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March 8

Scientific journals

I went investigating today to see about subscribing to a meteorological journal. Upon seeing the prices, I quickly reconsidered the wisdom of that idea. Am I interpreting it correct that these prices are up to around $110 an issue?! If so, what on earth causes such massive prices for an academic journal of all things?! Ks0stm ^(T•C•G) 01:21, 8 March 2010 (UTC)

The usual problem is very low circulation, meaning they have to charge each subscriber a lot. A lack of advertising can also be a factor. StuRat (talk) 01:40, 8 March 2010 (UTC)

Price is determined more by what people are willing to pay than by cost. Cost sets a lower limit on price, but that is all. People (well, institutions, more often) are willing to pay that much for the journal, so the journal charges that much. Presumably, the publishers have determined that charging less wouldn't result in sufficiently more sales to get a higher total revenue. --Tango (talk) 01:44, 8 March 2010 (UTC)

Except not really, because most academic journals are actually sold to libraries and institutions in subscription bundles with various other journals from the same publisher. The cost of the bundle is generally much less than the sum of the face value prices on the individual components, so the institution generally ends up paying much less per work than the apparent price anyway. Dragons flight (talk) 03:47, 8 March 2010 (UTC)

The principal purchasers are institutional libraries, as they have priced themselves out of the individual market. alteripse (talk) 01:59, 8 March 2010 (UTC)

If you are interested in reading papers from a meteorological journal without having to subscribe, you should look into universities in your area. I see you're from Kansas. I don't exactly know how things work in Kansas, but in Nebraska, since UNL is a state school, the library offers library cards to Nebraska residents [1], and also has a high school students program [2]. Perhaps the universities in Kansas have similar policies. —Bkell (talk) 04:59, 8 March 2010 (UTC)

I'll check my local universities, but I don't know if they will have them since neither of them have a meteorology program. I might have to discuss this with a student at one of them who started a weather club. Thanks. Ks0stm ^(T•C•G) 14:46, 8 March 2010 (UTC)

Even if your local university libraries don't have this particular journal, they can probably get it through interlibrary loan. Anyway, it's worth investigating. —Bkell (talk) 19:46, 8 March 2010 (UTC)

Traditionally, academic journals provided important services - organization of peer-review, proof-reading, typesetting, printing, and dissemination. Due to the low circulation, prices had to be high - and, in fact, library subscriptions are often much more expensive than individual subscriptions. Within the last 20 years or so, this role of publishers has gone down. Authors are now expected to submit camera-ready manuscripts in many fields, and dissemination is increasingly electronic. Peer review is cheaper and easier too, thanks to electronic communication. As a result, scientific publishing is undergoing massive changes, and its hard to predict what will happen over the next 10-20 years. --Stephan Schulz (talk) 10:37, 8 March 2010 (UTC)

I'm not sure which journals you're looking at, but the link you provide above seems to say that the online addition of the Bulletin of the American Meteorological Society (BAMS) is free to non-AMS members. It looks like they have open access to all articles after 1970.[3] I'd suggest starting there. :-) -Atmoz (talk) 00:29, 9 March 2010 (UTC)

Atmospheric Chemistry and Physics is also an open access journal. -Atmoz (talk) 00:34, 9 March 2010 (UTC)

Colour of glass

How is colour added to glass? I especially want to know for 'blue'. -- Extra999 (talk) 07:52, 8 March 2010 (UTC)

Colour is added to glass by adding certain metal salts to the molten glass (see Glass colouring and colour marking). Blue is made with Cobalt salts, I believe. --The High Fin Sperm Whale 02:51, 8 March 2010 (UTC)

Substances Used in the Making of Coloured Glass may be your friend. Cobalt seems to be the key to blue glass. --Tagishsimon (talk) 02:48, 8 March 2010 (UTC)

Thanks. -- Extra999 (talk) 18:00, 8 March 2010 (UTC)

The Lions

Hello, I live in Langley, BC, and I was wondering if you can see The Lions from here. I did see one mountain that looked a bit like them, but it was tiny and off in the distance. So can you see them from Langley? --The High Fin Sperm Whale 02:40, 8 March 2010 (UTC)

Assuming clear air. the old-fashioned pre-metric rule for how far away the horizon is when you are at h feet above sea level is: distance (miles) = sqrt(h x 7/4). So if you stood on top of the taller of the two peaks (5,400 feet) - then the horizon would be about 97 miles away. So you should be able to see the peak from sea-level locations within 97 miles. Google maps says that the center of Langley is about 45 miles away. So the curvature of the earth certainly isn't an obstacle. Whether there are intervening obstacles...I'm not sure. Whether the atmosphere is clear enough...I don't know. But if I had to guess, I'd say you'd be able to see the peaks on a clear day. SteveBaker (talk) 03:52, 8 March 2010 (UTC)

That's a neat formula. A back-of-the-envelope calculation (starting with the formula Steve provided) yields a metric approximation: distance (km) = sqrt(h[meters] x 15). This metric version is gives answers that are 0.5% greater (about a km for most peaks) than the formula SB gave above. In this specific case, 5400 ft is about 1646 m, yielding a visibility estimate of 157 km, or 97.6 miles (pretty close). The error (relative to the original formula) drops to 1.2% if you use 14.9 instead of 15 in the square root - but I am not sure that's worth it -- Scray (talk) 12:25, 8 March 2010 (UTC)

If I could see them, would they be quite small? --The High Fin Sperm Whale 21:32, 8 March 2010 (UTC)

I just looked at this using Google Earth -- I don't think you'll be able to see The Lions from Langley; it looks like Grouse Mountain is directly in between, and high enough that you won't be able to see over it. Looie496 (talk) 23:49, 8 March 2010 (UTC)

Google Maps shows the peak of Grouse is about 10 miles from the Lions and at 1200' it's only a quarter the height of the Lions - the geometry doesn't seem enough for it to block the view. Using the magic equation again says that you can see Grouse Mountain from 46 miles away and The Lions from 96 miles away. So at 46 miles away from Grouse (which would be 56 miles from The Lions), Grouse would be below the horizon - and the Lions would still be in your line of sight. Langley is only about 30-ish miles from Grouse Mountain - I don't see how it could possibly block the further peaks. I'm skeptical about your Google Earth results - the numbers just don't work. SteveBaker (talk) 04:24, 9 March 2010 (UTC)

Grouse Mountain is actually 1200+ meters high, not 1200 feet. It might still fail to block the view, but it's a close call. (Our article seems to have some confusion on the numbers, but it definitely should be meters.) Looie496 (talk) 20:54, 9 March 2010 (UTC)

bombardment of hydrogen isotopes with neutrons

What happens when a plasma made up of all the different isotopes of hydrogen is bombarded with neutrons? 71.100.11.118 (talk) 03:32, 8 March 2010 (UTC)

Then it would become heavier isotopes, first deuterium then radioactive tritium. --The High Fin Sperm Whale 03:34, 8 March 2010 (UTC)

...and thereafter (in the presence of all three isotopes)? 71.100.11.118 (talk) 03:51, 8 March 2010 (UTC)

I suppose that if tritium was bombarded with neutrons, a neutron would decay into a proton and electron, forming helium. --The High Fin Sperm Whale 03:57, 8 March 2010 (UTC)

Is there any evidence for this say at higher densities and lower temperatures as close to absolute zero as possible and under maximum pressure or in high temperature, high pressure plasma? 71.100.11.118 (talk) 04:14, 8 March 2010 (UTC)

It is interesting that Hydrogen-4 and Hydrogen-5 and Hydrogen-6 will not be produced, since they actually decay back to tritium in sub attosecond timescale by giving off neutrons. (actually in a zeptosecond which apparently is well below the measurable time scale). Graeme Bartlett (talk) 06:50, 8 March 2010 (UTC)

Can persistent high blood pressure be someone's fault?

(1) Is it possible for someone (annoying and clingy and argumentative and stubborn, but never really cruel - just basically someone immature who doesn't play well with others) to drive someone's blood pressure up so high that they would be in medical danger and possibly even suffer long-term damage after being stabilized? (2) Or is it more likely that the hypertensive crisis would cause the person with high blood pressure to perceive the immature individual as more of a problem than s/he actually is? (3) And if the latter is the case, is it likely that the animosity the person with high blood pressure felt would pass when the blood pressure returned to a normal range? —Preceding unsigned comment added by 71.108.171.138 (talk) 03:50, 8 March 2010 (UTC)

There is a tested and proven correlation between stress and hypertension. The statement "stress causes hypertension" is not the same as "stress is correlated with hypertension." Therefore, you are making two jumps: annoying person causes stress and stress causes hypertension. As such, it is unlikely to find many references that justify that double-claim. -- kainaw™ 03:54, 8 March 2010 (UTC)

(4) Does that mean it's unlikely that one person's faults could singlehandedly drive another person into hypertensive crisis? (5) And more importantly, could high blood pressure cause a person to think or behave irrationally, particularly to prompt feelings of anger or paranoia? —Preceding unsigned comment added by 71.108.171.138 (talk) 03:58, 8 March 2010 (UTC)

It's hard to prove a negative, but all evidence suggests the answers are 1 No, 2 No, 3 No, 4 Yes, and 5 No respectively. alteripse (talk) 04:21, 8 March 2010 (UTC)

Hmmmmm . . . if I follow your answers correctly, you're saying that high blood pressure can prompt or exaggerate angry feelings (which is all I meant by "irrational thinking," by the way . . . such as blaming someone for something that really isn't his or her fault, and no clear-headed person would truly think it was . . . but ira est furor brevis)?

No. Ira sit furor brevis, sed non hypertensio. I went back and numbered your questions so you can match up the answers correctly. Hypertension is dangerous because it is asymptomatic (silent). The fluctuation with emotional upset results from adrenaline, and adrenaline elevations from emotions may be perceptible because of other adrenaline effects, but tend to be too brief to represent a long term health risk. There is a less well understood epidemiologic relationship between chronic life stress and hypertension but the mediating factors are not known and may include other things associated with poverty rather more than simply prolonged emotional stress. alteripse (talk) 11:42, 8 March 2010 (UTC)

Thanks. And Alteripse, you rock. Okay, let me try to sign this one properly, because I'm not one of those idiots out to destroy Wikipedia. 71.108.171.138 (talk) 17:21, 9 March 2010 (UTC)

Stress is a contributing factor to hypertension, and perceived annoyance may contribute to stress. For your other questions, see insomnia#Causes, panic attack and psychosis. ~AH1^(TCU) 02:12, 14 March 2010 (UTC)

menstrual period information

menstrual period information —Preceding unsigned comment added by Lorir7 (talk • contribs) 03:55, 8 March 2010 (UTC)

Asking or offering? You know, I'm sure Wikipedia has an article on this. At least one. —Preceding unsigned comment added by 71.108.171.138 (talk) 03:59, 8 March 2010 (UTC)

I suggest you start at Menstruation, and go from there. Dolphin51 (talk) 04:00, 8 March 2010 (UTC)

See below a question "menstrual period correlation with Metonic and other lunar cycles". Cuddlyable3 (talk) 11:40, 8 March 2010 (UTC)

Orbit

The moon orbits around the Earth and the Earth orbits around the Sun and the Sun orbits around the center of the Milky Way. What does the Milky Way orbit around? 71.100.11.118 (talk) 04:32, 8 March 2010 (UTC)

I don't believe the Milky Way follows a periodic orbit. They usually only exist when there are just two bodies of significant mass to consider (eg. when considering the Earth and the Sun, you can ignore the Moon and other planets as being too small or too far away to do much, or when considering the Earth and Moon, the Sun and everything else is too far away to worry about). For the Milky Way, that doesn't really work. The Local Group contains a large number of galaxies, several of which are too large or close to ignore. Over a short period of time, the Milky Way will act as though it is orbiting the centre of mass of the Local Group, which is somewhere roughly in the middle of the Milky Way and the Andromeda Galaxy (which, between them, make up most of the mass of the Group). Over longer time periods, it is much more complicated. --Tango (talk) 04:49, 8 March 2010 (UTC)

...humm. Thinking in terms of center of mass and the fact the that whole Universe is suppose to be related or connected by gravity what center of mass would the center of mass of the local group be attacted to? 71.100.11.118 (talk) 08:46, 8 March 2010 (UTC)

There is no center of mass for whole universe. See Cosmological Principle. manya (talk) 09:16, 8 March 2010 (UTC)

But nearby us, Great Attractor plays some role. - manya (talk) 09:24, 8 March 2010 (UTC)

The centre of mass of the Virgo Supercluster, I guess. I don't know where that is, but I would guess it is somewhere fairly near the Virgo Cluster, which is near the geometric centre of the Virgo Supercluster. Beyond the scale of superclusters, objects aren't usually gravitationally bound to each other, so it doesn't really make sense to talk about what they are attracted to. The Hubble Flow is far more important on those scales. --Tango (talk) 17:10, 8 March 2010 (UTC)

The ISS orbits the earth every 90 minutes or so. The moon orbits the earth once a month. The earth orbits the sun once a year. The sun orbits the galactic core every 250 million years. If our galaxy did orbit something, the orbital period would be so long that it could easily be longer than the age of the galaxy. Put another way, the objects involved would be changing so much over the period of any possible orbit that this couldn't be anything really stable. SteveBaker (talk) 04:10, 9 March 2010 (UTC)

Why is hunger so mild?

Is there a biological reason for why starvation is not intensely painful? It seems to be one of the most painless ways to die naturally, excluding instantaneous deaths, and is nothing like having cancer or dehydrating. --99.237.234.104 (talk) 04:48, 8 March 2010 (UTC)

Well, I've never had cancer or dehydrated, so I can't compare them . . . and I've never starved either for that matter. But I've skipped enough meals to wonder what on earth makes you think that starvation isn't intensely painful. That clawing sensation of your empty stomach cramping up begging for food? Ouch. Really, I think I'd prefer dehydration . . . I've never heard what it feels like, beyond that you'd be really really thirsty, which I imagine would be terribly unpleasant but much less painful than starvation. To try to take your question seriously, though, starvation is less acute a condition than dehydration. When you need water, you need it within a day or two at most to keep functioning. In the wild, animals often have to go for many days, longer at times, without food, and they need to be able to focus on other things and function in spite of the discomfort in order to keep up the search for food and other necessities and survive. In time of dehydration water is almost always going to be the first priority, but in starving times there are likely going to be many intervening priorities, as it may be quite some time before food can be found. So it wouldn't do to have hunger be as keen a drive. But in the final stages, of course it's intensely painful. And it's not terribly pleasant up to that point either . . . especially since it's drawn out over several weeks.

One major symptom of dehydration is extreme headaches - not pleasant at all. It is far quicker than starvation, though (about 3 days, rather than 3 months). --Tango (talk) 04:56, 8 March 2010 (UTC)

Dying of starvation is not at all pleasant and takes a very long time. The reason hunger is usually a very mild sensation is because you rarely get very hungry. Most people eat several times a day but they could go months without food, so clearly they are eating when hunger is still at a very early stage. See Starvation#Signs and symptoms for a description of some of the things that happen to your body when you don't eat. One part that jumps out at me is "All movements become painful due to muscle atrophy". --Tango (talk) 04:56, 8 March 2010 (UTC)

Ah, headaches. True enough. I've wondered often enough when I've downed a couple of Tylenol with a glass of water if it wasn't the water that relieved the headache at least as much as the medicine.

I've heard that for about the first three days of not having anything to eat, it is painful because your stomach starts to shrink and cramp, thus causing pain. Then, for the next 40 days, it stops hurting and your body starts to digest fat reserves. After that, it starts to hurt again, because your body starts digesting the muscles. Your eyes are one of the first to go. --The High Fin Sperm Whale 05:13, 8 March 2010 (UTC)

I have fasted for seven days at a stretch, water only, many times. It's not painful. Climbing stairs gets more tiring after 5 days or so. The hunger seems more psychologically strong in the first 3 days, then it gets weaker. Your sense of smell gets quite acute - it becomes disgusting to be near a fast food place or anywhere where there has been poison used recently. At 7 days, there are no problems with sight. —Preceding unsigned comment added by Marklawrence17 (talk • contribs) 08:06, 8 March 2010 (UTC)

Eyes aren't muscles. And look at that link . . . there's a lot more to the pain of starvation than the initial stomach cramps. —Preceding unsigned comment added by 71.108.171.138 (talk) 05:16, 8 March 2010 (UTC)

The eyes do have & need muscles however and if these go your vision will almost definitely go, see Extraocular muscles, Muscles of orbit, Ciliary muscle, Iris dilator muscle & Iris sphincter muscle for example. Whether there are really the first to go, I don't know but it's probably your vision will be strongly negatively affected if they start to atrophy whereas movement might be incredibly painful but possible even after your limb muscles have partially atrophied. Since headaches came up, I'm surprised no one mentioned hunger or fasting can cause headaches as well I presume due to mild hypoglycemia. However when it comes to real starvation, I don't know if this will persist since it seems likely when your body adapts it shouldn't be a problem. Nil Einne (talk) 06:43, 8 March 2010 (UTC)

Hypoglycemia is a very short term problem - your body will switch to reserves within hours, at most. --Tango (talk) 17:12, 8 March 2010 (UTC)

Actually I'm starting to wonder if it's so simple. [4] for example reports headaches as a problem in a semi-starvation diet. Similar reports with anorexia nervosa [5] and other starvation diets. I can't find any great source (lots of naturopath and similar websites and most stuff are discussing 'starvation' as in a few hours or an inadequate/semi-starvation diet rather then full starvation per se) but my impression is that it's likely to be a persistent problem for real starvation. Definitely from personal experience as well as from other people I know, I can say fasting for 12-24 hours or so can causeheadaches although it likely varies from person to person. Of course in the long term hypoglycemia may not be the primary cause but other things like inadequate electrolytes, dehydration (which can be a problem during starvation) and lacking essential vitamins and minerals. Of course, if you starving yourself by choice rather then by necessity, e.g. as part of a hunger strike you may consume drinks with sufficient electrolytes etc which would I presume change things. But for example, headaches are listed as a symptom of rabbit starvation which isn't starvation per se but it would seem likely whatever causes headaches there would happen in real starvation. Of course headaches may not be the worse symptom by a long shot over the long term but over the short term, I'm not convinced headaches due to dehydration are necessarily worse then due to fasting or starvation. In the 1+ day window where you're starting to become at risk at death and in the same time frame for dehydration things would be different I expect. Of course it almost definitely varies from person to person and as I hinted at above those adapted to it would probably fare better then the average person in the developed world Nil Einne (talk) 18:54, 8 March 2010 (UTC)

There are plenty of people who have voluntarily starved to death (See Hunger strike for some examples). To my mind, that sets limits on just how bad the symptoms could be. SteveBaker (talk) 04:04, 9 March 2010 (UTC)

Yes, it means that, by definition, the symptoms can't be unendurable. Sufficiently motivated people can endure a hell of a lot, though. --Tango (talk) 04:09, 9 March 2010 (UTC)

There are also people who burned themselves to death as protest. This is a very high upper limit. — DanielLC 21:45, 9 March 2010 (UTC)

That's nothing like a comparable example though. You can pour gasoline over yourself and light the match without pain. Once you've done that, the pain - however bad - can't cause you to change your mind...you're committed. When starving yourself to death in a hunger strike - you can give up and eat at any time if the pain gets to be too much. Some people have gone without eating for more than two months with the opportunity to give up and eat any time it became unbearable. That's a very different thing from an initially painless "impulse" act where the pain comes after the point of no return. SteveBaker (talk) 05:02, 10 March 2010 (UTC)

Isn't there a destructive process of "Ketosis" which sets in after a day or two of starvation, so that the breath smells a bit like acetone or fruit, due to the body metabolizing fat rather than carbohydrates? Could the headache come from the brain having to use ketones as fuel? Edison (talk) 17:46, 9 March 2010 (UTC)

fixed your ketosis link--Polysylabic Pseudonym (talk) 12:36, 10 March 2010 (UTC)

Given the amount of fat an average western person has available, I don't think you can call ketosis destructive. The brain practically always has glucose on which to run, which is a good thing because it can't run on anything else (can't be bothered providing citation - don't know if such exists). If you don't have sugar, your body can convert protein to glucose. If you have neither sugar nor protein, I think you're in trouble. In any case everyone one on (the first stages of) an atkins diet is in ketosis. Ketosis sets in within about 3 days of not eating carbohydrates (sugars), you don't have to be starving. --Polysylabic Pseudonym (talk) 12:36, 10 March 2010 (UTC)

Taking another side to the question, one thing that strikes me is that painful hunger is not conducive to the body getting more food. If it complains too much, it hinders you ability to help it. I am, however, not an expert on the subject, and am clearly applying personification to evolution. - Jarry1250 ^{[Humorous? Discuss.]} 17:52, 9 March 2010 (UTC)

Yes, I was thinking that if hunger was as unendurable as not being able to breathe, people would probably end up killing themselves trying to eat rocks or ashes or sticks. Googlemeister (talk) 21:42, 9 March 2010 (UTC)

An interesting website

Resolved

 – Cuddlyable3 (talk) 11:35, 8 March 2010 (UTC)

I'm no sure if this is the right desk to ask this on, but I'm having trouble finding a website that i once visited. It was someone's personal website and he/she discussed topics including what a Neanderthal language might have been like, including a translation of genesis into his hypothetical neanderthal, and a list of scientific inaccuracies in Star Trek. There was also a fictional account of how civilization in the future was destroyed by people wanting to learn new words constantly to fit in with the latest dialect, so they overused neuroplasticisers and gave themselves brain damage. Does anyone know of anything like this? 74.14.109.146 (talk) 06:49, 8 March 2010 (UTC)

perhaps http://adamjamesnall.blogspot.com/ ? —Preceding unsigned comment added by Graeme Bartlett (talk • contribs) 07:07, 8 March 2010 (UTC)

You're thinking of http://www.xibalba.demon.co.uk/jbr/index.html. Coincidentally I just discovered this page two days ago, at the end of a chain of link-following starting with a random Wikipedia image which turned out to be one of the Sammarinese euro coins, which led me to San Marino, which led to Akademio Internacia de la Sciencoj San Marino, which got me curious about Esperanto, so I did a Google search for learn esperanto, and the fourth result was Learn Not to Speak Esperanto. (Now why in the world can I remember all of that?) —Bkell (talk) 07:21, 8 March 2010 (UTC)

Ah, yes, it's that one. As I believe is customary, I hereby grant you one (1) internet. 74.14.109.146 (talk) 08:12, 8 March 2010 (UTC)

Yay! I have an Internet! —Bkell (talk) 08:29, 8 March 2010 (UTC)

menstrual period correlation with Metonic and other lunar cycles

How does the human female menstrual period compare with all of the various lunar cycle and with which one does it correlate best? 71.100.11.118 (talk) 08:43, 8 March 2010 (UTC)

THe Wikipedia article Menstrual cycle notes that the menstrual cycle varies from woman to woman and the average is 28 days. The moon takes 27.32 days to revolve around the Earth; the period between full moons is 29.53 days. Opinions differ on whether moonlight influences menstruation (see Lunaception) or the similarity of cysles is a coincidence. See also the article on the McClintock effect supposed to synchronise the menstrual cycles of women who live together.Cuddlyable3 (talk) 11:24, 8 March 2010 (UTC)

If the lunar cycle influenced periods then all women in the world would have their periods on the same day... 195.35.160.133 (talk) 11:49, 9 March 2010 (UTC) Martin.

scientists

Do all scientists keep notes? What are some famous scientists who never kept any notes and worked in a very haphazard way? —Preceding unsigned comment added by Milticcason (talk • contribs) 09:07, 8 March 2010 (UTC)

I would think that every scientist would want to keep notes, if they could. Perhaps there were some illiterate scientists (particularly in societies that hadn't yet developed a written language). Also, some might not want to take notes as that might provide proof that they were engaged in an illegal activity. Those studying anatomy, for example, often illegally obtained bodies for dissection. StuRat (talk) 09:21, 8 March 2010 (UTC)

To your first question, the short answer is "no". Just as there are different learners out there (some learn from lectures, some from reading, some from copious note-taking, etc) there are different researchers - and I've seen the full range of laboratory records, from none to compulsive. As indirect evidence, I cite the plethora of guidelines like this that admonish lab personnel to document what they do - because these would be superfluous if people weren't "haphazard". Certainly, there may be some who keep no records to hide malfeasance, but there are others who just don't keep anything we'd recognize as useful records (except when they publish - but that's not "notes"). -- Scray (talk) 11:55, 8 March 2010 (UTC)

Not a scientist, but Srinivasa Ramanujan (possibly one of the greatest mathematicians of the last century) kept very few notes for at least some time. See 'Ramanujan's notebooks' on that page. 131.111.248.99 (talk) 13:24, 8 March 2010 (UTC)

Usually scientists are now taught that good laboratory practice requires the maintenance of a laboratory notebook. While I'm sure there might have been famous scientists who succeeded despite their lack of note keeping (though I'm sorry that I can't think of any examples), this would make replicating experiments (one of the key points of the scientific method) difficult, and would limit the ability of the scientist to review past experiments to draw inferences on what might have caused things to turn out in an unexpected fashion. (It has been said that great science isn't heralded by "Eureka!", but by "Hmm, that's curious".) -- 174.21.235.250 (talk) 16:09, 9 March 2010 (UTC)

Although I was an engineer, not a scientist, I always found that how ever many notes I made in my lab book, they were never enough and I had to re-perform at least some tests!--79.76.188.14 (talk) 23:12, 9 March 2010 (UTC)

gravity versus electromagnetic forces

What is the formula that shows the point of balance between the electromagnetic repelling force of orbiting electrons and the pull of gravity between two atoms of hydrogen such that it can be applied to multiple atoms of hydrogen right up to the size of a star? Also, what is the formula for the density of hydrogen atoms due to gravity and the diameter of the whole? 71.100.11.118 (talk) 09:53, 8 March 2010 (UTC)

The high temperatures in a star mean that most of the hydrogen atoms are ionised - their electrons are stripped away, and the free electrons and protons form a plasma. The main force opposing gravitational collapse in a main sequence star, in which fusion is still active, is not electromagnetic repulsion - it is the thermal pressure arising from the energy released in the fusion reactions, which appears as kinetic energy in electrons and protons plus radiation pressure from photons. When a star has insufficient fuel to continue fusion, other forces such as electron degeneracy pressure become important. See our article on stellar evolution for more details. Gandalf61 (talk) 10:30, 8 March 2010 (UTC)

Okay, is there a thermal versus gravitational formula and a formula to show the rate of fusion versus the amount of hydrogen (star mass, diameter or size)? 71.100.11.118 (talk) 22:44, 8 March 2010 (UTC)

Lorentz transformations

If the velocities between two reference frames were such that the relative motion were not parallel to one of the axes, what would the lorentz transformations look like? —Preceding unsigned comment added by 173.179.59.66 (talk) 10:32, 8 March 2010 (UTC)

It would be a combination of a rotation and a normal Lorentz transformation, see Lorentz group and Poincaré group 157.193.173.205 (talk) 13:17, 8 March 2010 (UTC)

Read Lorentz Transformation#Matrix form. 174.58.105.234 (talk) 18:38, 8 March 2010 (UTC)

Okay, so how would you be able to derive this formula? 173.179.59.66 (talk) 19:32, 8 March 2010 (UTC)

For instance, like this. DVdm (talk) 19:53, 8 March 2010 (UTC)

about thrusters used in the spacecrafts

hey.. please someone let me know about the working of the thrusters in the vaccum(space) in the absence of any medium which would provide a reaction to the craft's linear motion.. e-mail address deleted —Preceding unsigned comment added by 116.73.242.109 (talk) 11:23, 8 March 2010 (UTC)

See the article about the Rocket engine which obtains thrust in accordance with Newton's third law that says "For every action force there is an equal, but opposite, reaction force". It needs no external material to form its jet and therefore it can drive a spacecraft. See the article Spacecraft propulsion. Cuddlyable3 (talk) 11:32, 8 March 2010 (UTC)

To help to visualize this, think of a ship as having forward thrust if it can eject material out the back faster than any material hits the front. In the case of boats and planes, water or air hits it at the front of the propeller or jet, at a low speed, and is then accelerated and leaves the end at a higher speed. In the case of a space ship in a vacuum, nothing (or very little) hits the front end, so ejecting anything from the end will give it forward thrust. Obviously, the faster you can eject material, such as burning rocket fuel, the more thrust is provided. StuRat (talk) 17:14, 8 March 2010 (UTC)

Think about it like this: Suppose there were two bowling balls out there in space with a big compressed spring between them. When the spring un-springs, the two balls both fly off in opposite directions - right? It wouldn't make sense for one ball to stay still and the other one to fly off into the distance. Well, in a rocket engine, the exhaust gasses are one bowling ball, the rocketship is the other and the hot expanding gasses inside the motor are the spring. The fuel acts both as the "reaction mass" (the second bowling ball) and the force that causes that mass to fly off in one direction and the rocketship to head off in the other. SteveBaker (talk) 03:54, 9 March 2010 (UTC)

Nice analogy Steve Stanstaple (talk) 19:05, 9 March 2010 (UTC)

My favorite analogy for understanding this idea: let's say you're on a little rowboat, and you're holding a brick, and you throw the brick out the back of the boat as far as you can.

What happens to the boat? It goes forward a little. Is it because the brick has something to push against (the air)? No, it's because *you* -- and the boat, which you're attached to through your butt -- were pushing against the brick!

Now keep a pile of bricks on your boat, and throw them all out the back, and that's your thruster. You can now boldly go to the other side of the lake. --Sean 19:53, 9 March 2010 (UTC)

It's something I puzzled over as a child. I used to imagine sitting in the back of a van and trying to propel myself be throwing stones out the back. I wondered whether I needed to hit the stones of the ground to get the 'push', and if so, how did the van know whether I hit the ground? The spring bound bowling balls released idea is really satisfying for some reason. Stanstaple (talk) 20:08, 9 March 2010 (UTC)

Happiness

I was watching the simpsons and there was a chart which showed that less intelligent people are happier. Is there any evidence to support this claim? Any studies? —Preceding unsigned comment added by Doorelore (talk • contribs) 11:56, 8 March 2010 (UTC)

If you search Pubmed there are plenty of studies which correlate intelligence with suicide rates and similar ideas, which may be relevant. Unfortunately, I don't have access to these. Perhaps someone else will :) Regards, --—Cyclonenim | Chat  12:17, 8 March 2010 (UTC)

I think someone once said 'Ignorance is bliss'. Is ignorance the same as lack of intelligence? —Preceding unsigned comment added by 79.76.232.131 (talk) 15:08, 8 March 2010 (UTC)

I would say ignorance was the lack of knowledge, rather than the lack of intelligence. --Tango (talk) 17:16, 8 March 2010 (UTC)

I would expect the correlation between intelligence and happiness to depend greatly on the culture and time period. That is, do we reward or punish stupidity and intelligence ? In a primitive society, the stupid aren't likely to survive, or, if they do, barely get by. In more developed societies they may have all their basic needs met and may also be legally protected from those who would cheat them. As for intelligence, this was far more valued by the US, during the Space Race, when engineers and scientists were needed to beat the Soviet Union. Now the intelligent are often ridiculed as "nerds", as in the TV show The Big Bang Theory. There have even been cultures in which the intelligent have been exterminated, as in Cambodia under Pol Pot. StuRat (talk) 17:00, 8 March 2010 (UTC)

Matt Groening, in addition to creating The Simpsons, touched upon this topic several times in Life In Hell. I can't find it online, but one strip featured — and I'm sure I've piled on inaccurate details, but you'll get the idea — one relatively happy guy watching TV, compared with a morose grad student, speaking about Nietzsche and the futility of existence and the inexorable approach of death, followed by total nothingness until the heat death of the universe; and the caption was, "Which one had too much education?" Anyway, sorry, I don't have a reference to a study about this. It is WP:OR on the part of Matt Groening. Comet Tuttle (talk) 18:58, 8 March 2010 (UTC)

I think I would be much happier if I grew up stupid in some working class family, than I am now. I would never have questioned and left my religion, I would never suddenly descend into worries about how meaningless life is, I would never suddenly start wondering about how did the universe get here in the first place, if not by supernatural powers, etc. And StuRat, nerds are ridiculued as nerds, but most intelligent people aren't regarded as nerds. If you I guess it's because you work in a computer proffession and wear glasses. Well that's sickening, maybe get contacts?--92.251.221.135 (talk) 21:42, 8 March 2010 (UTC)

You'd be hard-pressed to find a current US TV show where physicists are shown to be cool. And, incidentally, I do wear contacts. StuRat (talk) 22:01, 8 March 2010 (UTC)

Strange, over here (Ireland) there are lots of programs advocating science. Most of them seem to be BBC though.--92.251.221.135 (talk) 23:18, 8 March 2010 (UTC)

We have science documentaries here, mainly on PBS, but a sitcom portraying math and science experts in a positive way ? No. StuRat (talk) 02:13, 9 March 2010 (UTC)

Please remember that they aren't just physicists on The Big Bang Theory, they are nerds. They speak Klingon, go to Comicon and spend probably thousands of dollars on comic books. Those traits seem to be more coupled with social ineptness, not intelligence per se (which many real people seem to appreciate). --Mark PEA (talk) 19:03, 9 March 2010 (UTC)

My point is that when the intelligent are portrayed on US sitcoms, it's almost always as nerds (meaning having those traits you listed). For another example, on Frasier, while perhaps not the typical nerds, Frasier and especially Niles were often portrayed as objects of ridicule, such as Niles' obsessive cleanliness and inability to tell Daphne he liked her. StuRat (talk) 15:13, 10 March 2010 (UTC)

It's not a sitcom and she is female, which makes a difference, but Samantha Carter is pretty cool. Daniel only gets cool later on and McKay is not cool, but at least there is one! --Tango (talk) 04:19, 9 March 2010 (UTC)

This is most likely going to vary between time and place, as StuRat stated. However, it would seem that if one were more intelligent, they would more effectively deal with problems in their life, and thus more likely than not be happier. 66.69.254.68 (talk) 04:39, 9 March 2010 (UTC)

Happiness is a cigar called Hamlet —Preceding unsigned comment added by 79.76.188.14 (talk) 23:14, 9 March 2010 (UTC)

It may be that intelligence test scores (which are not the same thing as intelligence) are correlated with introversion, which in turn is correlated with depression. —Tamfang (talk) 18:59, 12 March 2010 (UTC)

Artificial diamond

How is artificial diamond made? -- Extra999 (talk) 18:10, 8 March 2010 (UTC)

http://en.wikipedia.org/wiki/Artificial_diamond#Manufacturing_technologies —Preceding unsigned comment added by 157.193.173.205 (talk) 13:12, 8 March 2010 (UTC)

I've also seen a method constructing diamonds from peanut butter and charcoal in a microwave. However it is also said to be very dangerous. ~AH1^(TCU) 01:59, 14 March 2010 (UTC)

What is meant by decreasing the "vacuum"???

What is meant by decreasing the vacuum?? Is it increasing the vacuum pressure hence decreasing the quality of it?? Or decreasing the emptiness??? —Preceding unsigned comment added by 119.235.54.67 (talk) 13:10, 8 March 2010 (UTC)

It depends entirely on the speaker who makes that comment. This is identical to the vagueness over "decrease the air conditioning." It could mean "decrease the amount of cold air produced by the air conditioner to make it warmer" or it could mean "decrease the temperature setting on the air conditioner to make it colder." -- kainaw™ 13:38, 8 March 2010 (UTC)

Seasonal fruits

Is it possible to fool plants into growing and fruiting at the wrong time of year, using environmental control and temperature etc? Or do plants somehow know if it's the wrong time of year even if the conditions are perfect for growth in their artificial environment? —Preceding unsigned comment added by Techcolis (talk • contribs) 13:45, 8 March 2010 (UTC)

You can certainly trick the plants. Mostly it takes the right temperatures, lighting and water. If the plant has that, it will be quite happy. For fruiting, you might need to artificially pollinate since the natural pollinators (usually wind or insects) might not be present in the artificial environment. Googlemeister (talk) 14:22, 8 March 2010 (UTC)

I believe polytunnels are used for this purpose to grow strawberries year-round. They don't taste as nice, though. Vimescarrot (talk) 19:23, 8 March 2010 (UTC)

To be pedantic, I don't think that's much of a trick at all. Seasonal could be taken to refer to seasonal conditions. DRosenbach ^{(Talk | Contribs)} 19:58, 8 March 2010 (UTC)

From what I was told years ago, this is done all the time with poinsettia plants to make them blossom near Christmas. Dismas|^(talk) 00:37, 9 March 2010 (UTC)

This is definetly possible, as it is how greenhouses work all over the world. I'm sure there are many mechanisms that will cause a plant to bud, flower, and later bear fruit, one of these being growing degree days (see http://en.wikipedia.org/w/index.php?title=Growing_degree_day&redirect=no ). Other factors include the amount of light, nutrient levels, soil moisture, etc. Different plants respond to different environmental cues, of course, so you would have to consult a gardening or horticulture text if you have a specific species in mind. Most likely, plants don't know what "time of the year" it is, per se, but these mechanisms make seasonal variation in light and temperature a strong predictor for growth (This is all from a dendrology course, sorry I haven't cited all this) 68.153.29.23 (talk) 03:42, 13 March 2010 (UTC)Joseph

English name of an object

What is the English name of the green object that you see here? It need to put fuel on the vehicles. Do you know if there is a similar image on Commons? --Aushulz (talk) 15:39, 8 March 2010 (UTC)

There has to be a better word, but the only thing coming to mind at the moment is "nozzle". Falconus^{p t c} 15:43, 8 March 2010 (UTC)

According to gas pump it is indeed called a "nozzle." Falconus^{p t c} 15:52, 8 March 2010 (UTC)

(ec) Agree with "nozzle" or "fuel nozzle" - most would understand this. U.S. fuel pump labeling generally refers to it as the "handle" (as in "Remove handle and begin fueling"), but that's not specific enough out of context to be useful. -- Scray (talk) 15:54, 8 March 2010 (UTC)

(UK) I've never heard it referred to as anything other than the (fuel) nozzle. —Preceding unsigned comment added by 131.111.248.99 (talk) 16:22, 8 March 2010 (UTC)

UNLESS, of course, the OP is referring specifically to only the green plastic part of the handle assembly, and not all the metal parts? DaHorsesMouth (talk) 03:11, 9 March 2010 (UTC)

On commons there is an image for the hydrogen fueling nozzle, but I am searching one image of gasoline one.

@DaHorsesMouth: I am referring to the green part and the metal part, too, so the object to take fuel except the tube. --Aushulz (talk) 14:46, 9 March 2010 (UTC)

I added my request here. Thank you everybody. :) --Aushulz (talk) 14:48, 9 March 2010 (UTC)

Charting unknown part of space

In this video, at 3:08, why is it unknown part of the universe in a Bow tie shape? --Reticuli88 (talk) 16:49, 8 March 2010 (UTC)

Probably because it's blocked by something with a bow tie shape, from Earth's POV, such as the most dense portion of the Milky Way galaxy. StuRat (talk) 17:18, 8 March 2010 (UTC)

It's not clear from the picture but I'd bet that the "charted" region is two cones, whose axis is perpendicular to the plane of our galaxy — though I'd expect the cones to be wider than that. —Tamfang (talk) 19:06, 12 March 2010 (UTC)

adaptaion of bones to our environment

how do bones adapt to our environment —Preceding unsigned comment added by Chibu86 (talk • contribs) 18:09, 8 March 2010 (UTC)

They don't really. Bones are essentially the same in all humans, whatever environment they grew up/live in. Do you mean how have bones adapted to our environment, as the human race evolved? --Tango (talk) 18:13, 8 March 2010 (UTC)

You will fail if you turn in that answer. Bones vary greatly according to the environment, lifestyles, and diet of all humans. Bones remodel constantly and adapt to the environment in several important ways. Some examples: 1. One of the most obvious, if exotic, is the steady loss of bone mass in a weightless environment. This is currently a substantial limit to the time humans can spend in space. 2. Bones remodel in response to stress and use. The bones of a person who gets little exercise or physical work are lighter and weaker. Muscular activity is an important factor in maintenance of bone mineralization. 3. A new scientific frontier is the role of bones in regulating energy metabolism (i.e., calorie intake, expenditure, and adiposity). Here is an example [6] 4. Bones change shape in response to environmental shortages of minerals or vitamin D. This reshaping is called rickets. How many more do you need, or have i just done your homework for you? alteripse (talk) 18:37, 8 March 2010 (UTC)

Can you be more precise in your question?

If you carry out heavy labour ( or weight-lifting/training etc.) then those bone that carry the load will thicken to compensate or in zero gravity de- mineralize. Is that what you mean? --Aspro (talk) 18:31, 8 March 2010 (UTC)

In concert with the above stated answers save for the first, bones certainly adapt -- see functional matrix hypothesis and wolff's law. DRosenbach ^{(Talk | Contribs)} 19:55, 8 March 2010 (UTC)

Your second point is good, although I'm not sure I would count behaviour as environmental (although I suppose it is affected by environment). Your other points don't sound like adaptations to me, just changes. A change needs to be beneficial in some way to count as an adaptation, in my book. --Tango (talk) 22:59, 8 March 2010 (UTC)

An adaptation is a controlled, "active" response to an environmental change. All 4 examples are such; none is simply "damage suffered passively". Whether in some combination of circumstances the adaptation has more negative than positive questions does not make it not an adaptation. Broaden your understanding of the word. alteripse (talk) 02:03, 9 March 2010 (UTC)

The one definition in wikt:adaptation that doesn't just reference another word concurs with my understanding of the word. --Tango (talk) 04:23, 9 March 2010 (UTC)

Adjustment to extant conditions: as, adjustment of a sense organ to the intensity or quality of stimulation; modification of some thing or its parts that makes it more fit for existence under the conditions of its current environment Thanks for the link. I assume this is the def you were using. I agree completely. It was the only def that made any sense in the context. I provided 4 examples of adjustment by bone to conditions. Not sure I understand your difficulty with this concept. alteripse (talk) 11:33, 9 March 2010 (UTC)

It's perhaps worth remembering that if we're discussing biology here, acclimatisation is probably the better term to use since it sounds like were discussing changes in an individual in response to the environment, not adaptation by natural selection of populations Nil Einne (talk) 12:21, 9 March 2010 (UTC)

My problem is with the "more fit for existence" bit. How does rickets make you more fit to exist in a environment with scarce vitamin D? It is caused by the deficiency, but I don't think it something the body does in order to cope better, the body just has no choice. --Tango (talk) 23:03, 10 March 2010 (UTC)

Looks like we're getting into a semantic argument here. FWIW, the use of the term "adaptation" to describe physiologic changes to environmental conditions is perfectly valid (see light adaptation for a widely accepted example). I think Alteripse gave a good answer in terms of examples of how bones can be altered by environmental influences. However, if the OP is interested in the mechanistic "how", as in "how is bone remodeling accomplished?" then the articles on osteoclast and osteoblast will provide some insight. --- Medical geneticist (talk) 14:10, 9 March 2010 (UTC)

Just to be clear, I wasn't saying the term is invalid but that (in my experience which is primarily in molecular biology and genetics area) the use of the term in the not evolutionary context is often avoided in biology for clarity and because of the confusion it can cause. In medicine and physiology, things may be different, I can't speak to those areas (hence why I specifically mentioned biology). Light adaptation is perhaps not the best example, since you're discussing something that occurs primarily in minutes (human adaptation to spaceflight which is partially relevant here would be a better example). I would note adaptive system says something similar although it's unsourced and the whole article is in a rather poor state. Of course asking how something adapts, is different from calling it an adaptation, the later is the only one I would avoid. Of course acclimitisation isn't perfect either since it seems to suggest climate rather then generic environmental changes and adaptation is widely used when it comes to bones Nil Einne (talk) 21:11, 9 March 2010 (UTC)

Truth or myth about rebuilding the brain?

«we are learning that hard exercise also stimulates increases in neurotransmitters, like serotonin, norepinephrine and dopamine, all of which we worry about in all of the above maladies. But the research he details in Spark shows further effects on the whole range of biochemistry beneficial to well-being and behavior. Some of these chemicals literally rebuild the brain.»

is that that easy?--Mr.K. (talk) 18:59, 8 March 2010 (UTC)

"Analogy is the core of cognition," but this is an example of a relatively simplistic description of the process of brain remodelling that occurs continuously throughout life. Not sure what you are asking. alteripse (talk) 19:08, 8 March 2010 (UTC)

Agreed. There is certainly some rebuilding of the brain, as in all our other organs, but it's not 100% in all cases, of course. StuRat (talk) 19:11, 8 March 2010 (UTC)

There is some science behind this, but most popular accounts way overstate the story. We have an article, brain fitness, that's supposed to be about this topic, but unfortunately it's a sucky article. Looie496 (talk) 22:48, 8 March 2010 (UTC)

Well, they can't "literally" rebuild the brain. They might improve it's functioning or something - but they could only possibly "figuratively" rebuild it. But think about this - would you really want your brain "literally" rebuilt? Doing that would erase all of your memories, wipe your personality, delete all of your learned skills. You might as well die! SteveBaker (talk) 03:15, 9 March 2010 (UTC)

I'm not sure what you mean by "literally", here. There is often partial physical rebuilding, as in forming new connections, after something like a minor stroke, as well as just with normal learning. We could even think of problems like senility being an "inability of the brain to rebuild itself". StuRat (talk) 14:57, 10 March 2010 (UTC)

So how did we all get here in the first place?

Why did the big bang happen? What caused it? Why did that exist? Why doesn't nothing exist? Doesn't this pretty much discredit atheists?--92.251.221.135 (talk) 21:49, 8 March 2010 (UTC)

I'm not sure how questions can discredit a philosophical statement. Normally evidence is required to discredit something. that being said we can address the earlier questions :

• Why did it happen? - Why not?
• What caused it? - Big Bang has a fairly decent description, but the short answer is either "we don't know" or that question might not have meaning.
• Why did that exist? - This seems to be a statement saying that teh creator of the creator (big bang) had to exist. The counter-argument athesists would present is, if everything needs to have been made by something, then what made "God"?
• Why doesn't nothing exist? - Maybe it did at some point, but noone was there to ask that.

Chris M. (talk) 22:00, 8 March 2010 (UTC)

(edit conflict) We don't know, we don't know, we don't know, we don't know, and no. Why would it discredit atheists? I've always seen it as more of an argument for discrediting theists, since it doesn't match up with any creation story in anything much more than a metaphorical sense. Vimescarrot (talk) 22:01, 8 March 2010 (UTC)

It seems to me that it would very much discredit atheists, because, is it the First law of thermodynamics, that states that matter and energy cannot be taken out of nowhere. --The High Fin Sperm Whale 22:16, 8 March 2010 (UTC)

No one said anything about anything coming out of nowhere. Beach drifter (talk) 22:35, 8 March 2010 (UTC)

• A) Not knowing where the Bigbang came from doesn't mean it came from nowhere.
• B) Conservation of energy is a consequence of time homogeneity. If time started at the Bigbang than there cannot be time homogeneity at the instant of the Bigbang because it is a boundary. Therefore the Bigbang is not required to obey conservation of energy.
• C) As far as we know the total energy of the universe might be exactly zero.
• D) Within the framework of general relativity time homogeneity is not really required at the scale of the universe as a whole.
• E) God coming from nowhere is a problem for theists as well.

Any of the answers above make your point moot. Dauto (talk) 22:57, 8 March 2010 (UTC)

The Fist Law of Thermodynamics really only makes sense in very few possible spacetimes. It is meaningless in a space that is expanding or contracting (see ADM mass, General Theory of Relativity). 74.14.109.18 (talk) 22:52, 8 March 2010 (UTC)

You have the exact same questions with or without God. That is "Who created God ?", or, if you assume that God always existed, why not skip the middleman and assume that the universe always existed (maybe in the oscillating universe mode). StuRat (talk) 21:57, 8 March 2010 (UTC)

Except God would be spiritual, not physical, so laws of physics would not apply. --The High Fin Sperm Whale 22:43, 8 March 2010 (UTC)

If God does not have a physical component, then how can he interact with the physical universe? If he does have a physical component, then how did that physical component arise? —Bkell (talk) 23:39, 8 March 2010 (UTC)

And there isn't a law of physics that says "the universe must have started from nothing". All the mass of the universe always having existed doesn't violate any laws of science, AFAIK. However, there is an intuition that everything must come from somewhere, and that includes gods just as much as matter, leading to the turtles all the way down concept. StuRat (talk) 14:52, 10 March 2010 (UTC)

I don't believe in God. Just sayin you know, how did we get here. Nothing can just come from nowhere, so how did we come from nowhere?--92.251.221.135 (talk) 23:13, 8 March 2010 (UTC)

As Beach drifter and Dauto wrote above, the Big Bang theory doesn't say it "came from nowhere". The little dense point of matter and energy may have been around for 92842049820958 quadrillion years, or infinite years, or there may have been no movement of time at all before the Big Bang — we do not know. Comet Tuttle (talk) 23:19, 8 March 2010 (UTC)

Yes but why did it exist?--92.251.221.135 (talk) 23:21, 8 March 2010 (UTC)

The short answer is that we don't know. However, the other side as long as you are making comparisons to atheists is that the same problem exists for any other notion (such as a deity) just as much. An eternal chain of causation going backwards is logically consistent if a bit counterintuitive. No matter how far you go back you will always be able to ask "so why that?" JoshuaZ (talk) 23:24, 8 March 2010 (UTC)

The reason I mentioned atheists and not theists is because theists can argue that well their God is supernatural why does he have to have a begining?--92.251.221.135 (talk) 23:25, 8 March 2010 (UTC)

But did you honestly expect an answer to any of this? Beach drifter (talk) 23:35, 8 March 2010 (UTC)

Of course not==92.251.221.135 (talk) 23:35, 8 March 2010 (UTC)

I created the world. Bus stop (talk) 23:47, 8 March 2010 (UTC)

May be you didn't expect an answer, but I gave you five answers. Dauto (talk) 23:48, 8 March 2010 (UTC)

Actually, one of the attractive things about the Big Bang as an explanation is that it offers the possibility to cut off that eternal regress of "What created the thing that created the thing that created the Big Bang?" - the idea that time itself was also created in the Big Bang would means that there was no "Before" - problem solved. Or the idea that two universes were created - one with time running backwards - and ours with time running forwards...again, no "before". We don't (yet) know that either of those things are true - but if they are then that's it. Origins problem solved! Any "God" explanation really begs the question "Where did God come from?" and if you answer "He just is" or "He always was" we have to slap you! When science says that the big ban "Just is" or "Always was" - we're told it's an inadequate answer - but when cross out "Big Bang" and write "God" instead - suddenly that's an OK answer for the religious guys. I don't get it! SteveBaker (talk) 03:08, 9 March 2010 (UTC)

"There was no before" doesn't solve the problem "why was there an after?". Is there a theoretical difficulty with nothing at all ever existing? It doesn't sound very problematic, on the face of it. 81.131.20.244 (talk) 00:40, 10 March 2010 (UTC)

Your original question was how can everything come from nothing. That question was answered. Now you are asking a slightly different question which could be paraphrased as "Why does the universe exist at all?". That one is even easier to answer. Five words: It exists because it can. Dauto (talk) 03:56, 10 March 2010 (UTC)

It wasn't actually my original question, and "because it can" is not actually an answer in this case. Why can it? It shouldn't be able to. 81.131.52.202 (talk) 11:43, 12 March 2010 (UTC)

"We don't know - so it must be God." is a deeply unsatisfying answer. Why not "We don't know - so it must have been created by a mad scientist from the year 3010 who had a terrible accident with his time machine" ? Or "We don't know - so it must have been Harry Potter who magiked into existance because HE'S REAL!!!", or "We don't know - but we strongly suspect it has to do with the nature of singularities." - all of those are every bit as valid as "...it must be God". So long as we don't know - it's really better not to make any assumptions whatever about what that means. It would be different if there was evidence of God or Gods doing other things in other parts of the physical world - but there isn't...not a scrap. Since there are a literal infinity of other possible explanations - we have to say "We don't know." and mean it. SteveBaker (talk) 02:45, 9 March 2010 (UTC)

I'm sorry no one else here has given you the correct answer. It all happened Last Thursday, actually, although some will try to convince you that it was just five minutes ago. Imagine Reason (talk) 12:41, 9 March 2010 (UTC)

If nothing existed, then it would continue to be nothing until something came along. Something came along (you're reading this), and being a stable something, it now it remains. The most relevant article I know of is Many worlds hypothesis, but it's rather bunged up with scientific abstractions. The final episode of Star Trek: The Next Generation, All Good Things... explores the concepts of being and non-being rather more accessibly. Vranak (talk) 18:29, 9 March 2010 (UTC)

Where do photons come from after spontaneous emission? Also, don't virtual particles spontaneously appear in vacuum without any prior cause? --Mark PEA (talk) 18:53, 9 March 2010 (UTC)

If this is addressed to me, I have no idea. Although I believe there are allowances made for the spontaneous creation of matter (or was it energy) on the rim of black hole. Little help? :) Vranak (talk) 20:27, 9 March 2010 (UTC)

Hey cool, two days (nearly three) late. Everything's already said. Wish I was here earlier so I could say "what makes your god (which you can't perceive, touch or demonstrate the existance of) so special that it can exist from nothingness while the universe (which you can perceive, touch and prove the existance of to yourself, at least) can't?" and then answer "Nuffin". If your god can exist from nothing, or forever, so can my universe. God's spiritual? So? Spiritual can't affect (or effect, for that matter) the physical - evidence: Efficacy of prayer. You may keep your god so long as its role is limited to pressing the big red "start universe" button. But I, personally, won't believe such a pathetic deity. --Polysylabic Pseudonym (talk) 12:54, 10 March 2010 (UTC)

and as a postscript, how can a theory of origin discredit atheists? Do you think the only alternative is theism? Do not the inconsistencies in the Christian bible discredit Christians? Does not the lack of evidence for any interventionist god discredit practically all theists? Does not the Invisible Pink Unicorn discredit any remaining theists? I am of the belief that the only people left arguing are:

• those profiting from deluding the susceptible
• those too poorly educated to have the ability to analyse the claims of the above profiteers
• those too stupid to know better
• those who argue for fun

I tend to think that those who bring such arguments to the science ref desk are simply doing it for fun, though I can't see where one can find fun in a loosing argument, especially where those responding enjoy doing so as much as I do. --Polysylabic Pseudonym (talk) 13:08, 10 March 2010 (UTC)

Hey! Don't start in on the IPU (mhhbb)! The IPU discredits those she feels like discrediting (and those who don't put pinapple and ham on their pizzas - but that's a religious debate for another day). SteveBaker (talk) 14:28, 10 March 2010 (UTC)

No, really, it's fun feeding this troll. --Polysylabic Pseudonym (talk) 13:08, 10 March 2010 (UTC)

What, no one has mentioned the anthropic principle yet? —Tamfang (talk) 20:14, 12 March 2010 (UTC)

Please, AGF. Posing a question about the universe that suggests the existance of God is not trolling. ~AH1^(TCU) 01:53, 14 March 2010 (UTC)

White Sussex hen

[Query moved from Talk:Chicken#White Sussex]

I have a couple of White Sussex and one sits in her coup. She use to lay daily, now she has stopped and sits in her nest. I think she thinks she has chickens —Preceding unsigned comment added by 121.217.45.250 (talk) 01:40, 8 March 2010 (UTC)

She could be broody (wanting to sit on eggs to hatch them). If so, she'll flop back onto the nest when you lift her up, often making a long, low squawk, fluffing her feathers and pecking at your hand. If taken off the nest she'll cluck about low to the ground and fluff her feathers, or even flop onto the ground and brood there.

You could give her a dozen eggs and let her hatch them. They must of course be fertile, so you need eggs from hens who've been with a male, or if you don't have a male, you'll have to buy hatching eggs. All the eggs must go under her at once, so they hatch together (if she's sat on eggs for different lengths of time, it may be best to discard them and start again). If it takes you a week or so to get a clutch together you can keep her sitting by giving her golf balls. Usually broodies will only sit in the nest they have chosen, but sometimes you can move them to a more convenient place – if you do, put her in a dark, secluded place where she can't easily get out (I use a large bucket with hay in, and a board over the top). If other hens can get at the nest, mark her hatching eggs and keep collecting any new ones from the other hens, or they'll start to develop too. Put her off the nest every couple of days for ten minutes or so to eat and drink and do a dropping, or she may foul the nest. If she does, or if a broken egg contaminates the others, wash the dirty eggs in quite hot (not warm) clean water and dry them carefully, and some may survive if you're lucky (a bit grubby is OK: they only need cleaning if coated with muck). If you smell bad egg in the nest, sniff each egg carefully until you find the off one, then remove it, or it will burst and spoil everything.

The eggs will take 21 days to hatch from when they go under her. When they do hatch, let her brood the chicks on the nest, then after a couple of days remove any unhatched eggs, or move her and the chicks elsewhere (once they're cheeping she'll stick with them wherever they are). Feed them moistened poultry feed, which she will show to the chicks, and water of course; the food only has to be moistened for the first few days. Best not to feed layers' feed to chicks for any length of time, as it has too much calcium which can mess up the development of their joints; you don't however need the special chick food they sell, just ordinary growers' feed. Once running about they can go outside – she'll brood them to keep them warm, shelter them from rain and sun, and defend them valiantly from cats, dogs and any other passers-by. Keep them separate from the other hens at night in a safe corner or hutch until they're well feathered. The hen will keep the chicks together, but she will not always notice the one at the back, so don't let her explore long grass or piles of junk, as a lost chick will get cold or be eaten.

Alternatively if you don't want her to sit or can't get any fertile eggs, put her in an airy, well-lit, wire-floored cage off the ground until she goes off the idea (it may take a week or so).

Good luck! Richard New Forest (talk) 23:45, 8 March 2010 (UTC)

I think it might be a good idea to move this back to the article talk page - we're not allowed to give medical (including veterinary) advice here. Tevildo (talk) 23:59, 8 March 2010 (UTC)

I don't think this is a medical advice question. Comet Tuttle (talk) 00:02, 9 March 2010 (UTC)

Anytime you can eat your mistakes, it's just dietary advice. :) Franamax (talk) 00:23, 9 March 2010 (UTC)

It is an excellent answer and corresponds to my experience. It is animal husbandry, and not "veterinary advice." It is akin to advising how to grow tomatoes. My significant other says "It sounds like poetry." Edison (talk) 02:27, 9 March 2010 (UTC)

March 9

Yellow hands

A young girl I know has a peculiar yellow tint to her hands, and I'm wondering what it could be. She is east Asian, but there is a distinct almost "stained-yellow" color to her hands, as if she was soaking them in a brown ink every day. She is healthy, I was thinking it might just be increased carotene? Any ideas? 210.153.207.42 (talk) 00:58, 9 March 2010 (UTC)

I should note that only her hands are visibly colored. 210.153.207.42 (talk) 01:00, 9 March 2010 (UTC)

Saffron is that color, but I'm not aware of anyone dying their hands with it intentionally, although I suppose it could bleed into their hands from preparing foods with saffron that require lots of hand manipulation. StuRat (talk) 01:58, 9 March 2010 (UTC)

It's possible, though her hands have been like that (as far as my noticing goes) for at least a year. Maybe she really likes paella. 210.153.207.42 (talk) 02:43, 9 March 2010 (UTC)

The color you describe sounds a little like Henna. Paul Stansifer 03:14, 9 March 2010 (UTC)

Yes, to be honest I thought the same thing, but again I don't understand why it would last so long, nor why she would be continuously using henna! I was actually under the impression that it was likely to be an internal thing, which is why I mentioned carotene. It does look like the skin itself is colored, though I can't tell why it would only coloring the hands. 210.153.207.42 (talk) 03:58, 9 March 2010 (UTC)

There's certainly precedent for people having very yellow skin as a side-effect of eating much too much carotene, so that's a reasonable thought - but it still seems odd for it to be restricted only to the hands. ~ mazca ^talk 09:05, 9 March 2010 (UTC)

Mind you, it's not like I've seen her whole body. Her legs and face aren't yellow though. 210.254.117.185 (talk) 10:31, 9 March 2010 (UTC)

Turmeric is a pretty good yellow dye. It's dyed several of my pots and utensils and cups. It's common in SE Asian cooking, and is reputedly good for your skin. Indeterminate (talk) 05:21, 9 March 2010 (UTC)

Tobacco can stain fingers yellow, but that wouldn't usually be the whole hands. --Tango (talk) 05:38, 9 March 2010 (UTC)

I now have a great mental image of a small girl chain-smoking huge cigars held in her fist. ~ mazca ^talk 09:05, 9 March 2010 (UTC)

Localized jaundice. I have this, on my face and hands. —Preceding unsigned comment added by Fire2010 (talk • contribs) 19:50, 9 March 2010 (UTC)

Handling nitroglycerine or cordite? —Preceding unsigned comment added by 79.76.188.14 (talk) 23:17, 9 March 2010 (UTC)

How young is the girl? I've seen it more then a couple of times when girls have strangely yellowed hands and it was my fiancé's younger sister who gave me the answer. She was only 15 and started using this "sun cream" which was not only sun block but also "fake tan" in one bottle. Since you use your hands to apply it, your hands soak up a lion's share of the ointment, if you don't wash them immediately, which girls never do since girls never read instructions, especially 15 year old ones. ;) I'm not guaranteeing this is the case here, but everything you've said so far seems to fit with this theory.Vespine (talk) 00:46, 10 March 2010 (UTC)

The OP says she's been like this for a year. She'd have to be a rather 'slow learner' for something like that to continue for so long. Either that or this fake tan stuff is a lot nastier then I thought if it lasted that long from one or two instances Nil Einne (talk) 03:51, 10 March 2010 (UTC)

Well my fiancé's sister is 17 and she still uses the stuff. Apparently yellow hands are a small price to pay for vanity.. Actually my fiancé teases her because even I agree the entire "fake tan" effect is a ridiculous orange and blotchy, especially around her face! But the younger's sister wants to do what she wants to do and no one can tell her otherwise.. Vespine (talk) 04:18, 10 March 2010 (UTC)

I'm not surprised she still uses it. I am surprised she hasn't yet learnt to wash her hands immediately after application... The word I said earlier does seem to apply. Nil Einne (talk) 15:52, 11 March 2010 (UTC)

Having read this post a few days ago, I could not help but think of it when I heard a quickly-read side effect of Cymbalta on a television commerical: "yellowing of the skin." AlexHOUSE (talk) 23:16, 11 March 2010 (UTC)

I guess the obvious answer is there are probably plenty of reasons, we'll never know which. If the OP is genuinely interested, they could befriend this person and ask them at some stage in the future when it doesn't seem inappropriate (obviously don't do this if you're going to completely forget about the person once you know). You can even come back months or whatever from now when you know and tell us if the person consents Nil Einne (talk)

plastic? it breaks weird

is the window in this

http://www.youtube.com/watch?v=PH5OMyuAppg

plastic? it breaks weird —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 01:09, 9 March 2010 (UTC)

Yes - it certainly looks like plastic of some kind. When you hit a piece of glass, it's so brittle that cracks propagate outwards to the edges of the pane. But plastic can bend enough to stop cracks from propagating - so you get those kind of rounded chunks falling out. Also, you can see the intact panes bending in the wind. It's hard to be sure though. SteveBaker (talk) 02:26, 9 March 2010 (UTC)

They look like storm windows to me. They are commonly plastic on the outside and (usually) placed over glass on the inside. If there was glass on the inside, you wouldn't see it after the axe went through. Some people put up storm windows without real windows behind them. So that could be the case here. -- kainaw™ 06:25, 9 March 2010 (UTC)

Comments on YouTube suggest the window material is Plexiglass (Poly(methyl methacrylate)) but from its apparent flexibility I expect it is vinyl. Cuddlyable3 (talk) 21:52, 9 March 2010 (UTC)

Cover slips are often made from glass but break like plastic. ~AH1^(TCU) 01:47, 14 March 2010 (UTC)

plant growing

A technical? question about growing large plants. I assume that while more sunlight = more energy for the plants, and thus a brighter area can support a larger number of (non-shady) plants, too much sunlight evaporates too much water and thus there is a balance between the amount of sunlight a plant can get vs. the available water. If extra sunlight was redirected towards (not focused at) a large garden area, and care is taken to keep the ground cool/moist (the redirected light could be aimed parallel to the ground so as not to heat it directly), would this make the area more fertile? Am I thinking in the wrong direction? A large greenhouse isn't really feasible, and this can't really be a big expensive/mechanical operation. 210.153.207.42 (talk) 04:10, 9 March 2010 (UTC)

Sorry, but that just wouldn't work. The reason is is that the sun produces infrared waves (heat) along with the visible light. So even if the light is not focused, wherever you can see the sun's light, there will be heat. However, I believe the best thing to do would be to redirect the light at the plant's leaves, but not the ground. This way, the plant would take energy from the sun, but it would not dry up the soil. Hope this helps, --The High Fin Sperm Whale 04:20, 9 March 2010 (UTC)

Yeah, that's exactly what I was proposing, by aiming the reflected light parallel to the ground, rather than at the ground. 210.153.207.42 (talk) 05:06, 9 March 2010 (UTC)

Whether it will result in better plant growth will depend on whether it was sunlight that was the limiting factor before. It could be that they have plenty of sun and actually need more water, or more nutrients in the soil, or more physical space, etc. If one of those things is limiting the plants' growth then more sunlight won't help. --Tango (talk) 05:42, 9 March 2010 (UTC)

Thanks! What about in a more complex forest, with large tree growth, and smaller ferns and bushes underneath? I've seen a lot of Canadian shield forest (and badly planted artificial forest) where tall trees block out the sunlight leaving almost none for the undergrowth, so I'm thinking of a way to promote more plant variety. 210.153.207.42 (talk) 05:51, 9 March 2010 (UTC)

And also, what is the limiting factor for space? If there is plenty of sunlight/nutrients won't plants be able to grow around each other? 210.153.207.42 (talk) 05:55, 9 March 2010 (UTC)

If there is room to grow around things, then there isn't really limited space. A plant that is growing between two large rocks may not be able to grow as big as it would otherwise do, simply because there is nowhere for it to grow into. It is quite unusual for space to be the limiting factor, I think, but it isn't impossible. --Tango (talk) 23:06, 10 March 2010 (UTC)

You may be interested in Forest gardening. In biological systems, something may be held back by a limiting factor, but once that limiting factor is overcome then another limiting factor is in control. Difficult to know what the limiting factor may be, it could easily not be lack of sunlight. I take it you are in a hot dry area. You could consider trickle or Drip irrigation or mulching to conserve water. It may be simply that there is not enough diversity of seeds for what you want, or they are dormant for lack of water, or that fertilizer would help. I would consider scattering a variety of seeds, possibly with fertilizer, and supplying water. Too much sunlight may scorch the plants. Many plants seem to like moist warmth, but what is best will vary from species to species. You could consider a polytunnel, perhaps home-made, but perhaps your plants will wilt in the heat. For large plants it is better and quicker but more expensive to buy them already grown from nurseries. The polytunnel article only mentions small ones, but I was thinking of ones seven or eight feet in diameter, which are quite common where I am. 78.146.202.143 (talk) 19:59, 9 March 2010 (UTC)

It is more likely, from what you have described, that the plants are being held back by lack of water rather than lack of sunlight. Even in Britain, which is as far north as Newfoundland and hence has less intense sunlight, plants which have access to water such as being by a stream are especially lush. 92.26.160.145 (talk) 20:51, 10 March 2010 (UTC)

I haven't built anything yet, I'm in the planning stages, and I'm just wondering how to obtain the most fertility (self-sufficient, within a restricted area) without relying on fertilizers/overly mechanical irrigation techniques. I'm actually in a fairly moist cool area, near Vancouver, though my goal is to promote as much variety and "lush" as possible, so I figured with my relatively high latitude, sunlight was likely to be a limiting factor. It's apparent that there are likely to be many other limiting factors, dependant on soil type, so I'll keep that in mind too! I will definitely consider having some kind of underground water "polytunnel", as well, if I can easily borrow from a nearby stream (without harming the stream). Thanks for the info! 210.254.117.185 (talk) 05:56, 11 March 2010 (UTC)

A polytunnel is above ground. The ones I am familiar with are more than big enough to stand up in. They are in the shape of half a cylinder, and are formed of a very large sheet of clear polythene stretched over very long rods bent into a U-shape and stuck into the ground. Trickle pipes are usually just left on the surface. You could try building a pond. 89.243.212.29 (talk) 14:58, 11 March 2010 (UTC)

price wiki

Is there a wiki where one can enter the price, date, store location and UPC or PLC of the item and that tracks price changes and/or differences over time and location? 71.100.11.118 (talk) 05:57, 9 March 2010 (UTC)

I don't know about a Wiki, but there are many price comparison websites on the net. —Preceding unsigned comment added by Fire2010 (talk • contribs) 19:48, 9 March 2010 (UTC)

You may be able to find or create one at Wikia. ~AH1^(TCU) 01:44, 14 March 2010 (UTC)

Name of an "larva"

Resolved

Hi, about six or seven years ago my sister received a present that was like an aquarium for insects. Basically, it was like a plastic pool that you filled with water and then there was a packet of dried "insects" that, when applied to water, would "hatch" and eventually start swimming around. I remember the box saying that those "insects" (or "larvae" or whatever) were "millions of years old" but that could've been an exaggeration to boost sales. From my memory, the older ones had tails. Does anyone know the name of the insect/amphibian? 144.124.16.28 (talk) 07:47, 9 March 2010 (UTC)

Sea monkeys. Stupid me. Thanks anyways. 144.124.16.28 (talk) 07:53, 9 March 2010 (UTC)

That's the marketing name. They are typically really brine shrimp. I will mark this Q as resolved. StuRat (talk) 15:00, 9 March 2010 (UTC)

Mobile phones on airplanes

I have to turn off my mobile phone when on an airplane because it intefers with the plane's navigation system - But while it's turned off, I can receive SMS and also calls to my mailbox - why don't these signals cause problems for the airplane too? Thanks for info, --AlexSuricata (talk) 12:50, 9 March 2010 (UTC)

They do cause the same issues (to the extent that there are any real issues of concern - entirely another debate). What sort of phone do you have that when turned off, it is still on? Mine, fwiw, is very much off when it is off. --Tagishsimon (talk) 12:57, 9 March 2010 (UTC)

(ec) I'm pretty sure that, when your phone is off, it doesn't receive anything; messages get queued up by the phone company for delivery when you first turn it on. This is why there's some delay between turning the phone on and getting messages. Paul Stansifer 12:59, 9 March 2010 (UTC)

And as for the voicemail messages, those are not stored on your phone at all - if you do not answer your phone, the call gets directed to your mailbox in your cellular carrier's system. When you turn your phone back on, you're simply receiving the notification that there are more messages in said mailbox than there were before. Text messages (SMS) are stored on your phone itself, but they queue in your carrier's SMS delivery system while your phone is not connected to the network, such as when it is off or in an area with no service. They are released when your phone next makes contact with the network. Coreycubed (talk) 14:48, 9 March 2010 (UTC)

I've always suspected that the ban on cell phones in the plane was more about not annoying other passengers than safety. However, people are less likely to violate the ban if they think the plane will crash in flames when they turn it on. StuRat (talk) 14:56, 9 March 2010 (UTC)

I did not turn my phone off the last time I was flying, and noticed the battery drains really fast. Is that because the phone is moving to a different cell tower every 30 seconds? Googlemeister (talk) 15:06, 9 March 2010 (UTC)

It's for the same reason that it drains faster out in the middle of nowhere...it has to struggle to find reception...weak reception/searching for service kills phone batteries, and there's not much service 40,000 feet (12,000 m) in the air. Ks0stm ^(T•C•G) 15:13, 9 March 2010 (UTC)

Obligatory WP:WHAAOE link: Mobile phones on aircraft -- Coneslayer (talk) 15:19, 9 March 2010 (UTC)

And since we unsuccessfully avoided Tasishsimon's "entirely another debate" statement, the real reason we aren't supposed to use portable electronic devices on aircraft is because they emit harmful pilot killer rays! Coreycubed (talk) 17:04, 9 March 2010 (UTC)

Half life zpe device for book

Hi guys

What would be a good alternative that is more realistic ( i say more, but still) way of acheiving the effects of the zpe gun in Halflife 2? A machine that if it existed would be Like mechanical telekinesis. I know this is not possible with technology ( at least not at the moment) but what forces would you need in real life to acheive this kind of thing. would electron manipulation work? I ask this because In real life even if you could manipulate zero point energy or vacuum energy it wouldnt be strong enough?

So are there any Ideas ?

R —Preceding unsigned comment added by 79.67.141.98 (talk) 14:26, 9 March 2010 (UTC)

For those not familiar with Half-life, perhaps you might summarize what the thing does? Here's what I'm reading into it: you point the gun at something -- say, a crate 100 feet away. The crate glows with cool blue light, and then by swiveling the gun, the crate moves, staying in line with the barrel. Then you release the trigger and the crate falls. Good enough? So, with that sort of thing, you've got to cancel mass. That's the simplest (in terms of linguistic expression) means of lifting the crate and moving it around on the end of a really long arm. And it can't be done. There's no "mostly realistic" or "more realistic" about it. Worse, it's the sort of tech that absolutely breaks a story unless you can set hard limits on it (F=ma has just become absurd, and that's pretty core to how everything works). So if you want to use it, fine, any technobabble will do. Oh, and it needs a power source. I recommend tritanium batteries. They're rechargeable, you know. — Lomn 14:39, 9 March 2010 (UTC)

Oh, and to borrow from Baseball Bugs' recent comment on a related subject, if the writer is smart, he won't waste much time explaining the weird tech, as explanations often do little but further open the door to rebuttal. I'd say the key exception is where the explanation reveals a plot point and/or closes a plot hole. For example, in The Mote in God's Eye Niven and Pournelle spend a fair bit of time on the theory behind the Alderson drive because limiting FTL travel is essential both to their presentation of how the universe is explored and to keeping the "sci" in "sci-fi" from floating straight out the airlock. — Lomn 14:52, 9 March 2010 (UTC)

There is no possibility of creating a real gravity gun -- it violates the principle of conservation of momentum. Looie496 (talk) 20:39, 9 March 2010 (UTC)

Not necessarily. Perhaps it transfers momentum to the ground. — DanielLC 21:32, 9 March 2010 (UTC)

This is clearly not a possible device - but for a sci-fi story, stick to the rules:

1. There shall not be more than one or at most two impossible technologies.
2. All impossible technologies must have limitations that are commensurate to their power.
3. Make up a name and handwave the explanation for how it works.

SteveBaker (talk) 04:46, 10 March 2010 (UTC)

nuclear power station sites

Since it will take at least 10 times the number of nuclear power stations the US now has to displace the current usage of fossil fuel how many sites have been evaluated and/or selected to become nuclear power stations since George W Bush told the American Congress that the US was addicted to oil? 71.100.11.118 (talk) 16:15, 9 March 2010 (UTC)

Nuclear_power_in_the_United_States#Resurgence may help to answer your factual questions. Please note that the Reference Desk is not the place to start a debate or advance a particular position. -- Coneslayer (talk) 16:25, 9 March 2010 (UTC)

Please note that I can not prevent the news media from reporting that Barack Obama was taking another look at nuclear energy or that George W Bush told the American Congress that America is addicted to oil, both of which are facts I could care less about debating but merely want to know in which what, if anything is being done in accordance with pub.ic statements made by American Presidents. You on the other hand might want to start an argument over what you have been told you can and can not do as a good little Wikipedia boy or girl while I could care less. 71.100.11.118 (talk) 16:42, 9 March 2010 (UTC)

"pub.ic statements made by American Presidents" ? Are we talking Bush ? StuRat (talk) 05:00, 10 March 2010 (UTC)

You're welcome for the help. -- Coneslayer (talk) 16:45, 9 March 2010 (UTC)

The question in its distilled form is "How many sites have been evaluated to become nuclear power stations?" The answer is found in the article linked above; 26 applications received, 7 more expected. Six reactors have been ordered. We currently have 104 nuclear power plants. By your own math, we would need an additional thousand. No need for anything other than AGF here; myself, I could not care less. Coreycubed (talk) 16:51, 9 March 2010 (UTC)

I seem to remember hearing that "could care less" has been misused enough to now be a synonym for its opposite. But I couldn't care less, so I'm not going to follow it up with a question to the language desk... or a check of a dictionary --Polysylabic Pseudonym (talk) 03:11, 12 March 2010 (UTC)

From the time the first electric power central station went in service in 1882 until the 1970's, utilities had to scramble to add an average of 7% more generation each year, which means doubling it every 10 years (varying with the economy and local conditions). This was due at first to more and more homes and business getting wired for electricity, then with its increased use for more purposes. Saturation eventually occurred, and efficiency /conservation efforts helped to limit growth. Transmission lines were planned and generation sites were selected and purchased years decades ahead to allow for this growth. Larger and larger generator were installed until they were over 1000 megawatts each. When the growth of demand for electricity fell off in the 1970s, the new generations sites were deferred and ultimately many were cancelled. A utility might have planned for ultimately 4 1000 megawatt nuclear units at a site, but cut it back to 2, while some other 4 unit site was cancelled entirely. Where you see a 2 unit nuclear plant, the ultimate may have provided for 4 units. The cancelled sites are likely just rented out as farmland at present, but transmission lines rights of way may have been purchased years ago which provide for the lines to crisscross nearby to allow for a variety of outlets for the power. "Ultimate" or "many years in the future" future system plans are still in drawers at the electric utilities, which could provide for much more nuclear generation than was ever built, perhaps double the existing number of nukes at a given nuclear utility. Load flow studies were done which modelled loads several times as great as present, noting what generating and transmission would be needed. Present nukes are designed to operate without trying to follow the daily peaks and troughs of demand, but rather as "base load" units ideally running night and day at a constant output. Smaller fossil units and peakers accomodate the peak loads and can cycle up and down. Better, cheaper and higher capacity energy storage would let the base load units do their constant output thing while storage near the load centers helped accomodate peaks without overtaxing transmission lines or running fossil units. Certainly the public would yell "Not in my backyard," as they always did, if utilities announced plans to build 346 and 765 KV AC and 500 KV DC transmission lines and nuke stations with cooling lakes or cooling towers near their communities. The upside of a nuke plant is that the property taxes enrich the local schools and municipalities. The downside could be more Chernobyls if design and operation are not adequate. Edison (talk) 17:22, 9 March 2010 (UTC)

That leads to my conclusion that, due to real threats (like terrorism) and perceived threats (like The China Syndrome), we need to build nuclear plants more defensively. They could be constructed in old mines, far from population centers, in areas with stable geology, with the cooling towers up above. Hopefully, then, even if there was an explosion, the radiation would be confined to the mine. Another advantage would be that spent fuel could just be left in the mine, not hauled cross-country to a disposal site. You would, however, still have the risk of delivery of the nuclear material, unless it could also be processed from low-grade ore at the reactor site. It would be necessary to build more transmission lines, due to the remote nature of such a set-up, and they should be buried, for several reasons: 1) aesthetics, 2) to make attacks by terrorists more difficult, 3) to limit electromagnetic interference with nearby electrical equipment, 4) so they don't "spook" people who are afraid of medical side-effects. StuRat (talk) 14:32, 10 March 2010 (UTC)

The increase of cost of doing something like that would make them even more infeasible and economically draining than they already are (the capital costs are already basically prohibitive for major nuclear expansion without major government financing). A more serious goal would be to engineer the containment building to withstand a direct and purposeful crash with a 747 (they can already withstand a lot, but I'm not sure about that), to the degree that it wouldn't release significant nuclear material. Anything more than that is probably overkill (if someone is literally dropping bunker busters or nukes on your reactor, you have other problems). Note that at the moment we have zero evidence of terrorists doing any kind of successful attack on reactors whatsoever, and it would take a very non-trivial effort (e.g. a crashing 747) to do serious harm to the reactor vessel (they are very rugged). A more serious terrorist threat would be the spent fuel that is kept on site. The clever terrorist is going to attack "softer" targets (some of which—like chemical storage platforms—could do as much or maybe even more damage than a reactor). (And, arguably, the concern with terrorism is a bit overblown here, as far as threats go.) --Mr.98 (talk) 15:16, 10 March 2010 (UTC)

I am not sure on the containment building taking a hit from a 747, but It is a fairly rugged building. According to our containment building article, one location tested a containment building by hitting it with a jet at 450+ mph and it basically only scratched the outer concrete layer. Googlemeister (talk) 15:40, 10 March 2010 (UTC)

But what you're missing is that, no matter how safe it actually is, the perception of danger and corresponding public opposition will lead to delays and cost overruns or even the cancellation of the project. And I have to think that building in an abandoned mine would have to be cheaper than the massive containment building needed to protect it from a 747. StuRat (talk) 17:38, 10 March 2010 (UTC)

I strongly endorse the idea of building the plants at a site which is easily protected and using high capacity transmission lines to carry it to the load center, coupled with local energy storage at the load center. Human frailty, unforeseen multiple failures, or terrorism could breach any containment than has been built. In the worst case, people many miles downwind would have to evacuate in a very short time, and I have severe doubts about how successful such an evacuation of Chicago, or New York City would be, given the Hurricane Katrina fiasco in New Orleans. If a terrorist had control of one plane with one large conventional bomb, or an ANFO bomb in a large truck, attacking a chemical storage facility, a nuke plant, fuel storage pools, or perhaps a dam could cause a multiplicative effect of damage compared to just dropping the bomb on a target city. No dam, chemical plant or nuclear plant has security guards on site prepared to fend off a very large force of well armed and well trained suicidal attackers. Edison (talk) 18:10, 10 March 2010 (UTC)

But putting it in a mine is not necessarily going to fix those issues. In fact, waste disposal in mines has indeed been tried, and run into massive public opposition. One of the first attempts in the US to find a permanent disposal site involved an abandoned salt mine in Lyons, Kansas (Project Salt Vault)... it ran into massive problems. In part because mines have complicated geology once you really start looking at them. Yucca Mountain is in an abstract way an ideal site—middle of nowhere, under a mountain, nobody lives on it, government owns all the land already. Yet it has hardly been controversy-free, or problem-free. Anyway, I'm honestly not sure one is going to overcome public fears by technical means, however ingenious. As for the containment v. mine costs—I don't know. The nice thing about a containment building is that you don't have to contain the whole plant; only the core is important, and that is relatively small compared to the rest of the plant. --Mr.98 (talk) 00:13, 11 March 2010 (UTC)

Surely you solve a NIMBY issue by moving the reactors out of people's back yards, right ? StuRat (talk) 06:25, 11 March 2010 (UTC)

As a matter of interest, here is a video of the plane crash test that Googlemeister mentioned. 131.111.248.99 (talk) 20:37, 10 March 2010 (UTC)

So then it is fair to say that without military dictatorship to order construction of 1,000 more nuclear plants in the next 3 years that we remain pretty much permanently dependent on foreign oil? 71.100.11.118 (talk) 02:12, 12 March 2010 (UTC)

It certainly would be much better if the US could have an alternative energy infrastructure up and running when the oil runs out, but it doesn't look like that's going to happen, due to a lack of political will to do what it would take (such as heavy taxes on oil and subsidies on alternative energy). So, failing that, oil prices will skyrocket and then there will be a huge surge in alternative energy production, with years of blackouts and brownouts before they get up and running. I'd also expect people to start producing their own power, with windmills and solar panels, as power from the grid will be unreliable for many years. So, while pure capitalism does ultimately fix such problems, there can be huge disruptions before the "balance is restored". StuRat (talk) 13:26, 12 March 2010 (UTC)

The US would not have electrical interruption on the scale you describe. In 2008, only 1.1% of the US electricity was petroleum (http://www.eia.doe.gov/cneaf/electricity/epm/table1_1.html). What would be the big problem would be how to run the millions of cars and trucks we have. Googlemeister (talk) 16:32, 12 March 2010 (UTC)

What's the average amount of caffeine in a single medium roasted coffee bean?

From what I know, the amount of caffeine is actually reduced when brewing and roasting a bean, but how much is the amount left in a single roasted bean before brewing? IllusionalForce (talk) 17:50, 9 March 2010 (UTC)

There is lots of data about mass of caffeine per serving and mass-fraction of caffine in a bean. Either of those would allow you to calculate it, all you need to know (and I don't know it) is the typical mass of a coffee bean. DMacks (talk) 18:59, 9 March 2010 (UTC)

Do you mean Arabica coffee beans or Robusta coffee beans. There are two different species of coffee plant typically used in making coffee; Robusta has more caffeine per bean (according to our article, about twice the caffeine) but has a less desirable flavor profile. So, you'd of course first have to know WHICH coffee bean you are working with. --Jayron32 04:42, 10 March 2010 (UTC)

Convert to mhtml

Moved to WP:RD/C.

Black is black?

Black is black because it reflects nothing - right? So how come I can see a sheen of reflected light from some black painted objects? —Preceding unsigned comment added by 79.76.188.14 (talk) 21:12, 9 March 2010 (UTC)

Because it's not quite black. — DanielLC 21:26, 9 March 2010 (UTC)

See the article on Specular reflection. It is quite difficult to get a truly black non-reflective surface but a school's black Chalkboard is close. If you paint it with a transparent shiny varnish it becomes shiny black which is still 'black' but specular reflections. Cuddlyable3 (talk) 21:30, 9 March 2010 (UTC)

Black is black because of a low level of diffuse reflection, not because of a low level of specular reflection -- in other words, it's quite possible to be shiny and still be black. The level is never zero, though, it's just a matter of degree. Most things that we call black emit more light if placed in bright sunlight than a white object will if placed in a dim room, in fact. Looie496 (talk) 21:43, 9 March 2010 (UTC)

Above are good answers. Also consider that black is sometimes used in a relative sense. "Black" on your computer monitor is where no energy is intentionally spent illuminating it. It's still not black, but rather "as dark as it gets". 03:35, 10 March 2010 (UTC)

When we talk about "color" we're using a very minimal short-hand for the complexity of what's really going on. Humans generally use "color" to talk about the light that is scattered off more or less equally in all directions from the surface ("diffuse" or "lambertian" reflection). We do that because for most materials, the light that's "specularly" reflected (like a mirror - angle of incidence equals angle of reflection...roughly) takes on the color of the light source and has more or less nothing much to do with properties of the object. Shine a red light onto a shiney black surface and the specular reflections are red - shine a green light on it and it reflects green. But diffuse reflection is modified by the spectral characteristics of the material. The properties of the material are evident in the diffusely reflected light - but not so much so in the specularly reflected light. So if you want to talk about the nature of the object and not the nature of the light source - then you have to talk about the diffuse reflectivity - which is what we (mostly) do. Hence, there are 'flat' black objects and shiny black objects and really good mirrors that are also technically "black" because they don't scatter light in a lambertian manner at all. Our failure to have a consistent name for the color of a mirror (most people say "silver"...which isn't a color at all!) is a measure of the incompleteness of the way we name things. Materials like polished copper that specularly reflect in unusual ways almost defy description - we say "coppery" which really is a failure of linguistics! SteveBaker (talk) 04:06, 10 March 2010 (UTC)

Los Bravos discussed "black is black" in 1967. Edison (talk) 17:50, 10 March 2010 (UTC)

magnetic field

How strong of a magnetic field would be needed to rip the iron out of a human's blood a'la X men 2? Googlemeister (talk) 21:32, 9 March 2010 (UTC)

If it can be done at all (and I'm rather skeptical), it would take a stronger field than humans have ever been able to generate. Iron in blood is paramagnetic (weakly) and not ferromagnetic like bulk iron. Dragons flight (talk) 22:35, 9 March 2010 (UTC)

A magnetar's magnetic field would be able to kill at 1000km by tearing water out of tissues. No idea if that's the first thing that the magnetism would do to kill you, though. Paul Stansifer 05:57, 10 March 2010 (UTC)

Frogs start flying due to diamagnetic effects well before the iron is ripped out of their blood. http://en.wikipedia.org/wiki/Diamagnetism#Diamagnetic_levitation . 157.193.173.205 (talk) 08:13, 10 March 2010 (UTC)

I should point out that in X-men 2, Magneto isn't ripping out hemoglobin. Mystique injected some sort of liquid metal, presumably ferrous, into the guard's body. So removing it from his body should require a far less powerful magnetic field than that required to affect hemoglobin; an MRI is capable of pulling ferromagnetic metal implants from your body. —ShadowRanger ^(talk|stalk) 21:15, 10 March 2010 (UTC)

Reaction type

What type of reaction is 2Na₂O₂ + 2H₂O -> 4NaOH + O₂ ? --70.250.214.164 (talk) 21:34, 9 March 2010 (UTC)

I believe that would be a displacement reaction. --The High Fin Sperm Whale 22:18, 9 March 2010 (UTC)

(Edit conflict with below) Or more generally, an Oxidation-Reduction reaction. The oxygen in the sodium peroxide has an oxidation state of -1. Some of it is oxidized to the 0 state in O₂, while some of it is reduced to a -2 state in the hydroxide. I'm not sure I'd call this a displacement reaction at all, really. Buddy431 (talk) 22:48, 9 March 2010 (UTC)

Lorentz dilation?

Suppose a rod is moving at a speed v relative to an observer, with the rod oriented towards the direction of motion. In the observer's reference frame, the length of the rod can be determined by measuring the time Δt it takes for the rod to pass the observer. Then, L=vΔt. In the rod's reference frame, the time it takes for the observer to pass the rod, Δt₀, can also be measured. Likewise, the length of the rod can be calculated by L₀=vΔt₀. We then have L₀/Δt₀=L/Δt. Substituting Δt=γΔt₀, we arrive at the equation L=γL₀. However, it should be L=(1/γ)L₀. What have I done wrong? 173.179.59.66 (talk) 21:41, 9 March 2010 (UTC)

Wait, I think I got it: It should be Δt₀=γΔt, right? 173.179.59.66 (talk) 22:17, 9 March 2010 (UTC)

Yes, right. It is Δt₀=γΔt. Dauto (talk) 03:50, 10 March 2010 (UTC)

When you write L=γL₀, it means that Δt₀=0, which means that you are considering two measurement events occuring at the same time in the (x₀,t₀) system, which means that the rod is moving in that system, which means that it is at rest in the (x,t) system, which is not the case.

So you should have L₀=γL (and thus L=(1/γ)L₀), with Δt=0, so the rod is indeed moving in the (x,t) system.

Now you take this equation Δt=γΔt0. This is valid for two measurement events satisfying Δx₀=0, i.o.w. occuring at the same place in the (x₀,t₀) system, but you said that the rod is passing the (x,t) observer. That means that you need two events satisfying Δx=0, for which the transformation indeed produces Δt₀=γΔt. DVdm (talk) 22:52, 9 March 2010 (UTC)

Nomogram construction

I have a nomogram of height & weight = body area. The scales are arranged in three vertical columns, the idea being that one takes the known value of height on the far left, aligns a straight edge to the weight on the far right, and the central point on the straight edge is the surface area on the central column.

What I am trying to do is rearrange the whole nomogram to a different layout - ideally a circular one, something with turning discs maybe, but I'm damned if I can come up with a way of working it and I've about decided that it's impossible. But I'd thought I'd ask you clever chaps...? FreeMorpheme (talk) 22:25, 9 March 2010 (UTC)

I'm not sure I get what you mean by a circular layout, but it seems like you basically want something like a circular slide rule -- since area equals length times width, you need a mechanical way of doing multiplication; a slide rule does that by adding logarithms. Looie496 (talk) 23:40, 9 March 2010 (UTC)

What equation are you using to relate height & weight to body area? SteveBaker (talk) 03:34, 10 March 2010 (UTC)

The equation is square root of (height x weight / 3600). I need to print this out and I would prefer to make some arrangement of discs, but I don't see a way unless the actual discs are geared, which is a bit much for cardboard 195.60.13.52 (talk) 15:36, 10 March 2010 (UTC)

In my original answer I somehow misread "weight" as "width", but even so, with the formula you are using, this is easy to do with a circular (or linear) slide rule -- they handle multiplication and square roots quite easily. Looie496 (talk) 17:10, 10 March 2010 (UTC)

I do not think you could do it with rotating discs of carboard, as the rotation of two of them would not determine the position of the third scale. But you could just have an ordinary graph with axis of height and weight, and the area being readable at their coordinates. With "contour lines" delineating the diferent areas, it could be interesting to look at. 78.151.126.97 (talk) 17:20, 10 March 2010 (UTC)

You can make a dense grid of 'body area' numbers indexed by height and weight and print it in concentric circles on a disk. You'd effectively be using polar coordinates such that the distance from the center of the disk is "height" and the angle around the circle is "weight" (or you could do it the other way around). Print the weights around the circumference of the disk. Now you need a second, rotating disk on top of that with a pointer on the outside and a radial slot cut into it. You'd rotate the disk until the pointer pointed to your weight - then look at a "height" scale printed next to the slot - and read out the number that's showing through the slot next to your height. This approach works for any function of two parameters. However, the precision of the result depends on how small you can print. But since the equation you're using to calculate body area is horrifically approximate anyway - this hardly matters.

If you want, you could use a third disk with a spiral slot cut into it and rotate that to select the appropriate number from the first disk by looking through the "window" formed by the intersection of the slots in the second and third disks. SteveBaker (talk) 14:06, 11 March 2010 (UTC)

Properties of metals

I noticed that, although many metals have useful properties, they are balanced out by severe disadvantages. For example, iron is extremely strong, but it corrodes easily and falls apart, lead is malleable, ductile, and corrosion-resistant, but highly toxic, etc. Why is it that every metal with any practical use is "balanced out" by having some significant flaw? --70.250.214.164 (talk) 22:49, 9 March 2010 (UTC)

What about Stainless steel or titanium or aluminium? —Preceding unsigned comment added by 79.76.188.14 (talk) 23:02, 9 March 2010 (UTC)

Everything in the universe can be described as having some good characteristics but lacking others. You are asking about an aspect of how our brains categorize things, not properties of metals. alteripse (talk) 23:08, 9 March 2010 (UTC)

But there's no pure metal which has good properties with no significant disadvantages. --70.250.214.164 (talk) 23:19, 9 March 2010 (UTC)

I think that's partially because alloys are, chemically, a significantly different thing than pure metals (on the other hand, aluminum and titanium are pure metals, as mentioned above, and they have few undesirable properties). And, in the other direction, plenty of materials are useless; you just don't hear about them because they're not useful. Paul Stansifer 04:31, 10 March 2010 (UTC)

God set it up that way in order to fool us into believing that He doesn't exist. Looie496 (talk) 23:35, 9 March 2010 (UTC)

Did you actually look up titanium? I cant find any disadvantages--79.76.188.14 (talk) 00:08, 10 March 2010 (UTC)

When powdered or shaved, titanium has a high chance of burning or exploding. --70.250.214.164 (talk) 00:13, 10 March 2010 (UTC)

So do most things —Preceding unsigned comment added by 79.76.188.14 (talk) 01:16, 10 March 2010 (UTC)

I think we can vindicate 70.250's view by acknowledging that many metals make useless insulators. --Tagishsimon (talk) 01:36, 10 March 2010 (UTC)

They're also pretty useless as thirst-quenchers. –RHolton≡– 19:07, 10 March 2010 (UTC)

I bet they are really great thirst quenchers! If a thirsty man were to drink 8 oz of molten lead, I bet he would no longer be thinking about thirst. Googlemeister (talk) 20:21, 10 March 2010 (UTC)

But he could still use a good quenching. -- Coneslayer (talk) 13:41, 11 March 2010 (UTC)

Expanding on comment by Alteripse: It's people that put an assessment on metals, they aren't good or bad, except in context. Gold is a great conductor. But in some situations, one does not *want* conductivity. Get one of the several hundred page books on materials, if your mind is wandering this direction. It's rather fascinating all the qualities metals have. Cheers, Piano non troppo (talk) 03:32, 10 March 2010 (UTC)

Indeed: gold and lead are malleable and ductile but not very hard. Their malleability and ductility (and general workability) are related to their softness. Being malleable and ductile is good if you want to make wire or jewellery but less good if you want to make cranes and bridges. Similarly, titanium has a very high melting point which is good if you want to use it at high temperature, but makes it hard to smelt, melt, and work with. Magnesium corrodes and is likely to catch fire, but that means you can use it for flares and in fireworks which is good. Lead is very heavy which is what you want for fishing weights and perhaps for roofing but rubbish for airplanes. --Normansmithy (talk) 13:21, 10 March 2010 (UTC)

March 10

crazy raccoon

http://www.youtube.com/watch?v=El_m4iitN5k&feature=related

i saw this with a bird too when i was a kid is that why they go in the middle of the street so they can get killed because there suffering to much and want to die i know its weard how i have said it —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 00:04, 10 March 2010 (UTC)

It is not very likely that the animal in the video is attempting suicide-by-car. The consensus in the youtube discussion is that it was rabid, the symptoms of which include malaise, headache and fever, progressing to acute pain, violent movements, uncontrolled excitement, depression, and hydrophobia. I hazard they are more cogent reasons for the sort of behaviour seen on the video. --Tagishsimon (talk) 00:14, 10 March 2010 (UTC)

yes it could be rapid and mabye thats why its suicidal? like iv said iv seen this before in nature, with the bird i moved it out of the road and it just walked back into the road and waiting patiently til it got run over. which it did. —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 01:39, 10 March 2010 (UTC)

See anthropomorphism. You are projecting human traits onto an animal. There is zero evidence that animals commit suicide in this way. There are any number of plausible reasons why an animal would be stupid enough to hang around in the middle of the road. I have to dodge stupid pheasants and grouse pretty much every time I drive my car, as they saunter into the middle of the road. I find it most easy to believe that they just have not got an understanding of the threat represented by my car. Quite why you reach for a suicide motivation is beyond me. --Tagishsimon (talk) 01:54, 10 March 2010 (UTC)

Is there a question here? Dismas|^(talk) 05:15, 10 March 2010 (UTC)

Arguably yes: "is that why they go in the middle of the street so they can get killed". More succinctly, do animals commit suicide? At least, that's the one I've been answering. --Tagishsimon (talk) 05:21, 10 March 2010 (UTC)

And oops, sorry, that's with the exception of Bubbles the chimpanzee owned by Michael Jackson, who was alleged, according to our article, to have tried to commit suicide. And now we're on to something: Bubbles (chimpanzee)#cite_note-40 provides a bunch of references for a discussion of animal suicide. Who knew? --Tagishsimon (talk) 05:27, 10 March 2010 (UTC)

did you people read what i wrote im not talking about dodging pheasants or squirrels im talking about moving it out of the road and it just walked back into the road and waiting patiently til it got run over. which it did. —Preceding unsigned comment added by Thekiller35789 (talk • contribs) 05:32, 10 March 2010 (UTC)

That contradicts the description of the video, which says: "Just so you know...HE DID NOT GET HIT...A few people actually got him out of the road and back in the woods." --99.237.234.104 (talk) 06:47, 10 March 2010 (UTC)

He's now talking about the bird he mentioned later, which did indeed get run over. Vimescarrot (talk) 11:28, 10 March 2010 (UTC)

I'm talking about the general principle. Animals have little appreciation of the risks of the road. Find one on the road, shoo it off the road, and like as not it will wander back on the road. Maybe settle down in the middle of the road for a nice long sleep if it's warm. None of this is a suicide intent. I don't know how many times and in how many different ways I can say, just because an animal did something which if human would be taken as a conscious and premeditated suicide bid does not mean that it is the same for the animal. But whatever. If you want to live in some sort of manevolent Beatrix Potter world, be my guest; I'm done with this. --Tagishsimon (talk) 11:54, 10 March 2010 (UTC)

Also note that few, if any, animals are likely to fully understand death (that is, that they will cease to exist), therefore "suicide" isn't likely to have the same meaning for them. There may be animals that have instincts which cause them to do things which result in their death (like whales that beach themselves), but that doesn't necessarily mean they know that doing so will result in their death. (Although whales may be one of the few species that really do understand death, as we do.) StuRat (talk) 14:13, 10 March 2010 (UTC)

I have seen dogs and cats which appeared to be cognizant of the danger from cars. They cross the street in the middle of the block so they can be sure a car is not about to turn the corner and hit them. They time their crossing so avoid cars. Animals get old and sick and in pain, or perhaps they just get depressed. "Suicide by car" or "suicide by hunter" is not something I would rule out. It would be quicker and arguable less unpleasant than "suicide by not eating or drinking" which an elderly cat with cancer once did. Edison (talk) 17:44, 10 March 2010 (UTC)

They know that getting hit by a car would hurt, but understanding the possibility or meaning of their own death is probably beyond a dog or cat. As for not eating when sick, it's likely just a loss of appetite. StuRat (talk) 18:04, 10 March 2010 (UTC)

I'm with StuRat, much more likely the loss of abilities due to illness or old age would acount for death on the road. any number of illnesses of older animals could lead to loss of appetite. Richard Avery (talk) 19:33, 10 March 2010 (UTC)

The "few species that really do understand death" can't include humans. Just look at all the religious stories of the afterlife and you'll see that humans, as a whole, don't understand what death is about. Until relatively recently (a few thousand years ago), people didn't even know that consciousness rests entirely in the brain and that damaging the brain would end all thought processes. An animal would have no chance of knowing this. --99.237.234.104 (talk) 19:17, 10 March 2010 (UTC)

Well, perhaps some are intelligent enough to know that something more than just pain will occur, and that they will cease to exist (at least in the way they have existed). This requires a leap from seeing other dead animals and thinking that the same thing could happen to them. StuRat (talk) 19:45, 10 March 2010 (UTC)

Dolphins are commonly described as one of the few non-human animals that appears to actively commit suicide. Of course it is not (yet?) possible for us to know what they are really thinking, but they can at various times choose to do things that in other contexts they appear to know would kill them. --Mr.98 (talk) 18:52, 10 March 2010 (UTC)

slouching

When I'm at the office I slouch and sometimes walk in a slouched position and I feel that it is a pain to adjust into a straight position. However, when I have to do moderate exercise (jogging, sprinting, abdominal exercises etc.) I noticed that after a while I'm involuntarily standing straight and its hard to slouch. Why is so? --121.54.2.188 (talk) 01:53, 10 March 2010 (UTC)

Slouching is a result of very relaxed muscles. Exercise tends to result in the opposite of relaxed muscles. --Tagishsimon (talk) 01:56, 10 March 2010 (UTC)

Could be you find your job boring. One is more alert and clear thinking when properly erect. The Alexander techniqueis about practising good posture and movement until it feels natural again.--Aspro (talk) 09:28, 10 March 2010 (UTC)

It could also be due to sitting in a bad position due to poor workplace ergonomics. Here is some more information:[7][8] --Normansmithy (talk) 15:52, 11 March 2010 (UTC)

Minkowski Diagram

In Newtonian physics for both observers the event at A is assigned to the same point in time.

This image comes from Wikipedia's article on Minkowski diagrams, and shows what such a diagram would look like in Newtonian physics. In the accompanying text, it says that the time coordinate in the ct and ct' are the same (as one would expect), but from the text it would appear that ct' is a little greater than ct. Help? 173.179.59.66 (talk) 04:54, 10 March 2010 (UTC)

I took the liberty to fix your red link. I'm not sure I understand your question. Dauto (talk) 05:12, 10 March 2010 (UTC)

OK, I think I understand it now. t and t' are the same coordinate, that is t=t' but they use different scales in the diagram. I other words, a unit of time t and is represented by a shorter segment than a unit of time t'. Dauto (talk) 05:42, 10 March 2010 (UTC)

Okay great, thanks. PS the article should be clearer. 173.179.59.66 (talk) 13:43, 10 March 2010 (UTC)

chrome sink

i unscrewed my handles from my bathroom sink today for cleaning and theirs a long brown metal rod attaching them. what is that metal its a dull dark brown? i at first thought it was brass but its darker and not shiny almost like lead. what is it?

Chrome plating is porous to moisture (and too expensive to be fashioned out of solid sheet) so not very good for sinks unlike stainless steel. Are you sure its chrome? They could be just cheap Ferritic Stainless Steel which has oxidised -after all their out of sight, so you just after durability. [9]--Aspro (talk) 09:33, 10 March 2010 (UTC)

Almost certainly brass that has just oxidised to be darker than "fresh" brass. --Phil Holmes (talk) 15:08, 10 March 2010 (UTC)

is brass what they plate chrome? —Preceding unsigned comment added by 67.246.254.35 (talk) 20:25, 10 March 2010 (UTC)

hello? —Preceding unsigned comment added by 67.246.254.35 (talk) 06:12, 11 March 2010 (UTC)

Chrome is what they use to make chrome. Brass (and bronze and copper) is another metal commonly used in sinks - especially for things like water connections. The last three oxidize to give green to greenish black to black. However if you have a bit of emery cloth (sandpaper), you can try rubbing off some of the oxidation. If it was brass/bronze/copper, you'll see the copper-colored unoxidized metal below the layer of oxidation. By the way, it may take us a while to get to your question - lag times of several hours are not unknown - we're all volunteers here. -- 174.21.235.250 (talk) 16:05, 11 March 2010 (UTC)

Inorganic Reaction Mechanisms

How could one tell whether a substitution reaction is proceeding via an associative rather than a dissociative reaction pathway? Is there a standard test? 188.221.55.165 (talk) 10:37, 10 March 2010 (UTC)

Yep. Just look at the entropy of activation.

From Dissociative substitution: "The entropy of activation is characteristically positive for these reactions, which indicates that the disorder of the reacting system increases in the rate determining step."

From Associative substitution: "The first step is typically rate determining. Thus, the entropy of activation is negative, which indicates an increase in order in the system."

Variations are also possible, notably the Sn1CB mechanism.

See User:Benjah-bmm27/degree/2/transition metal mechanisms and Eyring equation for more details.

Ben (talk) 13:48, 10 March 2010 (UTC)

weather

hOW —Preceding unsigned comment added by 216.178.90.202 (talk) 12:12, 10 March 2010 (UTC)

What you mean to ask? -- Extra999 (talk) 18:00, 10 March 2010 (UTC)

How to turn of the caps lock key? Richard Avery (talk) 19:26, 10 March 2010 (UTC)

I suppose he was to write "How to stop an hurricane?", but the hurricane was so fast... --Aushulz (talk) 19:45, 10 March 2010 (UTC)

We may never NOAA what the real question is. 10draftsdeep (talk) 20:16, 10 March 2010 (UTC)

If you want to know how weather works, I suggest you start by reading weather. If you have any specific questions after reading that article, we would be happy to help. --Tango (talk) 23:18, 10 March 2010 (UTC)

Bubbles

When a soft drink is under high pressure, as in an unopened can, bubbles don't form. When the pressure is released, bubbles emerge from liquid. Why does high pressure prevent the CO₂ from forming? 173.179.59.66 (talk) 14:06, 10 March 2010 (UTC)

The Bubbles ocupy a volume V and require an energy WORK=PV in order to form. At high pressure that energy is just to high and the bubbles won't form. Dauto (talk) 14:13, 10 March 2010 (UTC)

(ec) The CO2 doesn't "form" - there isn't a chemical change going on. The CO2 is already there, it's just dissolved in the liquid. However, the amount of a substance that can remain dissolved in a liquid depends on pressure and temperature. When you reduce the pressure by opening the container, the liquid can't keep so much of the CO2 dissolved - so it comes out of the solution as bubbles. You can see the same effect with (for example) salt dissolved in water. If you get some really hot water and dissolve salt into it until no more will dissolve - then let it cool - you'll see a lot of salt crystals form as the cooler water can't keep so much salt in solution. In that case it's heat that does it - but pressure works the same way. SteveBaker (talk) 14:16, 10 March 2010 (UTC)

Yeah, I had meant CO₂ bubbles from forming...but my question is why higher pressure prevents gas from nucleating. I guess that there's some sort of equilibrium between the gas entering and the gas leaving, but I would have expected that you would just get bubbles going in and out, with no net gas difference. —Preceding unsigned comment added by 173.179.59.66 (talk) 15:53, 10 March 2010 (UTC)

I believe the reason for what you describe not happening is that the smaller a bubble of gas in liquid is, the greater the relative surface tension trying to shrink it is. Consequently, a tiny bubble has a hard time forming but, once formed, an easier time growing. This means that, ignoring temperature for the moment, above a certain pressure a potential bubble forming from dissolved gas would have insufficient internal pressure to overcome both external pressure and surface tension, so it cannot get started. If however the pressure drops sufficiently, and aided by nucleation sites if present, the bubbles once started will tend to grow further. A related phenomenon is the knocking sometimes heard in not-quite-boiling water caused by bubbles trying to grow but, due to turbulence, being deprived of steady-enough heat supply and collapsing again. I'm sure someone will be along soon to improve on or correct this hasty lay approach with all of that good stuff like proper physics an' maths an' graphs an' reference links. 87.81.230.195 (talk) 17:37, 10 March 2010 (UTC)

Well yes, that's pretty much what happens, although the bubbles never get large enough to see. StuRat (talk) 17:27, 10 March 2010 (UTC)

Are you talking about the surface tension of the liquid or of the gas?173.179.59.66 (talk) 14:53, 11 March 2010 (UTC)

The reason you don't see bubbles forming in a closed container, but you do in an open container is due to LeChatelier's Principle. Basically, when the system is closed, there is an equilibrium established such that the CO₂ concentration in the headspace over the liquid and in the liquid itself stop changing. On a molecular level, individual CO₂ molecules are both entering and leaving the soda in a closed bottle, but in bulk, the CO₂ is basically not leaving or entering, the entire system is in balance. Because CO₂ is a gas, when you open the container, the CO₂ concentration drops, which throws off the equilibrium. Via LeChatelier's Principle, when you remove a substance from a stable equilibrium, the system will work to replace it. So the CO₂ begins coming out of the solution to replace the lost CO₂ gas. However, as long as it is open, equilibrium is never established, so the gas keeps coming out in bulk until the soda goes "flat". --Jayron32 21:56, 10 March 2010 (UTC)

Yes I understand that, but I would have expected that there would be bubbles going both way, as gas goes in and out of the fluid (as I mentioned above). To make sure I understood 87.81.230.195's explanation, does the increased pressure make the pressure inside the liquid increase as well, preventing bubbles from forming? Or is it the incoming gas molecules knocking the nascent bubbles and preventing them from fully developing? 173.179.59.66 (talk) 00:02, 11 March 2010 (UTC)

At equilibrium, the bubbles don't aggregate. There's no impetus to, as the flow happens as single molecules of CO2 move in and out at a dynamic steady state. Imagine it this way. If you picture a school building when class is in session. Occasionally, there's someone walking down the halls; like a kid leaving class to go to the bathroom, or another kid going back to class from the bathroom. The kids will tend to walk down the halls one at a time; there are always kids in the halls, but only a few, because the kids are pretty much staying where they are, and those in transit aren't likely to clump together. This is like the situation with the bottle closed. There is some movement of CO2, but the rate at which it is happening is relatively gentle, and counterbalanced by CO2 moving in the other direction. When the bell rings at the end of the day, well, that's like opening the bottle of soda. The kids ALL pile into the halls, and now their movement is very different than the occasional kid going to or coming back from the restroom. Now the kids all cram together and rush, in big clumps, out the nearest door. That's the same thing with the soda. Once there isn't an equilibrium, the CO2 in the soda is rushing out of the soda to reestablish that equilibrium. In that rush, they tend to aggregate and form bubbles because of the increased rate of "getting out" of the solution. --Jayron32 02:35, 11 March 2010 (UTC)

at equilibrium under pressure, the rate of exchange of CO2 molecules is slow and even - hence no bubbles. when the pressure is released from the top of the can, however, the CO2 comes out of suspension in the liquid at rate faster than can be transpired across the surface of the liquid; consequently you get pockets of gas forming inside the body of the liquid (aka bubbles). You can think of it as the liquid increasing its available surface area for transpiration - the surface of each bubble becomes a release area for dissolved gasses. it's basically the same process that causes the bends in diving (nitrogen in the air tanks is absorbed in the bloodstream under the pressure of the ocean, and turns into bubbles in the blood if the diver comes up too quickly), and why champagne is served in tall, thin flutes (decreased surface area at the top increases the number and life of bubbles formed). --Ludwigs2 03:14, 11 March 2010 (UTC)

@Jayron32: If the carbonated liquid were to be put under pressure by Nitrogen gas, then, by LeChat's principle, there would be an outflux of carbon dioxide and an influx of nitrogen. But there wouldn't be any bubbles. I don't think LeChatelier's principle is sufficient to describe the formation of bubbles; it's a statistical phenomena, but the carbon dioxide molecules themselves don't have any individual desire to re-establish the equilibrium. So the question becomes why does the outflux of carbon dioxide increase once the pressure above decreases?

@Ludwigs2: Why does the CO₂ come out of suspension so fast when the pressure decreases? 173.179.59.66 (talk) 14:44, 11 March 2010 (UTC)

In other words, why is the nucleation of bubbles pressure dependent? 173.179.59.66 (talk) 16:26, 11 March 2010 (UTC)

Structure of the earth

In this chapter of Journey into the Interior of the Earth one of the protagonists argues that a liquid layer in the interior of the earth will experience tides. (He presents this as an argument against the existance of a liquid layer as the displcements due to tides would cause daily quakes, which are not observed)

I know this is fiction, but does the outer core or mantel really experience tides? If it does, how much would the displacement due to tides be?

Would the model described in the chapter have sounded plausible to geologists in 1864(when the book was written)?

Brief summary of model:

-The earth is hollow.

-The heat in the interior is caused by water reacting with alkali metals.

-Since the heat source is located inbetween the surface and the centre, temprature would go up as we go down but then reduce as we go deeper than the heat source.

Also this model of a hollow earth:Structure of the Earth#Historical development of alternative conceptions, based on the flawed caluclations of the masses of the earth and the moon, assumes that the density of earth material will be the same as that of moon material. Was there any historical reason for this asumption?

Diwakark86 (talk) 14:36, 10 March 2010 (UTC)

Yes, the whole Earth experiences a tidal deformation due to the Moon's gravity; this note in Scientific American puts the tidal range at 25cm. That article also points to two presentations given by the operators of two particle accelerators, really the only people whose structures are large enough, and sensitive enough, to care. -- Finlay McWalter • Talk 16:52, 10 March 2010 (UTC)

At the time you're talking about, scientists seem to be settled that the Earth isn't hollow - the calculations done before and around that time mentioned in the Age of the Earth article all assume the Earth isn't hollow. The Hollow Earth article is somewhat disappointing, in that it doesn't give any idea as to what general credence these ideas were given - it would appear that, as soon as people started seriously thinking about the interior of the Earth (in a scientific fashion) they thought of it as not being hollow. By the time of Murchison it was clear that the Earth was stratified to at least a nontrivial depth, but I don't think it was until large scale seismic studies were carried out (e.g. by Mohorovičić) a few decades later that the gross structure of the Earth became, to a limited extent, observable. As to the source of heat, Kelvin's calculations trying to age the Earth assumed it didn't generate its own heat, but that its warmth was a fossil of its creation (and thus put the Earth as being rather young) - but at that time no-one was at all clear as to how old the Earth was, and it wasn't until later that the mounting evidence of the great age of the Earth made it necessary that it contain source generating heat. I don't think anyone by that time would believe the third element of the model you discuss, as by that time physicists had a sufficient grasp of thermodynamics. So, all in all, I doubt that any scientist who seriously studied the known results about the Earth's interior would believe the model you discuss, but geology was a very young science with very few real practitioners, and with very limited means of finding things out. -- Finlay McWalter • Talk 16:52, 10 March 2010 (UTC)

As for the Moon having the same density as the Earth, that depends on the model you use to explain their formation. If you believe they formed together from a dust cloud, then they should have a similar composition, although the heavier materials might have found their way down to the Earth and the lighter materials formed the Moon, so the Moon might be expected to be somewhat less dense (which it is). If you believe the Moon was captured from some other source, then it could be made from completely different material and thus have a completely different density. A more recent theory is that during the Earth's formation, or shortly after, a giant meteor hit that ejected the material which formed the Moon. In this case, the Moon might be a mix of the Earth's material and the meteor's, while the Earth would also have some of the material from the meteor, again leading to somewhat similar densities. You might think that the higher mass and hence gravitational attraction on Earth would lead to a greater density. It's actually the opposite, since most terrestrial material isn't very compressible in that range of g, and objects with less gravity tend to lose their lighter gasses and liquids to space. StuRat (talk) 17:23, 10 March 2010 (UTC)

As to the "Was there any historical reason for this asumption?" part of Diwakark86's question, there really wasn't much evidence to distinguish which of these theories of Lunar origin might be true (there's not nearly enough evidence now, alas). All they had to go on was the appearance of the Moon - it's vagely Earthlike, in that it has flat bits and mountainy bits, so one might as well assume, absent any better evidence, that its composition is vaguely Earthlike too. It wasn't until the examination of the Allan Hills meteorite in 1982 that science began to realise that actual physical samples of moonrock were already available on Earth (as Lunar meteorites). So, with what little evidence they had, it's a reasonable assumption for the geologists of 1864 to make. -- 87.114.240.222 (talk) 17:52, 10 March 2010 (UTC)

Even lunar meteorites, like the samples returned by astronauts, provide samples only from the outermost part of the Moon. If you only had samples from the surface of the Earth, they wouldn't tell you that the core is largely iron, or how big it is; likewise with the Moon's internal structure. --Anonymous, 21:52 UTC, March 10, 2010.

Biogas from plant and animal waste

Copied this from article space, where I am going to request deletion. I have let the page author know I have moved the question to here Gonzonoir (talk) 15:09, 10 March 2010 (UTC): I'm a boy from Botswana and i'm thinking of compiling a project on the comparisons of producing biogas between using rotten plant materials and cow-dung, so if you have got any piece of information which i can use be free to help me out and the god lord will bless you, i just want to make things better in my country and make my parents proud of my achievements. Originally posted by Ofentse mmereki (talk) 15:03, 10 March 2010 (UTC)

Optimum gas production per cubic metre requires a mix of both dung AND plant matter. The ratio is usually discovered by trial and error based on what is most available. See this section for more info:Anaerobic_digestion#Feedstock--Aspro (talk) 16:03, 10 March 2010 (UTC)

Back in the 1970's some third world country had a project to install a zipper in old truck inner tubes, to allow the insertion of dung. Methane would be produced in the tube and eventually it would be inflated to a pressure sufficient to allow the gas to be transmitted via a rubber tube to a gas ring on which the family could cook. The next day, open the zipper, clean it out, repeat the process. Surely someone has worked on this since the 1970's to improve it and make it larger scale. A larger scale version of the same plan might work like the gas producing plant in my great-grandfather's house from the late 19th century, but using dung and plant material to produce methane in place of the carbide he used to produce acetylene gas. A metal tank outside the house had a suspended or floating dome to maintain pressure containing the gas over a water reservoir into which the carbide was dropped whenever the pressure dropped below a setpoint. Metal pipe carried the gas into the house, wherein it went to gaslight fixtures and a cookstove in the kitchen. Please observe safety precautions with methane, since it is explosive, and the gas or its combustion products can cause asphyxiation. Commercial gas plants add an odorant so that leaks are detected, since methane has no odor of its own. I wonder if the dung and rotting plant material would provide their own odor when the gas was used? In a place where dung is commonly used for fuel, the odor should not be that novel. One important consideration is avoiding an explosive mixture of oxygen with the methane in a reservoir or in pipes. Some results at Google Book Search include (which discusses an improved methane generator), (which says the leftover slurry can be sold as fertilizer),(which says 5-6 bovines can provide 40 cubic meters of gas per day), (which has some simple designs), as well as [10], [11], [12], [13], and [14]. Edison (talk) 17:38, 10 March 2010 (UTC)

Heating through air resistance

I ride a motor-cycle to work, around 30 miles on freeways. Last few mornings it has been cold. This got me to thinking about heating through air resistance. Re-entering spacecraft experience extremely high temperatures, and even jet aircraft wing leading edges heat enough to make them a viable target for IR-based air-to-air missiles to lock on. So, my question is, how fast would I have to drive to heat up my hands to 37 degrees Celsius? Assume I'm at sea level and the airflow to my hands is completely unobstructed. --John (talk) 16:57, 10 March 2010 (UTC)

Aerodynamic heating is generally due to the air being compressed as an object passes through it. Per compressible flow, there is little compression (thus little heating) until Mach .3, about 230 MPH. Keep in mind also that moving air will speed up heat transfer away from your hands, making them feel colder. So I would expect your hands would be colder while moving for any speed that you're able to ride (solely considering aerodynamic effects). anonymous6494 17:13, 10 March 2010 (UTC)

When I pump up the tyres of my bicycle, the end of the pump gets hot. 78.151.126.97 (talk) 17:22, 10 March 2010 (UTC)

From memory the ‘frictional’ coefficient is 0.007 deg C per knot of wind speed. Small but is useful in meteorology.--Aspro (talk) 17:47, 10 March 2010 (UTC)

That seems too low. Based on that, and a knot (unit) being 1.151 mph, a plane going 1151 mph would only be heated 7°C. I suspect it's nonlinear, with more of an effect at higher speeds. StuRat (talk) 18:21, 10 March 2010 (UTC)

Right Stu, that coefficient is useful until the speed gets to be high enough for compressibility to start playing a greater roll. As anon said above, that speed is usually considered to start in the neighborhood of mach 0.3 or so. Googlemeister (talk) 19:14, 10 March 2010 (UTC)

Meteorology it is at sea level. (Motor cyckles not much higher). Otherwise it does go non linear (log ‘e’ I suppose). The batteries in my slide rule have gone flat, but there is a bit about this for those smarty pants who are good at mental arithmetic.[15]] Now lets see: carry one and add it to the first number you thought of... Foreseeable problems: High pressure turbulence will cause sevier bruising (Try skying behind a jet-ski in the wash of the water jet!) . Fighter pilots ejecting (or even bailing out) at high speed get bruised from air blast. The expanding air (after being compressed on the leading edges) will under go adiabatic cooling thus freezing the local tissue towards leeward side of the flesh. The local police forces will see an opportunity for issuing a months worth of speeding tickets on one night that this motorcyclist driveS though. Inquirer is obviously on a higher plane than the rest of us and would be better off in a Buddest monetary where he could write a squeal to the Zen and the Art of Motorcycle Maintenance.--Aspro (talk) 20:40, 10 March 2010 (UTC)

Also the NASA article points out that it is British Thermal Units (or Joules, Ergs, Watts etcs) that is the energy units to consider first and full most. The Temperature rise of air molecules in themselves does not contribute much to the question asked, which is about positive heat balance via increased linear speed.--Aspro (talk) 21:00, 10 March 2010 (UTC)

This is a tough one. Gut feel says that the answer is clearly going to be much faster than a motorbike could go - because the wind-chill effect of removing the 37 degC heat from your hand has to be overwhelmed. But we don't want 'gut feel' - so that won't do!

But we're not going to come up with a good number. Perhaps the best way to think about this would be from a thermodynamic angle. I guess we could figure out the coefficient of drag of the bike+rider, then we can calculate the drag force - and from that the amount of energy from the engine of the bike that's going into overcoming drag. That energy has to go somewhere - so we could consider what fraction might go into heating the air that the bike leaves behind in it's wake and what fraction is heating the skin of the bike and the rider - and make a stab at what fraction of that would be warming your hands. Knowing the energy input we should be able to figure a temperature rise. My big problem is that there could be three orders of magnitude of estimation in all of those guesses - so the answer might come out to be "Somewhere between 10mph and 1000mph." - which isn't really much use.

Another angle would be to consider things that actually do move very fast through the air. We know that at the speed of an airliner (400 to 600mph maybe), the skin heating is overwhelmed by the cooling effect of the cold air blasting past. Airliners might "ice up" but they don't get hot from the friction. On the other hand, aircraft that fly at Mach 3 and up have to be made of exotic metals and have active cooling on their leading edges to avoid melting. Similarly, spacecraft slowing down from orbit get incredibly hot when they are moving fast - but wind up being only slightly warm by the time they slow down and touch down. Meteors that people have found within minutes of hitting the ground as meteorites are reported to be merely warm, or even chilly to the touch. That strongly suggests that you're going to need to be moving considerably faster than Mach I...but again, so much depends on the air density and the shape of the object that we can't easily extrapolate from that to what you'd need on a bike.

Some questions can't be answered without an experiment - and this is probably one of them.

SteveBaker (talk) 00:53, 11 March 2010 (UTC)

Steve, to address your airliner point, airliners fly where the ambient temperature is between -40 and -70 deg, and air density is about 30% that of sea level, so there would be more then 3x as much heating if the aircraft was at sea level, but you are right, massive air resistance heating occurs at supersonic speeds, mach 0.9 has some heating, but it is a lot lower then mach 1.1. Googlemeister (talk) 14:26, 11 March 2010 (UTC)

Nanomaterials

what is the cause behind the invention of nanomaterials? —Preceding unsigned comment added by 118.102.186.3 (talk) 17:08, 10 March 2010 (UTC)

Bored scientists. Dauto (talk) 17:11, 10 March 2010 (UTC)

Bored scientists who had read There's Plenty of Room at the Bottom yet who (perhaps wisely) didn't pay too much attention to Engines of Creation.

Actually - it's not really "bored" scientists - it's scientists who are being paid to research things that can make the people who employ them very rich...which they are beginning to succeed at. SteveBaker (talk) 18:11, 10 March 2010 (UTC)

I suppose the reasons are similar to any other invention. That is: fame, money, to help mankind, etc. StuRat (talk) 18:14, 10 March 2010 (UTC)

What do you mean by "cause" here? Motivation of inventors? Or the scientific/technological path that led to them? --Mr.98 (talk) 22:39, 10 March 2010 (UTC)

(Arabic question)

أريد تقرير علمي عن تشريح الخشب النباتي —Preceding unsigned comment added by 95.170.208.114 (talk) 18:25, 10 March 2010 (UTC)

Hi. I don't know if you will be able to read my response, but all of our responses on here are generally in English. You could ask at the language desk but I still don't know if they will be able to help you with your question (which appears to be about reports on a wood plant, according to Google Translate). If you are unable to ask your question in English, then there are probably better places to ask it than here, as this is basically an English-only resource. --Mr.98 (talk) 18:47, 10 March 2010 (UTC)

مرحبا. أنا لا أعرف إذا كنت سوف يكون قادرا على قراءة ردي ، ولكن كل ردودنا على هنا عادة في اللغة الإنجليزية. هل يمكن أن نطلب من مكتب في اللغة ولكن ما زلت لا اعرف ما اذا كانت سوف تكون قادرة على مساعدتك في سؤالك (الذي يبدو أنه حول تقارير عن مصنع الخشب ، وفقا للمترجم جوجل). إذا كنت غير قادر على طرح سؤال في اللغة الإنجليزية ، ثم ربما يكون هناك أماكن أفضل ليطلب منه من هنا ، لأن هذا هو في الأساس باللغة الإنكليزية فقط على الموارد. -- السيد.98 (نقاش) 18:47 ، 10 مارس 2010 (تعم)

The above post translated by machine from Arabic:

hello. I do not know if I will be able to read my reply, but all our responses to here usually in the English language. Can we ask of the Office of the language, but I still do not know whether it will be able to help you in your question (which appeared to be about reports of wood factory, in accordance with a translator Google). If I was unable to a question was raised in the English language, and then there may be better places to ask him from here, because this is in the Foundation in English only on resources. -- السيد.98 (debate) 18:47, 10 march 2010 (prevail) Cuddlyable3 (talk) 10:24, 11 March 2010 (UTC)

Hmm. When you translate "talk" into Arabic and then back into English it becomes "debate". Think those translators might be a bit biased? Zain Ebrahim (talk) 11:59, 11 March 2010 (UTC)

Fun with online translators: Take any national anthem - translate to the language of your choice, translate it back again - enjoy songs like "The asterisks and strips indefinitely". 13:48, 11 March 2010 (UTC)

The lyrics were inspired by the patriot who said, "I only regret that I have but one asterisk for my country." -- Coneslayer (talk) 13:52, 11 March 2010 (UTC)

Prices of some raw materials

Hi all. I need to know the prices of these raw materials, that need for a case-study of a chemical plant:

• Ethylene (99,9% mol)
• Hydrogen chloride (99,8% mol)
• Chlorine (99,9% mol)
• Vynil chloride (99,9% mol)

I have another question: assuming that I'll buy more than 100000 ton/year of each one, I need to consider "spot price", "contract price" or what else? --Aushulz (talk) 19:02, 10 March 2010 (UTC)

Homework question?--Aspro (talk) 21:07, 10 March 2010 (UTC)

I am thinking that if you are buying 100000 tons per year, you should not be asking here! Issue a tender in the appropriate forum and see what the responses are. If you need a large quantity you may need a reliable supply and a contract. Check out Commodity market and spot price and futures market. Graeme Bartlett (talk) 09:01, 11 March 2010 (UTC)

Another thing that will alter the prices will be the required level of purity. 99.9999% pure materials cost much more the 99.9% pure ones. Googlemeister (talk) 15:21, 11 March 2010 (UTC)

@Googlemeister: You're right. I added requested purity.

Some other suggestion? --Aushulz (talk) 16:55, 11 March 2010 (UTC)

Dehydrated people

I seem to recall reading somewhere (don't think it was here) the percentage of dehydration needed before medics start giving intravenous fluids. Can someone help me find it please? --TammyMoet (talk) 19:10, 10 March 2010 (UTC)

Our article (Dehydration#Symptoms and prognosis) indicates that severe symptoms start to set in around the 10% mark. The Treatment section says that IV fluids would be given in emergency situations, or when severe symptoms are manifest. I'm not sure if there is a hard and fast rule as to when to administer IV (in contrast to orally administering fluids). Coreycubed (talk) 20:22, 10 March 2010 (UTC)

Thank you. There's such a lot of crap talked about hydration, I want to find some decent evidence, and that article might have some pointers. --TammyMoet (talk) 21:21, 10 March 2010 (UTC)

is it possible to express matter in the form of sound?

I read an interesting article that there are some specific "verses" which when uttered create specific sounds which represent the embodiment of desired matter. In simple words - hypothetically speaking - if i needed to see a person or procure a desired object by repeating some specific words/ sounds it is belived that the matter you seek or the person you seek materialises in front of you.

My question is can matter be represented as sound waves? —Preceding unsigned comment added by 213.130.123.12 (talk) 20:52, 10 March 2010 (UTC)

That doesn't sound like science, more like some weird science fiction. The closest thing to representing an object with sound waves would be the reflected sound from SONAR, where all of the waves, collectively, can be used to reconstruct the shape of the object from which they reflected. StuRat (talk) 21:05, 10 March 2010 (UTC)

A few things to bring us back to the realm of reality. No, matter is not sound. Matter is energy (see mass energy equivalence and wave particle duality for more details), however sound energy isn't of the correct "type" to properly contain matter information. Well, sort of. Via mass-energy equivalence, we can find the "mass" of a particular sound, if we know the energy that it represents (in sound, intensity is directly related to energy). But that doesn't mean we could represent actual matter as sound waves; that's because matter is energy plus. What matter is, is energy confined by quantum numbers. Quantum numbers are basically the information that tells one particle to be a proton, and another to be an electron, and another to be a neutron. If we convert that matter into energy, we can, from the energy, directly calculate how much mass contributed to the energy via E=mc^2. However, when matter turns into energy, quantum numbers are lost. So there is no way to recreate the form or shape of the matter from merely the energy information. You'd be missing the quantum number information. So, even if we could convert a chunk of energy into pure sound energy (and I suppose we could, there's nothing in the theory that would prevent it), there would be no way to extract from that sound energy the form of the matter in terms of how it was organized. The quantum number information is lost completely. So, you could tell roughly how much matter was converted to a sound, again via E=mc^2, but you'd never be able to reconstruct the form of that matter. There are "quasiparticles" of sound called phonons, but these shouldn't be considered particles on par with those of the standard model; instead they are merely the consequence of applying the mathematics of wave particle duality to sound waves. Treating sound as a particle works mathematically, but you cannot isolate or deal with a real "phonon" the way you can with, say, a "photon". --Jayron32 21:44, 10 March 2010 (UTC)

Jayron, everything you said is quite accurate except the part where you say a phonon is less real than a photon. Dauto (talk) 22:15, 10 March 2010 (UTC)

Sufficiently high energy gamma rays (photons) will decay into pions (a.k.a. matter) http://en.wikipedia.org/wiki/Greisen%E2%80%93Zatsepin%E2%80%93Kuzmin_limit . Maybe (?) a similiar mechanism exists for extremely high energy phonons? (after all, the sound wave is a consequence of electromagnetic interactions between neighbouring atoms in matter, and these interactions involve photons, which can decay into pions at sufficiently high energy ...) 83.134.158.50 (talk) 07:09, 11 March 2010 (UTC)

edited to add : certainly I'm not suggesting a human voice can generate phonons of sufficiently high energy to create pions, let alone to create a macroscopic object 83.134.158.50 (talk) 07:12, 11 March 2010 (UTC)

Were the words of these "verses" printed for you to try? No? I wonder why not! This is utter nonsense. If it were possible to create physical objects by uttering magical spells - I really think the major manufacturing companies of the world would be using large teams of carefully trained poets on all of their production lines - and they aren't. SteveBaker (talk) 13:44, 11 March 2010 (UTC)

It's possible to have pictures encoded within a radio signal. See slow-scan television. So in a way, yes, you can represent matter with sound waves. I think that's the closest you're going to get though. 75.157.57.12 (talk) 22:03, 11 March 2010 (UTC)

March 11

Spinach and strength

It says on the article that spinach doesn't make you stronger because of a miscalculation in its iron content. But if it did have a lot of iron, would it make you stronger? I never heard of iron making a person stronger before.. ScienceApe (talk) 00:31, 11 March 2010 (UTC)

Please take a look at Human iron metabolism. Inadequate iron causes Iron deficiency anemia and will make one weaker. On the other hand, iron overload is toxic and won't make you stronger. 88.242.232.209 (talk) 01:11, 11 March 2010 (UTC)

_{You'll just get overwrought. Richard Avery (talk) 07:52, 11 March 2010 (UTC)}

As opposed to cast down. Gwinva (talk) 08:01, 11 March 2010 (UTC)

Steel yourself against such ironic posts. Cuddlyable3 (talk) 10:58, 11 March 2010 (UTC)

Ferrous to answer this question, we need more information. SteveBaker (talk) 13:30, 11 March 2010 (UTC)

Ore you could experiment. Googlemeister (talk) 14:23, 11 March 2010 (UTC)

Popeye#Spinach says that "Early references to spinach in the Fleischer cartoons and subsequently in further stories of Popeye are attributed to the publication in 1870 of a study by Dr. E von Wolf which, because of a misprint, attributed to spinach ten times its actual iron content.[34] The error was discovered in 1937 but not widely publicized until T.J. Hamblin wrote about it in the British Medical Journal in 1981." - so the whole thing is down to a misprint. (That is so sad - the millions and millions of suffering children who were practically force-fed this disgusting so-called food by parents who were desperate to help them in later life...and it's all some simple misprint.) SteveBaker (talk) 13:40, 11 March 2010 (UTC)

I find spinach very tasty. So does my two year old. Dauto (talk) 14:42, 11 March 2010 (UTC)

Yeah, Steve, I think you're focusing too narrowly on a particular error here and missing the big picture, probably because of your personal dislike for the veggie. Spinach doesn't have as much iron as they thought, and anyway the notion that most people need more iron is a bit dated (iron is a necessary but rather toxic mineral and it's easy to get too much). But that doesn't mean you shouldn't eat it! Leafy greens have all sorts of things most people don't get enough of, starting but definitely not stopping with just plain fiber.

I also enjoy spinach, mainly raw. Try a salad made of spinach leaves, red bell pepper, a few Kalamata olives and a little feta. Possibly some avocado although that makes it less Greek. Pour some olive oil over the top, and then squeeze half a lime on it; you could sprinkle a little salt if you absolutely have to. Really really good! --Trovatore (talk) 20:41, 11 March 2010 (UTC)

Ah - one of those recipes. Basically, smother the noxious food item with as much strong smelling & tasting stuff as possible in order to avoid having to taste it! You can get your nutrition from all manner of other leafy greens - various cabbages and lettuces, brussel sprouts, bean shoots, leeks - you name it. You don't need spinach for health. SteveBaker (talk) 01:21, 12 March 2010 (UTC)

Most lettuce I find too mild. Iceberg in particular I don't want anything to do with. You can tell that its antioxidant content is low, just because it's not strongly colored. Antioxidants tend to be pigments (all those double bonds).

Cabbage, on the other hand, I just don't like. Brussels sprouts, broccoli, all those cruciform vegetables, are palatable when cooked, but I don't care for them raw, and I think raw is probably best.

But my favorite leafy greens are the ones packaged as spring mix or herb salad — I like those even better than spinach. Still, spinach beats ordinary lettuce hands down. --Trovatore (talk) 02:02, 12 March 2010 (UTC)

I ate raw spinach and got Salmonellosis. 88.242.232.209 (talk) 23:04, 11 March 2010 (UTC)

Nothing in this life is free of risk. Yes, bacterial contamination is an ongoing issue. It would be a pity if that stopped people from eating veggies. --Trovatore (talk) 23:44, 11 March 2010 (UTC)

Fluorescence in polar and nonpolar environments

It's said polar environments give emission with longer wavelength (i.e. red-shift) because "reorientation of polar solvent molecules compensates for charge separation", from my lecture notes. Why is that? My prof is so horrible and he has even worse notes. I looked at the wikipedia page for fluorescence but it doesn't explain these topics. —Preceding unsigned comment added by 142.58.129.94 (talk) 01:05, 11 March 2010 (UTC)

It sounds like you might be talking about Solvatochromism. Basically, a compound can absorb light, and in doing so, is changed to a higher energy form, that has different properties and structure than the lower energy form. Depending on the dipole moment of the lower and higher energy states, a polar or non-polar solvent may stabalize one or the other forms. This means the wavelength of light absorbed is dependent on the polarity of the solvent. Some compounds have a high degree of solvatochromism, such as Brooker's merocyanine.

However, I've never heard of fluorescence being related to solvatochromism, and the statement from the lecture notes means nothing to me. Perhaps a bit of context is needed: what are you studying right now? What class is it (i.e. upper level physical chemistry vs. freshmen biology)? What's in the solution (I assume you have a solution, as you're talking about polar and non-polar wavelengths environments)? Buddy431 (talk) 02:15, 11 March 2010 (UTC)

nitrile gloves

why do nitrile gloves smell like diarrhea? —Preceding unsigned comment added by 67.246.254.35 (talk) 01:34, 11 March 2010 (UTC)

Psychology. Namely, yours apparently. You believe them to smell like diarrhea, so they do to you. I think they smell something like nitrile gloves. --Jayron32 02:21, 11 March 2010 (UTC)

no iv asked others and they agree —Preceding unsigned comment added by 67.246.254.35 (talk) 03:24, 11 March 2010 (UTC)

I have to agree with Jayron32, they smell like nitrile. It's plastic-like mixed with a bit of sulfur. -- Flyguy649 ^talk 03:44, 11 March 2010 (UTC)

whatever the smell why do they smell that way shouldn't they be inert? its synthetic rubber —Preceding unsigned comment added by 67.246.254.35 (talk) 06:08, 11 March 2010 (UTC)

I'm not sure of the physiology behind smell, so don't know whether smell and reactivity should be related. However, rubber definitely isn't inert - e.g. it burns fairly readily (and smells awful when it does so!). 131.111.248.99 (talk) 11:42, 11 March 2010 (UTC)

yes i know rubber burns. u know what i mean by inert it shouldn't smell. obviously if u burn it it will. why does nitrile smell bad shouldent it just smell like latex or rubber? —Preceding unsigned comment added by 67.246.254.35 (talk) 23:22, 11 March 2010 (UTC)

advances needed to truly democratize the Internet?

I saw an article headline yesterday stating that most people consider the Internet (and by implication internet access) an inherent right. That led me to consider the recent events in western China where the government essentially pulled the plug on the Internet altogether. Similar events have happened in Iran lately. It seems, above and beyond any firewall/filter/proxy shenanigans, that if you go high enough up there is always someone who can just pull the plug and blackout a large swath of the Earth.

So, that led me to wonder about what sort of distributed hardware would be needed to prevent (or mitigate) this wholesale silencing? Knowing very little about the underlying structure of the Internet, the best idea I could come up with was interlinking WiFi hotspots that use solar/manually rechargeable battery sources. You would need an awful lot though to perpetuate a network on any useful scale... and there's certainly nothing to stop your favorite local authority figures from confiscating/banning such devices, so I readily admit it's not a very good idea. I know Wikipedia is not a crystal ball, but I hope I've given enough solid background to qualify this as a reasonable technology question. Succinctly put - how does the series of tubes become ownerless? 218.25.32.210 (talk) 01:37, 11 March 2010 (UTC)

By getting larger and being owned by many people. The problem isn't that they need to be "ownerless"—it's that you need them to have lots of owners, all of whom are interested in maintaining autonomy, none of whom want to be shut down by the government. (Or so a classical capitalist would argue.) If your entire economy is linked up to a lot of different service providers, that provides a rather resistant incentive against pulling the plug.

As for the technical suggestion... are you suggesting that the internet itself would be constituted solely on the WiFi linkages between individual machines? I don't think that would be robust enough unless you had an extremely high density of participating machines, and even in such a case, the density would have to be limited to local cities. It certainly wouldn't link up the world that way—China and Japan would never be linked by WiFi alone, since there is nobody sitting in the middle of the ocean with Wifi (or certainly not enough to have a worthwhile connection). Maybe at the edges you would have satellite connections or something, but you're going to be concentrating your infrastructure somewhere. (Concentrating it all in satellite connections is not necessarily a great idea if you afraid of governments, either—satellites can be shot down, can fail, can probably be hacked, etc.)

I'm not sure the answer to this is technological in nature, or at least not limited by the networking technology. Connecting countries requires big cables. A government presumably knows where these are. They could, in theory or in practice, shut them down or monitor their use. Increasing the number of cables can make this harder, but not impossible (it is still a finite number of cables). Increasing the number of participants would make shutting them down more problematic in some countries (but not all). A more robust solution might be to mingle political traffic with economic traffic in an invisible way (e.g. through encryption)—with a goal to make it so the government can't shut down political speech without a significant sector of their entire economy. (Note that I would not call this "democratizing" the internet. You are making it more robust, but that's not the same thing as "democracy.") -Mr.98 (talk) 03:26, 11 March 2010 (UTC)

Additionally, the novel Cryptonomicon proposes something along these lines, relying primarily on strong encryption as the means to ensure long-term communications/economic freedom. --Mr.98 (talk) 04:27, 11 March 2010 (UTC)

(e/c) This is actually not strictly a science question, but I'll answer it anyway. the internet was designed from its inception to be (technically speaking) a surveillance system. What I mean is that the client/server architecture is geared towards more-or-less static sites which are viewed by an assortment of viewers. Pragmatically, what this means is that anyone with the proper access can restrict and monitor everything that is viewed - the static servers have to advertise their locations on the web so that viewers can find them, so authorities always know where people are going to be looking. for an analogy, a campus I know was specifically designed with one building for all student groups and meetings, and that building was designed with (physical) firewalls that could be closed so that campus police could quickly and easily isolate and contain any student protests.

Peer-to-peer networking has started to break that client/server architecture up a bit - there were some people using peer-to-peer to get information and videos out during the Iran election troubles, and we all know the problems that the music industry has been trying to gain authoritative control over. but even with peer-to-peer a dedicated group with the proper access can track down, monitor, and suppress internet traffic. There's really nothing anonymous on the internet: best you can hope for is to throw enough sand over your electronic tracks to confuse anyone watching.

Internet democracy (should such a thing ever be tried) would require some legal guarantees to certain kinds of internet privacy and freedom. this has been specifically excluded in nations like China, Iran, and the US where the government explicitly retains the rights to monitor digital communications. I think the EU has some (weak) guarantees in place, but I suspect it will be decades before legal ethics catches up with changes in technology, so I wouldn't hold my breath. --Ludwigs2 03:40, 11 March 2010 (UTC)

How about dial-up ? That is, if the people in China can call outside the country and connect to an ISP there, they can stay online. Of course, there are long distance fees for that, but hopefully only pennies a minute. During their next Tiananmen Square massacre, they could connect up to get the real news and download their pics. Now, China could always block all international calls, but that would certainly hobble the economy. They might just block calls to phone numbers owned by ISPs, though. It would be nice if everybody outside China had a way that, when they get a call from China, it would just hook them up to the Internet automatically. I suppose China could also develop snooping software that would listen to every call, and disconnect anything that sounds like data transmission, but that would probably also knock out faxes, which are used in business. StuRat (talk) 06:14, 11 March 2010 (UTC)

So the problem is that if a government decides it doesn't want its people talking to the rest of the world - then nothing involving wires or optical fiber would solve the problem (if it is a problem...which we can discuss) because those wires can be cut/filtered/monitored at the borders. Radio signals (like Ham Radio's Packet radio) are lacking in bandwidth - and can still be monitored - and perhaps even jammed. What is needed is a wireless - narrow-beam technology that's hard to intercept, impossible to filter and impossible to jam. That would require some kind of "direct-to-satellite" approach where you'd send your data via narrow-beam radio signals or lasers aimed at a satellite and the results would be beamed back using normal transmission mechanisms. Such a system would be horrifically expensive - and would require someone with deep pockets to launch and maintain the satellites. The problem with that is how it gets paid for. Individuals couldn't pay for it using credit cards because those kinds of transactions are easily spotted in the local banking system. It would have to be advertising-funded, but that still leaves the system open to blocking by a government banning the sale of products and services that advertise over this subversive communications system.

The real solution is that people who don't want an oppressive government who shuts down their internet have to get rid of that government. In the end, that's the only way. If you have an oppressive government then all of the technological solutions in the world won't help because they can simply ban use of whatever device is required to access it - clamp down on the importation or manufacture of such gizmo's and use secret police to track down and imprison people found using them.

Bottom line: This isn't a technological problem - and you can't solve it with technology either.

SteveBaker (talk) 13:25, 11 March 2010 (UTC)

It isn't an issue of 'cutting wires'; the issue is that the internet relies on identifiable numeric addresses as distribution points. If you know what addresses are used for distribution, you can control them. wireless and satellite systems will not solve the problem unless they somehow bypass the IP infrastructure of the net, because otherwise a source will still have an identifiable internet location that can be blocked. --Ludwigs2 18:02, 11 March 2010 (UTC)

Cooking oatmeal

Why does it seem to take longer to cook oatmeal when you add the sugar before microwaving than if you cook it, then add the sugar? —Preceding unsigned comment added by 66.112.225.118 (talk) 05:43, 11 March 2010 (UTC)

Sounds like another homework question. To brake the bonds so that the crystals dissolve, is in this case Endothermic. You can even freeze water with a mixture of photographers hypo!--Aspro (talk) 08:38, 11 March 2010 (UTC)

Note:, you’d still better read up on it. This is only half of what you need to know but was provided in case your completely stuck, but it is not the whole answer.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misevaluation, but it is our policy here to not 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 how to solve such problems. Please attempt to solve the problem 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. --Aspro (talk) 08:57, 11 March 2010 (UTC)

I'm sorry but this really doesn't sound like a homework question to me, more like a question arising from some piqued curiosity, from observing what happens to porridge in the microwave. I'd personally appreciate a good answer to this question - and my homework days are long gone! So would you please tell me, even if you won't tell the OP? --TammyMoet (talk) 10:06, 11 March 2010 (UTC)

It is important to understand this phenomena before mixing together substances that may cause one’s bench apparatus to undergo rapidly disassembly. So I will link to a pdf of a Dissolution Reactions Pre-Lab Script for your further edification - the answer is out there -enjoy! [16]--Aspro (talk) 11:20, 11 March 2010 (UTC)

(edit conflict) I agree with Tammy: this seems unlike a homework question. Here's my explanation, 66: when you heat something up, its temperature will rise to a different extent, given the same amount of energy, depending on the material. The energy needed to raise a certain amount of a substance by a certain number of degrees is called its specific heat capacity. Water takes about 4.2 joules to raise one gram by one degree Celsius, for example. When you cook the oatmeal alone, you only need to put in enough energy to heat up the oatmeal to the right temperature. You then add room-temperature sugar. But when you add the sugar into the oatmeal and cook the mixture, you've got to put in energy to heat up the sugar too - I'm not sure how its SHC compares to water or oatmeal, but still, it's going to mop up some of the energy that would previously have just heated the oatmeal. You need to put more heat energy into your food, to get it to the same temperature as your plain oatmeal, as a result. Since microwaves operate at constant power (energy transfer per second), you just leave it on for longer. In a nutshell: you have to heat up the sugar too. I could possibly have explained it without the SHC link but it would make interesting further reading for you. Brammers (talk) 11:54, 11 March 2010 (UTC)

Sugar is a poor absorber of microwave energy – instead it will take up heat from the water in the porridge. The specific heat capacity of the sugar will only take a few seconds worth of power (each spoonful = about 5 grams, or in other words a very, very small percentage of the whole total SHC). As the pdf suggests: the braking of bonds simply requires more energy than any energy released by the sugar molecules entering the solute and thus slows down cooking. However, the cooking instructions that I have seen on the side of the boxes always seem to be very generous as to cooking time required. Nor have I ever seen any suggestion to increase cooking time if sugar (or salt if you live in Scotland) is added first. Porridge isn’t so touch or go as a soufflé. The difference, I would imagine, is so small as to be unnoticeable unless set as a homework question. Maybe if one was cooking a very big goldilocks and the three bears size pot of it, it might be more noticeable but then microwaving that amount is a very inefficient use of power. I am asuming that this involves pre-steamed Quaker Oats type oatmeal, as ordinary rolled oatmeal takes so long to cook that the effect would be very difficult to measure. --Aspro (talk) 12:35, 11 March 2010 (UTC)

expansion of the universe

If exponential expansion of the universe can not be ascribed to a polar force of gravity then how about a force like centripetal force; i.e., expansion being due to the universe spinning? 71.100.11.118 (talk) 09:49, 11 March 2010 (UTC)

Spinning relative to what? How do you explain the expansive force at right angles to the plane of the alleged spin? Cuddlyable3 (talk) 11:02, 11 March 2010 (UTC)

I'm continually amazed that people come up with these 'classical' ways to try to explain such phenomena. Do you really think scientists wouldn't have already thought of trying such a simple explanation? Of course they did! But it had some horrible flaw and was discarded in favor of the much less intuitive answer that we have today. If there were a simple "classical" explanation, then Occam's razor would certainly have us using it instead of the theory we currently subscribe to.

In this case, there are a bazillion problems - there would be coriolis forces (which we do not observe) - there would be the question of where the center of rotation would be - because the expansion of the universe would look very different from the perspective of someone out on the edge of this rotating object than to someone who just happened to be in the middle. The idea that the earth would just magically happen to be in the precise center of the expansion is just vastly too improbable and smacks of geocentricism - which went out the door in the 16th century! Also, the universe is three-dimensional (at least) - if it were spinning about (say) a "North-South" axis like the earth does - then the expansion would only be in a plane parallel to the "Equator" - but here in the real universe, all objects are moving away from us - including the ones vertically above and below us which would experience no centrifugal force in a simple rotating universe. There are (I'm sure) dozens of other reasons why this explanation won't fly. But since all it takes is one flaw to destroy a hypothesis - this one is busted and needs no further investigation. SteveBaker (talk) 13:01, 11 March 2010 (UTC)

All it takes to fix one flaw is some handy dark matter! Also, I like your tautology "[geocentricism] smacks of geocentricism". Aaadddaaammm (talk) 13:53, 11 March 2010 (UTC)

There is a simple classical (i.e., non-quantum) model of the accelerating expansion, and it does involve a "repulsive force" that's proportional to distance like the original poster imagines. That's not the problem. It's not hard to write down a law that fits the data; the question is, why that law? There are two terms in the force law; what physical principle leads to those terms being present and other terms being absent, and what principle sets the value of the constant factors on each term (the force constants G and Λ)? Quantum field theory does seem to predict a lower bound for a certain unitless combinations of those constants, but the prediction is ludicrously higher than the observed value; no one can find a reason why the real-world value should be so small. That's the problem.

Centrifugal force doesn't work because it would lead to expansion only perpendicular to the rotation axis, which isn't what's observed; but the other problems Steve mentioned don't exist. Rotating cosmological models don't have a center of rotation, just as the expanding models don't have a center of expansion. The rotation axis has a direction but not a position. But we wouldn't be any better off anyway if the data supported a rotating cosmology, because we still wouldn't know why it's rotating at that particular rate along that particular axis. If there were evidence that the universe was rotating, physicists wouldn't be asking, "hey, what if the universe is rotating?"—they'd be asking "why is the universe rotating?". And that's what they're asking now: why is the expansion accelerating? And, incidentally, why isn't it rotating? -- BenRG (talk) 20:49, 11 March 2010 (UTC)

Well whenever there is an explosion in the universe like a supernova things slow down and come to rest. I assume this is in part due to the gravity of the remnants in the presence of empty space. The classical model of exhaustion of the energy from the explosion fits and this is what you would expect from a theory like the Big Band. This leaves a lot of questions that require lots of speculation just like a blind man trying to work his way through unknown territory ahead.. One idea I can't find considered is the possibility the things like permissivity might change in opposition to thinking according to classical physics. The idea applied here would mean that a greater distance can be traveled in the same amount of time the further from the Big Bang in time and space the distance is or that gravity has a polar force we can call anti-gravity. What are the flaws in these theories other than that they step on the toes of the classical or current model? 71.100.11.118 (talk) 15:01, 11 March 2010 (UTC)

Always ask, is there a way to falsify my theory? Until you've done that you've not a scientific theory. Imagine Reason (talk) 15:35, 11 March 2010 (UTC)

nuclear candle

sir, can we model a nuclear fuel rod by using a common candle.many articles referring to CANDLE are found like. Potential of CANDLE reactor on sustainable development and strengthened proliferation resistance ETC

REGARDS SCI-hunter (talk) —Preceding undated comment added 11:07, 11 March 2010 (UTC).

CANDLE is in capital letters because it's an acronym, it stands for "Constant Axial shape of Neutron flux, nuclide densities and power shape During Life of Energy-producing reactor" - which has to be one of the most contrived acronyms I've ever seen! (But, I suppose, more memorable than a CASONFNDAPSDLOEPR reactor). Anyway, it has nothing whatever to do with wax cylinders with a bit of string up the middle. If you're still interested in "CANDLE reactors" then you can read more about them here. SteveBaker (talk) 12:45, 11 March 2010 (UTC)

Also known as a Traveling wave reactor --Aspro (talk) 12:51, 11 March 2010 (UTC)

From what I read - it seems to be a particular kind of TWR (ie not all TWR's are "CANDLE reactors" - but all CANDLE reactors are TWR's) - but the literature is very opaque if you're not an expert (and I'm certainly not!). SteveBaker (talk) 13:02, 11 March 2010 (UTC)

As both burn from one end to another ( like a candle) there is plenty of opportunity for confusion. I have put “CANDLE reactor” on the CANDLE disambiguation page but will hold off creating and redirecting it to the TWR article. --Aspro (talk) 13:10, 11 March 2010 (UTC)

okay i understand wax candles have no significance with a CANDLE in above reference i have made.But can i have any reference of modeling a fuel rod's nuclear reaction by a candle.Modeling neutrons in reactor by air around candle,the products of nuclear reaction by flame in a candle.Even if no proof is availaible,is that comparision apt.

Thanks in advance 218.248.11.214 (talk) —Preceding undated comment added 21:27, 11 March 2010 (UTC).

No, I don't think so. They are very different physical processes. --Mr.98 (talk) 22:57, 11 March 2010 (UTC)

I agree - there is really no kind of analogy at work here. SteveBaker (talk) 00:50, 12 March 2010 (UTC)

Shielding against Electro magnetic induction

How do you design a Faraday Cage to shield against interference from heavy C Band radio frequencies and what is the recommended material for the cage. —Preceding unsigned comment added by Shielding Buff (talk • contribs) 11:47, 11 March 2010 (UTC)

I believe a Faraday cage must be made of an electrically conductive material, so a wire mesh would be used. As for the ideal spacing of the wires, I will let others answer that. StuRat (talk) 13:33, 11 March 2010 (UTC)

Birds fall out of the sky?

What could cause the phenomenon described in this article? [17]

Aaadddaaammm (talk) 13:42, 11 March 2010 (UTC)

A large release of gas in a localized area, not enough oxygen for the birds to breathe. —Preceding unsigned comment added by Fire2010 (talk • contribs) 14:01, 11 March 2010 (UTC)

(edit conflict)Turbulent weather is typically the reason for raining animals. The following is an extract from the article:

Doppler Image from Texas showing the collision of a thunderstorm with a group of bats in flight. The color red indicates the animals flying into the storm.

In the case of birds, storms may overcome a flock in flight, especially in times of migration. The image to the right shows an example where a group of bats is overtaken by a thunderstorm.. The image shows how the phenomenon could take place in some cases. In the image, the bats are in the red zone, which corresponds to winds moving away from the radar station, and enter into a mesocyclone associated with a tornado (in green). These events may occur easily with birds in flight. In contrast, it is harder to find a plausible explanation for rains of terrestrial animals; the enigma persists despite scientific studies.

Zain Ebrahim (talk) 14:03, 11 March 2010 (UTC)

Who knows. turbulence of the type described above is vanishingly rare in Somerset, UK. As the article says it is reported to have happened happened in several places in the world in the last year or two. There seems to be a strong clue in the second paragraph where it is reported that many of the birds had broken wings, beak, legs and internal damage. In my experience it requires more than gravity to cause that sort of damage in a bird, particularly a smallish bird like a starling. The report contains a likely scenario for the horrendous carnage incident and the force of the birds flying downwards in a panicked attempt to evade a predator could account for the birds' injuries. What is more interesting is the end of the report where the witness describes what she found. ... "like a scene from a horror film like Hitchock's 'The Birds'", well, no, because all the birds were alive in the film. Richard Avery (talk) 14:09, 11 March 2010 (UTC)

The OP's link refers to a "whoosing sound", which makes me think of strong downward winds, perhaps a microburst. StuRat (talk) 14:35, 11 March 2010 (UTC)

Hmm some interesting possibilities. The predator evasion theory doesn't sit too well with me - I give these little birds more credit than flying into the ground to avoid being eaten. I noticed that bit at the end too, Richard - it's kind of the opposite of "The Birds". Aaadddaaammm (talk) 14:53, 11 March 2010 (UTC)

A lot of birds did (fictionally) die in the film, from smashing themselves into buildings and such to get at the people inside. Deor (talk) 17:44, 11 March 2010 (UTC)

A bird falling out of the sky is one of the imageries used in the Dutch film De Vierde Man to symbolise the death of the black widow's 2nd husband. --Kvasir (talk) 18:04, 11 March 2010 (UTC)

The bird of prey theory sounds silly to me, too. StuRat (talk) 17:56, 11 March 2010 (UTC)

Birds falling out of the sky is nothing, try | fish falling out of the sky. --Kvasir (talk) 18:00, 11 March 2010 (UTC)

Fish falling out of the sky is easier, that pretty much has to be from a waterspout. StuRat (talk) 18:03, 11 March 2010 (UTC)

Although this sounds logical, and is the answer usually resorted to by meteorologists and others attempting to explain away anomalous falls, most of the many instances of such fish, etc falls seem to have occurred with no waterspout, or even the sort of weather in which waterspouts commonly occur, in evidence. (I have no alternative explanation, but I am unconvinced from a long interest in Forteana that the waterspout one holds water.) 87.81.230.195 (talk) 22:10, 11 March 2010 (UTC)

Why do birds fall out of the sky every time you walk by? Just like me, they long to be close to you. Deor (talk) 21:33, 11 March 2010 (UTC)

Pressure in a liquid

Imagine a small particle inside a liquid. The pressure of the liquid will exert forces on it. There will be a downward force caused by the weight of the liquid above it, and an upward force caused by the water below the particle resisting the weight of the water above it, both forces equal in magnitude. My question is, are there any horizontal forces? I would imagine that the answer is yes, but I can't think of any way that the forces would arise... 173.179.59.66 (talk) 14:31, 11 March 2010 (UTC)

Yes, if the particle is floating in equilibrium, then the forces on all sides are equal. To help visualize this, think of a hole halfway up a can full of water: a stream is pushed out by the horizontal forces. Now think of two bricks with wet mortar in between. In gets squeezed out, right ? Well, think of the water above the hole in the can as one "brick" and the water below the hole as another. StuRat (talk) 14:39, 11 March 2010 (UTC)

That's exactly the explanation I'd give - but now I think about it, how do two exactly opposing forces (up and down) produce a force at 90 degrees to both? Aaadddaaammm (talk) 14:55, 11 March 2010 (UTC)

The stuff you are squeezing is a fluid (lots of small mobile particles), not a single solid. Consider if you have two spheres stacked but not quite perfectly aligned. As top one falls, it falls off to the side because the force (gravity, straight down) is acting a little sideways rather than straight at the bottom one. Another way to think is that the particles are all in constant motion in every direction. As the side comes closer, they cannot move that way but up/down is still available. And they may also bounce at an angle off the side, continuing to move up/down but coming back to center left/right. Fluid statics might have some info. DMacks (talk) 17:36, 11 March 2010 (UTC)

Boiling water

When boiling water, I've seen small bubbles form, sticking to the side of the pan. The same thing happens (sometimes) when I leave a glass of water sit for a while. Why is this? 173.179.59.66 (talk) 14:56, 11 March 2010 (UTC)

They are formed from the dissolved atmospheric gases coming out of solution. That’s why once formed they don’t grow any more. I.e., More oxygen and nitrogen can dissolve in cold water than warm at standard atmospheric pressure.--Aspro (talk) 15:01, 11 March 2010 (UTC)

see also nucleation157.193.173.205 (talk) 15:59, 11 March 2010 (UTC)

Is it true that freezing recently boiled water gives very clear ice cubes, for the reason Aspro mentions? --Dweller (talk) 15:58, 11 March 2010 (UTC)

Yes, boiled water does give clearer cubes for this reason; boiled distilled water is even better. In the days before domestic freezers, the companies that made large blocks of ice (which they then sold for people to put in their cool-boxes) kept ice clear by placing a tube in the center of the freezing can and bubbled air slowly through the water. This kept the dissolved minerals in constant circulation. Because it is the minerals and other foreign particles in water that serve as nucleation sites, the bubbles that did form, just floated up to the surface and burst. --Aspro (talk) 16:43, 11 March 2010 (UTC)

Okay, is there a physical explanation to why cold water holds more gas than warm water? 173.179.59.66 (talk) 16:11, 11 March 2010 (UTC)

This explanation is probably incomplete, but the basic reason is that warm water doesn't trap gas well. When warm, the water molecules are moving around more, with less static positions. The more energetic gas molecules have an easier time escaping under these circumstances. Cold water moves less, and is more organized in structure, so any gas that gets trapped has a harder time leaving. In both cases, the air molecules are occasionally dissolving, the only difference is that they are released more quickly by warm water, while cold water traps and holds them. —ShadowRanger ^(talk|stalk) 16:30, 11 March 2010 (UTC)

Cool, thanks. While we're on it, is there a significant pressure dependancy on a liquid's ability to trap gasses? 173.179.59.66 (talk) 17:20, 11 March 2010 (UTC)

Well, if the gas is under pressure, then it will dissolve more rapidly, and the final equilibrium will have more dissolved gas than water of the same temperature would have under lower pressure. In all cases it's a balance; how much gas is going in vs. how much is going out. —ShadowRanger ^(talk|stalk) 17:24, 11 March 2010 (UTC)

This sounds like some great potential content (if we can WP:V to get to the real underlying reasons) for Solubility#Factors affecting solubility. DMacks (talk) 17:27, 11 March 2010 (UTC)

Temperature of Diet Coke

I like Diet Coke. I normally drink it from plastic 2 litre bottles. Sometimes from 330ml cans. Occasionally (very occasionally) from those dinky glass bottles you see in American films and soaps, but are rarely sold here.

Anyway, it's my perception that Coke from glass bottles and cans is considerably colder when I drink it than it is from the plastic bottles. This, of course, all from the same fridge and the same position in the fridge.

Is this a flaw in my perception or is there some reason why it may be true? I had considered that it might be the volume of the container, not just its material that's the issue, but hey, you're the Scientists. --Dweller (talk) 15:08, 11 March 2010 (UTC)

Have you tried transfer some from each container into a couple of the same type of drinking vessels and then judging? It might be that your lips on the lower heat conductive bottle is affecting your perception.--Aspro (talk) 15:17, 11 March 2010 (UTC)

Interesting. I don't drink directly from the plastic bottle, but often drink direct from the can. So, I should pour from a plastic bottle into a chilled empty can, for a rigorous comparison? --Dweller (talk) 15:39, 11 March 2010 (UTC)

Maybe ask a friend to pour some coke from a chilled can into one glass and some from a chilled plastic bottle into another identical glass. Then you taste each and compare. I think that would be rigorous enough. Zain Ebrahim (talk) 15:43, 11 March 2010 (UTC)

Would it be double blind if the friend marked which glass was which (say a sticker with #1 for the can an #2 for the bottle or vv) and left the room before you entered? Googlemeister (talk) 15:46, 11 March 2010 (UTC)

If you look at the three-dimensional clay model of the sensory homunculus ( just over half way down on this page), you will see that the lips contribute a great deal of the sensory information and so could over rule neural pathways in other parts of mouth and oesophagus. [18] This is why holding a piece of pair under the nose of someone who is blindfolded and whist giving them a slice of apple to eat. They will report that they are an eating pair because smell tends to over rules the sense of taste. (do they do these types of experiments in skools any more?)--Aspro (talk) 15:54, 11 March 2010 (UTC)

Here's a link to just the pic: homunculi.jpg. StuRat (talk) 18:12, 11 March 2010 (UTC)

All this talk about double-blind tests ... what's wrong with using a thermometer?157.193.173.205 (talk) 15:58, 11 March 2010 (UTC)

I thought someone would ask me that. Thermometers don't get on with me. I've never had a thermometer for home use that was both readable (mercury thermometers for me are the Emperor's New Clothes; so are Magic Eye pictures.) and reliable (the electric-stick-in-your-ear one we recently bought at great expense and fanfare resolutely refuses to give the same reading twice. We tend to take an average of three). --Dweller (talk) 16:02, 11 March 2010 (UTC)

You are comparing drinking from a chilled glass bottle or chilled can with drinking from a glass at room temperature, and you wonder why one feels colder than the other? Perhaps it is because the can is chilled but the glass is not? --Normansmithy (talk) 16:07, 11 March 2010 (UTC)

Okeydokey, I'll chill the glass and see. Thank you. --Dweller (talk) 16:12, 11 March 2010 (UTC)

Let see if I can guess the next question: Help! How do you un-stick a lip that's got frozen to a glass?!!!--Aspro (talk) 16:17, 11 March 2010 (UTC)

Well? !! What’s the answer Dweller? Or have you suffered a brown out?--Aspro (talk) 18:54, 11 March 2010 (UTC)

I have a feeling I must be missing something here or this is too obvious. Glass and metal have much, much faster thermal transfer rates than everyday plastics. When you touch the plastic lip of the 2L bottle to your mouth very little heat will be lost from your body. On the other hand, a metal or glass container will act as a kind of heat sink and provide you with a much cooler mouth feel. 64.235.97.146 (talk) 19:30, 11 March 2010 (UTC)

Yes you hav emissed something: the first reply!”It might be that your lips on the lower heat conductive bottle is affecting your perception.”--Aspro (talk) 21:16, 11 March 2010 (UTC)

If you don't have a scientific measure of the actual temperature of the liquid then it's likely that what's happening is that those very large bottles are getting cold on the outside and (let's say) for about an inch into the liquid - but that the majority of the liquid in the center simply isn't getting cold by the time you take it out of the fridge to drink it. The cans and bottles not only have smaller amounts of thickness of liquid for the fridge to chill - but also they both conduct heat better than plastic, so the contents get cool faster for that reason too. The way to test this supposition is to try drinking from one of the small 16oz plastic bottles that coke sometimes comes in. In that way you'd be controlling all aspects of the experiment except the volume of the container. SteveBaker (talk) 00:45, 12 March 2010 (UTC)

Fermi problem: neurons vs. transistors

So, I was thinking the other day about the sheer number of transistors that a successfully replicating yearly (via their biological symbiotic species, humanity), and I got to wondering: are transistors the fastest-growing species of life on Earth? Certainly they are being pretty successful. But a professor recommended comparing like-for-(relatively)-like. Thus, I'd like to know if anyone could help estimate the relative numbers of 'operational' neurons vs. 'operational' (or still capable of operation) transistors on planet Earth.

I have no idea where to begin answering this question, but trust some of you might be able to Fermiment some figures.

Thanks, 130.209.241.193 (talk) 15:12, 11 March 2010 (UTC)

Hmm. I think your prof. has sent you off on a tangent, the successful answer of which, will add little to the sum of human understanding. --Aspro (talk) 15:28, 11 March 2010 (UTC)

This page from 2006[19] suggests 10^19 transistors were made per year in 2006, although this has probably increased by a few orders of magnitude. You could probably extrapolate. You could try and count the number of microprocessors and estimate how many transistors they are likely to have, but remember that far more microprocessors are in embedded applications than in personal computers (on the other hand a simple microcontroller may have 10^5 while a new Intel processor may have 10^9), and don't forget RAM. Neuron will tell you there are about 10^11 neurons in the brain, and world population has lots of statistics. --Normansmithy (talk) 16:22, 11 March 2010 (UTC)

If you want to extrapolate figures for the present day, Moore's Law will help you calculate the increase in transistors per device, and you can multiply this by the growth in the number sold. I'm sure you can guess rough death rates for transistors and neurons. --Normansmithy (talk) 16:31, 11 March 2010 (UTC)

You'd have to squint pretty hard to see transistors as a life form. They're being made by humans, not other transistors. Paul Stansifer 17:53, 11 March 2010 (UTC)

I have to agree with Mr. Stansifer above. I'm not really sure if there is a meaningful question here. Transistors are not a life form by any definition of which I am aware. Certainly they do not grow, reproduce, consume raw materials, produce localized decreases in entropy, nothing. I am quite open to the idea of artificial life, but a minor electrical component is not it, in my opinion. Nor is a neuron a species either, though it is alive. I suggest reframing your question, if possible. — Knowledge Seeker দ 19:10, 11 March 2010 (UTC)

Ditto; ditto etc., ... Good scientists (IMO) have been those who have been able to identify the questions that are worth answering. Might I suggest, you suggest to your prof. to “post here, ” his reason why you should waist ‘spend your limited time’ on this? Just take a step back and think... there are billions of more important avenues of inquiry and speculation. Think your prof. is doing you a disservice to encourage you to travel down this route, a route which yields no meaningful insight to anything. It can only produce a non-sequitur.--Aspro (talk) 19:39, 11 March 2010 (UTC)

surely this would make hydrogen the most successful lifeform? Hydrogen obviously isn't life, but nor are transistors. They exhibit none of the characteristics listed here.--92.251.227.109 (talk) 19:42, 11 March 2010 (UTC)

It's weak - but arguable. Transistors cause humans to make more transistors. That's more like a virus than a proper "living thing" - and their descriptions are held as memes rather than genes...but they spread in similar ways. Person A buys an iPhone, person B sees it and becomes infected by the meme - causing him to buy one and thereby cause another iPhone to be manufactured. Eventually, people become immune either because they already had one or because their minds become immune to an old, tired meme. The iPhone evolves into the iPhone-II. Survival of the fittest applies - so poor phone designs die and good ones reproduce. Yeah - it's a hell of a stretch.

But as of a few years ago, I recall that someone had figured out that the total amount of memory devices ever manufactured was not equal to the storage capacity of a single human brain. So even if you could consider them to be in some manner like a lifeform - they are horribly outnumbered. SteveBaker (talk) 20:14, 11 March 2010 (UTC)

Free Particle

The free particle article only dealt with a particle of well defined momentum, so I thought I'd clarify a few things here, and get them added to the article, however I ran into problems with my understanding of the maths. This is quite elementary QM so I am a bit concerned by how trouble some it has been.

I guess this is a little bit of spot the mistake.

For well defined momentum, the momentum $p=\pm {\sqrt {2mE}}$, allowing us to define a propogation operator $U(t)$ where $\left|\psi ,t\right\rangle =\mathrm {U} (t)\left|\psi ,0\right\rangle$ defined by the schrodinger equation.

$\left|\psi ,t\right\rangle =\mathrm {U} (t)\left|\psi ,0\right\rangle =e^{\tfrac {-i\mathrm {H} t}{\hbar }}\left|\psi ,0\right\rangle =\int _{-\infty }^{\infty }dp\left|p\right\rangle \left\langle p\right|e^{\tfrac {-i\mathrm {E} (p)t}{\hbar }}\left|\psi ,0\right\rangle =\int _{-\infty }^{\infty }dp\left|p\right\rangle \left\langle p\right|e^{\tfrac {-ip^{2}t}{2m\hbar }}\left|\psi ,0\right\rangle$

thus

$\psi (x,t)=\left\langle x|\psi ,t\right\rangle =\left\langle x\right|\mathrm {U} (t)\left|\psi ,0\right\rangle =\int _{-\infty }^{\infty }dp\left\langle x|p\right\rangle \left\langle p\right|e^{\tfrac {-ip^{2}t}{2m\hbar }}\left|\psi ,0\right\rangle =\int _{-\infty }^{\infty }dx'\int _{-\infty }^{\infty }dp\left\langle x|p\right\rangle \left\langle p\right|e^{\tfrac {-ip^{2}t}{2m\hbar }}\left|x'\right\rangle \left\langle x'|\psi ,0\right\rangle$

since

$\left\langle x|p\right\rangle ={\tfrac {1}{\sqrt {2\pi \hbar }}}e^{\tfrac {ipx}{\hbar }}$

therefore

$\psi (x,t)={\tfrac {1}{2\pi \hbar }}\int _{-\infty }^{\infty }dx'\int _{-\infty }^{\infty }dp\,e^{\tfrac {ip(x-x')}{\hbar }}e^{\tfrac {-ip^{2}t}{2m\hbar }}\psi (x',0)$

given that the particle is initially localised at $x=0$, therefore $\psi (x,0)=\delta (x)$

$\psi (x,t)={\tfrac {1}{2\pi \hbar }}\int _{-\infty }^{\infty }dx'\int _{-\infty }^{\infty }dp\,e^{\tfrac {ip(x-x')}{\hbar }}e^{\tfrac {-ip^{2}t}{2m\hbar }}\delta (x')$

performing first the integral over p

$\psi (x,t)={\sqrt {\tfrac {m}{2\pi i\hbar t}}}\int _{-\infty }^{\infty }dx'\,e^{\tfrac {im(x-x')^{2}}{2\hbar t}}\delta (x')$

and then x

$\psi (x,t)={\sqrt {\tfrac {m}{2\pi i\hbar t}}}\,e^{\tfrac {imx^{2}}{2\hbar t}}$

thus the probability

$P(X=x)=|\psi (x,t)|^{2}={\tfrac {m}{2\pi \hbar t}}$

the probability distribution is independent of $x$, and infinite everwhere at $t=0$ despite the boundary condition that it was localised at $t=0$. Help! —Preceding unsigned comment added by 129.67.39.49 (talk) 16:10, 11 March 2010 (UTC)

Your inital state wave function is not normalized correctly, I don't think.Dauto (talk) 19:28, 11 March 2010 (UTC)

One thing that jumps out is that $\int _{-\infty }^{\infty }dx'\,e^{\tfrac {im(x-x')^{2}}{2\hbar t}}\delta (x')=e^{\tfrac {imx^{2}}{2\hbar t}},$ rather than 1. Rckrone (talk) 19:37, 11 March 2010 (UTC)

True, for some reason when writing I was thinking of $\delta (x-x')$, I have corrected the mistake.

I'm not sure if the math is right here or not, but it's worth thinking about what result you expect to get for this problem. If you start out with a particle truly localized at a point, then it's evenly distributed across the whole momentum space (it can't really be represented by a distribution at all). After any non-zero time t, the distance it would move is proportional to the momentum, so it would be evenly distributed across the whole position space (again not really representable with a distribution), so I don't know if you can expect a sensible answer. Rckrone (talk) 22:38, 11 March 2010 (UTC)

I think the math is fine. I get the same result. The classical analogue is infinitely many particles flying apart from a point with momenta evenly distributed in momentum space. The density falls off like 1/t. Total energy (or probability) is "conserved" inasmuch as it's always infinite. This also shows up in the low-density nonrelativistic limit of big bang cosmology (with the same 1/t falloff). To get nice time evolution you need to start with a nice normalizable wave packet, as in the example at the end of Wave packet#Mathematics of wave packets. -- BenRG (talk) 23:03, 11 March 2010 (UTC)

I haven't checked the math, but the result seems plausible. If you recall the Heisenberg uncertainty principle, no particle can have both definite momentum and definite position. If you insist that the particle is truly in a momentum eigenstate, then it must have equal and uniform probability of having any possible position. Or in the limit of truly infinite space, the "normalized" wavefunction goes to zero everywhere. Dragons flight (talk) 01:16, 12 March 2010 (UTC)

Too much Potassium in diet

what are the negative effects of having too much potassium in one's diet? Also, are there are any negative effects of having too much chlorine in one's diet?--92.251.227.109 (talk) 19:34, 11 March 2010 (UTC)

Not sure about too much potassium in the diet, but Wikipedia has an article on Hyperkalemia, which is too much potassium in the blood. Does that article help? Zain Ebrahim (talk) 19:43, 11 March 2010 (UTC)

See Potassium_chloride#Biological_and_medical_properties. --NorwegianBlue ^talk 19:44, 11 March 2010 (UTC)

I already read that article, but it only talks about overdoses, not simply consuming more than you should.--92.251.227.109 (talk) 19:48, 11 March 2010 (UTC)

Chlorine in the diet is always in the form of compounds ( chlorine is too reactive to exist in it’s atomic form). Most of them are better avoided ( I avoid over generalizing by calling them all toxic). I think ( off the top off my head0 that too much potassium will just be pissed out. Although pottasium nitrate ( for curing bacon etc.,) has been linked tio cancer .--Aspro (talk) 19:47, 11 March 2010 (UTC)

Ah right that's very helpful thanks! What would happen to someone with kidney failure who could not urinate, who took in a lot of potassium?--92.251.227.109 (talk) 19:48, 11 March 2010 (UTC)

That is indeed a problem. They try to limit their potassium intake, and also may use potassium binders, such as sodium polystyrene sulfonate. See Sodium_polystyrene_sulfonate#Medical_use. StuRat (talk) 19:55, 11 March 2010 (UTC)

If they can’t piss it out: Their potassium/sodium balance would be servilely compromised -is the short answer to that . Can you expand on that. Remember: we don’t give medical advice. --Aspro (talk) 19:58, 11 March 2010 (UTC)

Have you read Renal_failure yet? --Aspro (talk) 20:00, 11 March 2010 (UTC)

I hear Obama is trying to get something through congress to help people with medical problems the same way as here in Europe. Do you have to ask these questions because your American?--Aspro (talk) 20:06, 11 March 2010 (UTC)

I'm not American I don't have kidney problems. I just dined at a friend's who used a 1:1 mix of potassium chloride and sodium chloride instead of regular sodium chloride table salt and I got curious. Also I have my own opinions of government run healthcare services after some stuff the Irish government pulled (forced every insurer to pay a state-owned insurer money, forcing some companies out of the market).--92.251.227.109 (talk) 20:10, 11 March 2010 (UTC)

Here in the UK we have products under the such names as “Lo Salt” with 60% or less sodium. Remembering what I said about medical advice: Unless one has kidney, heart or diabetes problems, this modified form of salt should be OK. Even then, it depends on the individual case. In my view it is better just not to see a doctor in the first place-- ignorants is bliss- but from a doctor’s point of view “this behaviour is not very profitable” Large amounts of potassium salts will also stop the heart but no normal person will want to drink this amount. It ( the cardiac muscle) will just not be able to re-polarise – but that’s for another time. --Aspro (talk) 20:29, 11 March 2010 (UTC)

Erhummm.., I have just re-read that post above...
”I just dined at a friend's”

One can just imagine it.....”Heard you had 92.251.227.109 round for dinner last night... AND WHAT did he think of your culinary skills?

Hmm well! He thought my choice of table salt very interesting! Ho! Ho! Ho! --Aspro (talk) 20:54, 11 March 2010 (UTC)

I actually attended a lecture at Columbia University Medical Center recently given by nephrologist Dr. Len Stern, who spoke a great deal about the terrible effects of high potassium diets. He showed a graph of what is termed an "ideal protein diet" and how it results in a much greater potassium intake than is ideal. So, while I cannot describe the effects of such a diet and cannot comment on particulars, you may take the initiative and find Dr. Stern's email address from Columbia's website and ask him for the details. DRosenbach ^{(Talk | Contribs)} 00:47, 12 March 2010 (UTC)

Chemical compounds with many elements

What is the chemical compound with the most chemical elements inside it? --84.61.135.112 (talk) 20:34, 11 March 2010 (UTC)

It's probably not near the highest, but DNA must have quite a few. StuRat (talk) 20:44, 11 March 2010 (UTC)

DNA is a very complicated molecule, but it doesn't actually have too many elements in it. I think is just has Nitrogen, Oxygen, Hydrogen, Phosphorus, and, of course, Carbon. Maybe it has some sulfur in it too, but it only has about 5 or 6 elements at the most. --The High Fin Sperm Whale 20:50, 11 March 2010 (UTC)

I assume you mean distinct elements, as opposed to "atoms per molecule"? DNA definitely wins on the latter, but probably not the former. Nevertheless, I suspect a carbon-based molecule would win for overall diversity, since carbon chains allow for a near infinite number of attachment points. You'd need to construct it artificially, but you could theoretically stick most of the (non-noble) periodic table on a long enough carbon chain. —ShadowRanger ^(talk|stalk) 20:55, 11 March 2010 (UTC)

Fluoride is a very reactive halogen and will encapsulate most compounds . Is this the the tree your barking up?--Aspro (talk) 20:58, 11 March 2010 (UTC)

Of the top of my head it’s most things from Hydrogen to Uranium.--Aspro (talk) 21:01, 11 March 2010 (UTC)

If metal alloys are valid answers, one of those? Googlemeister (talk) 21:02, 11 March 2010 (UTC)

Here is a molecule (CAS #289501-11-7) with 9 different elements: C33 H40 Cl N O P S Si . I name: Phosphonium, [(3S,4Z)-4-chloro-3-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-5-(2-methyl-4-thiazolyl)-4-penten-1-yl]triphenyl-, iodide (1:1)

Addicts - do they prefer to be cured?

I've never been addicted to anything, except perhaps tea. Would an addict, such as an alcoholic, like to be perfectly cured and lose all interest in or cravings for alcohol? Or is their desire for alcohol so strong that they would prefer to stay an alcoholic even if a perfect cure is available? 78.146.0.232 (talk) 21:40, 11 March 2010 (UTC)

Before or after they are cured? Depending on the alcoholic, they may or may not be aware of the consequences of their alcoholism. And they may or may not have a reason for drinking; in many cases it's a form of self-medication for depression. If they are aware of the damage they are causing and lack an ongoing reason to drink, then clearly then most of them would presumably welcome a cure that removed all physiological and psychological cravings. On the other end of the spectrum, they might not, or they might return to alcohol even after the cure is applied, as the ongoing reasons for self-medicating have not been addressed. —ShadowRanger ^(talk|stalk) 21:45, 11 March 2010 (UTC)

Elaborating: By and large, people don't prefer being addicted. But if they have reason to quit, the pull of alcohol isn't overriding their free will all the time, or even for particularly long periods. The problem is that in normal circumstances, staying sober means the alcoholic must maintain perfect control at all times; one slip up can undo all their work. If a cure could be devised to immediately remove dependence, that would make it *much* easier to stay sober. —ShadowRanger ^(talk|stalk) 21:48, 11 March 2010 (UTC)

As an example of someone who might not take the cure: I know someone (details unspecified for privacy reasons, I'll use singular "they" to describe) who drinks about a liter of wine a day (down from two liters, which had been the usual amount for decades). I doubt they have been fully sober for more than an hour a day in over a decade. But they don't see any consequences from their actions, as their significant other is an enabler who denies there is a problem, and their siblings drink more than they do. On top of that, they grew up a victim of sexual abuse and have never come to terms with it. The wine is likely treating depression resulting from the abuse, and the consequences of the drinking are relatively minor (today, though the decreased inhibition led to some awful behavior when they were younger). Since they don't see a problem, and the drinking is treating an underlying condition, they might resist a cure. —ShadowRanger ^(talk|stalk) 21:54, 11 March 2010 (UTC)

Is there more alchohol in a liter of wine, or a 6 pack of beer? Googlemeister (talk) 22:02, 11 March 2010 (UTC)

Depends on the wine and beer, but generally wine is something like 11.5% alcohol and beer is something like 4%. A standard beer can is 12 oz of liquid, thus a six pack is some 2.88 oz of alcohol. A liter of wine (33.8 oz of liquid) is 3.89 oz of alcohol. So the wine wins in the alcohol content contest. But again, answers may vary depending on type of wine and beer, and amount of beer in the six pack. --Mr.98 (talk) 22:36, 11 March 2010 (UTC)

In the particular case in question, the wine of choice is a dry red wine, with 12.5-13% ABV IIRC. So the daily intake of alcohol is about 4.25 oz. One drink is usually considered to be about a half ounce of alcohol, so this is about 8.5 drinks. The reduction from 17 drinks per day to 8.5 does not appear to have affected the level of inebriation (low level, but noticeable, particularly into the early evening), so it's likely that the person in question's liver has been damaged such that metabolization of alcohol occurs more slowly. —ShadowRanger ^(talk|stalk) 23:32, 11 March 2010 (UTC)

Mix 'n' Match genetic sequencing

Chimpanzees and humans, for example, are said to have 99% of their genes in common. Dodos and mammoths have some but not all of their genes available from dead specimens.

Would it be possible to replace the missing genetic material with material from a related living species such a a pigeon or elephant, and get a living creature as a result? If not, why not?

Is it currently technologically possible to synthesise a sequence of genes just from chemicals in a laboratory, put them in an egg, and get a living creature as a result? 78.146.0.232 (talk) 22:11, 11 March 2010 (UTC)

Well, you have two issues here. One is whether you can fill in missing spots of DNA. I am not particularly sure this is possible but I wouldn't put it totally beyond very clever computational geneticists who happened to be very lucky about what was missing. If it was something specific to the species, and you had no other samples, then I imagine you would be out of luck. If it were something common, then you are OK. The second is whether you can take that raw DNA and make a living creature out of it. At the moment, the answer is, "it's really hard," but in another fifty years or so it probably won't be so hard. The relevant article part seems to be Extinction#Cloning; see in particular the case of the Pyrenean Ibex, which was made un-extinct for a short amount of time, on the basis of one very good tissue sample. --Mr.98 (talk) 22:55, 11 March 2010 (UTC)

I've read some articles on genetic sequencing that claim an incredibly high success rate at reconstructing DNA from fragments. I believe similar proposals have been made to resurrect the Woolly Mammoth by filling in gaps in a reconstructed genome with DNA from an elephant, then replacing the DNA in an elephant embryo and bringing it to term in an elephant surrogate mother.[20][21] It's supposed to be possible, just extraordinarily expensive (Less plausible proposals involve using frozen mammoth sperm to impregnate a modern day elephant). Similarly, resurrecting Neandertals might be possible, but the ethical concerns make it highly unlikely to occur in my lifetime. A note: Dinosaurs died out far too long ago to leave DNA that could be reconstructed by the technique in question, so no, Jurassic Park won't be happening soon. —ShadowRanger ^(talk|stalk) 23:24, 11 March 2010 (UTC)

It's hard to believe that you'd have a problem here. Let's say that 99% of the DNA in your sample is destroyed. What that means is one of two things: EITHER...

1. 99% of cells have ruptured or something and have no useful DNA inside and the remaining 1% of the cells are intact...so just find a good cell and then use Polymerase chain reaction to make the stuff by the bucketful...OR...
2. Each cell only has 1% of it's DNA left intact...but if you take the DNA from a million cells, you can find any given stretch of the DNA in lots of different cells so all you need to do is to sequence the fragments and write some rather simple software to stitch it back into an intact strand.

I can't think of any but the most contrived set of circumstances in which you'd need to take DNA from another species. Just find another cell in the same creature - the odds of the same bit of DNA being missing from every single cell in your sample seems astronomically unlikely. The only way I could imagine there being "gaps" would be if a spectacularly large amount of damage had been done and the sample size was microscopic. SteveBaker (talk) 00:31, 12 March 2010 (UTC)

The sample size may indeed be microscopic, as in the Jurassic Park scenario, where the blood in the gut of a mosquito preserved in amber is the source. And, while dino DNA can't survive by being frozen like a mammoth's, that doesn't mean there's no way it could survive. Here's one possible case: [22], [23]. StuRat (talk) 00:54, 12 March 2010 (UTC)

I see a couple problems with the idea of filling in the gaps of an extinct species with another:

1) If you have gaps in the extinct species, then how do you know that the missing DNA is identical to the donor species ?

2) If the species of interest has badly degraded DNA, you may only have tiny fragments left, maybe only a base pair or two each. With such small strands, it may be impossible to determine where each fits into the sequence, and thus to figure out where the gaps are. Just like decoding a cypher, you need sequences of a certain length to even begin the process. StuRat (talk) 01:18, 12 March 2010 (UTC)

March 12

Looking for a bird

Does anyone know of a complete list of species featured in The Life of Birds? In particular, I am looking for one bird species, it must have been in "Signals and Songs" (episode 6). Its song sounded like early electronic analogue synthesizers, or someone rapidly turning a ham radio dial. I think Attenborough's commentary mentioned that it had to learn to produce something like 40 different sounds in order to get its song right. I think it was North American, small, and dull-coloured (mostly brown). Thanks in advance! ---Sluzzelin talk 01:22, 12 March 2010 (UTC)

Reflex subwoofer query

I made a ported (reflex) sub-woofer with a vertically upward firing drive unit and a vertically downward firing port for bass instrument reproduction. I found that increasing the distance between the port and the floor (to about twice the ports diameter) seems to give a much richer sounding bass then when I used only a single diameter spacing (as recommended in some sources as the min). Why is this, and how does the spacing between port and floor affect the response/efficiency of the system? In particular, why do larger spacings seem to give more 'fruity' bass with apparently increased high frequency response?--79.76.188.14 (talk) 01:47, 12 March 2010 (UTC)