color/brightness and the position relates to your ability to focus the image, Heisenberg merely imposes limits on how sharp and color-accurate your photo can be. But that limit is a very tiny one - you can make pretty good photos! SteveBaker (talk) 14:29, 1 May 2010 (UTC)

Photons don't have trajectories; they aren't like the lines of geometric optics. Light is a wave. But you can, in principle, record the electromagnetic field strength at an aperture and computationally simulate the propagation of the light beyond the aperture, through a simulated lens and onto a simulated sensor. Astronomers actually do this at radio frequencies—see Very Long Baseline Interferometry. I don't know whether it's possible at visible frequencies. -- BenRG (talk) 06:49, 1 May 2010 (UTC)

I think the OP is describing something like the compound eye of an insect. There are devices called plenoptic cameras or light-field cameras that attempt to do the same thing. I don't think these cameras are completely lensless, but they chop the light field up into smaller bits rather than passing it all through one humungous lens, which might be what the OP is looking for. --Heron (talk) 09:54, 1 May 2010 (UTC)

Thanks for the answers! I have heard that particles at the quantum level were unpredictable, so that's why I wondered if it would be possible here. In that case I have an expansion to my original question.

Is there any way to make a _surface_ into a camera without using lenses? I specifically want to avoid something like a compound eye, which is really just a lot of small lenses instead of one big one, right? The only way I thought it might be possible is by measuring the photons, but if they can't be measured directly, is there any other way to do this without using a physical lens? I'm thinking of the physical limitations of lenses, in that any camera is only as good as its lens or the corrective measures applied to the lens, but if there were a way to resolve images from sensors, then there wouldn't be this problem. 210.254.117.185 (talk) 10:41, 1 May 2010 (UTC)

No, you can't, actually. The last part of the double slit experiment article discusses this. If you fire photons at a surface individually through the double slits, and let them be detected one at a time, each hitting the detector before the next is fired, you still get an interference pattern; in other words, even if you design an experiment such that light is treated as particle in the most direct way (firing individual photons one at a time) you STILL get wave-like properties. So you can't design a surface which will resolve an image in the way that a lense would, since such a surface would require that the light act solely as a particle. --Jayron32 14:34, 1 May 2010 (UTC)

I recall that the cameras on one of the Mars landers did not have any lenses, and looked slit-like. 92.29.142.124 (talk) 12:22, 1 May 2010 (UTC)

I dunno. According to this, they seem to all have conventional lenses. 210.254.117.185 (talk) 14:30, 1 May 2010 (UTC)

What I was thinking of was static and earlier than the Rovers. Edit: It may have been the earliest lander, when people were concerned about dust storms scouring a lens. Edit2: I was thinking of Viking 1, which shows two slit like things in its photo what may be cameras or imagers. I havnt been able to find anything about these on the internet. 78.151.115.180 (talk) 14:37, 1 May 2010 (UTC)

You should read the papers linked from http://graphics.stanford.edu/projects/lightfield/ - those guys have made a variety of interesting cameras - including a single pixel camera that can take 'normal' photos - a way to transform a photo so you can see it from the perspective of the light source...all sorts of interesting stuff that results from doing numerical analysis of the 'light field'. SteveBaker (talk) 14:29, 1 May 2010 (UTC)

I've heard about those single-pixel cameras - how on earth do they work? 78.151.115.180 (talk) 14:39, 1 May 2010 (UTC)

They slowly scan the thing being photographed, one pixel at a time. The examples I saw take about 15 minutes to take a grainy/blurry photo. -- kainaw™ 14:43, 1 May 2010 (UTC)

Well, you could do it like that - but you'd still need a lens or a pinhole-like aperture - and that's not how the Stanford camera works. Their single pixel camera is an omni-directional detector. What they do is to use 'structured light' - by flashing light on different parts of the scene, the camera builds up a picture from the perspective of the light source. (That's a horrible over-simplification - read their paper to get a more complete answer.) SteveBaker (talk) 16:15, 1 May 2010 (UTC)

Which paper is that please? 92.28.253.63 (talk) 10:56, 3 May 2010 (UTC)

Jayron's answer above is completely wrong. Uncertainty principle applies just the same whether you are using lenses or not. It just turns out that lenses (and mirrors) are the easiest way to disentangle the information contained in the photons into a useful format that allows for an image to form. Dauto (talk) 15:42, 1 May 2010 (UTC)

Yes, exactly. The uncertainty principle imposes strict limits on the ultimate quality of photography - but it says nothing about how you take the photo. Also, the plank constant in the uncertainty principle is a teeny-tiny number! The amount of imprecision that the uncertainty principle causes is utterly negligable in practical photography. What would happen if you tried to take an insanely high resolution image (thereby forcing an accurate position measurement onto the photon) would be that the color and brightness of the image (related to the momentum of the particle) would become less precise. But we're an awful long way from the uncertainty principle imposing limits on the quality of our photography! SteveBaker (talk) 16:15, 1 May 2010 (UTC)

That's not right either. The uncertaity principle does play a role in the optical resolution of a telecope (Assuming high quality lenses). That's in fact the main reason why large telescopes are built. The secondary reason is the increased brightness obtained with larger telescopes. Dauto (talk) 19:36, 1 May 2010 (UTC)

Again, thanks for noting that. I apologize for leading the discussion astray. Of course, we do have surfaces that accurately resolve images without lenses. They are called mirrors. --Jayron32 16:38, 1 May 2010 (UTC)

The uncertainty principle that people have been talking about is already present in classical optics (Maxwell's equations), where it's called the diffraction limit. The classical version of the inequality is Δx Δk ≥ 1/2, where k is the wave number. Quantum mechanically, you can use the de Broglie relation p = ħ k to write it as Δx Δp ≥ ħ/2. Quantization adds shot noise in low-light situations, but aside from that, imaging is governed by Maxwell's equations. When you are limited by shot noise, it does matter how you take the photograph—measurements before and after the light passes through a lens don't commute with each other, meaning that you can't tell from the before-lens measurement what the after-lens result would have been. This problem disappears when the photon count is large because the photons behave as "identically prepared systems" and you can recover complete information about the preparation by doing different measurements on different photons. -- BenRG (talk) 01:06, 2 May 2010 (UTC)

Thanks for the answers and links guys. The digital post-re-focus camera is pretty insane!! So I guess the question is not if images can be resolved from surfaces, but how high resolution they can be. Telescopes are limited by the accuracy of the lenses they use, but the resolution of a surface seems to be restricted by our ability to resolve the properties of photons. I imagined a very long, thin tube with the "sensor" surface on the inside of it, in order to block all the photons from outside of a small patch of sky, but I imagine the wave properties of light will make it impossible to create an image of anything too small/far away. Thanks again! 210.254.117.185 (talk) 01:24, 2 May 2010 (UTC)

If I'm not mistaken, taking a photo by measuring the angle, and without using a lens, is exactly what a hologram does. Ariel. (talk) 02:52, 2 May 2010 (UTC)

Titration curve: part 2

My question is very similar to the one I asked earlier, but it's different enough that I thought I should ask separately.

If I have HCl of a known concentration & volume, being titrated with NaOH of known concentration, and I add x mL of NaOH. How do I determine the exact relationship between pH and x, with no approximations whatsoever? I know that I can use Jayron's method for pH's close to 7 and conventional methods for pH's far from 7, then combine the 3 resulting functions into one, but I can't help but think there has to be an exact mathematical formula for the titration curve. --99.237.234.104 (talk) 04:45, 1 May 2010 (UTC)

You can always use an ICE table. First, react the two species to completion. Then, use those values as the Initial values in the ICE table. This will give you the relationship Kw=([H+]initial + x)([OH-]initial + x). Solve the quadratic equation for x, add that x value to the initial H⁺ concentration, and take the negative log. Note, though, that there are surely some error bars on your amounts of H⁺ and OH^-, so there's little use in getting an "exact" value in this way unless you have very close to equal amounts of acid and base. Buddy431 (talk) 05:31, 1 May 2010 (UTC)

Dry nose when sleeping upright

If I fall asleep during the day, in an upright posture, for instance while sitting on a train or at a desk, I invariably awaken with a very dried-out nose. This never happens if I fall asleep lying down. Why might this be the case? 129.174.184.114 (talk) 06:31, 1 May 2010 (UTC)

I didn't know humans had wet noses. Are you a dog? --TammyMoet (talk) 09:14, 1 May 2010 (UTC)

We do have healthy wet noses, on the inside. This came up on this very desk a month ago, in a question titled "juicy nose". 86.21.204.137 (talk) 12:21, 1 May 2010 (UTC)

I am rather certain that the response then was the same as now: We cannot diagnose how a questioner's nose works without physically inspecting the questioner. -- kainaw™ 14:44, 1 May 2010 (UTC)

Why are people whispering? — Knowledge Seeker দ 17:48, 1 May 2010 (UTC)

name of shooting device

i saw this

http://www.youtube.com/watch?v=fRLCh0Re_LA&feature=PlayList&p=2CA7AB94E58204FB&playnext_from=PL&index=0

what is the name of the shooting device he is using? not the gun but the device that the gun is attached to that makes it have no recoil. its not called a bench rest because thats something else. i want to buy one and need to tell the gun store exactly what im talking about —Preceding unsigned comment added by Tom12350 (talk • contribs) 10:49, 1 May 2010 (UTC)

Please don't post the same question on more than one desk. There is a recoil on the gun, it goes back about two inches. Finally I imagine your gun store has access to You-Tube and can view the vid for themselves. Caesar's Daddy (talk) 13:43, 1 May 2010 (UTC)

The page that video comes from is here, which suggests it's part of a benchrest shooting setup. The Wikipedia article claims that most benchrest shooting setups are custom made. -- Finlay McWalter • Talk 13:57, 1 May 2010 (UTC)

Physics

Hi, please help with these two questions:

1. Estimate what's the difference between cp and cv of chosen metal. (Instruction: Find the temperature coefficient!)
2. Does specific heat of metal have constant value or does it depend on temperature interval? —Preceding unsigned comment added by Atacamadesert12 (talk • contribs) 13:09, 1 May 2010 (UTC)

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know.

Try reading specific heat the answer to half of your problem is right there in the introduction. SteveBaker (talk) 14:13, 1 May 2010 (UTC)

I tried really hard to solve this problem, but all i could do is this: 1. Table of specific heat capacities: it's written that the cp of copper is 0.385 J/(g·K) and cv is 3.45 J/(cm3·K). I just don't understand how to compare them as they have different unities (J/(g·K) and J/(cm3·K)) and what does the temperature coefficient have to do with it? 2. "These quantities are "intensive quantities", meaning they are no longer dependent on amount of material, but capture more directly the dependence on the type of material, as well as the physical conditions of heating."----> So specific heat capacity doesn't depend on mass but it depends on the temperature interval? Actually I had to do 6 pages but this was too tough... —Preceding unsigned comment added by Atacamadesert12 (talk • contribs) 19:09, 1 May 2010 (UTC)

Why would it depend on the interval? Dauto (talk) 21:57, 1 May 2010 (UTC)

Relations between heat capacities might help a little, but honestly you're going to get the best answer for this class by looking at the text and notes you got for this specific class. For example, I know that specific heats of metals do vary with temperature, but rarely enough for it to be an issue for most calculations you'll be doing. Therefore, your class might be expected to say "No, it's constant and doesn't vary with temperature", because that's what you are supposed to assume. But equally, your class might be expected to say "It varies, and here's a table of how the specific heat of ____ varies with temperature". Without being in your class, we can't tell what answer you're expected to learn. 86.178.225.111 (talk) 00:17, 2 May 2010 (UTC)

We could help by pointing out that the unit for Cp is Joules per (gram * degree Kelvin) and for Cv is Joules per (cubic centimtre * degree Kelvin) - so to compare them, all that's needed is to find out how much a cubic centimetre of copper weighs. --Phil Holmes (talk) 09:50, 2 May 2010 (UTC)

Excitation of an atom

Can a an atom in the excited state jump to another higher state when a photon is incident on it? —Preceding unsigned comment added by Rohit.bastian (talk • contribs) 14:26, 1 May 2010 (UTC)

DO you mean the atom itself or do you mean the electrons of an atom? --Jayron32 15:01, 1 May 2010 (UTC)

The answer is yes. Jayron, that's nit picking... Dauto (talk) 15:47, 1 May 2010 (UTC)

He and his brother are in a higher state. Amen. Cuddlyable3 (talk) 16:44, 1 May 2010 (UTC)

Certainly. That's how we get Balmer lines in absorption, amongst many other things. Modest Genius ^talk 20:28, 2 May 2010 (UTC)

Measuring general radio/tv/phone wave strength

For an elementary school science project that is testing how terrain and weather affect wireless communications, what is the best way to measure the "strength" of radio/tv/phone waves? I figure that it will require an extremely wide-band antenna. What circuit could be used to get a general measure of strength (voltage, amperage, whatever)? Can this be completed by elementary school students or is the construction far too difficult? -- kainaw™ 14:31, 1 May 2010 (UTC)

A simple AM receiver can be built using instructions in just about any hobby electronics kit. It doesn't even have to be an amplified circuit. An unpowered AM receiver circuit will pick up radio waves just fine; the early experiments in radio broadcasting used unamplified circuitry. An unamplified circuit would make it easier to quantify the strength of the received signal. You could likely detect the strength of the received signal by hooking the leads from the receiver to a multimeter RATHER than a speaker. History_of_radio#Wireless_experiments_of_the_19th_century discusses some of these experiments. I have seen demonstrations of David E. Hughes's experiments using stuff you can get at a hardware store. At the most basic level, you can demonstrate radio using a speaker and a decently strong spark, without so much as an antenna or receiver circuit. This article at Howstuffworks.com actually contains some pretty good stuff on radio, how it works, and how to build simple transmitters and receivers at home using basic materials. The section titled "The Simplest AM Receiver" shows you how simple such a receiver can be. --Jayron32 15:40, 1 May 2010 (UTC)

Many Mobile phones and PC's equipped for Wireless LAN can display a crude scale of signal strength so no construction is needed to use them. An unamplified Crystal radio will not separate stations well, the voltage you could measure at the output is dc plus large ac variations, and the size of antenna required does not lend itself to portability. An easier choice is a cheap Transistor radio of an older design using discrete components. You can connect a voltmeter to the internal AGC line and the reading will be a (rather non-linear) indication of received signal strength. In principle you could do the same with a car radio but they are harder to open up. However professional equipment is needed to take calibrated measurements over a wide frequency range. Running a Spark-gap transmitter will get you into trouble you can do without.Cuddlyable3 (talk) 16:37, 1 May 2010 (UTC)

I was planning to use old radios, but the goal is to measure as much of the signals out there as possible all at once. There isn't much. There are no local television stations, one FM radio station that sometimes comes in, two AM radio stations, only one cell tower (owned by Verizon), and tons of CB radios. I figured that if necessary, we could measure the strength of the FM station since it fluctuates regularly, but I was hoping to get a better set of reliable data by trying to measure everything that is out there all at once. -- kainaw™ 18:05, 1 May 2010 (UTC)

The trick to making a great science project is not about the equipment - it's about the methodology. I think, in your position, I'd take my cellphone and a paper map of the area. Find out where the cell towers are and pick a suitably large area with hills and other terrain which you have free access to. Then walk around the area methodically writing down the number of bars you're getting on your phone every 100 meters (or whatever). If you can borrow a handheld GPS - or if your phone has GPS, you can get your position from that. If you get it right, you should end up with a map covered with numbers. Now you can look at the contour lines on the map and the locations of the towers and color the map with regions where you got 0, 1, 2, 3, 4 or 5 bars. When you do this, try to hold the phone in the same orientation each time - try to do all of your testing in similar weather condition.

Once you have data - try to form some results - does the number of bars depend on the distance from the cell tower? Do intervening hills make a difference? Did you need to be able to see the tower to get a good signal? Can you form a hypothesis from this data? Perhaps you could test your hypothesis by finding a different area with a different cell tower and predict where you think you'll get good reception and where bad. Then test your hypothesis by actually going to those places and seeing if you get the number of bars you predicted.

SteveBaker (talk) 18:42, 1 May 2010 (UTC)

If you have a budget, you can buy a HAM base (or a standalone receiver) and a VU meter. A VU-meter runs you anywhere from $5 to several hundred dollars (depending on accuracy, digital/software features, etc). Depending on the number of bands you care about, a receiver can run anywhere from $200 to several thousand dollars; at a certain point, you buckle down and buy a mixer too, to expand the frequency capabilities of your receiver. This transceiver unit costs a lot, $2000, but includes a neighborhood spectrum analyzer; or you can use a cheaper but less-interesting Wattmeter display. It operates from 500 kHz to 54 MHz, so if you want to go up to VHF (to listen in on television, commercial radio, and so on), you need to buy a good mixer. Unfortunately, this gear is expensive, technically difficult to use, and requires at least intermediate understanding of radio theory (specifically, how frequencies add when you mix and modulate). The good news is, in receive-only mode, you could train your students to dial in each frequency and record the measured signal level fairly "cook-book"-style. This is really the only way you can sweep out ALL frequencies and get a raw power measurement. If you want to restrict yourself to just a few commercially-used frequencies, such as detecting quality of reception from a commercial AM/FM/UHF/VHF/digital-broadcast television station, your best bet might be to hack up a voltmeter to the inside of a commercial radio or television. Two problems with this: so much stuff is done with an integrated circuit, it might be impossible to locate a place to connect your voltmeter probes. Secondly, so many of these systems have so much signal conditioning, including gain control, that it will be hard to decipher what the actual received radio power is. Nimur (talk) 20:37, 1 May 2010 (UTC)

Boiling

why did water or any liquid comes up when boiled.? —Preceding unsigned comment added by Legend killer harshit (talk • contribs) 14:32, 1 May 2010 (UTC)

The gas form is less dense than the liquid form, so it rises. -- kainaw™ 14:34, 1 May 2010 (UTC)

As the water (or whatever) boils, it turns from a liquid into a gas. If you boil a certain amount of water, the resulting gas (steam) takes up about 800 times more space than the water did. Steam is 800 times lighter than water - so the bubbles formed in the liquid rush to the surface and escape into the air - but between forming and reaching the surface - they take up more space. The combined effect of all of those expanding bubbles forces the level of the liquid in the container to expand.

The answer is actually a little bit more complicated than that. When you boil ordinary tap water, the dissolved air in the water actually comes out of solution at a lower temperature than when the water boils - so you do get small bubbles forming before the water gets hot enough to boil. Those bubbles also increase the volume of the water by a small amount - so the volume of the water starts to increase a little before it actually boils. But the biggest expansion happens (as you say) when the water hits boiling point. SteveBaker (talk) 15:43, 1 May 2010 (UTC)

Question - Helium Canister

Why don't helium canisters float away? —Preceding unsigned comment added by Taratrapie (talk • contribs) 14:56, 1 May 2010 (UTC)

1. The helium is compressed, and so more dense than the air around the canister. 2. The canister is more dense (i.e. has more mass per unit volume) than the air around the canister. This being the case, the canister fails to displace sufficient air to equal its weight, and so sits there unmoved. --Tagishsimon (talk) 15:02, 1 May 2010 (UTC)

In otherwords, the heavy metal that the canister is made out of compensates for the boyant force of the helium given that it is lighter than air. In order to float, the entire container must be lighter than the a chunk of air the same size as the container. For a relatively light and thin balloon, this works. For the heavy metal container, it doesn't. However, if you place a full helium cansiter on a scale, it WILL weigh less than an empty helium canister. --Jayron32 15:15, 1 May 2010 (UTC)

Jayron's answer is incorrect. Remember - the helium is under pressure. Helium is about 7 times lighter than air at the same temperature and pressure. But if you put just 8 cubic feet of helium into a 1 cubic foot tank - then the tank would be heavier than it was when it was full of air. Bottled gas says that a typical gas tank is pressurised to 200 to 400 times atmospheric pressure - so helium at that pressure is between about 30 to 60 times denser than atmospheric-pressure air - so a fully pressurized helium tank will be considerably heavier than an empty one. The tank would have to be about 97% to 99% empty before it would start to weigh less than a tankful of air. SteveBaker (talk) 15:35, 1 May 2010 (UTC)

Correct, of course. (chances are, you can safely ignore any answer I ever give. I am wrong more often than I am right). What I should have said was that a canister of helium would weigh less than a canister of air filled to the same pressure. That would have been correct. What I said above was total bullshit. Just ignore me. --Jayron32 16:00, 1 May 2010 (UTC)

Proving references to back up claims not only helps others find more information on the subject by following the links, but also makes sure what you say is always (or as near as can be) correct :) 82.43.89.71 (talk) 19:20, 1 May 2010 (UTC)

Sky

I was looking at the sky today and then I thought about how the earth is spinning through space at amazing speeds. Why don't the clouds be affected by the spinning of the earth? Or is this exactly how the wind is made? —Preceding unsigned comment added by Goei--inkso (talk • contribs) 15:05, 1 May 2010 (UTC)

One way of thinking about this is to consider that air - gases - have friction. And space has a frictionless vacuum. If an atmosphere of gas is held around a planet by gravity, as our atmosphere is, then it is certain to take more notice of the spin of the glove it is attached to, through the mechanism of friction, than it is to be influenced by the vacuum of space. I'll leave you to read Wind#Cause for more on that subject. --Tagishsimon (talk) 15:08, 1 May 2010 (UTC)

The clouds ARE affected by the spinning of the earth. See Coriolis_effect#Meteorology. The fact that the earth is spinning effects the general path clouds take as they move across the earth. You don't see this standing under them because of the scales involved, but if you watch animations of weather patterns, such spinning effects become clearly visible. --Jayron32 15:13, 1 May 2010 (UTC)

Indeed. And this is explained at Wind#Cause. Sigh. --Tagishsimon (talk) 15:39, 1 May 2010 (UTC)

Modern crystal radio

Would a modern crystal radio with an earpiece be useable for recieving long-wave, medium-wave, or FM broadcasts in the UK? 78.151.115.180 (talk) 16:38, 1 May 2010 (UTC)

I don't know how usable it would be, as you need to be in a silent room to hear anything. StuRat (talk) 16:43, 1 May 2010 (UTC)

(edit conflict)Sort of. The problem with crystal radio is that it is an unamplified circuit, so it needs a pretty strong source. It also cannot directly decode an FM signal, which requires something more advanced than a diode to resolve the signal. However, in principle they can resolve any AM signal, regardless of the wavelength of the source, without any modification. They can resolve FM signals using slope detection, i.e. since FM signals also display AM properties at the boundaries of the bandwidth of the signal, you can "fudge" it by tuning an AM tuner to those boundaries. It produces a noisy, inferior signal, but it can be done. --Jayron32 16:46, 1 May 2010 (UTC)

BBC world service on 648 KHz has a very powerful signal that can easily be picked up with a crystal radio all over Western Europe. This signal so strong that the lack of selectivity of the crystal radio will make it difficult to hear weaker stations like radio Five Live on 693 KHz. Count Iblis (talk) 17:06, 1 May 2010 (UTC)

Thanks. Is there a list anywhere of the wattage of different radio stations, or even what their signal strength may be in various places in the UK? A minature crystal set pernamently tuned to the World Service would not be a bad thing. 89.242.97.110 (talk) 11:09, 2 May 2010 (UTC)

Why do we forget our dreams?

Is it known why, if we don't actively try to remember our dreams as soon as we are awake, we will forget our dreams, even though they might seem vivid just moments ago? --98.114.146.35 (talk) 19:40, 1 May 2010 (UTC)

Its probably not a bad thing to forget your dreams; you have a limited (very large, but still techinically finite) amount of storage capacity in your brain, it makes sense to fill it with stuff that you need on a regular basis (like people's names, how to do stuff, whether or not you left the oven on, where exactly was that bear's den? What was my wife's birthday? etc. etc.), versus dreams, which are pretty much useless when awake (as much as I would like to savor that night I spent with Brooklyn Decker...) That your mind sort-of-automatically knows which stuff to file away as "important" and which stuff to discard is pretty cool. Lucid_dream#Dream_recall and Dream#Recalling_dreams contains some methods for training yourself to remember dreams (caveat emptor, YMMV, etc.). --Jayron32 20:32, 1 May 2010 (UTC)

It is not known why that happens at the physiological level, but I'll tell you my hypothesis. The storage of memory in the brain is thought to depend on a mechanism called long-term potentiation (LTP), which we know quite a bit about. One of the things we know about LTP is that it takes place in two phases. The first phase produces a memory trace that lasts for a few minutes. The second phase, which is dependent on protein synthesis, produces a trace that lasts for hours or longer. My hypothesis is that during the REM sleep stage (when dreams occur) there is an alteration in brain chemistry that disables the second phase of LTP. In order to make a dream memorable it is usually necessary to think about it very soon after waking, before the temporary trace has disappeared bu after awakening has re-enabled the long phase of LTP. I don't know of anything in the literature that contradicts this explanation; but I don't know of anything that proves it is correct either. Looie496 (talk) 23:11, 1 May 2010 (UTC)

This is WP:OR - but I have a compelling hypothesis for dreaming that fits all of the available facts. It appears to me that the brain is doing something akin to 'defragging' the disk drive on your PC. It's rearranging memories for greater efficiency.

If we pursue this 'defragging' analogy, what happens in your computer is that the PC moves blocks of data off of the hard drive, into RAM and then writes them back out to the hard drive in a more "logical" position. Block by block, it rearranges the files on the disk into a more streamlined arrangement that allows the computer to get at the blocks that make up the file very quickly. It used to be the case that you had to make sure that you weren't running any programs at the time you did this - but modern PC's now allow that.

This analogy isn't backed up by much evidence - but it fits the facts perfectly - and is very compelling:

• Dreams (or at least "REM sleep") is very important to us. We can do without it for a while - but if we don't get enough REM sleep over an extended period of time, we get slower, stupider, and ultimately: seriously mentally deranged! If your PC isn't defragged, the files gradually get more and more chopped up and spread all over the disk, like shuffling a deck of cards. Getting at those files starts to take more and more time. Defragging streamlines all of that - puts all the bits of a particular file next to each other...like sorting a deck of cards.

• Our bodies are 'cut off' during REM sleep so we don't 'act out' our dreams while the data is being moved around. This is a good fit for the old "don't run programs while defragging" rule because your software would see temporarily screwed up files while they were being rearranged. Less intelligent animals (dogs, for example) haven't quite mastered this - and when they dream, you can see their feet twitching like they are running - and there are little barks and such. We only move our eyes around under the eyelids.

• If you don't wake up - then the result is that your memories are streamlined and more efficiently accessible - you wake up feeling more alert and refreshed. You don't remember this rearrangement of memories because everything was 'turned off' while they were being moved around.

• If you do wake up - then it's like you stopped the computer midway through 'defragging'. What's in the computer's RAM memory when you do that is just a random collection of bits and pieces of different files you have on the disk. This fits perfectly with the human experience - your short term memory ("RAM") is full of random bits of real long-term memories that were in the process of being re-organized at the moment you wake up.

• If you wake up during a particular dream (and therefore stand a chance of remembering it) - then that section of your memory hasn't been properly 'defragged'. The next time you sleep, the brain has to go back and try to sort that bit out again. If you wake up again, the same stuff is in your short-term memory the next time - and it seems like you had a 'recurring dream'.

But in this hypothesis, your memory doesn't ever contain any kind of "story" - the dream wasn't like a movie playing in your head. It was just random bits of memories, put together in any old order. When you wake up, your short term memory ought to be empty - but it's full of random bits of memories. What is your conscious mind supposed to do with a bunch of completely random bits of old memories that are packed into short term memory just as if they had just happened? That's easy - we think they were true short-term memories - things that just happened to us. We try to put these into a sensible sequence of actions - but it's difficult because it's basically a mess. The brain doesn't put these 'stories' we invent at the moment of waking up into long-term memory unless we specifically concentrate on doing that (eg by writing them down) - so the stories disappear as soon as short term memory expires.

In this hypothesis, the dream didn't actually "happen" at all - it's a bunch of old memories that seem to have just happened if we happen to stop the memory reorganization right in the middle. If that hypothesis is true (and it seems entirely reasonable) - then the issue of 'remembering' wouldn't come up. A dream isn't like a story or a movie unless we wake up while the REM phase is happening. You don't "forget" your dreams - you simply never remembered them in the first place...the dream literally didn't happen unless we woke up.

From what little we know of how memories are stored - there isn't enough storage space for all of our memories to be retained in full detail for life. We forget things that aren't important, we simplify memories where detail is unimportant - some process in the brain must be doing that reorganization on a daily basis - and REM sleep fits the bill perfectly.

I must emphasize that I know of no evidence that this hypothesis is true - but as far as I can tell, it fits all of the facts perfectly. SteveBaker (talk) —Preceding undated comment added 00:47, 2 May 2010 (UTC).

Nice theory, but it doesn't seem to fit with the phenomenon of lucid dreaming. It is possible to realise you are dreaming and take control of the dream - that couldn't happen if the dream never actually happened. --Tango (talk) 00:56, 2 May 2010 (UTC)

Having read Feynman's account of lucid dreaming - I'm inclined to the view that lucid dreams are not REM sleep. He found that when he engaged in this activity, he lost all of the benefits of sleep and he consciously decided not to pursue it because he was concerned for his intellect and state of mental health. That actually fits what I believe. The idea that the brain starts to defrag things - then the conscious mind steps in and starts directing a 'story' (albeit when still "asleep") simply disrupts the memory re-org that's in progress and turns things over to conscious thought. In effect, lucid dreaming isn't the same thing at all. SteveBaker (talk) 13:36, 2 May 2010 (UTC)

Steve's theory has a lot in common with the theory proposed by Francis Crick and Graham Mitchison in 1983, see PMID 6866101. (You can find a pdf online using Google Scholar if you want one.) There isn't a lot of evidence to support it though. There is lots of evidence relating sleep to cleanup of memory, but it mostly points to slow wave sleep rather than dream sleep. Gulio Tononi, in fact, has been pushing a sort of "defragging theory" of the function of slow wave sleep for the past few years, in papers such as PMID 16376591. Also, most sleep researchers favor the idea that dreams play out in real time rather than being stitched together ad hoc on waking. The evidence is somewhat sketchy, mainly involving studies relating eye movements during dreams to the experienced events reported on waking, but it does seem to trend in that direction. Looie496 (talk) 01:08, 2 May 2010 (UTC)

Well, like I said - it's just a hypothesis. The sketchy nature of dream recall seems to me to make correlation with eye movement during REM an 'iffy' piece of evidence at best...but I'm no dream researcher! I originally trained as a cyberneticist (that's what my degree is in) - and cybernetics is all about looking for ways to compare what happens in biological situations and in robotics and computing - so it seems natural to me to look for these kinds of analogies as ways to suggest answers to things that are tough to study in the brain. Sometimes it produces useful insights - sometimes not.

The 'real time' nature of some dreams is certainly a problem for my hypothesis - and it's evident in watching dogs sleep - they seem to lack some of the ability we have to 'turn off' motor control during REM. This gives us a handy way to observe dreams playing out - but unfortunately, not in human subjects. So you see their feet twitching, first one by one like they were walking, then all four together, like they were running, then you hear tiny little barks and sometimes chewing motion with drooling. That's certainly compelling evidence for a real-time dream of squirrel chasing, catching and devouring...but these motions are not long enough to account for the length of dreams that I recall. The entire dog-dream seems to last under a minute - but the evidence (see REM sleep) is that REM lasts for 15 to 20 minutes at a stetch.

So I imagine that what we're seeing is either the recall or the storing of one of the snippets of a memory being pulled into short-term memory in preparation for putting back into long term memory in a different form. The idea that short bits of actual memory have to be replayed in realtime as they are re-organized isn't such a strange idea. After all, the ability to do this stuff had to evolve somehow - and perhaps the ability to re-record short term memory back into long-term requires the memory to be replayed in something like realtime. So this problem isn't necessarily devastating for my hypothesis.

Also, it couldn't be that REM sleep was the whole picture - otherwise, presumably, we'd sleep for only one to two hours a night and have just REM sleep and nothing else. So there are any number of other possibilities. One is that 'long-wave' sleep is a planning process where the brain figures out what needs to be reorganized - and REM is the actual reorganization. That would neatly explain the alternation between the two kinds of sleep. It might also be that long-wave sleep does contain 'real-time dreams' but that the process of erasing all memory of them actually works OK if we're woken up in the middle of them. The fact that dream recall only happens if you wake up during REM (or very shortly afterwards) might well be a failure of the "forget it - it's only a dream" mechanism - or (more likely, IMHO) that REM leaves this 'junk' in our short term memories and we need enough time after that to allow short-term memory to naturally fade away.

The problem I have with other theories is the question of why we dream at all? It's clearly a costly process (in terms of all of this brain activity consuming energy) - and it's clearly essential to our mental health (if you don't dream - you get into a lot of trouble) - so it must have evolved for some rather critical reason. We know that other mammals have 'REM sleep' with dreams (certainly dogs and cats do) - so we can say for sure that it evolved long before big-brained humans needed it. Without the need to dream, why sleep at all? Sleep is pretty dangerous from a perspective of being vulnerable to predators and such like - so it must have a rather massive benefit or we'd evolve to not do it. We know that birds sleep - so the evolution of sleep must go back at least as far as the split between mammals and reptiles - so dinosaurs must have slept. We even know that some birds, whales and dolphins sleep with only one hemisphere of their brains at a time in order that they can stay conscious 24 hours a day. So this is clearly a vitally important bit of what makes brains tick.

The 'defragging' idea seems to be the only idea I've come across that has a compelling explanation of the need for sleep and why we feel so terrible when we don't get it. Arguments that we have to 'rest our bodies' are patently untrue. If I lay still in bed, reading a book all night - I still feel crap in the morning. My body got all the rest it needed - but my brain didn't get to defrag. SteveBaker (talk) 13:36, 2 May 2010 (UTC)

Difficulty remembering dreams is very useful to help you keep track of what really happened and what happened in a dream. If we remembered our dreams perfectly, we wouldn't know if they had actually happened or not. --Tango (talk) 00:56, 2 May 2010 (UTC)

During a dream, our waking sense of logic is often hindered or corrupted. When we wake and logic is slowly restored, the context of the dream may no longer be realistic, rendering the details of the dream as conceptual gibberish. ~AH1^(TCU) 01:10, 2 May 2010 (UTC)

Since this seems to be a thread of original research, I'll say mine as well. I'm of the opinion that we actually do remember every single dream (and indeed almost everything we experience in real life too), but 99% of the time we just can't access it because the brain stores these memories without any links to anything else to trigger the memory. My "proof" is that several times I've suddenly remembered vividly dreams which I had years ago, which I didn't even properly remember at the time I had them. 82.43.89.71 (talk) 13:01, 2 May 2010 (UTC)

I have some questions about your hypothesis:

1. Why would we evolve to store all of that useless information?
2. Why would we evolve to generate it all?
3. What is the point in storing a memory of a dream that we can't subsequently recall?
4. How do you know that you just "remembered" a dream you had years ago - and that your brain didn't just pop a random thought into your head at the instant you "remembered" it rather than at the time you think you remember it from?

You have no means to prove that you had the dream years ago...unless you wrote it down or something - and then you're remembering the thing you wrote - not necessarily the dream itself. Recovered memory is the term for a memory of something that you thought you'd forgotten. As our article points out: "the authenticity of recovered memories has often been challenged; in some cases recovered memories are fictitious". No matter how vividly the memory is suddenly recalled, it can still be completely false. So your "proof" doesn't stand up to careful scrutiny - and unless you can use your hypothesis to explain other things (like why it is that we remember dreams only when we wake up during REM sleep - and what the purpose of all of this complex mechanism is) - then it's not much of a hypothesis. SteveBaker (talk) 15:18, 2 May 2010 (UTC)

Evolution doesn't require everything to be beneficial, as long as it isn't significantly harmful. --Tango (talk) 22:36, 2 May 2010 (UTC)

But if it's not benefecial or harmful then it's just random so how could it become so widespread? Also, storing every single dream (and almost everything else) is harmful to the extent that you would need energy to store that information. Zain Ebrahim (talk) 23:42, 2 May 2010 (UTC)

Football

When a football is tossed into the air, it's usually spinning pretty fast. As the ball travels along its path, the axis of rotation changes and dips with the football. I was wondering what force causes the torque necessary to produce the change in angular momentum. 173.179.59.66 (talk) 20:29, 1 May 2010 (UTC)

Assuming you mean an American football, the answer is that gravity does that. The dynamics of a ball's flight is described by the science of ballistics, sadly our articles on ballistics are weighted towards the forensic aspects of firearms and handguns and bullet trajectories, but strictly speaking ballistics studies the motion of any non-powered flight. The article External ballistics discusses some of the forces at play, in some serious detail, and if you replace any mention of the word "bullet" with "football" you get the basics. Specifically, a football's flight is stabilized by the Magnus effect, which is also discussed at External_ballistics#Magnus_effect. To put it simply, there is a downward force on the football because of the interaction between the spinning ball and the air blowing past it as it sails through the air; this downward force tends to act more on the nose than on the tail. A ball thrown without spin will maintain the same angle in the air; such a ball, if thrown straight and with no other forces acting on it, will tend to land at the same angle thrown (thus, if thrown nose-up, they land nose-up). Spinning balls will tend to land nose down if thrown nose up. --Jayron32 20:43, 1 May 2010 (UTC)

Thanks. 173.179.59.66 (talk) 02:56, 2 May 2010 (UTC)

Coiling microphone cable during use.

Hi, when recording audio using a (battery) powered electret microphone, should I be concerned with the arrangement of the excess cable? Can it be coiled or will this lead to distortion of the audio recording? --84.13.77.150 (talk) 22:43, 1 May 2010 (UTC)

Try it and see. If it leads to distortion that you can't hear, does it really matter? --Tango (talk) 00:58, 2 May 2010 (UTC)

Of greater concern is avoiding laying the microphone cable next to an electric cord carrying AC power. If a mic cable is layed next to a power cord, you can get a mains hum in the mic circuit; if they must cross, always do so at right angles to minimize the effect. However, I am not sure that the mic cable poses too much of a threat to itself. --Jayron32 02:06, 2 May 2010 (UTC)

Jayron beat me to some points, but 84.13 are you thinking of the general practice in the Professional Audio industry to not coil cables? This is very likely to be more applicable to AC mains power cables, where if you do neatly coil up cable, you are effectively forming an inductor.(also see Inductance) Which means that any time the current changes direction, (which is 50/60 times a second) there will be a loss of power as heat. If you have a big pile of cables supplying a bank of power amplifiers at a rock concert, all neatly coiled, there is a risk of overheating, melting, shorts and fire. Though any cable that carries a lot of power where the signal changes continuously ie. audio speaker cables from the power amplifiers to a bank of 'high power' speakers will also experience the heating effect, to a lesser extent. See this website/section, Do not keep your cables coiled about 2/3 of the way down the page. This effect is unlikely to be noticeable with the cable of a battery powered microphone.
The 'inductors' action may also have an effect on the audio, but is unlikely to be noticeable, though as Tango says "Try it and see". And lay cables as per Jayron32 to minimise hum. If you coil your cables you are also more likely to get cross-talk between channels. --220.101.28.25 (talk) 02:52, 2 May 2010 (UTC)

Another source: John Vasey,"Concert sound and lighting systems " 3rd edition, page 10, 1999, Focal Press, ISBN 0-240-80364-7. --220.101.28.25 (talk) 03:49, 2 May 2010 (UTC)

May 2

Moth Help

I live in Boston, MA---my apartment is flooded with these tiny little moth type creatures.

They're incredibly easy to kill, but their numbers are becoming worrisome!

Is there a common moth that infests in this time of year, or mayhap a well known reason to be surrounded by them? We don't leave out food!209.6.54.248 (talk) 00:40, 2 May 2010 (UTC)

You may want to check your pantry, if you have one. If they are flour moths, you don't have to leave food out to have a problem. Looie496 (talk) 01:35, 2 May 2010 (UTC)

(edit conflict) Are you sure they are moths? I haven't known moths to swarm like that. Having grown up outside of Boston, swarming insects include mosquitos, gnats, and mayflys. The only one of those that may be confused for tiny moths may be mayflys. Do you live near a swampy area or wetlands like the Back Bay Fens or something like that? --Jayron32 01:40, 2 May 2010 (UTC)

Moths don't usually accumulate for food. Light is the more usual source. At university accomodation we have lots of them about where light is abundant. Regards, --—Cyclonenim | Chat  02:54, 2 May 2010 (UTC)

Make sure they aren't eating your clothes. If so, wash any clothes they've started on, with bleach. Then store them in an air-proof container (those Space Bags are a good choice). I had a problem with moths and found tiny brown worms (their larval stage) at the top my walls, adjacent to the ceiling. I went around the whole house and killed any that I found there, and they went away. StuRat (talk) 10:55, 2 May 2010 (UTC)

When I lived in an apartment, pest control was the landlord's responsibility. You might want to talk to your building superintendent or whatever that job is called these days. --Anonymous, 20:23 UTC, May 2, 2010.

Re-engineering the universe for increasing computational capacity

In "Computational capacity of the universe" (Phys Rev Lett 88 (23):237901), Seth Lloyd estimates the storage and cumulative data-processing capacity of the universe to be proportional to ρc⁵t⁴/ħ, where t is the age of the universe, ρ is its density, c is the speed of light and ħ is the reduced Planck constant.

From Moore's law#Other formulations and similar laws, I gather that human needs for data processing and storage are increasing exponentially, which means that eventually they'll outpace the polynomial growth that Lloyd's formula implies. This means that if our needs for computation are to be satisfied, the universe will eventually have to be re-engineered to accommodate them; and if that's to be done in a way that keeps the equation valid, either ρ or c has to start growing exponentially, or else ħ has to start decaying exponentially. (NB: I'm extrapolating to its logical conclusion the general observation that when reality and human needs come into conflict, it's reality that gets changed, at increasingly fundamental levels.) Has it been studied which constant would be best to manipulate, assuming equally straightforward ways are someday found to manipulate all of them? (I'd tend to favour c, given that it would have the side effects of lowering communication latency and extending the raange of interstellar travel, but I'm probably not aware of all the considerations.) NeonMerlin 03:35, 2 May 2010 (UTC)

You're not going to manipulate any of these constants; first of all there is no need given the size of the numbers involved. Humans are in no danger of exceeding the computational capacity of the universe, however defined, for any timescale measured in units smaller than billions of years. Secondly, your statement "when reality and human needs come into conflict, it's reality that gets changed, at increasingly fundamental levels" is patently rediculous. Fundemental physical constants, like the speed of light or planck's constant, can't be manipulated to magically "create" new computational capacity. Its just silliness. --Jayron32 03:51, 2 May 2010 (UTC)

I think he's trying to say that as scientists run out of technology to explain the universe they will almost be forced to make up elaborate stories to perpetuate their point of no return theories that constantly alter previous realities to compensate for the lack of human knowledge. —Preceding unsigned comment added by 98.221.254.154 (talk) 04:19, 2 May 2010 (UTC)

C is in that equation because of it's connection to energy. The amount of calculation a particle can do is related to it's energy, and the energy of a particle is related to c. The implication of this is that to change c you are also changing the energy content of every particle in the entire universe - and where would you get such energy? Ariel. (talk) 04:19, 2 May 2010 (UTC)

I don't buy this anyway - forget about the underlying technology and think only about speed-of-light issues.

What use is computational power if it's situated in the next solar system? A computer has to shuffle data around - and if it takes 4 years to ask for a number from Alpha Centauri and four more years to get the answer back, that's going to be a pretty spectacularly slow machine. In any computation, there is a trade-off between storing something for later use - and recalculating it when needed. As the size of the machine grows, the balance tilts towards recalculating rather than storing. So as your computer grows to the size of a planet (which, in effect, is what the Internet has become), you get a 'law of diminishing returns' where you have to cache information locally rather than reaching out across the network to get it. The bigger computer can store much more information - but it becomes so slow to fetch it that you have to store it locally.

When you think about a computer that's distributed between (say) here and Neptune - the round-trip time to ask for and get back some information is around 8 hours. So the result of any calculation that takes less than 8 hours is better computed locally than being distributed over the larger computer. We might want to use the storage system on neptune (for example) for storing all of the DNA sequences of long-dead people - on the grounds that we seldom need that within 8 hours of asking for it...but if Wikipedia were stored 8 hours away - it would be useless to us.

Now consider storage on Alpha Centauri. At 8 years access time, we can't even store the results of major research programs over there. If we stored the DNA sequence of some obscure plant over on that part of the system - then it would be simpler to re-sequence the DNA of the plant than it would be to fetch it from way over there. If we stored the design for an airplane over on Alpha Centauri, it would be faster to redesign it from scratch than it would be to fetch the old design from storage in memory outside of our solar system!

When you get to the scale of a galaxy - the round-trip time exceeds the duration of an entire civilisation. It's hard to envisage a question that a human might ask where the answer could still be useful to us when it gets here 100,000 years later. There would be no point in storing things in memory on the other side of the galaxy since there would be no way for any future member of your civilisation to get it back again!

When you get to the size of the universe, you have many more problems. You ask the question of a far distant galaxy - and by the time the answer gets back, we've evolved into a different species - or the sun has exploded and we've all moved someplace else. What possible storage or computational needs could we possibly have where the answer could be useful so much later? Why store something that your species could never possibly retrieve again in the future?

While we might want something with more power than we can reasonably fit into a few planets - we simply can't have that. Our present exponential growth of computing needs will ultimately be cut short. However, the amount of growth we have left with nanotech computers, quantum computers and biological computers leaves us an immense amount of headroom before we really start to hit these limits. Humans run into these kinds of resource limitations all the time...and ultimately, we cannot grow forever.

SteveBaker (talk) 14:01, 2 May 2010 (UTC)

I guess you make another point in favour of raising c, as soon as a way is found to do it. NeonMerlin 15:52, 2 May 2010 (UTC)

You can't just arbitrarily alter the value of c. By what means would you go about changing the way the Universe works? What part of the word "constant" escapes your understanding! --Jayron32 00:48, 3 May 2010 (UTC)

Indeed. E=m.c². So if you change 'c' you've either got to find enough energy from somewhere to keep the mass of the universe the same - or if you're stuck with a finite amount of energy - then the mass of everything in the universe would decrease as the square of the change in 'c'. So if, for example, you decided to increase 'c' so that you could get to Alpha Centauri in a few months, you'd need to increase 'c' by (let's say) a factor of 10. That would decrease the mass of everything in the universe by a factor of 100 - which would instantly cause all of the stars to explode because they wouldn't have enough gravity to withstand the radiation pressure. You can't just tinker with fundamental constants without causing major upsets. Changing 'c' is premium-quality craziness! SteveBaker (talk) 13:46, 3 May 2010 (UTC)

NeonMerlin, you should ignore Seth Lloyd; he's silly. And when you see growth that looks exponential, you should fit a logistic curve to it, not an exponential curve. -- BenRG (talk) 17:39, 2 May 2010 (UTC)

Aztec knives

What are these Aztec knives made of? Flint? --The High Fin Sperm Whale 04:58, 2 May 2010 (UTC)

The image description says that they're made of flint. Is there some reason you don't believe this? Dismas|^(talk) 05:07, 2 May 2010 (UTC)

This site [13] has one made of chalcedony from the Ethnologisches Museum (berlin). The light coloured ones in the picture in question (rhs) to me look like quartz, but it may simply be the light shining off them. --220.101.28.25 (talk) 05:26, 2 May 2010 (UTC)

Sorry, I missed the image description. However, there is such thing as lightly-coloured flint (see this). --The High Fin Sperm Whale 20:14, 2 May 2010 (UTC)

Quartz is very difficult to knap due to its prominent grains. Quartzite is sometimes used, but even that makes for a very rough finished product. When I first saw the question, I assumed they were going to be obsidian, which the Aztecs put to good use in making weapons, but these are indeed flint or chert. Matt Deres (talk) 23:35, 2 May 2010 (UTC)

Another spider question

How many spiders does one eat while sleeping during the course of one's life? Alaphent (talk) 09:41, 2 May 2010 (UTC)

A quick Google search suggests as little as 4 but as many as 7-8. Although this page suggests the whole thing is a load of rubbish. Dismas|^(talk) 09:54, 2 May 2010 (UTC)

"For a sleeping person to swallow even one live spider would involve so many highly unlikely circumstances that for practical purposes we can rule out the possibility. No such case is on formal record anywhere in scientific or medical literature," says a spider expert at the Burke Museum: http://www.washington.edu/burkemuseum/spidermyth/myths/whileyousleep.html Rimush (talk) 10:31, 2 May 2010 (UTC)

One such case is in a Post mortem report (video): Misadventurous ingestion of Musca domestica by geriatric female was initially treated by a chelicerate arthropod taken orally, with consequent evolution of treatments until equine injestion and consequent termination. Cuddlyable3 (talk) 15:21, 2 May 2010 (UTC)

I woke up once when a spider lowered itself onto my cheek, which was a close call. StuRat (talk) 10:45, 2 May 2010 (UTC)

The Straight Dope : Does the average person consume four spiders per year in his sleep?. This article discusses it a bit. In it, he explains why the chances of swallowing a spider during your sleep is virtually zero, except in the case where an egg-sac hatches nearby. In that case you might inhale a few new-born spiders. But new-born spiders are so tiny that you wouldn't even notice if you were awake. APL (talk) 16:12, 3 May 2010 (UTC)

Stupid insects and spiders

I've had numerous times when an insect or spider walked right up to me, or even on me, and then I promptly killed it. Can't they see me ? Don't they have an instinct to avoid animals a million times their size ? StuRat (talk) 10:45, 2 May 2010 (UTC)

We're so massively beyond their scale and world-view that I doubt that they (the ones that don't seem to react to our movements, that is - it may be different for the ones that feed upon us) even see us as lifeforms, nor possess the intelligence to see us as such. --Kurt Shaped Box (talk) 12:26, 2 May 2010 (UTC)

Isn't there a story in the Odyssey or Sinbad the Sailor of a ship's crew landing on the back of a floating turtle and thinking it's an island? If a human sailor, albeit mythical, with some 100 billion neurons in his brain, can conceivably make this mistake with a turtle a few hundred times his size, I can't see a spider, with a brain of a mere 100 thousand, could make such a distinction when walking on a human a few hundred thousand times its size. Tonywalton ^Talk 00:07, 3 May 2010 (UTC)

StuRat, what is your opinion of this? Count Iblis (talk) 14:28, 2 May 2010 (UTC)

(Baker's law of website design: Large fonts, too many colors strange placement of text on page == Nut-job - you don't actually have to read the text to know this with 95% certainty) SteveBaker (talk) 14:41, 2 May 2010 (UTC)

And actually, this is no place to discuss people's opinions of such things. This is a Reference Desk. --Mr.98 (talk) 20:01, 2 May 2010 (UTC)

A spiders' brain is a very tiny thing indeed. They don't have a lot of space to store all of the kinds of behaviors that might turn out to be useful. The have to prioritize. Web building - yep, that's necessary. Mating behavior - yep. Feeding - yep. Avoiding being eaten by a bird - maybe. But the probability of an individual spider being killed by a large animal is so amazingly small that the evolutionary benefit to carrying that around doesn't make it worth-while to do so. Spiders who somehow gained that ability would have to expend more energy to support the growth & maintenance of that larger brain - and (evidently) that extra 'cost' would exceed the statistical benefit. It's worth remembering that the spider couldn't "learn" this human-avoidance behavior - because the first failure means death. It also can't be taught the behavior from it's parent because spiders lack language and they don't hang out with their parents for very long. So this would have to be an 'instinctive' behavior...and that means that it has to be contained in the spider's DNA. So we're not only talking the cost of having a brain big enough - but also the cost for every cell in the spider's body of storing the "instinct".

Worse still, how many large animals actually go out of their way to kill spiders? Cows don't, sheep don't. I bet most large animals don't. That means that many species of spider didn't evolve with large spider-killing animals around them. Humans spread across the planet very rapidly in evolutionary terms - and many species are still playing catch-up. Even large, smart animals haven't evolved the necessary fear of humans. A large bear that might attack a human hasn't evolved to realise that we carry guns - or that if you do kill one of us, a posse of humans will come along the next day and hunt you down - or that if bears in general pose a problem for humans in general, we're going to round you all up and relocate you somewhere you don't want to be. Bears aren't stupid - they simply haven't had time to evolve to cope with the rapid pace of change on the planet.

A bigger question is why are you (an otherwise intelligent human) indiscriminantly killing spiders? All but a few species are harmless to us - and help keep the population of other insects (like flies and wasps) to a minimum. Flies and wasps are harmful to humans (flies spread diseases and wasps sting us). So we should perhaps ask instead: "How come large, super-smart animals like StuRat don't have an instinct to carefully avoid killing beneficial spiders?"

SteveBaker (talk) 14:39, 2 May 2010 (UTC)

That would be because, even if there's only a small risk of a spider bite, this risk isn't worth the even smaller benefit. Also, waking up with a spider crawling on you is just as unpleasant as an insect. StuRat (talk) 14:56, 2 May 2010 (UTC)

However here in the UK there are no harmful spiders at all, yet people still squash them, Perhaps people just don't like spiders. Tonywalton ^Talk 00:07, 3 May 2010 (UTC)

Some sources state that the factoid about eating spiders in your sleep is a myth, but while awake people eat more spiders and insects in food (example). As for killing spiders, there's a Russian superstition that killing 40 spiders brings a person good luck, and on the other hand some people eat fried spiders. ~AH1^(TCU) 23:47, 2 May 2010 (UTC)

@ StuRat so you don't ever do things with a small risk like driving, or crossing the road? These activities are way more risky than an encounter with a wee spider in the UK. Why not just say they frighten you because you've never taken the time to understand them. There must be a law somewhere that states that fear is directly proportional to the individual's ignorance of the feared object. Caesar's Daddy (talk) 07:57, 3 May 2010 (UTC)

I suppose you could call it ignorance, in that not knowing which spiders are harmful, we tend to just kill them all to be safe. As for driving, there's a huge benefit to driving, like allowing me to hold a job, while there's no such huge benefit to tolerating spiders on me. StuRat (talk) 13:48, 3 May 2010 (UTC)

Well, there are no harmful spiders in the UK - so if that's where you live, you can stop killing them without any additional risk. There is some benefit to tolerating them - so on balance, that's the rational thing to do. The main problem for the spiders, however, is not the rational - it's the irrational. Of course, here in Texas...not so much. We have quite a few nasty little buggers who certainly need to be squished on sight if found in your home. I've had one hand swell to twice it's normal size following a spider bite...it's no fun! But still, it doesn't take buy 10 minutes to dig out a list of venomous spiders and learn to recognize them. Brown Recluse and Black Widows get squished without a fair trial - but even so, some - like the pink-kneed tarantulas are quite magnificent animals and get treated to a half mile car trip in nice cosy box to someplace I can safely release them. SteveBaker (talk) 20:04, 3 May 2010 (UTC)

Then, of course there is Cochineal - which is an insect from which red food coloring is made. Take a look at all the foods containing "E120" - 70,000 crushed insects per pound of coloring. SteveBaker (talk) 13:41, 3 May 2010 (UTC)

Burning fat without burning muscle

Hi. I've been working hard in the gym over the last few months, and I have developed quite big arms and chest muscles. Now, I would like to burn some fat which has accumulated in my belly in order to start developing a six-pack. Which kind of exercise is best to burn fat, without burning any of my hard-earned muscles? Is aerobic or anaerobic exercise better? Should I eat before the exercise, or not (so that the body burns fat faster)?

Thanks a lot! --81.44.96.96 (talk) 09:45, 2 May 2010 (UTC)

Keep excercising but eat less calories. 89.242.97.110 (talk) 11:11, 2 May 2010 (UTC)

Fewer calories is one thing, but the source of those calories is also important. For example, you wouldn't want to cut protein, as that's needed to maintain those muscles. StuRat (talk) 12:20, 2 May 2010 (UTC)

Western eat far more protein than they need anyway. 89.242.97.110 (talk) 12:26, 2 May 2010 (UTC)

On average, yes, but we still get many people on crazy diets who don't get enough. StuRat (talk) 13:09, 2 May 2010 (UTC)

The reverse is more likely. Excessive protein is bad for you, see Protein (nutrient) 89.242.97.110 (talk) 20:44, 2 May 2010 (UTC)

(ec) No, that ("Keep excercising but eat less calories") is not the answer. The answer is, be absolutely certain to eat 0.7-0.8 grams of protein per pound that you weigh to keep your muscle. For example, if you weigh 180 pounds, then 180 * 0.8 = 144 grams of protein. That's a lot! It's equivalent to the protein from 28 egg whites per day (ie two and a half cartons of eggs). Or a steak like this. If you eat less than that while continuing to exercise, you will lose muscle, period. (Of course, the easiest way to get your protein intake may be a protein powder). Now as for losing FAT while you exercise and retain MUSCLE, yes, it is true that if you eat fewer calories you will lose weight, but that is not the right way to lose weight while keeping muscle, as your body will realize you're only getting, say, 900 calories, and you will just lose fat and muscle and everything. The correct thing to do is to keep a normal intake, say 2500 calories, including, crucially the amount of protein that I listed (150 grams, say, if you weigh 180 pounds), absolutely continue to do weight training (if you don't use your muscles, they will disappear), do this weight training, say, every 3-4 days. Then, every day, get on the elliptical machine, and use it until it shows that you have expended 3500 calories. The elliptical machine, on a fair resistance setting, is a monster at burning calories. Now, you might not FEEL like you've just burned more calories than your whole daily intake (2500) but you did: the machine does not lie, as calories are a measure of physical work (ie a physics concept) and if you've done that physical work (moved resistance) by definition you have burned those calories.

So, that is where the fat-burning comes in. Now you must keep very strictly to a 2500 calorie diet, and every day burn 3500 on the elliptical machine on a fair resistance level. At that rate, you will lose 1000 calories per day. 1 pound of fat is 3500 calories, so every three and a half days you will lose a pound of pure fat. If you continue doing this, while not stopping with either the weight training, the proper amount of protein, and the 2500 calories of real good food, you can have a real six-pack, totally toned and defined everything, etc. I have personally developed a six-pack using the above methodology and can attest to it. Hope this helps. 84.153.248.35 (talk) 12:31, 2 May 2010 (UTC)

Even for a body-builder, I don't think your protein requirements would be as high as that. Exessive protein is just used as calories. Do you have any quality independant scientific sources for the above please? I imagine the sellers of high-protein supplements are going to try to convince you that you need a lot of it. 89.242.97.110 (talk) 13:03, 2 May 2010 (UTC)

Please refer to this [14] Science Desk question regarding protein intake and "strength training", from ≈4 days ago. It has references that look "quality independant scientific". (I must admit that I answered this question!). 89.242.97.110 is quite right to ask for references, they should always be provided. Ref.Weight_lifting_and_training
♥ Recommended 'normal protein' RDA (Recommended Dietary Allowance) is 0.8 grams per kilogram of lean bodyweight (1 kilogram=2.2 pounds) ie. Higher than what you thought was a high figure! exactly the same as I provided - see below.
♥ For muscle building an intake of 1.6-2.2 grams per kilogram of bodyweight is recommended.
Aerobic exercise would be best for 'fat burning' as it can be carried on far longer than anaerobic exercise. Short, high intensity exercise is not as good at calorie burning as moderate 'long term' exercise. See also Weight Loss/Dieting--220.101.28.25 (talk) 13:38, 2 May 2010 (UTC)

Particularly see the "Fat loss versus muscle loss" Section--220.101.28.25 (talk) 13:46, 2 May 2010 (UTC)

hey, we're saying the exact same thing! You just said "For muscle building an intake of 1.6-2.2 grams per kilogram of bodyweight is recommended" and your figure of 1.6 grams per kilogram is exactly the same 0.72 grams per pound that I listed!! So my number is the same as your number, 1.6 (in per kg). Now, your range goes higher, it goes up to 2.2. grams per kilogram you weigh. That is 0.99g per pound that you weigh. Even while you are trying to really body-build and gain muscle mass, I think that is just a teeny bit too much. You won't have any use of the extra amount over 0.8 grams per pound you weigh. But the low end of your range is 0.72, just like I said (0.7-0.8), and the high end of your range, 0.99, is just a little bit over what I said. So basically we are in total agreement. The original poster can go ahead and "play it safe" and take 0.99g per pound he weighs daily, or he can follow my advice and take 0.7g-0.8g per pound that he weighs. But we both agree that any more than that and he will not benefit, and any more than that and he will lose protein. 84.153.248.35 (talk) 14:23, 2 May 2010 (UTC)

Burning 3500 kcal on the elliptical each day is absolutely insane. That would take about 5.5 hours at normal resistance. And advising our OP to sustain a deficit of 1000 kcal a day without first talking to a doctor is NOT appropriate. This is why we have the no-professional-advice rule. Btw, the RDA for protein is (as 220 says) 0.8g per kg of lean body mass. Also, a lot of the energy your body burns is through normal metabolism - see Basal metabolic rate. Zain Ebrahim (talk) 14:59, 2 May 2010 (UTC)

To the OP: to get a handle on what 84 is talking about I recommend you read Basal metabolic rate and the article on Harris-Benedict equation might also be interesting. As for your question, I suggest talking to the personal trainers at your gym. Zain Ebrahim (talk) 15:06, 2 May 2010 (UTC)

← ← @84 No real need to whisper! ;-) I think here I have seen 0.8 gm and read it as per Kg not per pound. Perhaps not a good idea to mix 'imperial' and 'Metric' quantities ie 0.8 grams per pound is not as 'scientific' as we should try to be. I was actually answering 89.242.97.110s' comment that they thought the protein requirement was too high. So yes we are basically in agreement, with the references!. Throw a few conversions in here, 800 grams (1.8 lb), 1,600 to 2,200 grams (3.5 to 4.9 lb), the upper figure does seem high! But, everyones metabolism is different. Arnie Schwarzenegger could probably, once, have done that easily. And if it's not 'used' it will just be er, 'excreted'. Wasteful.

I was mainly trying to provide references, very important here. Doesn't matter what you know/believe to be true, must be wp:verifiable! Has been some real turmoil caused by editors, in all Good Faith, giving rather wp:POV opinions.

As Zain says (beating me to it) talk to a 'pro', though I'd suggest a nutritionist/ dietician or similar. We can't give specific advice for a person, we can't even see them! Guten Nacht! 84 and all. :-) --220.101.28.25 (talk) 15:53, 2 May 2010 (UTC)

Protein (nutrient) suggests 0.8g per kg for a mature adult, and the relevant reference from there also says that extreme amounts of protein is harmful. 0.8g per kg for a person weighing 180lbs is about 65g of protein. 100g of raw peanuts contains nearly this amount according to High protein diet, but many foods in the everyday diet already contain some protein so there may be no point in deliberately eating protein-rich food as the excess is just used as calories by the body. 89.242.97.110 (talk) 20:49, 2 May 2010 (UTC)

@81.44.96.96: This Men's Health article (entitled "how to lose muscle") has some very sensible suggestions. It amounts to eat, sleep, rest, and exercise sensibly; to break any of these you'd have to be behaving fairly immoderately . Unfortunately every gym has a few people who think progress is made only by suffering. -- Finlay McWalter • Talk 17:22, 2 May 2010 (UTC)

Good advice there, Finlay McWalter. Moderation in all things. This seems a good reference for Protein intake:"Contemporary Issues in Protein Requirements and Consumption for Resistance Trained Athletes", Journal of the International Society of Sports Nutrition. 2006; 3(1): 7–27. Published online 2006 June 5. doi: 10.1186/1550-2783-3-1-7. Retrieved 3 May 2010. --220.101.28.25 (talk) 15:05, 3 May 2010 (UTC)

Take your finger out of my butt, please...

With MRI and other technologies, are we getting any closer to eliminating the highly invasive digital rectal exam and colonoscopy ? The MRI seems to carry far less risk, so that would be another advantage. What's the current limitation preventing replacement, a lack of resolution in the MRI images ? StuRat (talk) 12:25, 2 May 2010 (UTC)

If you know another way of removing prostate fluid for microcellular examination post it here! MRI doesn't resolve down to cellular level AFAIK. --TammyMoet (talk) 13:00, 2 May 2010 (UTC)

I can think of one more enjoyable way to produce prostate fluid... However, I don't believe "removal of prostate fluid" is a normal part of either of the procedures I listed as candidates for elimination. StuRat (talk) 13:12, 2 May 2010 (UTC)

DRE is obviously cheaper and easier than any kind of other technique—it takes five minutes and a greased finger, and the analysis happens "in real time" without any money spent on fancy machines or their operators. So I doubt that's going away anytime soon, even if it isn't the most fun medical procedure in the world (it's hardly the worst, though—I don't find it as bad as getting blood drawn, personally). Colonoscopy is a different thing altogether. I suspect the problem is that current MRI tech doesn't allow the fine-grained manipulation of the colon itself, or resolve in color, that makes a big difference. The colonoscopy can also remove polyps in realtime as well during the procedure, and the tissue can be analyzed in the lab later—that's handy. An MRI is going to maybe tell you there are things in there, but still require you to go in and get them. So that's not as useful. --Mr.98 (talk) 13:48, 2 May 2010 (UTC)

Is the OP's dislike of the colonoscopy procedure based on imagined or actually experienced discomforts? I tolerated the examination easily and found the experience interesting. I was able to watch my inside view on a TV screen and discuss what was going on with the nurses. I was surprised to see that the colon bore is more triangular than round, and of course am reassured that nothing untoward was discovered. The only significant discomfort came as flatulence on my way home after the colonoscopy. MRI is slow to give a result, needs a major expensive installation, and this video may persuade the OP that it has its own risks: "There are obvious potential hazards to people and equipment in the area (of the MRI)...The magnet environment under certain circumstances can be a dangerous place...Complacency can be fatal." Cuddlyable3 (talk) 14:54, 2 May 2010 (UTC)

The other thing about a colonoscopy is that you can remove tissue samples at the same time, thus removing the need for two procedures. I had an MRI scan last year, and the procedure itself wasn't unpleasant. However, the recovery took days: I was disoriented and dizzy immediately, I couldn't drive home, and I couldn't sleep properly. Comparing it with the gastroscopy I had a few years previously, of the two procedures I prefer the gastroscopy! --TammyMoet (talk) 15:36, 2 May 2010 (UTC)

TammyMoet your account is interesting because there seems to be no reliable information about persisting aftereffects of MRI. If yours was not a (rare) reaction to the contrast agent you may have been given, I would ask whether you suffer from claustrophobia. Cuddlyable3 (talk) 17:18, 2 May 2010 (UTC)

No it wasn't a reaction to gadolinum, and as I had some free time after the procedure I spent some of it on the internet looking for the cause of my reaction. It doesn't appear to be that rare, and I left my experiences on a particular website which was set up by a radiologist in the UK collecting such experiences. I don't suffer from claustrophobia. I have my own explanation as to what happened, which as it falls into an area called by some "pseudo-science" or "woo woo" doesn't belong here. --TammyMoet (talk) 18:25, 2 May 2010 (UTC)

This is NOT MEDICAL ADVICE but you might find this article by Harriet Hall over at SBM interesting. Vespine (talk) 22:39, 2 May 2010 (UTC)

According to a couple of web links I dug up on the spur of the moment, the cost of an MRI ranges from $400 to over $2500 depending on the details of the procedure. Enough said, I think. Looie496 (talk) 22:52, 2 May 2010 (UTC)

That makes it more expensive than DRE, but I don't know about colonoscopy. Googling around seems to indicate that colonoscopies range from $1K to much more depending on what is done (assuming uninsured, in the US). --Mr.98 (talk) 23:38, 2 May 2010 (UTC)

CT and MRI are being evaluated as alternatives to colonoscopy (see virtual colonoscopy). There several significant limitations, however. For one, they're newer technologies, so we don't have studies showing that they are good screening methods (do people undergoing CT colonography have a lower mortality rate after 20 years? 30 years?). Also, the resolution is not nearly as good as direct visualization. CT involves ionizing radiation. MRI is quite expensive and wouldn't really afford a cost savings over colonoscopy. One of the major drawbacks is that the patient still must drink the preparation the night before (and in my experience, the part about colonoscopies that patients usually dislike is taking the preparation, not the procedure itself), so the virtual colonoscopy isn't necessarily more comfortable than actual colonoscopy. And then, finally, imaging studies have no way to obtain samples (until we develop a Star Trek–style transporter), so if there is any abnormality seen, the next step is to to a full colonoscopy (and another round with the preparation). Since polyps are seen on a fair number of colonoscopies, this would mean that a number of people would have to undergo two preparations and twice the expense. Regarding the digital rectal examination, it's fast, cheap, and safe. It's going to be very difficult to develop a replacement procedure. — Knowledge Seeker দ 00:17, 3 May 2010 (UTC)

soy

it seems overnight every fast food place in America switched to soybean oil and soy flour ect. im allergic to soy. what am i supposed to do? —Preceding unsigned comment added by Tom12350 (talk • contribs) 13:30, 2 May 2010 (UTC)

Cook yourself, or don't eat fried food, or eat at a restaurant where they use different ingredients. Or perhaps you can desensitize yourself. Graeme Bartlett (talk) 13:41, 2 May 2010 (UTC)

Might this constitute medical advice? Consult with a physician to determine what would happen if you eat soy from a fast-food restaurant. If the consequences are serious (and we aren't qualified or able to tell you), then you should not eat at fast food restaurants (or anywhere that you can't verify soy-free ingredient lists). Nimur (talk) 13:43, 2 May 2010 (UTC)

not just fast food places use soy every restaurant does including places like chilies tgf Fridays, moes ect. they also put it it hot pockets. —Preceding unsigned comment added by Tom12350 (talk • contribs) 13:47, 2 May 2010 (UTC)

Yes, eating prepackaged foods will require reading the label carefully for soy/soya. Making foods from scratch, like cutting up potatoes and frying them yourself, using an oil you choose, is a lot safer. StuRat (talk) 15:03, 2 May 2010 (UTC)

They will have made a decision based on profit margins. What you can do is write to them and explain that this means you can no longer eat there, since they do not offer a safe option for you. You can alert friends and family to your inability to eat at these places, so social events are held elsewhere (maybe someone's house): any enthusiastic friends might be encouraged to write to these places and explain that they are no longer able to hold their social events there, since they do not offer a safe option for you. Essentially, you make it clear to the companies that this decision has lost them custom. They might still consider it a good decision (who knows how this affects their profits), but you are adding weight to the other side.

I do sympathise: I've lived most of my life with someone extremely allergic to peanuts, and this sort of thing can accumulate. Luckily, things have changed over the years so that companies consider it in their interests to warn for nuts and peanuts, and some companies work hard to offer safe options precisely because there is a market for them. But eating out is still difficult, and always subject to change.

And, I hope it doesn't need saying, but absolutely do not follow Graeme's advice to attempt desensitizing yourself: people have died doing that. Any attempt at exposing yourself to something you are allergic to should be carried out under medical supervision, as advised by a doctor, so that you can be treated and even resuscitated if needed. 86.178.225.111 (talk) 15:08, 2 May 2010 (UTC)

My daughter has a sensitivity to both soy protein and cow milk protein, so I can sympathize. Who knew that virtually all brands of hot dog weiners have milk in them? Not I, until I had to start reading the labels on frigging everything. We have an article on soy allergy which helpfully contains a list of additives that do or may contain soy. Hope that helps. Some fast food places list ingredients and nutritional information on their websites, but beware of corporations that just don't give a crap about your health and lie to you. Matt Deres (talk) 01:24, 3 May 2010 (UTC)

Deepest part of ocean

Mariana Trench says that "[it] is the deepest known part of the world's oceans". I would like to know:

1. What are the odds that there is a deeper part? (I admit that this can be seen as inviting wild speculation, but perhaps it can be quantified based on the percentage of as yet unsurveyed area.)
2. I understand that the entire World Ocean has been measured from space using gravity-based algorithms, but would this be accurate enough to detect narrow trenches?
3. If not, would finding a deeper part be down to essentially luck or are there ongoing efforts to systematically measure the entire World Ocean? (I believe various navies were quite active in this respect in the 1960s but they probably have better things to do now.)

Thank you in advance. 83.81.60.233 (talk) 15:35, 2 May 2010 (UTC)

Trenches are formed by subduction zones, hence they are very special parts of the sea floor. Common sea floor is much shallower. Given that we know pretty well where all the subduction zones on this planet are and that there is great interest in studying them in detail, I would guess that it is pretty certain that the Mariana trench is the deepest part of the ocean without actually knowing what fraction of the general sea floor has been measured. --Wrongfilter (talk) 16:31, 2 May 2010 (UTC)

We have actually had quite accurate maps of the sea floor for fifty years, after the advent of Side-scan sonar. Widespread seafloor mapping was what led to our modern understanding of plate tectonics. It is highly unlikely that a large seafloor feature on scale with the Mariana Trench would have been missed by this point. --Jayron32 00:42, 3 May 2010 (UTC)

All the trenches are known, e.g. Oceanic trench#Major oceanic trenches. They are hundreds or thousands of kilometers long, and not easy to miss given even cursory surveys of the ocean floor. However, finding the specific deepest point in a given trench requires detailed mapping. I wouldn't be shocked if there happened to be a spot in one of them that was a little deeper than Challenger Deep (the deepest known part of Mariana), but the longer that record stands the less likely it becomes that we will find anything deeper. Dragons flight (talk) 05:19, 3 May 2010 (UTC)

More to the point, the size of such a place would have to be very small in order to evade our surveys - there comes a point where you'd have to be talking about a narrow crack or hole smaller than the precision with which we're surveying the ocean bottom.

If we found a five centimeter wide crack that went down deeper than Challenger Deep - would we count that? What about a one meter wide cave that wiggled down deeper - would that count? Assuming the answer to that is "No" then it's safe to say that Challenger Deep is the deepest spot of any reasonable size - and that we won't find anything that big and that deep in the future. Of course, these ocean trenches are extremely geologically active (that's why they are the way they are) - so it's quite possible that some future submarine earthquake could open up a deeper spot - or perhaps even fill the deepest bit with lava or an avalanche and thereby make some not-so-deep place become the new record holder. On balance though - I think it's pretty safe to say that Challenger Deep is truely the deepest spot within reasonable criteria. SteveBaker (talk) 13:35, 3 May 2010 (UTC)

Also, it's not clear whether it would be possible to have a tiny (e.g., 5 cm wide) crack that extended several kilometers in depth. Material properties of rock and sediments don't favor such an unstable structure. (If it existed, it would soon cave or deform and fill in). This is another reason why we don't expect such features except in large-scale subduction zones. Nimur (talk) 14:39, 3 May 2010 (UTC)

The important points have been touch on, but to add one thing, space gravity surveys can and do resolve trenches - they are still several tens of kilometers wide, much larger than the resolution of the free-air gravity maps. Awickert (talk) 17:14, 3 May 2010 (UTC)

5 cm? We don't even have maps of most of the Earth's dry surface that are that well resolved. The best available maps of most of the deep ocean are about 1-5 square km per pixel. As high priority targets, the trenches may be better mapped than that (though extreme depth also makes it harder to get good resolution). However, in general I think you are being overly optimistic about how well surveyed the oceans are. Could a canyon or fissure be hiding down there? Certainly. Are any deep enough to matter? Perhaps not. Dragons flight (talk) 18:45, 3 May 2010 (UTC)

Activating the Deepwater Horizon blowout preventer

Is there some intrinsic reason why this has been so difficult so far? Couldn't a blowout preventer be designed for wireless activation -- just press a button on a command ship and it stops flow? Or is there some fundamental reason that this is not an option when designing these things? Vranak (talk) 17:20, 2 May 2010 (UTC)

Wireless signals (radio) does not work under water. Radio waves are pretty much totally blocked by seawater. But take a look here - there are acoustically activated devices, since sound travels pretty well. Ariel. (talk) 18:39, 2 May 2010 (UTC)

Wireless signals do work under water, but not well. They are used to communicate with submarines: [15]. --Phil Holmes (talk) 10:26, 3 May 2010 (UTC)

My understanding of this event is that any such equipment on the rig itself would have been destroyed in the initial large explosion, subsequent fires, and the sinking of the rig's wreckage, and that no such intact and working equipment is still in place on the seabed, even if it was there in the first place, bearing in mind that at the time of the blowout the well was being modified rather than being in routine production. 87.81.230.195 (talk) 21:39, 2 May 2010 (UTC)

When the rig blew up, that did sever the communications with the preventer, but within the first 48 hours there were remotely operated subs at the site trying to trigger it. Apparently, the preventer isn't closing even when told to do so. Failure to activate, even when told to do so, indicates a more fundamental problem than just a communications issue. Dragons flight (talk) 22:11, 2 May 2010 (UTC)

Thanks very much guys. Vranak (talk)

Bacon curling

Why does bacon curl up when you cook it on a grill? I presume it'd be due to drying out, so there's less hydrolysed protein and thus curling would occur (the opposite to when your hair gets straighter when you shower) but I'm not sure if that's the actual reason. Regards, --—Cyclonenim | Chat  20:39, 2 May 2010 (UTC)

I don't know chemically what's happening but I've cooked a LOT of bacon I have thought about it so I'll tell you what I've observed:) I believe it is not the "meat", not the fat and not the rind that causes the curling, I think it is the sinewy connective tissue between the fat and the meat. I think it shrinks when it cooks and this is what causes the curling. I bake my bacon now because I like it really crispy and it's much easier IMHO in the oven and curling doesn't matter so much. But when I used to fry it, there was 3 spots on the bacon, where the fat "meets the meat" that I would cut through to stop it from curling. Vespine (talk) 22:29, 2 May 2010 (UTC)

I am pretty sure the curling comes from differential heating of the bacon. As noted, bacon consists of at least 3 different tissues: fat, meat, and connective tissue. All three of these will cook at different rates, and as they cook will contract or expand at different rates. Also, when you fry bacon, you set up a LARGE temperature differential, as the part of the rasher in contact with the pan is a LOT hotter than the rest of the bacon. Since baking bacon tends to evenly distribute the heat over all parts of the rasher, there is less curling. They make a device called "bacon press" designed to counteract this curling; you see them alot at diners where they make a lot of bacon on a griddle. See this Google Image search which shows you the many different styles of bacon press. The ones I have seen most often look like heavy rectangular trowels, but they come round and pig shaped as well. --Jayron32 23:56, 2 May 2010 (UTC)

I agree with Jayron; it's the temperature difference. And forget using a "bacon press" - cook your bacon on a cookie sheet with a rack. Place the bacon in a cold oven, set the thermostat for 400F, and cook until done (time will depend on thickness). Yum! Matt Deres (talk) 01:30, 3 May 2010 (UTC)

I endorse the oven method, and I'll add that the oven temperature is not at all critical... anything from 325–425 F works (at least), so if you're baking something else, you can probably throw the bacon in and it will be fine. The cooking time will, of course, vary with temperature. I've read that higher temperatures result in more bitter-tasting compounds, so I tend to use the lower end of the range, but I'm not sure it actually makes much difference. -- Coneslayer (talk) 13:11, 3 May 2010 (UTC)

To be honest the actual curling has never caused me any bother :P I tend to just grill mine plain and simple -- comes out curled but very tasty. Thanks for all the interesting answers. Regards, --—Cyclonenim | Chat  14:49, 3 May 2010 (UTC)

Electron excitation - discrete?

In A level physics, we are taught that an electron can be excited to a higher energy level by means of absorbing a photon, on condition that its energy exactly matches the energy difference between the levels. This makes sense, there doesn't seem to be a mechanism for where the "excess" energy goes. However, this can't really be correct, surely? I mean, you could never get it exactly the same. And this sort of thing happens all the time in the real world (e.g. in fluorescent tubes' outer coating). What actually happens? (Unusually, excited state seems to be written for the layperson, and hence fails to approach the issue.) 92.23.14.145 (talk) 20:43, 2 May 2010 (UTC)

I'm by no means a trained physcist so I'll let others rip apart my answer in due course, but this seems to me like just a fallacy in human logic rather than questioning whether it's actually true or not. "...get it exactly the same" - There is no "getting", there are stupidly large numbers of photons (and electrons) around, the chance of some being of the same energy is, I imagine, pretty high. Also, because energy is distributed in packets (quanta), the possibilities are slightly limited as the energy values have to be a certain factor of some constant (someone remind me which?). Regards, --—Cyclonenim | Chat  00:20, 3 May 2010 (UTC)

Ok, so in A level physics you have learned that atoms have precisely defined energy levels and that transitions between these levels are possible by absorpion/emission of photons which in this picture would ahve to have exactly the energy difference between the energy levels. You have correctly noted that this picture cannot be exactly correct.

What is wrong with this picture is the idea that an atom can both have an infinitely precisely defined energy level and be in a state that changes as a function of time. The precisely defined energy levels only appear if you ignore the coupling of the atom to the electromagnetic field. If you take this approximation serious then the atom cannot make any transitions as no interaction with the electromagnetic field means that it will not interact with photons at all.

The moment you take into account the fact that atoms do in fact couple to the electromagnetic field, then what you see is that the "energy levels" are no longer states with a precisely defined energy. The spread in energy of a state is inversely proportional to the spontaneous decay time of that state. One can heuristically unbderstand this using the time-energy uncertainty relation.

In practice this means that atoms can absorb photons that are within the the energy spread. Now this energy spread is quite small, but then each atom will have some random velocity causing its energy levels to appear to shift due to the doppler effect. This causes a gas of atoms to be able to absorp photons of a larger range of energies. This is called doppler broadening. Count Iblis (talk) 01:29, 3 May 2010 (UTC)

It's also worth pointing out that it is quite possible for photons of exactly the right energy to exist. Where the electromagnetic radiation (typically light) is created by an incandescent source (i.e. one that uses heat to produce the light), then the light produced is a broadband of every wavelength within the band. So the atoms only absorb the light whose wavelength exactly matches their energy gap. Hence Spectral line. --Phil Holmes (talk) 09:39, 3 May 2010 (UTC)

hot water

recently my hot water tastes and smells like scouring powder. my cold water is fine. can someone explain this? —Preceding unsigned comment added by Tom12350 (talk • contribs) 20:57, 2 May 2010 (UTC)

It might help someone to answer if you give some details about how your particular hot water system works: mains-fed instant gas heater, electrically heated hot water cylinder, hot rocks in a leather cauldron? (OK, the last isn't very common these days.) 87.81.230.195 (talk) 21:26, 2 May 2010 (UTC)

its a hot water heater tank. heated by either gas or electricity. —Preceding unsigned comment added by Tom12350 (talk • contribs) 22:12, 2 May 2010 (UTC)

The hot tap water in your tank may contain extra chemicals to treat the water. ~AH1^(TCU) 23:35, 2 May 2010 (UTC)

It may be water softeners? --Jayron32 23:43, 2 May 2010 (UTC)

That would be my guess, particularly if they just added a new batch of salt to the water softener or if it's been sitting for a while unused. Under those conditions you can get excess salt in your water. If the water softener is hooked up after the water heater, try bleeding some water directly off the hot water heater to see if it's good. If so, that would seem to implicate the water softener. It could just be a bad batch of salt in there, which isn't sufficient compacted, and thus dissolves too readily in the water. StuRat (talk) 01:53, 3 May 2010 (UTC)

"The magnesium corrosion control rod present in many hot water heaters can chemically reduce naturally occurring sulfates to hydrogen sulfide." [16]. You can change the rod to aluminium (they just unscrew out, although it might be hard to do in an old tank), or add a carbon filter before the water. If you choose a filter make sure you get one designed for it - otherwise it will clog up very fast. Ariel. (talk) 02:18, 3 May 2010 (UTC)

Infrared rainbow

Yesterday I took a near-infrared picture of a double rainbow. As expected, the two arcs are displaced towards each other relative to a visible-light rainbow. Is there a frequency at which the two arcs merge, and if so, what is it? --Carnildo (talk) 21:21, 2 May 2010 (UTC)

This region is called Alexander's band, and is discussed in both that article, and in the article Rainbow. Presumably, there will be some point at which the wavelengths of light from the two bows are identical as they pass one another; however I see no reason why this overlap point would be identical for every rainbow; it may be unique for each observer. --Jayron32 23:42, 2 May 2010 (UTC)

I can't see any reason why the overlap point wouldn't be the identical for every rainbow. The critical angles for total internal reflection are determined by the properties of water and air, I believe, which are essentially constant (on Earth, at least - other planets, eg. Titan, have different angles). --Tango (talk) 01:28, 3 May 2010 (UTC)

The two rainbows may very well never meet since the refractive index of water is not a monotonic function of the light's wavelength. Dauto (talk) 04:48, 3 May 2010 (UTC)

May 3

Plutonium

In the Simpsons, Homer's bag has plutonium in it and the police dynamite it, causing a nuclear explosion. Would this happen in real life? --75.33.219.230 (talk) 00:13, 3 May 2010 (UTC)

It wouldn't cause a nuclear explosion, but it would disperse toxic plutonium into the air. Think dirty bomb, not nuke. A decent real-life analog would be the 1968 Thule Air Base B-52 crash. Messy and expensive to clean up. Few if any immediate deaths; maybe some long-term health problems if plutonium was inhaled. Bad, but not as bad as a full nuclear explosion. (Making plutonium detonate in a full nuclear explosion is not easy—see Fat_Man#Technology for a decent description of why.) --Mr.98 (talk) 00:45, 3 May 2010 (UTC)

To explode a nuclear bomb you need to have enough material in one piece to reach the critical mass for the element. That's more or less it. The trouble is that when you have anywhere near that amount it starts to get really really hot and radioactive. So what you go is make a number of small pieces, and when you need it to explode shove them all together into one piece (like imagine a pizza, pull all the slices apart, then when it's time to explode push them all back together into a circle). Just exploding the plutonium will not make a nuclear explosion - it will just send plutonium everywhere, which will do exactly the opposite, since now you have lots of small pieces instead of one big one. Ariel. (talk) 02:26, 3 May 2010 (UTC)

This is not, in fact, how plutonium bombs work (so far as we know), but is a common misconception. Plutonium weapons use a solid piece of plutonium that is then compressed to a a high density. If you split plutonium into multiple pieces and then tried to combine it, you would have a fizzle, because the combination speed would be slower than the reaction speed. Nuclear weapon design has more detail on implosion physics. It is not the "small pieces" model, though this is often how it is erroneously explained in textbooks or encyclopedias (but not Wikipedia). --Mr.98 (talk) 12:02, 3 May 2010 (UTC)

Ummm, actually that is how Gun-type fission weapon operates. Implosion types mentioned above are more powerful, and are most likely the design used by the developed nuclear powers. Googlemeister (talk) 14:10, 3 May 2010 (UTC)

The article you linked to says plutonium CANNOT be used for gun-type fission weapons. --99.237.234.104 (talk) 20:15, 3 May 2010 (UTC)

From my reading it was because of the Pu240 impurities that were not removed in 1940s technology plutonium enrichment (with results similar to Helium 3 contamination), not that it was an inherent property of plutonium itself. Perhaps even with today's production methods we still can not remove the 240, or it is not cost effective? Googlemeister (talk) 20:55, 3 May 2010 (UTC)

Voice

I was wondering, hypothetically, if is it possible to prevent a boy's voice from breaking at puberty. I saw something on TV that put this question in my mind. Of course, I mean without surgeries, medications, etc. Thank you. 76.230.212.190 (talk) 01:07, 3 May 2010 (UTC)

I think you have ruled out the two methods that would work. Castration works (see Castrato for a description of precisely that) and I would expect hormone treatments (well, some kind of hormone suppressant) to work too. I can't think of any other way to do it. --Tango (talk) 01:31, 3 May 2010 (UTC)

(e/c) You'll need one or the other, unless the boy just happens to naturally keep his boyish voice - rare, but not unheard of. See our article about castrati and Kallmann syndrome for a semi-natural way this sometimes occurs. Matt Deres (talk) 01:34, 3 May 2010 (UTC)

You're missing another possibility: Don't speak for the entire length of puberty. Then your voice wouldn't break "at puberty". Of course, it'll probably break constantly when you start speaking again due to atrophy from disuse, but you didn't ask us to solve that problem. —ShadowRanger ^(talk|stalk) 20:56, 3 May 2010 (UTC)

Joke aside, voices crack for a lot of reasons. Puberty makes it nearly inevitable that it will occur sometimes, but you can do things to reduce the frequency. Tensing up makes cracking more likely, so try to relax. Cold water can temporarily constrict the vocal chords, so don't speak for a few seconds after taking a sip of ice water (or drink lukewarm or room temp water). The longer you speak, the drier your throat will get, increasing cracking, so you should drink, just avoid the really cold stuff. You can find other examples online; these tips are generally useful to public speakers of all ages. —ShadowRanger ^(talk|stalk) 20:56, 3 May 2010 (UTC)

River Geometry

There are rivers with various depth and width of flow.How do these parameters get fixed in the nature.Which laws of nature governs them ?.Are there any mathematical relationships? —Preceding unsigned comment added by Amrahs (talk • contribs) 02:23, 3 May 2010 (UTC)

I would assume the depth is related to how hard the material on the land is - soft earth will wash away and make a deep river, while rock won't (at least at first, the longer the river runs, the deeper it gets). The width of the river is related to the topology (elevations) of the land. Gentle hills will make a wide river, steep ones will make a narrow ones. Next the amount of water in the river depends on whatever is feeding that river. Once you know the amount of water, and the size of the river you get the flow rate. See Meander for information on why rivers make those strange winding shapes, it's quite interesting. Ariel. (talk) 02:29, 3 May 2010 (UTC)

Oddly enough, Wikipedia has an article that covers much of this, in some detail. See River. WHAAOE! --Jayron32 03:47, 3 May 2010 (UTC)

There is some maths or 'laws' associated with the branching of rivers, but I do not recall where to find it. 92.28.253.63 (talk) 11:02, 3 May 2010 (UTC)

Rivers are also somewhat fractal in nature, meaning that the rivers are similar to the rivulets which feed them, which are in turn similar to the creeks which feed them, other than scale. StuRat (talk) 13:20, 3 May 2010 (UTC)

Some of the early fractal work was developed by some colonial English engineer whose name I forget, H.... I think, who collated and studied time series for the periodic flooding of the Nile. Edit: it was Harold Edwin Hurst. 92.28.253.63 (talk) 15:22, 3 May 2010 (UTC)

Most of the properties of a river depend on its sources, the distance it has to travel to get to the sea - and the nature of the terrain in between. The ultimate source of a river is rainfall or snow-melt on high ground someplace. Because the water has run downhill, it tends to gather together to make small streams - and those streams merge to make a river. Because the water can only flow downhill, it will fill in hollows in the land to make ponds and lakes - and generally run down the bottoms of valleys. The nature of erosion means that over geological time, the river will make it's own valleys by wearing away the soil and rock and carrying the resulting sandy stuff down-stream. Rivers also get twisty because if (for example) there is a large, hard rock on one side of the river bed - it'll deflect the water off to the side, towards the other bank. If that bank is softer, it'll get eroded - allowing the river to make a diversion around the rock. That diversion points the flow of the water towards another bit of ground - and that too erodes.

These processes are sufficiently complex - and so sensitively dependent on things like precisely where a particular (now completely eroded) rock was half a million years ago - that although we understand all of the processes very well, and can make pretty good mathematical models - we can't predict the precise shape or flow rate of any particular river from first principles.

SteveBaker (talk) 13:24, 3 May 2010 (UTC)

Isnt that all obvious? 92.28.253.63 (talk) 15:20, 3 May 2010 (UTC)

Although most of what Steve says is pretty much correct and very straightforward, I will disagree with him on two counts. I think that we can pretty well figure out what shape a river will have (braided, meandering, etc.) based on a combination of bank cohesion, sediment flux, and aggradation rate. And although what Steve says about being deflected around rock and boulders is probably correct in itself, it is not generalizable in that way. Meandering in itself is actually a self-forced phenomenon by which any irregularity in the channel will cause the flow to become nonuniform and focus high shear stresses in one location and lower ones in the others. This in turn focuses zones of erosion and deposition in a positive feedback that gives the meandering river patterns that we see. (Likewise, this gives the patterns of bars in braided streams.) Awickert (talk) 20:48, 3 May 2010 (UTC)

There's a useful introduction to fluvial geomorphology here [17]. DuncanHill (talk) 13:27, 3 May 2010 (UTC)

(outdent) I actually work as a sedimentologist / fluvial geomorphologist, so I might be able to help!

1. First, the river article is really bad in terms of geomorphology and doesn't mention hydrology much. Fixing it up has been on my mental to-do list for a while, but you know how those things go...
2. River channel morphology is controlled by events that are large enough to move sediment and/or erode the bed or banks. Most flows do not change the channel.
3. There are downstream relationships (empirically-derived) that give the depth, width, and slope of rivers as a function of discharge. See river regime. But this doesn't answer your question.
4. The width of a river channel with noncohesive/nonvegetated banks is given by a critical value of shear stress against the channel banks. If the river is narrow (relative to the difficulty of its flows to carry bed sediments), the shear stresses on the channel walls will be higher than a critical value to move these sediments. Therefore, the banks will erode. But as a channel widens, bank shear stresses decrease. If it overwidens, this will result in deposition on the banks. This is how a channel maintains its width as well as its width:depth ratio. There are a whole ton of theoretically-sound (i.e., not just empirical) equations that describe this, but the end product is what I wrote here.
   • This changes with the application of bank cohesion (e.g., vegetation), but the same principle applies. It is just much harder to erode the banks, so the flows are deeper and narrower.
5. An endmember of bank cohesion would be a bedrock channel, and results in a completely different morphology because bedrock channels are sediment-supply-starved. Here, the channel is able to incise a deep canyon (much deeper than its flow depth) because it erodes its bed, but doesn't have a sufficient sediment supply for much deposition to occur.

Hope this helps, Awickert (talk) 17:34, 3 May 2010 (UTC)

space-time continuum

Do anybody 'feel' the 4-dimensional space-time continuum in everyday life? —Preceding unsigned comment added by Amrahs (talk • contribs) 02:28, 3 May 2010 (UTC)

Space time? Then yes - everyone. 3 dimensions space, 1 of time. Do you mean 4 space dimensions? Then no. Ariel. (talk) 02:32, 3 May 2010 (UTC)

If you're talking about 4 spatial dimensions (plus time), then the question is a slightly tricky one. Obviously nobody directly perceives anything more than 3 spatial dimensions, but if string theory is correct and we actually have over a dozen dimensions - then in a sense, the mere existence of everything around us would be a consequence of all of those dimensions - and because we 'feel' all of those things, we are all feeling the consequences of those additional dimensions. String theory claims that these extra dimensions are "small" so we can't detect them. Think of this as being stuck inside a long, narrow tube - the length of the tube allows use to move freely along it - but it's so narrow that we can't move sideways or up and down. In this situation, we have one 'large' dimension, and two 'small' ones. Of course, in such a situation, we can see the sides of the tube and be aware of their proximity because even though those dimensions are small, they are still larger than our bodies. But the extra dimensions in string theory are very small indeed - much, MUCH smaller than the size of an atom. So small, that we don't even notice that they are there - and so small that we have been unable to devise a means to measure or even detect them. SteveBaker (talk) 13:13, 3 May 2010 (UTC)

Isopropanol, Peroxides can Result in Explosion & Injury?

i was reading the article on here and it says Isopropanol can form Peroxides? i keep my bottle with out the cap on. does that help? how can i test for peroxides? also if it forms them wouldent that make it caustic? i use it on my skin. —Preceding unsigned comment added by Tom12350 (talk • contribs) 03:03, 3 May 2010 (UTC)

See Peroxide, especially the safety section. I am not sure isopropanol itself is much of a problem, but acetone can spontaneously form acetone peroxide and many ethers can form ether peroxides. It generally takes a pretty powerful oxidizer to oxidize an alcohol to a ketone, but from the ketone or ether to a peroxide, something as simple as excess oxygen and a radical initiator, like UV light, could do it. You could also run into serious trouble if you mix ANY organic compound with hydrogen peroxide, and many households have both hydrogen peroxide and several common organic compounds together. Not sure it's a huge problem in your bathroom cabinet, but it may be. --Jayron32 03:45, 3 May 2010 (UTC)

Here's the article, if anyone's interested: Isopropyl alcohol. The sources cited for the peroxide claim include a materials safety data sheet [18] and an incident report [19]. The MSDS claims that it "may react with oxygen in the air to form peroxides", while the incident report claims that "The probable cause of this explosion/injury was peroxide formation associated with Isopropanol, perhaps accelerated by grease metal/solvent reactions". It further elaborates that "Literature review indicates that Isopropanol, with air contact, can develop peroxides, which can explode when concentrated". However, the big thing to note in the incident is that the isopropyl alcohol was concentrated overnight, making a probably insignificant concentration of peroxides into an explosive concentration. Jayron's probably right that it's hard to oxidize isopropyl alcohol to acetone, so the concentration of peroxides built up in most cases will be extremely low. However, the moral of the story is:

1. Keep your isopropyl alcohol in a closed container, and don't open/close it frequently.
2. Don't concentrate any potential peroxides by allowing a large amount of isopropyl alcohol to evaporate.
3. If you are going to concentrate or heat the alcohol, test for peroxides first.

I don't think it's a big deal for households with isopropyl alcohol: if it was, we'd hear a lot more about it. This incident had a lot of factors that made an explosion possible (keeping it uncovered overnight, evaporating it to concentrate peroxides, and heating), none of which should be present at home. Furthermore, when reading the incident report, it appears that even the suppliers and lab workers were unaware of the danger, indicating that it doesn't happen very often, even under these more favorable conditions. Buddy431 (talk) 05:31, 3 May 2010 (UTC)

Before big bang

What was there before big bang ????????? --Extra999 (Contact ^me + _contribs) 10:50, 3 May 2010 (UTC)

A black hole according to an article "It's black holes all the way down" by Ben Gilliland in the Metro (Associated Metro Limited) of 30 April 2010, pages 22-23. It mentions an URL www.cosmonline.co.uk but I have not been able to find it yet. dit: You could see it here http://e-edition.metro.co.uk/home.html but it requires giving an email address (which is not verified). In the e-edition, its on pages 24-25. 92.28.253.63 (talk) 11:03, 3 May 2010 (UTC)

What was where before the Big Bang? --KägeTorä - (影虎) (TALK) 11:12, 3 May 2010 (UTC)

In fact, there may not even be a "before", as both time and space came into being at the big bang (but that's only one possibility, per A Brief History of Time). --Stephan Schulz (talk) 11:40, 3 May 2010 (UTC)

See also (seriously) Turtles all the way down, which does discuss the issue. --Jayron32 12:13, 3 May 2010 (UTC)

I usually respond with the question: "What was there bewhat the Big Bang?" :-) - DVdm (talk) 12:35, 3 May 2010 (UTC)

There are quite a few possibilities - and we don't know which is true, and (worse still) there are reasons to believe that we may not ever be able to know which is true. Certainly one possibility is that both time and space were created at the instant of the big bang - hence there is no "before" and no "there". Other possibilities are that the universe is cyclic with big bang leading to expansion, then slowing, then collapse and finally a big crunch that would be the source of the next big bang. Another possibility is that the universe is symmetrical in time - with the history of the universe being played out backwards before the big bang. Right now, most of this stuff is speculation. The best answer is "We don't know" - and I'd say that Occam's razor suggests that time and space both started at the big bang - so there simply was no "before". This is hard to get your head around - but there is no guarantee that physics will be readily comprehensible to human minds. SteveBaker (talk) 12:52, 3 May 2010 (UTC)

The other posibility is that the big bang represents a sort of "cosmic censorship" (see cosmic censorship hypothesis) in that, since it represents a singularity, that is everything is in the same place at the same time, there is no means of extrapolating anything earlier than the point of the big bang, meaning that while we may idly speculate as to what (or when) anything (or anytime) existed before the Big Bang, its moot because the nature of the big bang makes it impossible to verify any hypothesis about what may have existed before it. --Jayron32 12:56, 3 May 2010 (UTC)

A big mind-boggling question is why is there any universe(s) rather than just nothing. 92.28.253.63 (talk) 16:37, 3 May 2010 (UTC)

Depends on what you mean by why. If you mean "what processes brought the universe about instead of nothing happening at all" then see anthropic principle. At worse, its a meaningless question because we are here to ask the question in the first place, if the universe did not exist, there would not be an us to question why it did not exist. If you mean "for what purpose was the universe created instead of leaving behind nothingness" then you are starting to veer into territory that religion or philosophy rather than science is equipped to answer. Immediately below this post, SteveBaker will come saying that science is perfectly well equipped to answer questions of grand purpose, and then give no qualifying statement, or propose any experiment or method which would show how science could answer such questions. --Jayron32 18:25, 3 May 2010 (UTC)

Human centipede - possible in real life?

Apologies in advance if this question causes you to consider concepts that you'd rather not have considered...

In the movie The Human Centipede, the mad doctor character creates the titular outrage against nature by attaching three people together by their digestive systems (i.e. sewing person B's mouth to person A's anus, then person C's mouth to person B's anus - the idea being that it is then sufficient to feed only person A, with B and C being nourished by poop and second hand poop, respectively). Nasty, huh?

Now, the movie advertises itself as '100% MEDICALLY ACCURATE!' (granted, which may be one of those standard horror movie marketing things intended to further disturb the audience) and the director says that he actually consulted with a top surgeon to design a feasible series of operations by which the human centipede creation could be accomplished.

Question is this (for the medically-qualified here, mainly) - quite simply, would someone *really* be able to do carry this out in real life? If so, how long would the human centipede realistically be able to survive and what sort of medical complications might arise? I'd imagine that there would be a whole host of things that could go very badly wrong, very quickly.

I do hope that my question doesn't fall afoul of the RDs 'no medical advice' rule... :) --Kurt Shaped Box (talk) 12:24, 3 May 2010 (UTC)

Coprophagia ——but this not address the nutritional value to humans, which I suspect is inadequate. Graeme Bartlett (talk) 12:29, 3 May 2010 (UTC)

Just as an aside, I really was expecting that article to contain an user-created image of a man eating faeces. --Kurt Shaped Box (talk) 12:37, 3 May 2010 (UTC)

Apologies if you are a lady coprophagiac for the Male chauvinism exhibited by the above poster. Cuddlyable3 (talk) 20:58, 3 May 2010 (UTC)

As with many "based on a true story" films, there is no requirement for any claims the films make about their own accuracy to be true. Vimescarrot (talk) 12:51, 3 May 2010 (UTC)

The professional in the article you linked to mentions the necessity of an IV drip, essentially making the whole procedure redundant (you're just pointless making faeces go through two more digestive systems to no effect - you may as well attatch a fifty-foot tube to Person A's anus). Obvious complications would be the myriad diseases you can pick up from excrement (cholera is my first thought, there are dozens more) and, without an IV drip, malnutrition. Vimescarrot (talk) 12:58, 3 May 2010 (UTC)

The key phrase here is "based on" - meaning that they started with a perfectly normal story with nothing unusual or unexpected about it - and blew it out of all proportion. If you imagine a real-life doctor who did a study on the efficiency of the human gut and discovered (not unreasonably) that some percentage of nutrients remained on excretion. A movie "based on" that true story could certainly contain this much nonsense. Sadly, there are no legal requirements for the correctness of movie blurbs! SteveBaker (talk) 13:01, 3 May 2010 (UTC)

I bet there is some implied legal requirement for a movie advertisement to be accurate, as with other ads. If they put out a blurb for a movie claiming it's a kid's movie and it's really a porno, I think they could get in trouble, for instance. The movie Kindergarten Cop seemed close to that line, being advertised and titled as if it were a cute kid's movie, but actually being a violent movie no child should see. StuRat (talk) 13:09, 3 May 2010 (UTC)

(after ec)Thanks for the answers so far, guys. FWIW, I don't believe that it was ever stated that the movie is 'based on a true story' - just that the director asked a surgeon how *he* would go about sewing three people together, ass-to-mouth, if he was an insane doctor... --Kurt Shaped Box (talk) 13:10, 3 May 2010 (UTC)

Since most the nutritional value has been removed after the first run, starvation would be an issue for the 2nd person and even moreso for the third. A more realistic way to have one person medically feed others might be to splice their circulatory systems together, although this would require compatible blood types. If only one person was fed, they would then get hungrier, because much of the nutrition would be used by the other people. In this way, it might be similar to having a tapeworm. The other people, who would be denied food, would still be hungry due to an empty stomach, but might not starve, if enough nutrition was received through the shared blood. The person who does eat might eat 3x the normal food and still not gain weight. Have I just invented a new fad diet ? :-) StuRat (talk) 13:05, 3 May 2010 (UTC)

I haven't seen the movie, but the article on it seems to imply that the nutritional needs of the people are not met and that one of them begins to suffer from blood poisoning as a result of the arrangement. That sounds about right to me. Not only would the nutritional value of feces be very low, it would be full of all sorts of gut flora that is quite toxic to humans, and not nearly enough water to survive on. Person #2 in the conga line would probably get quite sick, which would probably mean that person #3 would get... less than nutritional byproducts as well. I think the centipede would not survive long—numbers 2 and 3 would probably get quite ill, and at the very least would dehydrate themselves. --Mr.98 (talk) 13:23, 3 May 2010 (UTC)

Source: "100% MEDICALLY ACCURATE" at 2:17 (video). The standard for Wikipedia is verifiability not truth. Cuddlyable3 (talk) 20:51, 3 May 2010 (UTC)

"Man-made global warming can cause volcanoes"

There was a documentary on C4 last night called "The Volcano that stopped Britain". Near the end they claimed that man-made global warming caused volcanos to erupt by melting the ice on top of them. How do they get away with spreading such nonsense? I like to think I'm pretty liberal but i've lost most of those views since seeing this. Aren't there laws against knowingly spreading lies?--92.251.130.74 (talk) 14:16, 3 May 2010 (UTC)

That's interesting, I was watching a program last night on National Geographic about the same volcano, and it spent a fair amount of time covering the mind boggling amount of ice that the volcano its self melted, though not nearly the amount of an event in I think 1996. Definitely seems like a major flaw in the program if they think man made warming could even approach the heating effects of a volcano. Beach drifter (talk) 14:30, 3 May 2010 (UTC)

Even if hte ice was melted, that wouldn't cause the volcano to spontaneously erupt would it?--92.251.130.74 (talk) 14:42, 3 May 2010 (UTC)

Perhaps it was a phreatomagmatic eruption, i.e. one pertaining to the contact between magma and water (from melted ice?) Regards, --—Cyclonenim | Chat  14:48, 3 May 2010 (UTC)

After reading several articles, it seems there are phreatomagmatic components to the eruption, but they are side effects due to the location, and not the cause. Beach drifter (talk) 14:54, 3 May 2010 (UTC)

I think the idea is that GW could cause ice sheets to melt, which causes post-glacial rebound which in turn could release pressure on volcanoes causing an eruption. I agree that its not really necessarily to scare monger like this with relation to GW - its bad enough as it is - but I guess it makes for exciting TV. 131.111.30.24 (talk) 16:03, 3 May 2010 (UTC)

Almost correct, but nothing to do with post glacial rebound (though both have the same cause). Awickert (talk) 17:40, 3 May 2010 (UTC)

(outdent) Removing ice sheets reduces the vertical confining pressure on a magma chamber, increasing deviatoric stresses and causing an eruption. This is also well-documented in a study in Iceland of lava flow volumes during the last deglaciation. To the original poster of this: if you've changed your views by calling something "nonsense" and "lies" without knowing what you're talking about, I suppose that's your call. Though I admit: modern-day documentaries can over-dramatize to the absurd, and sometimes bungle the facts, making skepticism natural. Awickert (talk) 17:40, 3 May 2010 (UTC)

(edit conflict) It's a real theory that melting glaciers can trigger eruptions due to decompressing active magma chambers. Basically, by removing the pressure of 100 m of ice (for example) you cause more of the superheated rock to melt and more gases to escape and this might cause an eruption to happen hundreds of years earlier than it would have otherwise. It is important to note that this is about triggering volcanoes and not causing them. Melting ice certainly doesn't cause a magma chamber to form. At best it might provoke an existing magma chamber into erupting a little bit early. It's not specific to global warming either, people argue about changes at the end of the last ice age triggering eruptions. Dragons flight (talk) 17:43, 3 May 2010 (UTC)

Even if that were true, the resulting eruption would be less explosive then it would otherwise have been, and therefore cause far less trouble then one that goes Krakatoa. Googlemeister (talk) 19:27, 3 May 2010 (UTC)

How do you know that? Awickert (talk) 19:57, 3 May 2010 (UTC)

Simple thermodynamics. If you have a pot on you stove filled with boiling water and place the lid on (for the purposes of this experiment you can assume this makes the inside of the pot airtight), as the water boils, it forms steam. Steam has a volume far larger then that of water, so without anywhere to go, the pressure increases. If the lid is lightweight, this pressure will force the lid up, and steam will escape and some water may boil out of the pot. Inconvenient perhaps, but not a catastrophe. If you make the lid heavy, or better yet, weld it to the pot, when failure finally occurs, the pressure differential will be far greater, and so will the damage. Googlemeister (talk) 20:42, 3 May 2010 (UTC)

Ah, OK. Thanks for your answer! Unfortunately, volcanoes aren't that simple, largely because there is no constant "burner" and the "lid" is both nonuniform in its material properties and evolving through time. So for example, with a heavier lid, the lava may freeze before it gets to the top, making less of an eruption. Or conversely, to bring in another issue, the eruption may be less damaging without the glacial lid because it won't trigger jokulhaups. (Also, as an aside, Icelandic volcanoes don't have the right composition to go Krakatoa...) So what you say is an interesting idea; when I get a chance I'll see if I can find anything published about it. But I would caution against making authoritative claims about complex systems based on simple models in the meantime (unless you do a little research and find out that you are indeed correct). Best, Awickert (talk) 21:00, 3 May 2010 (UTC)

OK - our OP needs to calm down and do the tiniest scrap of background research.

I don't see any problem (in principle) with the idea that (a) global warming melts glaciers and other ice deposits...which (b) reduces the pressure on the top of glacier-encrusted volcanoes...and (c) that it is possible that reducing the pressure on the top of the magma chamber of a volcano could trigger an eruption. Imagine a volcano that is just on the edge of having built up enough internal pressure so it's on the verge of exploding...just on the tipping point...then melting the glaciers could be enough to cause an eruption that might not otherwise have happened for another 100 or 1000 years. It might also change a slow oozing magma flow into a full scale explosion - as water from the melting ice could be flashed into steam inside the magma chamber, increasing it's ability to overcome the reduced pressure on top.

So this isn't nonsense (meaning non-sense) because it does actually make some kind of sense. I just don't know whether that's really what happened.

Whether that is specifically what happened in this case would require some considerable study. So I googled it. :-) It turns out that it's not just C4 the BBC who are saying this - this article in the Daily Telegraph newspaper claims the same thing. It turns out that their claim (and therefore, probably, C4's the BBC claim) is based on a study by the Royal Society who are a rather prestigious bunch of scientists.

Hence, I think our OP is WILDLY overreacting. C4 The BBC is most definitely not lying because a lie is a deliberate untruth - and they are only repeating what some extremely reputable scientists are saying. So it's not a lie. Channel 4 The BBC are doing their job - and in this case, they are doing it well...so quit complaining about that!

The guys at the Royal Society may be mistaken (a mistake is a non-deliberate untruth) - but they too are not lying. This is properly published, peer-reviewed work, in "The Philosophical Transactions of the Royal Society". That journal has been the gold standard for scientific reporting for 300 years (Sir Isaac Newton was published there!). So C4 the Beeb didn't say anything that's in any way unreasonable.

Now - if you wish to place your own extensive scientific training your privately obtained data and your own in-depth study into this subject matter against people who were published by the Royal Society - please feel free to do so...but don't expect us to be wildly sympathetic to your cause because the odds are very good that you're guessing! So, IMHO, you should assume that (like most BBC documentaries) this was well researched and based upon solid scientific sources. Certainly, the idea that there might be some law you could invoke is WAY out of the question!

SteveBaker (talk) 19:43, 3 May 2010 (UTC)

I thought it was channel 4 and not the BBC? C4 don't have the best track record on documentaries (The Great Global Warming Swindle springs to mind) so perhaps the OP was correct to be sceptical. 86.7.19.159 (talk) 19:58, 3 May 2010 (UTC)

I'm sorry - you're right. I'll fix my response. SteveBaker (talk) 20:39, 3 May 2010 (UTC)

Using the phrase "I like to think I'm pretty liberal but..." suggests the OP considers the issue a political not a vulcanological one.Cuddlyable3 (talk) 20:09, 3 May 2010 (UTC)

And if this were the rabid right-wing politics reference desk, I'd have answered accordingly...but since this is science - and AFAICT, they nailed the science perfectly - we have to take an appropriately offended stance. SteveBaker (talk) 20:39, 3 May 2010 (UTC)

Internal and external cell conditions - source?

I need to find a source (preferably in table form but I can always form one from the data) which provides cell conditions for Na+, Ca++, Cl- and K+ ions with respect to their concentrations internally and externally? Anyone know of such a source? Regards, --—Cyclonenim | Chat  15:50, 3 May 2010 (UTC)

Articles Nernst equation or Resting potential may help. Cuddlyable3 (talk) 17:02, 3 May 2010 (UTC)

Membrane potential also would be useful. The lede mentions all 4 ions. See also ion channel and Ion transporter and Plasma membrane Ca2+ ATPase and Na+/K+-ATPase. Cytosol#Ions discusses actual concentrations, and has a handy chart that lists difference between intracellual concentrations and blood concentrations. Extracellular fluid has some figures as well, though not in a handy chart. --Jayron32 18:19, 3 May 2010 (UTC)

Supporting ladder on stairs - sideways

I need to position a ladder on some stairs, sideways so that it leans against the wall at the side of the stairs. The stairs are eight inches deep, but the ladder is about 15 inches wide. Thus one foot of the ladder will dangle unsupported.

What is the best practical way to support the ladder firmly and safely? The stairs are not very wide either, and are covered in carpet. Thanks 92.28.253.63 (talk) 16:31, 3 May 2010 (UTC)

You'll need to find a device which extends the leg of the ladder on the downstairs facing side. Something like this, but I'll let more knowledgeable people give you advice on specific products. Note that this stabilises the ladder to the usual extent like it would on the floor, but particular care should be taken not to wobble the ladder whilst you're on it. Regards, --—Cyclonenim | Chat  16:34, 3 May 2010 (UTC)

Cut out a big block of wood and fix it to the lower stair, although obsiouly in a maner which you can remove it.--92.251.141.43 (talk) 16:40, 3 May 2010 (UTC)

In a professional setting, those needing to carry out work on stairs usually construct a scaffolding platform, as I myself have seen done on several occasions while employed in facilities maintenance: indeed, in the UK it is contrary to Health & Safety Regulations to carry out actual work more than 2 metres above the ground from a simple ladder, which should only be used for access and inspection; also, ladders should always be secured in place at top and bottom (the latter can be done by a workmate rather than mechanically). What an individual chooses to risk doing in a private setting is, of course, up to him/her, but you may wish to balance the worth of your intact neck against the cost of getting the job (whose specific setting, scope and duration we do not know) done by a trained professional.

As an alternative to both a straight ladder and to constructable scaffolding (i.e. tubes, clamps and boards), you might be able to buy, or more economically hire, a small mobile scaffold tower with the two sides adaptable to different base heights supporting a horizontal working platform, which are designed for this sort of work: I suggest you make enquiries at a local equipment hire firm, if you can find one. 87.81.230.195 (talk) 19:18, 3 May 2010 (UTC)

Buy a ladder like this one. Then you put the ladder sideways like this. You can get different sizes for that ladder, and there are other brands, which might be less expensive. Ariel. (talk) 21:03, 3 May 2010 (UTC)

Moment of Inertia

My textbook says that moments of inertia about principal axes are constant to the first order for small angular displacements. Is there any way to prove this? Thanks. 173.179.59.66 (talk) 16:53, 3 May 2010 (UTC)

Wikipedia's relevant articles are Moment of inertia and List of moments of inertia. A consequence of the definition of the Sine of an angle x (in radians)

${\begin{aligned}\sin x&=x-{\frac {x^{3}}{3!}}+{\frac {x^{5}}{5!}}-{\frac {x^{7}}{7!}}+\cdots \\[8pt]\end{aligned}}$

is that for small x

${\begin{aligned}\sin x&=x\end{aligned}}$ approximately. Cuddlyable3 (talk) 19:59, 3 May 2010 (UTC)

Alcohol for stage fright

Is alcohol an effective treatment for stage fright? Are there any other non-prescription drugs that are as good as or better? Thanks 92.28.253.63 (talk) 17:19, 3 May 2010 (UTC)

Wikipedia cannot offer medical advice. Alcohol is not a prescribed treatment for any known medical or psychological condition. If you are having trouble, please seek advice from a qualified professional, such as a psychologist, who works in this field. The internet, and random strangers that hang out there, is not the proper place to ask such questions. --Jayron32 18:13, 3 May 2010 (UTC)

How is stage fright a condition needing medical advice? I intensely dislike preforming in front of people, but it doesn't require a "qualified professional" to treat. Ks0stm ^(T•C•G) 18:29, 3 May 2010 (UTC)

Stage fright isn't a medical condition - but as soon as someone starts to ask us to suggest drugs to treat it - it becomes a request for medical advice...and our only answer is "If this concerns you - go see a doctor." In this case, it's possible that a doctor might prescribe something. SteveBaker (talk) 19:08, 3 May 2010 (UTC)

I'm not suffering from stage fright, and I do not like alcohol. I was asking in general terms, not medical advice. 92.28.253.63 (talk) 18:23, 3 May 2010 (UTC)

In that case, I reiterate that Alcohol is not prescribed for any known medical or psychological condition. Some people self-medicate using alcohol, usually to less-than-desirable results (alcohol-related violence, cirrhosis, drunk driving, addiction.) Anxiolytic are the class of drugs prescribed for anxiety problems, which stage fright certainly qualifies. None are actually availible over-the-counter, unless you count "herbal" remedies, or "off-the-label" remedies. --Jayron32 18:29, 3 May 2010 (UTC)

What you are describing is a result of abuse or over-consumption of alcohol. You can get nasty results if you overdose on pretty much any other chemical, from cough syrup (toxic psychosis), vegetable oil (Cardiac Arrest) or even water (Water intoxication). Googlemeister (talk) 19:23, 3 May 2010 (UTC)

I'm sorry, people have never abused alcohol before. Statistically speaking, there is not a significant number of people to have every overconsumed alcohol to even mention. I apologize for misleading people to thinking that there are ever negative consequences from using alcohol to excess. (as an aside, I am not a teatotaller. I regularly consume responsible amounts of alcohol.) --Jayron32 19:42, 3 May 2010 (UTC)

I'm not going to say anything about its effectiveness, but alcohol is very frequently used for such things. See Dutch courage. --Tango (talk) 19:24, 3 May 2010 (UTC)

So you are going on stage and feel nervous? Then Break a leg !. Cuddlyable3 (talk) 19:36, 3 May 2010 (UTC)

A well-known symptom of alcohol intoxication is the loss of social inhibitions, so it's reasonable to assume that stage fright would be reduced. However, whether the lack of stage fright would outweigh the decreased mental capacity caused by alcohol and make the show better overall, I can't say. --99.237.234.104 (talk) 20:08, 3 May 2010 (UTC)

However, we should not be advising people to treat an anxiety disorder by drinking. Such irresonsible medical advice is exactly what the medical disclaimer is about. Yes, people do drink because they have anxiety. However, to recommend that as a reasonable course of action, to actually state "Yes, it would be a good idea to drink alcohol to combat stage fright" is a fantasticly irresponsible thing to do. If anyone is seeking genuine advice on how to handle stange fright or any other anxiety disorder, see someone who knows how to treat anxiety disorders. Period. --Jayron32 20:28, 3 May 2010 (UTC)

I hardly think it's proper to call stage-fright an "anxiety disorder". This medicalisation of normal feelings is a pernicious trend in late 20th and early 21st century western society. I'd ask an actor or an acting coach for advice about stage fright. DuncanHill (talk) 21:04, 3 May 2010 (UTC)

I didn't advise anybody to do anything. My answer was a scientifically valid statement of well-known facts. --99.237.234.104 (talk) 21:12, 3 May 2010 (UTC)

construction, coal

During excavation for a new house, a seam of coal was uncovered. will the coal hold up to a foundation placed on top or is it too soft and will require pilings drilled through the seam and filled with rebar and concrete? It will be a large house and the foundation for the fireplace will be close or on the seam. thanks for any help on this. —Preceding unsigned comment added by Lhirsche (talk • contribs) 18:43, 3 May 2010 (UTC)

Really? You want to ask people on the internet about how to safely build your house? The answer almost certainly depends on the size, extent, and type of deposit. You need to talk to a structural engineer, geologist, or someone similar who can inspect the site and give you a professional evaluation. Dragons flight (talk) 18:52, 3 May 2010 (UTC)

There are lots of different foundation approaches for modern houses. No matter the type of soil or subsurface conditions, you'll need a proper foundation design. So even if there had been no coal there - you'd still be crazy not to have someone design you a proper foundation that's appropriate to the conditions. Specifically, I'd expect coal to be a pretty good rock to build onto - but if an expert says otherwise then there are other options beside the 'pier and beam' approach you are describing. My house is build on some of the soggiest clay imaginable with the bedrock 30' below the house...we have a floating 'waffle slab' that floats on the soil...and that's despite it having foot-thick concrete walls! But you have to consult an expert - the consequences of a foundation/slab failure can be utterly catastrophic. SteveBaker (talk) 19:05, 3 May 2010 (UTC)

There is more then one type of coal, from bituminous to anthracite. They would not have the same structural properties, so expert help is strongly recommended. Googlemeister (talk) 19:14, 3 May 2010 (UTC)

How convenient to have a coal mine under the fire place. What could possibly go wrong? Edison (talk) 19:48, 3 May 2010 (UTC)

Do you live in Centralia, Pennsylvania? Googlemeister (talk) 20:25, 3 May 2010 (UTC)

how much is $280,000 per year (inflation-adjusted) for 40 years worth today?

How much is $280,000 per year, but adjusted for inflation, ie this value goes up from year to year to account for inflation, and to be paid out for 40 years, worth today? Thank you. 84.153.250.110 (talk) 19:30, 3 May 2010 (UTC)

Do you mean, how much would being paid $280,000 per year, adjusted for Cost of living annualy, be worth if the first $280,000 payment was made 40 years ago? Or do you mean that you are going to be paid #280,000 this year, and want to know what the COLA payments will do to the money over the next 40 years? I am unclear on what you are asking. --Jayron32 19:35, 3 May 2010 (UTC)

Numerous websites will calculate the inflation adjusted values of money, a simple Google search will find them for you. This one shows that $280,000 in 1969 was equivalent to $1,620,160 in 2009. TastyCakes (talk) 19:38, 3 May 2010 (UTC)

Future inflation cannot be predicted. 40 x $280 000 = $11 200 000. Cuddlyable3 (talk) 19:41, 3 May 2010 (UTC)

Well it can be predicted, it just can't be predicted correctly ;) TastyCakes (talk) 19:45, 3 May 2010 (UTC)

Of course, even if you had a true figure, most people time discount; that is, they'd take 90% of something this year than 100% of it next year (rightly or wrongly). So it might be "worth" more or less today than it is in the future, depending on how you look at it.- Jarry1250 ^{[Humorous? Discuss.]} 19:56, 3 May 2010 (UTC)

If it's adjusted for inflation - then isn't the answer just $280,000 x 40 ? SteveBaker (talk) 20:11, 3 May 2010 (UTC)

If the question was asked correctly, then I agree, that's exactly what it is. Vimescarrot (talk) 20:28, 3 May 2010 (UTC)

Um, I'm the original questioner and your answers don't make sense to me. Let's simplify and say that you will be paid nothing until 40 years from now, at which point you will be paid the then-equivalent of $1,620,160 in today's dollars. How much would you pay for that to happen? Obviously it has to be far LESS than a million, since why would you tie your money up for 40 years for nothin'? What I want to know is exactly how much less. I think it has to do with the prime rate. This isn't homework.... 84.153.250.110 (talk) 20:54, 3 May 2010 (UTC)

Nothing

In the bits of space between the molecules, atoms, ions, &c., do forces still apply? What exists in the space between them in which gravity, magnetism and so on exist to allow the potential forces to exist. I suppose what I am asking is what nothing is, or what 0 actually means. If you could suck all the matter completely out of a given area does it still exist because there is no matter in it to describe it? -russ (talk) 19:54, 3 May 2010 (UTC)

Gravity, magnetism and other such forces are not transmitted by real physical particles that require a "something to exist between here and there" to work. DMacks (talk) 19:59, 3 May 2010 (UTC)

It was once thought that a medium called the luminiferous aether was required to transmit the electromagnetic force, but this idea was incorrect. The gravitational and electromagnetic forces propagate just fine through a vacuum. -- Coneslayer (talk) 20:00, 3 May 2010 (UTC)

There is almost nothing between the stars and planets - but the force of gravity still operates perfectly well. Gravity can be shown to operate between galaxies too - and the space between them has so little 'stuff' in it that we're down to one atom per cubic meter or so! So clearly forces can operate through a vacuum. On a smaller scale, the strong and weak nuclear forces operate at the scale of individual atoms - and (as you say) the atoms are separated by a nice, hard vacuum. The earth's magnetic field is responsible for deflecting charged particles from the sun - and that too operates out beyond our atmosphere - so you can tell that magnetic forces also propagate just fine through "nothing". SteveBaker (talk) 20:18, 3 May 2010 (UTC)

For people that have a problem with forces propagating through nothing, there's field theory. Fields are by no means necessary to explain or understand force propagation through empty space (see Action at a distance), but they do provide a helpful framework for understanding how things like "light waves" propagate through empty space (i.e. Q: "what" is vibrating in a light wave? A: the electromagnetic field). Insofar as concepts like "energy" are "real" so are fields. --Jayron32 20:25, 3 May 2010 (UTC)

But doesn't that mean that a vacuum must exist, which according to Wikipedia is 'only a philosophical concept and never is observed in practice'? -russ (talk) 20:12, 3 May 2010 (UTC)

Well, I don't have much time for philosophers - they cause more confusion than they do clarity. The question here is whether you should have a name for nothingness. A 'vacuum' is defined as the absence of matter - does that make it a useless concept? Not at all, it's an exceedingly handy word - and for beings who live in a world surrounded by air, the concept of a 'vacuum' is sufficiently different from normal existence that it makes sense to have a word for it. Beside, we use 'black' to mean an absence of light - and 'silence' to mean an absence of sound - are those also "only philosophical concepts"? SteveBaker (talk) 20:22, 3 May 2010 (UTC)

(also reply to pierhead above, EC with him below) Vacuum is an asymptotic condition, not a philosophical concept. Science is filled with concepts which are physically impossible to achieve, and yet are very real, such as absolute zero, big bang, speed of light, etc. etc. Being impossible to achieve is not the same as saying its only a "philosophical concept". Things like ontology and eschatology and epistemology are philosophical concepts. A vacuum is a very real, if physically unobtainable, condition. --Jayron32 20:37, 3 May 2010 (UTC)

Does not the absence of sound and light constitute an entity in which they are void? The void must surely still exist as those properties which propogate them still exist and are absorbed by their terminal entities? Is there, therefore no (realistic) nothing or zero? -russ (talk) or am i just being needlessly foolish? —Preceding undated comment added 20:34, 3 May 2010 (UTC).