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January 23

where does the RNA stored?

i know that in the cell nuke 99% DNA and 1% in the MITO's..

but what about the RNA? —Preceding unsigned comment added by 109.65.14.202 (talk) 00:41, 23 January 2011 (UTC)

Messenger RNA is generally not stored -- it is manufactured (in the nucleus via transcription), read (in the cytoplasm by ribosomes via translation) and degraded (by catabolic enzymes). Of course, prokaryotes don't have nuclei, so transcription occurs in the cytoplasm, and translation occurs while the RNA is being produced because ribosomes don't have to wait outside a nucleus. There are some RNA viruses, so it's maintained in these types of situations. DRosenbach ^{(Talk | Contribs)} 00:54, 23 January 2011 (UTC)

Read our RNA article. There are many different types with functions in different parts of a cell. See also List of RNAs. SpinningSpark 00:58, 23 January 2011 (UTC)

A large portion of the RNA in the cell at any one time is that making up the ribosomes. See rRNA. -- 174.31.216.144 (talk) 18:54, 23 January 2011 (UTC)

You can store it for a short time in nuclease-free water at -80 C or else for a longer time as a precipitate in 1 volume nuclease-free water, 0.1 volumes 3 M NaAc and 2.5 volumes 100% ethanol, at - 20 C. —Preceding unsigned comment added by 90.213.111.224 (talk) 01:19, 24 January 2011 (UTC)

Solute property

What's the property of solutes that makes the number of atoms in solution significant? I'm thinking of a chemistry lecture that discussed using aluminum chloride over sodium chloride because there's 4 atoms in the former and only 2 in the latter and ice will take much longer to form with double the number of solute molecules. I think the word begins with the letter "c." DRosenbach ^{(Talk | Contribs)} 01:03, 23 January 2011 (UTC)

Nope, it's a v. See Van 't Hoff factor. Unless you meant "c" as in colligative property. the Van 't Hoff factor is the numerical value which determins how much the solute "matters". Colligative properties are the properties the Van 't Hoff factor affects, like freezing point depression and osmotic pressure. --Jayron32 01:09, 23 January 2011 (UTC)

Yes -- colligative. thanx! DRosenbach ^{(Talk | Contribs)} 04:23, 23 January 2011 (UTC)

sex

what happens to girl's sexual organs when she is sexually aroused? — Preceding unsigned comment added by Pranashu1432 (talk • contribs) 04:31, 23 January 2011 (UTC)

See Sexual arousal#Physiological changes and Sexual arousal#Female physiological changes. Red Act (talk) 05:01, 23 January 2011 (UTC)

electrical

1. Why electricity is generated in 11kv in generating station & why it comes to 220volt in case of distributed to individual consumer? 2. how the current flows in the three phase plug ? 3. what is the function of each point of 5point plug in the switch board? — Preceding unsigned comment added by Khan2010sonali (talk • contribs) 04:51, 23 January 2011 (UTC)

Please provide a reference for what country has the "5point plug." Edison (talk) 05:35, 23 January 2011 (UTC)

3 phase + neutral + earth = 5 pins--Aspro (talk) 12:20, 23 January 2011 (UTC)

Electrical power is distributed at high voltages (usually quite a bit higher than 11kV for national grids) because that minimizes that transmission losses. It is transformed down to lower voltages for residential use because the high voltage requires impractically large shielding and safety devices. Historically the choice of residential voltage was informed by the need to run practical incandescent lamps directly off the grid voltage. Lots more information can be found in the Electric power distribution article.

The five pins in a five-point plug carry three live phases, offset 120° from each other, one common return/neutral wire (see three-phase electric power for lots of explanation and animations), and a protective earth pin. The precise shape and layout of these plugs differ between countries, and sometimes also between residential and industrial applications. –Henning Makholm (talk) 07:44, 23 January 2011 (UTC)

Addressing question 2, how the current flows in a three-phase plug: the current flows into the load through one phase and returns through the other two phases. Ideally, with a perfectly balanced load, there is no current at all in the neutral conductor. Which phases are delivering current and which returning current changes rapidly with time; any one phase current first rises to a peak, then falls to zero and then the current reverses. As Henning said above, this cycle is 120° apart for each phase ensuring that at least one is delivering current and one receiving current at any one time. The three currents added together algebraically sum to zero; which is why there is no neutral current. See three-phase and three-phase electric power. SpinningSpark 10:26, 23 January 2011 (UTC)

Schizophrenia AntiBiotics - 52%? success rate that treats and requires no anti psychotics

I myself and a large amount of people I know have schizophrenia

Months ago visiting Wikipedia I found an article that said schizophrenia had a 52% treatability rate with the listed antibiotic

Could you please provide this again information again? I haven’t been able to find it

I hope to forward it to medical institution —Preceding unsigned comment added by 202.124.74.73 (talk) 06:06, 23 January 2011 (UTC)

This question has been removed per our medical advice policy. If you have any questions about possible treatments, you should discuss this with your doctor or psychiatrist. Nimur (talk) 06:35, 23 January 2011 (UTC)

Nimur I put the question back because it does not meet the guideline what what constitutes a non-answerable request for medical advice. This is a request to find an article, not a request for a diagnosis and advice. Ariel. (talk) 11:14, 23 January 2011 (UTC)

You may be looking for E. Fuller Torrey although the 52% efficacy claim is not made in that article. SpinningSpark 14:04, 23 January 2011 (UTC)

Please be aware that Wikipedia can be edited by anyone, and so information which is speculative, unverified, and/or downright bogus is constantly being added to and removed from articles. material which appears and then disappears (never to return) most likely falls in one of those categories. --76.205.146.144 (talk) 14:21, 23 January 2011 (UTC)

I've had a look in some obvious articles like E. Fuller Torrey and Toxoplasmosis. Can't find any mention of the claim although it's hard to look for some specific wording in the history particularly without knowing when the info was there. As 76 has said, claims may be added to articles which lack support and these will usually be removed when noticed. It's also possible you're remembering wrong. For example the Toxoplasmosis link has evidentally been studied since 1953. These [1] [2] mention 52% in relation to Schizophrenia. So perhaps some of these details were in an article and you're remembering different bits of information as one, I do that some times. Nil Einne (talk) 15:00, 23 January 2011 (UTC)

The paper in question is probably PMID 19269110. Note though that it appeared in Medical Hypotheses, which is not generally considered a reliable source for Wikipedia's purposes. Looie496 (talk) 19:14, 23 January 2011 (UTC)

There is a pretty credible hypothesis that schizophrenia is caused by a viral infection in infancy whose long-term effects emerge decades later.[3] Bacteria don't come into that picture, from what I gather. 67.122.209.190 (talk) 21:49, 23 January 2011 (UTC)

Sussex cricket meteorite

I meteorite was reported to have landed in the middle of a cricket match in Sussex in July 2010, as in this this newspaper article:

http://www.dailymail.co.uk/news/article-1297724/Meteorite-crashes-earth-county-cricket-match-hitting-spectator-chest.html?ITO=1490

but I cannot find any report to say whether or not it was confirmed as a meteorite, which makes me suspect that it wasn't.

According to a review in New Scientist, 22 January 2011, of the book Incoming! by Ted Nield, it was 12 cm long, and split into 2 pieces, but the photo in the article shows the pieces as being 3 or 4 cm each.

Any opinion or information about whether this was a genuine meteorite, or what it was identified as?

FrankSier (talk) 11:44, 23 January 2011 (UTC)

I also posted this question in Yahoo! Anwsers and got a couple of very quick replies: it was not a meteorite, but probably something that fell off a passing aeroplane. See:

http://www.telegraph.co.uk/science/space/7919157/Suspected-meteorite-was-concrete-lump-that-fell-from-passing-plane.html

and

http://uxbridge.uxbridgegazette.co.uk/2010/08/uxbridge-meteorite-claims-prov.html

FrankSier (talk) 13:45, 23 January 2011 (UTC)

Some objects thought to be meteor fragments or green fireballs are indeed remnants of broken pieces of artificial satellites that often contain stainless steel. July is usually the early starting period of the Perseids meteor shower. Here are some reports of recent meteors mostly in the US: AMS. ~AH1^(TCU) 00:39, 27 January 2011 (UTC)

Heat generating gel

I bougght some bags with gel in that solidifies and gives out heat when activated by a mechanical shock. How do these work?--92.28.87.165 (talk) 12:08, 23 January 2011 (UTC)

We have an article about that:Heating pad.--Aspro (talk) 12:22, 23 January 2011 (UTC)

(edit conflict) Various mechanisms for releasing heat are described in our articles on hand warmers and heating pads. From your description, it sounds as if your bags contain a phase change material such as a a supersaturated solution of sodium acetate. Gandalf61 (talk) 12:26, 23 January 2011 (UTC)

Planck constant constant ?

Is it known for certain whether the Planck constant has always had the same value throughout the history of the universe ? If the value of h were changing slowly over time, at a rate that was too slow to be directly seen in local measurements over the last 100 years or so, what observable effects would this have ? Presumably, given conservation of energy, the frequency of light from distant galaxies would be shifted, but could this effect be distinguished from the cosmological red shift ? Gandalf61 (talk) 12:42, 23 January 2011 (UTC)

A change on the value of Planck's constant would also imply a change on the value of Rydberg's constant so the spectrum lines wouldn't simply shift around. Their spread would also change. That is not observed. Other chemical compounds would have their spectrum altered in even more complex ways. Some of them might even be completely unstable for values for h-bar much different than the currently observed ones. That severely constraints any possible variation on h-bar to a very minimal variation almost indistinguishable from no variation at all. Dauto (talk) 16:09, 23 January 2011 (UTC)

What I said above is true but that has not kept some very high profile physicist from speculating on the possibility of physical constants varying over time, starting with Dirac. See Physical constant#How constant are the physical constants?.

read this. Count Iblis (talk) 16:28, 23 January 2011 (UTC)

I think that Duff is wrong about this, and so is everyone who's expressed similar sentiments on the reference desk (which includes me). Imagine a physical theory with two continuous parameters. You can cover the parameter space with two coordinates, b and q. But you can also cover it with b and m, where m = b + q, or with m and q. These are all unitless parameters. But what does it mean for b to vary? It's one thing for b to vary with q held fixed, quite another for b to vary with m held fixed, and logically impossible for b to vary with m and q held fixed. So "variation in the fundamental constant b" depends on what other constants you've decided to take as fundamental, even though b is unitless. Adding units is equivalent to increasing the dimension of the parameter space and adding a corresponding number of symmetries. Does that affect what I wrote above? Not as far as I can see. Suppose we parametrize the same theory by x, y, and z, with b = x − y and q = y − z (and, therefore, m = x − z). The symmetry is that adding the same real number to all three of these coordinates leaves the physical theory unchanged. This is equivalent to saying that x, y, and z all have the same (nontrivial) units. Is variation in x physically distinguishable from variation in y? Yes: you can't use the symmetry to convert one into the other. On the other hand, if the parameters were b, j, and k, with q = j − k and m = b + j − k, then varying j and varying k would be physically equivalent. You have to look at the context. In the appropriate context, though, it's fine to talk about variation of a unitful physical parameter. -- BenRG (talk) 21:47, 23 January 2011 (UTC)

Indeed, whether a quantity is unitless or not is more a question of the conventions of measurement we adopt than it is a fundamental feature of the universe.

Another relevant point is that it is not really well-defined to say, "imagine that Planck's constant changed but all the other constants stayed the same", because that there are sufficiently many candidates for "all the other constants" that fixing them all also implicitly fixes Planck's constant. One needs to specify explicitly what else one supposes to be constant while the thing one is varying varies. If we're varying Planck's constant, saying "... while the mass of the electron, measured in Planck masses, stays the same" is different from saying "... while the mass of the electron, measured in kilograms, stays the same". –Henning Makholm (talk) 00:53, 24 January 2011 (UTC)

I agree with all of the above except the idea that a whether a quantity is unitless depends on our conventions of measurement. I the quantity has no unit, how could we change its value by changing measurement conventions? That's akin to changing the value of pi by changing choice of measurement conventions. It makes no sense to me. Dauto (talk) 04:16, 24 January 2011 (UTC)

Right, pi could probably not made unitful by choosing other units, so my assertion was too strong. (One could make a tortured claim that the unit of pi is radians, but there are strong arguments in calculus that radians ought be unitless too -- that's why it makes sense to use radians for anything in the first place). I was thinking of something like how different systems of electromagnetic units can make various quantities (such as permeability and permittivity) either unitless or not. –Henning Makholm (talk) 07:58, 24 January 2011 (UTC)

The way I prefer to approach this is by working in natural units and then rescaling certain variables leading to the appearance of conversion factors. Formally everything is then still dimensionless, but you are of course free to assign some dimensional factors to a particular conversion factor if you also multiply the variables it multiplies by the inverse of those dimensions. The issue is then if a change in some constants correspond to a change in the theory, as in BenRG's example. Count Iblis (talk) 13:32, 24 January 2011 (UTC)

Thanks for all the responses. I take the point about needing to be careful about defining which other quantities are assumed to remain constant before we can make "does the Planck constant vary with time" into a meaningful question. So ... if we assume that the values of the speed of light, the elementary charge and the permittivity of free space all remain constant, then the question, in effect, becomes "does the fine-structure constant vary with time ?". And according to our article, the jury is still out on that one. Gandalf61 (talk) 12:54, 24 January 2011 (UTC)

is it true that Scientists think people walked around for 150,000 being as intelligent as us but without written culture?

Is it true that Scientists think people spent 150,000 years walking around being as smart as us, but without any writing, schools, architecture, roads, etc etc? If they were as smart as us, why does Science say they took so long to found a school or start writing or make architecture? Isn't this proof that evolution is an interesting story, but obviously doesn't make much sense on a practical level...? 194.78.208.19 (talk) 13:09, 23 January 2011 (UTC)

How long was it before you wrote your first book or built your first aeroplane? If you have even done either of those things it would not have been before many people spent a great deal of time teaching you to write or explaining science and engineering to you. Knowledge and skills have been built up very slowly over many centuries, you are lucky to live in an age of printing and internet where this knowledge can be acquired very quickly. But to discover something new is not so easy and takes a lot longer the first time round. Once we have the knowledge it can be passed to others quickly, but finding it in the first place - well there are many things we still do not know, and may never know.

The growth of human knowledge has little connection with biological evolution. The rate of acquisation of knowledge does not prove anything about evolution one way or the other. SpinningSpark 14:16, 23 January 2011 (UTC)

(EC) I'm not that familiar with current theories of human evolution, but I don't see any reason to think human reached an intelligence maxima 150k years ago. (Of course even if we did there are still plenty of reasons why all those took a long time to develop although that's more of an anthropological/sociology question then a evolutionary one.) P.S. From a quick search I found Evolution of human intelligence and Behavioral modernity which suggest ~50000 years as more likely. You may also be interested in these to give you some idea of current theories of how human behaviour changed over time. Nil Einne (talk) 14:17, 23 January 2011 (UTC)

As far as anyone can tell, humans had all the modern mental machinery we have now some time bofore 150kya. See anatomically modern humans. SpinningSpark 14:52, 23 January 2011 (UTC)

My comment about 50k may not be correct, but from what I can tell the comment that human mental machinery was the same 150kya as 50kya is only one of the current theories. There's dispute over whether anatomically modern humans also displayed behavioral modernity and if they didn't, then suggestion that evolutionary changes resulted in the behavioural modernity. In particular quoting directly from the article (i.e. don't dispute it with me, fix the article if you believe the theory is fringe) "One theory holds that behavioral modernity occurred as a sudden event some 50 kya (50,000 years ago), possibly as a result of a major genetic mutation or as a result of a biological reorganization of the brain that led to the emergence of modern human natural languages." Note that anatomically modern humans only seems to refer to the skeletal and other structures which are preserved in fossils, not things like brain structure (i.e. mental machinery which would potentially affect intelligence) which are not. In fact without wanting to get into controversial stuff like Race and intelligence and Heritability of IQ (and of course we need to ask what intelligence is in the first place), I don't think it's clear that human intelligence 10kya was the same as it is now. Note that I'm not arguing this is the reason for our advancements, far from it, rather I'm arguing the premise that intelligence reached a maxima 150kya is at best unsupported and probably reflects a misunderstanding of evolution on the part of the 194 (akin to the common 'why did monkeys stop evolving' idea). To put it a different way, the changes between 150kya and now may perhaps be far less then say 300kya and 150kya, it doesn't mean there were no changes. Nil Einne (talk) 15:10, 23 January 2011 (UTC)

In any case, it makes little difference to the principle of the answer whether one takes it as 50kya or 150kya (although I think the anatomical evidence supports at least speech being around at 150kya). The point is that humans had the physical ability to write and build cities long before they actually started to do so around 10kya. The reasons for this happening so late on are to be found in social development rather than evolution. SpinningSpark 17:47, 23 January 2011 (UTC)

We've come to naturalize scientific research, when really it is one of the most awkward and profound creations of the human species. It requires so many things before you can really even begin. You need to have enough people so that enough wealth is generated in order to allow some people to sit around pondering imponderables. You need to have societies with enough tolerance of oddness to allow people to voice heretical or at least bizarre notions. You need to have religious institutions tolerant enough (as religiousity and religious institutions seem far more "basic" to the human species than science — they seem to spontaneously arise, even today) to be challenged in their monopoly of knowledge. You need to have a sense of philosophy, a theory of how knowledge works, and why you might want it. And then, even if you have all of that, you need to have people willing to experiment, be wrong, and work at the tedious, tedious job of organizing the near infinite amount of observable phenomena into useful categories. And lastly, you need enough of said people, and enough means for them to communicate, for them to become a real community, as one toiler cannot accomplish more than a few flights of genius even at their best (consider how little Newton accomplished as an individual, compared to the scientific output of his time; consider again that much of Newton's accomplishments were based on the data and work of others, at that!). So it's no simple thing. It looks simple now because we have had exponential growth in the scientific community and scientific output in recent years; our last decade of scientific work is probably as much in raw numbers as the entire 17th century put together. But it's no easy thing, and even that is largely because after World War II, states started to think, "hey, funding science in a major way is a way to real success." The modern scientific infrastructure is really that recent — 65 years or so. --Mr.98 (talk) 14:22, 23 January 2011 (UTC)

Providing basic needs can be met , what incentive is there for developing culture and skills beyond what is required to meet these. Nomadic and semi nomadic life doesn't favour the accumulation of many possessions other than the basics, therefore higher skills had no infrastructure on which to be formed. It was only with the advent of farming, that people invested time and effort in a plot of land and so stayed in one place, which in turn, provided the opportunity to develop larger settlements with more complex cultures and a broader development of skills. Farming also suggests by its very practice, that advantages can be had in the future by planning in the longer time frame and by the keeping of records. Living in permanent settlements also create new problems and that in itself drives invention. That only started about 12000 years ago. --Aspro (talk) 14:24, 23 January 2011 (UTC)

As Mr.98 mentions, population size is very significant. The rate of technological development makes more sense if you look at it in terms of people-years rather than chronological years. The human population of the world was so small under quite recently that most of the people-years have been in the last century or so (possibly more recently than that), as have most of our technological developments. --Tango (talk) 15:03, 23 January 2011 (UTC)

I'm inclined to agree that population size should be very significant. A quick Web search turned up [4], but I haven't tracked down the source and I can't say how reliable it is (probably it's a wild guess anyway). But the guess, anyway, is 100 million at Year 0, 500 million at Year 1000, 1 billion at Year 1800. But to this we should probably add another factor, which I don't present data on, which is the number of scientists; as I understand it, aboriginal societies theoretically would have had a great deal of free time to invent things, but probably much of it was constrained in ritual; post-agricultural societies grew larger populations but paid for it by spending most of their available man-hours tilling the land. It is only in certain times - the Renaissance, and recently - that are known for having a lot of random professions, of which some were inventive. But how to convert such blather into numbers?? Wnt (talk) 02:06, 24 January 2011 (UTC)

Before even looking at the rest of the question, I'd like to see a citation for the opening salvo "scientists think people ...". --LarryMac | Talk 15:33, 23 January 2011 (UTC)

As the discussion above goes into depth about, it's probably more like 50,000 years. But that's still a huge amount of time, compared to the amount of time we've had anything that looked recognizably like science (e.g., a thousand years at most, with a very liberal definition of science; 400 years with a more constrained but still liberal one; 100 years with a very modern definition). --Mr.98 (talk) 17:24, 23 January 2011 (UTC)

I'm not sure why we're putting so much effort into pandering to an ignorant Creationist question. (And I mean Creationist in the literal sense.) HiLo48 (talk) 17:21, 23 January 2011 (UTC)

It's not a bad question, frankly, and the answers have been very good, in my opinion, and we are supposed to assume good faith. If you don't want to put in effort, please feel free to abstain. Personally I do find it boggling to imagine how many years humans spent being essentially "primitive," only to turn around in a blink of an eye and suddenly start bounding around on the moon. I am not a Creationist under any definition. --Mr.98 (talk) 17:24, 23 January 2011 (UTC)

How are creationists supposed to learn better if no-one is willing to teach them? While many of them aren't actually interested in learning, this OP might well be one of those that is. We should assume so until given reason to conclude otherwise. --Tango (talk) 17:44, 23 January 2011 (UTC)

Yes agreed (@Mr. 98), either answer the question straight or leave it alone. There is nothing to be gained by insulting the OP, if they are genuine it is upsetting, and if they are troll you are feeding them. Regarding the years spent as primitives; note that there are still guys out there herding reindeer or whatever with no fixed abode and no modern amenities. Assuming our own current lifestyle is the pinnacle and everyone else should be aspiring to it is a little presumptious. SpinningSpark 17:47, 23 January 2011 (UTC)

I'm not asserting it's the pinnacle, but I am asserting it is radically different in many key ways. And I would argue that the number of people who still live as essentially "primitive" (I put the term in quotes because I am uncomfortable with it, but also uncomfortable with euphemisms that are supposed to imply that dying at age 35 of malnutrition is an "equally good" outcome) in today's world is very, very small compared to those who live essentially "modern" lives, even in very poor or undeveloped nations. The poorest modern Haitian is still leaps and bounds more "modern" in their outlook and lifestyle than the people who were living on that island in the 13th century. I will note that while I have an ambivalent relationship with modernity, I think anything which tries to argue that the past was "better" for most people, or that pastoral people were more "happy", is probably nonsense. --Mr.98 (talk) 18:37, 23 January 2011 (UTC)

Keep in mind that just because they didn't have writing, schools, architecture, roads, etc, they weren't just sitting around in a puddle of their own drool. You might be able to beat them in a novel writing contest, but they would seriously kick your ass in a contest of hunting/tracking, or a contest of "where are the edible roots/berries" or "where should I sleep tonight to minimize the chance of getting eaten". If you talked with a person from 150,000 years ago, they'd probably be despairing of the fact that most Americans don't have the first clue about how to disjoint a chicken (edible bird), let alone pluck one. It all depends on what's considered "important" at the time - and what's important changes with advances in technology. You don't get supermarket chicken without refrigeration, which requires electricity, which requires metallurgy, or trucks, which require petroleum refining, or mass agriculture, which requires animal husbandry, etc. etc. Picking up a pack of chicken breasts at the grocery store seems simple enough, but there's a *vast* amount of technology needed before you can even start to consider doing it. -- 174.31.216.144 (talk) 18:51, 23 January 2011 (UTC)

The liberal democracies of our present age are especially conducive to scientific advancement, I think. In the modern liberal democracies there is a minimum amount of social hierarchy. Conversely there is a lot of fluidity of social class. Movement from the lower classes to the upper classes takes place with relative ease. Communication from the lower classes to the upper classes is uninhibited, relatively speaking. And education is available to all (to an extent). This all fosters advancement of all of the rational (and irrational) disciplines of study, science being one of them. The hierarchical structure of societies past I think was an inhibition to the advancement of science. Bus stop (talk) 19:19, 23 January 2011 (UTC)

I take exception to the above comment about Americans not knowing how to disjoint a chicken. From my experience Americans disjoint chickens with aplomb. Bus stop (talk) 19:28, 23 January 2011 (UTC)

By "disjoint a chicken" I meant taking a whole butchered chicken and cutting it up into pieces (breast, leg, thigh, etc.) before cooking. While Americans do eat a lot of chicken, it's mostly obtained in the pre-cut-up (if not pre-cooked) form. Speaking as an American, I get the impression that most of my countrymen aren't all that handy in the kitchen for anything not "ready-made" (we have pre-washed salad and pre-washed & peeled carrots, for goodness sakes). My point was simply that even a professional scientist researching the cutting edge of atomic physics might be baffled when presented with a whole supermarket chicken, let alone one a live one. People 150,000 weren't any less intelligent, it's just that they applied that intelligence to different things. -- 174.31.216.144 (talk) 01:10, 24 January 2011 (UTC)

An interesting question might be: if we had all of our technology taken away from us, how long might it take to regain it? It might take 50,000 years. It might take 150,000 years. Bus stop (talk) 01:31, 24 January 2011 (UTC)

Mere decades, I'd say, assuming we still had all our ideas. (If not, we wouldn't really be "us".) 213.122.48.31 (talk) 01:41, 24 January 2011 (UTC)

Taking the technology away is not enough: you'd have to take away all the memories of how to read, how to make a primitive bow and arrow or spear, how to roast meat, and so on. You'd have to bring up a group of Feral children to have a comparable starting point. Even when such children were immersed in their contemporary society after being disciovered, they still did badly. 92.15.26.222 (talk) 11:46, 24 January 2011 (UTC)

92.15.26.222 and 213.122.48.31—let us say that somehow a remnant of humanity remained in the year 2011, the present year, on the planet Earth, bereft of all the accomplishments of the past 100,000 years—how would they fare? I think they would fare little better than humanity fared for the past 100,000 years. That is because there is probably little more intelligence, or cerebral capacity, in us than there was in those of us who were around 100,000 years ago. Let us say that the remaining population was comparable in numbers to the population size of our species 100,000 years ago. And let us say that those of us remaining were of above average intelligence but not interested in or knowledgeable of science, technology, religion, culture, or anything else that we consider our species' crowning achievements. This is a thought experiment. We can't be precise. We do not even know what qualities those of us around 100,000 years ago possessed. Let us say that we lost roughly every characteristic that would distinguish us from our forebears. It doesn't matter how. This is just a thought experiment. We could have had our tongues cut out and our hands removed, if the thought experiment required us to have no language. An invasion by aliens could accomplish this, conceivably. The question is: how would progress proceed? Rapidly? Slowly? If our cerebral capacities are little different than that of those of us 100,000 years ago, then civilization would advance at no faster pace. Bus stop (talk) 14:28, 24 January 2011 (UTC)

There are surviving cultures today that have no writing! I think the Mbuti qualify. Their lifestyle doesn't really support the development of writing. (Sure, nowadays, they could trade for pen/paper if they really wanted it, but they couldn't produce useful writing materials on their own. For example, anyone can make a clay tablet, but what good is that to a nomadic people with no pack animals?)

Of course your next question would be, why don't they change their lifestyle to be more like ours ("The wheel, New York, Wars and so on"), but people typically don't change their lifestyle unless some disaster forces them to. APL (talk) 20:45, 23 January 2011 (UTC)

I'm not sure I buy the latter sentiment. I'd bet that if the truly Western option was open to them, a lot would flock to it. As it is, their "Western" option is that of the wars in the Congo or the horrors of sub-African mining, which are no options at all.

Incidentally, a tablet can be quite useful for nomadic people, if it keeps track of property or debts. The earliest examples of writing that we have, if I recall, are ledgers of debts. --Mr.98 (talk) 22:00, 23 January 2011 (UTC)

Oh, sorry, I meant a roughly natural progression of forging the next step for your civilization, analogous to the path people would have had to take 100,000BC, not individuals simply transferring from one existing civilization to another. APL (talk) 22:35, 23 January 2011 (UTC)

It has been suggested that a lot of development happens for negative reasons, such as war, or population pressures. I've seen it argued that the Australian Aboriginal people, with no nasty, threatening invaders on the doorstep, had no need, and hence no motivation, to develop sophisticated weaponry, and its associated spin-offs. In addition, the absence of a practical beast of burden on the continent meant that even developing the wheel was pointless. Can you imagine a mob of kangaroos towing a chariot or a wagon full of stuff to sell down the road? They had no writing, but didn't have a need for it. HiLo48 (talk) 01:42, 24 January 2011 (UTC)

I was troubled by similar questions myself (barring the doubts about evolution) when reading about Pre-Columbian North America, from which it is apparent that the indigenous peoples of North America spent some 12,000 years not inventing the bow and arrow. I mean, 12,000 years is a really long time, and it's a really useful device, and it's only made out of sticks and string. What was stopping it happening? 213.122.48.31 (talk) 01:53, 24 January 2011 (UTC)

How is that apparent? The only mention of bows on the linked page says that some North American peoples did not use bows and arrows until about 1000 CE. It appears that projectile points are present in the entire archaeological record of humans in the America; it is very difficult to see from archaelogical finds whether the points were for arrows or spears, because the shafts and bows themselves tend to be biodegradable. So how would anyone be able to conclude that bows and arrows were not used in prehistoric North America? –Henning Makholm (talk) 02:08, 24 January 2011 (UTC)

I never liked the saying "absence of evidence is not evidence of absence". I think it conflicts with Occam's razor. 213.122.48.31 (talk) 02:21, 24 January 2011 (UTC)

The article mentions "some" peoples who didn't, but I haven't tried to hunt game in their regions with an atlatl. For all I know bows and arrows were invented a thousand times, and results were disappointing every time. Wnt (talk) 02:09, 24 January 2011 (UTC)

I wonder if something to do with optimism and encouragement might be the answer to the question about technology in general. Perhaps before progress can really take off, the idea of progress has to be invented. 213.122.48.31 (talk) 02:16, 24 January 2011 (UTC)

...and seen as a desirable thing. HiLo48 (talk) 02:24, 24 January 2011 (UTC)

Yep. 213.122.48.31 (talk) 02:26, 24 January 2011 (UTC)

It is likely that early civilizations did have some technology, for example the Baghdad Battery suggesting that Mesopotamians had electricity. However most inventions were created after civilization took place, and since early hominids are thought to not have built cities, much written communication would likely have been unnecessary. ~AH1^(TCU) 00:06, 27 January 2011 (UTC)

State of the art of photorealistic computer animated actors

In the movie Tron: Legacy, the actor Jeff Bridges appears as a younger version of himself using performance capture technology. I wonder when we can expect the technology to be cheap enough to be routinely used in movies, say with one out of ten movies having a character who's realized that way. If cheap enough, such a technology can allow important characters in a franchise like James Bond to have the same faces and physical appearance, even though the actors playing them may change over time. It would also expand opportunities for actors, by decoupling acting from having the right face and body. —Preceding unsigned comment added by 98.114.146.175 (talk) 15:06, 23 January 2011 (UTC)

Personally I thought the Tron technology was still terribly crude, but maybe that was just me. The Clu character looked like something out of The Polar Express to my eyes, and set off my uncanny valley sensors every time he was on screen (which was all too often!), but perhaps I am too sensitive. In any case, there has been speculation along these lines for a long time. See, e.g., the film S1m0ne. Personally I suspect that there will probably be something "lost" in such renderings, even as they improve. And the star system seems like it would mitigate against this to some degree (the public and the studios, to some degree, like having consistent "stars", much more than they do talent on its own). But it's certainly possible. --Mr.98 (talk) 17:29, 23 January 2011 (UTC)

I haven't seen the movie, but from seeing the trailer, I thought the young Jeff Bridges face was not 100% natural. But that was me seeing it knowing what they did. I'm not sure if I would be fooled if it were a completely unfamiliar face. I did think about the star systems angle, and I agree that it's an important factor. --98.114.146.175 (talk) 19:13, 23 January 2011 (UTC)

I had not known it would be computer generated, and it looked tremendously fake from moment one. It was really quite silly that they spent all that money on special effects, most of which look great, except for the rendering of one character who is in fact central to the entire film and is on screen a huge amount of the time. I have seen better CGI — Gollum was far superior, for example. --Mr.98 (talk) 21:52, 23 January 2011 (UTC)

The technology is embryonic. It will improve vastly. Like every new technology, it will succeed or fail on the basis of whether it makes money for the money people. I imagine that actors (as opposed to "stars") would be as likely to embrace this kind of technology as to fear it. One of the biggest problems actors face is aging. Particularly women. Conceivably, this sort of technology could render irrelevant such superficialities as youthfulness, physical condition, attractiveness, and even things like race and height. Actors could market themselves purely on the basis of abstract qualities like subtlety, charisma, comic timing, panache, etc. Indeed, they would have to market themselves on such qualities, since mere accidental beauty would no longer cut it. The Japanese will get there first, of course. LANTZY^TALK 19:31, 23 January 2011 (UTC)

Have you heard of Hatsune Miku? The article doesn't have any photos of footage, look "her" up on youtube. Vespine (talk) 00:16, 24 January 2011 (UTC)

As far as I know Hatsune Miku is just the name of a singing-synthesizer voice, like Microsoft Anna (except that I guess there are no pictures of Anna). Kyoko Date is a better example. The whole computer-rendered idol singer thing doesn't seem to have caught on all that much in the 15 years since she was introduced. -- BenRG (talk) 11:22, 24 January 2011 (UTC)

The singing-synthesizer voice software is vocaloid, Hatsune is a specific "voice" and actually has an associated "character" which has played concerts to live audiences.. Vespine (talk) 23:36, 24 January 2011 (UTC)

But her image isn't computer rendered. Her voice is. Kyoko Date is a computer rendered image with a real person's voice, which is what the original question was about (though it's not state-of-the-art, at least not any more). -- BenRG (talk) 00:12, 25 January 2011 (UTC)

Ummm, yes Hatsune is computer rendered, and projected onto the stage.. have you seen the youtube clips? A google image search is not very work safe, she looks like a manga character. Vespine (talk) 05:47, 25 January 2011 (UTC)

Are you talking about this? I thought that was a dancer in an animatronic costume, but I guess you're right. That's about as primitive as motion-capture 3D can get, though. -- BenRG (talk) 20:00, 26 January 2011 (UTC)

Yeah very true, photo realistic it ain't. But I thought it was quite relevant as it seems to be approaching the same, or similar conclusion, but from a different angle. In fact, what we have for "actors" in the future might be a bit of a mixture of the two. Vespine (talk) 22:01, 26 January 2011 (UTC)

Disease from eating sheep's lungs?

Does anyone know why it is illegal - since 1971 - to eat sheep's lungs in the US? Is there some kind of disease you can get from eating sheep's lungs and if so, what is it? I am just curious and can't find anything online. Only mention of the law itself and then, in the 80s, problems with scrapie / CJD from eating sheep's brains. Saudade7 19:42, 23 January 2011 (UTC)

Sheep's lung, carries with it the possibility of introducing the phenomena of spontaneous generation which may lead to a serious outbreak of Haggisess. These little blighter's are impossible catch unless the weather is cold, wet and windy. Even then ... oh, I just don't what to think about it! They are 'orrible! A small 4 ounce dose of boiled “neeps” taken orally is, so I have been told, a good antidoted, if you have been bitten by one of these hideous creatures. --Aspro (talk) 20:05, 23 January 2011 (UTC)

ahahahahahahaha! no. :-) Saudade7 20:18, 23 January 2011 (UTC)

Cute, very cute. The only lung-related disease I can think of that relates to sheep is anthrax, which (all things considered) would be a pretty good reason to ban them. I don't know why they would single out sheep lung for that, though - lungs of any herbivorous animal should be an adequate vector. --Ludwigs2 20:19, 23 January 2011 (UTC)

It's not illegal to eat lungs. It's illegal to sell them as food for humans. (And not just sheep's lungs, but any kind of livestock lungs.) If you raised and slaughtered your own sheep, you could make authentic haggis. And if you called it cat food, you could sell it too. As for why the USDA considers lungs to be unsuitable for human consumption, it's because of the high incidence of lesions in the lungs they inspected back in the early seventies. Such lesions indicate pneumonia, emphysema, hydatidosis, anthracosis, pleurisy, melanosis, and tuberculosis. Currently there is a blanket ban on using livestock lungs, but it is worth noting that cattle lungs have a much higher incidence of lesions than sheep lungs. So it wouldn't be surprising if the USDA were to ease the restrictions on sheep lungs while retaining the ban on bovine lungs. LANTZY^TALK 20:50, 23 January 2011 (UTC)

Wow Lantzy, thanks for such an authoritative answer! Saudade7 21:15, 23 January 2011 (UTC)

Bamboo in laptops

A well-know laptop manufacturer, which introduced a bamboo covered laptop claims that:

"Bamboo was picked (...) after research identified it as a quickly-replenishing resource whose utilization has almost no impact on the environment. Bamboo also has a tensile strength that rivals that of steel, "

Are both claims true?Quest09 (talk) 21:01, 23 January 2011 (UTC)

Probably, somewhat. From our Bamboo article, "Bamboo is one of the fastest-growing plants on Earth ... all bamboo have the potential to grow to full height and girth in a single growing season of 3–4 months." That's not the last word on sustainability, but it is a very good start. And this Scientific American article talks about the strength (or lack of) of Bamboos; our article phrases it thus: "the sturdiest [Bamboo] products fulfil their claims of being up to three times harder than oak hardwood but others may be softer than standard hardwood." --Tagishsimon (talk) 21:11, 23 January 2011 (UTC)

Fast-growing doesn't necessarily mean "almost no impact." Perhaps Bamboo needs huge amount of water. Besides that: the best bamboo for laminates, according to the article, is 6 years old. Thus, they don't use the strongest bamboo or they don't use the fastest growing bamboo. Right? Quest09 (talk) 22:27, 23 January 2011 (UTC)

Oh that particular problem is easily solved - you just get six lots of ground to grow your bamboo on and use every year's allotment in sequence. When you harvest your six year olds, you plant new bamboo, and wait for another year for your five year olds to get to be the six year olds. In fact, this is done in foresting everywhere, just on a much longer scale. TomorrowTime (talk) 22:48, 23 January 2011 (UTC)

Claims of "no impact on the environment" are tricky. Environmental impact comes from the aggregated effects of all parts of the production of a product. Usually when people claim that something has no effect on the environment it is because it is used on a small scale where it truly doesn't have much impact. Making a couple thousand bamboo lap top covers from bamboo has little impact on the environment, replacing most plastic pieces of everyday items with bamboo certainly would, in the form of land use, transportation and probably some unintended consequences that would be hard to imagine. Even things that seem low impact on the environment like wind turbines start to have major effects when used on a large scale, see Environmental effects of wind power. --Daniel 01:35, 24 January 2011 (UTC)

Speaking of which, why don't we grow any bamboo (as a crop) in the U.S.? Wnt (talk) 01:48, 24 January 2011 (UTC)

The National Center for Appropriate Technology discusses this question here. They summarize, "Countries that export this product have decided advantages over American farmers with respect to climate, labor, and processing costs." --Allen (talk) 02:11, 24 January 2011 (UTC)

"As strong as steel" is a fairly meaningless claim. Steel comes in an incredible variety of strengths: when I worked in a mechanical testing lab, I saw everything from 6 ksi steel (so weak I spent half an hour running additional tests to verify I was getting good data) to tool steel that was somewhere over 250 ksi (the test machine broke, rather than the sample). --Carnildo (talk) 02:49, 26 January 2011 (UTC)

Maybe "no environmental impact" refers to little or no net carbon footprint. However even your bones are stronger than oak (to constant pressure, not impacting forces), but only if Encyclopedia Brown is to be trusted. Also, tensile strength only refers to restistance to stretching, and does not refer to the ability of the laptop to withstand impact. ~AH1^(TCU) 23:55, 26 January 2011 (UTC)

Permutation of position weight matrix for biological problem solving

Hello,

I would like to know how to permute automatically a position weight matrix from JASPAR to TRANSFAC mode. In addition, I would be glad to know how to obtain automatically a position weight matrix from a Clustal of several sequences. Thanks in advance. --79.12.129.97 (talk) 21:53, 23 January 2011 (UTC)

Isn't transfac just a simple transpose of a jaspar matrix, with a little formatting? Section 6.ii.3 at this page has examples. It looks like the JASPAR database can export in transfac format. There are many flavors of PSSM generators - what is your goal? -- Scray (talk) 02:09, 25 January 2011 (UTC)

I am trying to make some positive controls to find out in what condition algorithms as Clover and similar work well. So I decided to test a well-known promoter with a series of PSSM. I formatted some of them in TRANSFAC mode but, as you can imagine, it is a tedious operation (I tried to export TRANSFAC matrices from JASPAR database, but I failed). In addition, I experienced difficulties in finding all the PSSM needed. So I would like to transpose them automatically and also to generate them from a Clustal, when required. Consideration on how to avoid false positive and false negative are also particularly welcome. --87.6.128.123 (talk) 10:59, 25 January 2011 (UTC)

I am familiar with the Clover (software) package from Atlassian, but my sense is that you are referring to something else. The transform would be pretty easy to do in a number of environments, including R and Perl, but even something as simply as Microsoft Excel could do most of the work (a simple matrix transform is the most tedious part). You may find related answers at biostar. BTW, I think you are confusing the software program Clustal with "multiple sequence alignment" - the two are not synonymous in the least. -- Scray (talk) 01:45, 26 January 2011 (UTC)

The Clover I mean is this (the Clover linked by me above doesn't fit so much the problem, LOL). Performing the transposition with Excel could be a valid solution, thanks (I am unfamiliar with R and Perl). I used the word Clustal informally to depict a multiple sequence alignment obtained with Clustal. Thanks also for the useful link. Any other eventual suggestion for the control of false positive and false negative is still welcome. Greetings. --87.3.134.159 (talk) 15:47, 26 January 2011 (UTC)

Sterile chicken tells no tales

If I cook, say, a chicken at 200 C (375 F?) in an oven, switch the oven off and don't open, so air is not travelling into the oven, will the chicken be sterile and therefore keep for a very long time? —Preceding unsigned comment added by 90.213.111.224 (talk) 23:53, 23 January 2011 (UTC)

No oven is airtight, in fact it is far from it, so the chicken will become contaiminated at roughly the same rate as if the chicken were left on the counter. If we're talking about a fully cooked bird, a few hours likely wouldn't hurt it, but it definately wouldn't keep until, say, next thursday. --Jayron32 23:58, 23 January 2011 (UTC)

Add to that the fact that an oven isn't an autoclave. The chicken wouldn't keep even in a hermetically sealed oven, as there are still residual microbes even after cooking. Cooking kills a large portion of the bacteria, but not all. -- 174.31.216.144 (talk) 00:55, 24 January 2011 (UTC)

So I'd be better off cooking it in an autoclave? Would it come out crispy? —Preceding unsigned comment added by 90.213.111.224 (talk) 01:13, 24 January 2011 (UTC)

LOL. (Yes, and my apologies in case that was an innocent question.) The issue with your question is that normal cooking will kill most bugs on the outside, but the inside is never quite as hot. Bugs in the middle will survive in numbers sufficient to grow rapidly at room temperature. HiLo48 (talk) 01:21, 24 January 2011 (UTC)

There is such a thing as canned chicken so it is possible to fully sterilize a chicken (it's possible at home too, it doesn't require special equipment). Ariel. (talk) 01:55, 24 January 2011 (UTC)

The chicken will probably keep until next month if you disjoint it before cooking (to be absolutely sure that it cooks right through), then freeze it after a short cooling period. There are risks in home freezing, but dangers can be avoided with care. Unfortunately, freezing will spoil the crispy effect unless you re-cook it. An autoclave (pressure cooker) will not achieve a crispy exterior and is just a way to boil at a slightly higher temperature. I've never tried sealing chicken in an airtight jar (after thorough cooking), but I suspect that there would be too many risks for this to be recommended. Dbfirs 08:04, 24 January 2011 (UTC)

It's not difficult to can meats, but there is more to it than just cooking it and sealing it in a jar. --Sean 15:08, 24 January 2011 (UTC)

Ah yes, thanks for the link. I assume that the secret (to ensure safety) is the higher cooking temperature, longer time, and airtight seal. Dbfirs 19:46, 24 January 2011 (UTC)

January 24

2012

will the earth end in 2012 — Preceding unsigned comment added by Tommy35750 (talk • contribs) 01:12, 24 January 2011 (UTC)

Highly unlikely if you ask me, but see 2012 phenomenon. PrimeHunter (talk) 01:18, 24 January 2011 (UTC)

(EC)We do not engage in speculation on the reference desks. However our article on the subject is at 2012 phenomenon. --Tagishsimon (talk) 01:19, 24 January 2011 (UTC)

There is no accepted scientific reason to think that the Earth might be significantly more likely to end in 2012 than in any other year. That is, there is no accepted scientific reason to think that the Earth has anything greater than almost no chance of ending in 2012. For a scientific viewpoint of Earth ending, skip the 2012 phenomenon article, which is about a sociological phenomenon that has essentially nothing to do with science, and read Risks to civilization, humans and planet Earth. Red Act (talk) 02:03, 24 January 2011 (UTC)

NASA says no at this link. Phew. Comet Tuttle (talk) 18:30, 24 January 2011 (UTC)

Probably not.NASA--Cjc811 (talk) 19:17, 24 January 2011 (UTC)

Look at this site Maybe--Cjc811 (talk) 19:18, 24 January 2011 (UTC)

Don't look at that site, it's just an idiot's ramblings. --Tango (talk) 19:41, 24 January 2011 (UTC)

No reason why it shouldn't except applications of inductive logic as flawed as the optimism of someone who has jumped from a 100 story building and notes that nothing bad has happened after he has fallen 80 stories, 81 stories, 82 stories, ... and who concludes that therefore he might fall without limit, right? The Earth has hosted lifeforms for hundreds of millions of years, so it will continue for hundreds of million or billions more, right? Edison (talk) 02:52, 25 January 2011 (UTC)

This recent article predicting a supernova of Betelgeuse in 2012 is a clear example of the 2012 phenomenon, since those "predictions" of a star emerging from Orion would have been correct should this actually occur. However, even though the diameter of Betelgeuse has shrunk by 15% in the past 15 years, this estimate is highly uncertain due to blurry imaging and differences in development of the technique, though if the estimate is correct, this corresponds to nearly a 40% decrease in volume, although mass has also been decreasing, suggesting the star is shedding its outer layers (spectroscopy of the star may indicate changes); this may represent either an early or a late stage of pre-supernova changes in the star, though periodic changes similar in magnitude also occur in non-near-supernova variable stars, even though those stars too are often red supergiants that are nearing the supernova stage; according to the original article version, a supernova of Betelgeuse may not occur for another million years. Generally, many scientific (and pseudoscientific) predictions imply that "something" of significance may be at an increased likelihood of occurring in 2012, but that it will likely not be the end of the world and may simply represent a self-fulfilling prophecy. ~AH1^(TCU) 23:48, 26 January 2011 (UTC)

Of course if Betelgeuse does go supernova, it will do so some time in the late Middle Ages, and the world did not end then. As far as I know, I wasn't actually here at the time. 148.197.121.205 (talk) 14:30, 28 January 2011 (UTC)

the lower dendrites

in a neuron, there are the upper (receiving) dendrites. and there are the lower and smaller-in-amount (giving) dendrites.

i know this is not the acceptable names for this parts (upper, and lower), so what is the right way to call these so-called "lower dendrites"...?

thanks and blessings. —Preceding unsigned comment added by 109.65.14.202 (talk) 01:35, 24 January 2011 (UTC)

Have you read our Neuron article? Perhaps the word you're looking for is "axon". –Henning Makholm (talk) 01:53, 24 January 2011 (UTC)

Yes, almost certainly "axon". Looie496 (talk) 02:53, 24 January 2011 (UTC)

hey, i have read the article but i understand that the Axon is a fiber which kinda' connect the "upper" dendrite, to the "lower" one... what you guys say is that THE "LOWER" ONE IS THE AXON...

i i understand right,

thanks. —Preceding unsigned comment added by 109.65.14.202 (talk) 12:10, 24 January 2011 (UTC)

There are various neuron structure types, but the most common one taught is the pyramidal neuron: this has a single axon (the signal sender) projecting from one side of the soma (cell body) with a "tree" of many dendrites (signal receivers) projecting from the other side. The axon itself has a number of axon terminals that sort of resemble dendrites, but are structurally different.

So it looks like you are confusing the axon terminals (signal senders) with actual dendrites (receivers) that are on opposite ends of the (pyramidal) neuron. SamuelRiv (talk) 18:32, 24 January 2011 (UTC)

c-1 m/s

If I've understood things correctly, no massive object can be accelerated to the speed of light because, as you approach c, relativistic effects increase the energy required to accelerate ad infinitum.

So, what would happen exactly if I took a 1-kilogram dumbbell moving at c - 1 m/s and exerted a force of one newton on it? At what speed would it be travelling after this?

Thanks. Leptictidium (mt) 07:31, 24 January 2011 (UTC)

Your "1 kg" object has a relativistic mass of over 12,000 kilograms, and will accelerate at less than a tenth of a millimeter per second per second, and become heavier all the while. Someguy1221 (talk) 07:41, 24 January 2011 (UTC)

It's actually worse than that. Assuming that you measure the force in your restframe (i.e. in the frame where the dumbbell moves at (c -1)m/s, then the force relates to momentum and velocity as $F={\frac {d}{dt}}p={\frac {d}{dt}}(\gamma mv)$ (here "m" = 1 kg is the invariant or rest mass, and γ is the Lorentz factor). Doing the derivative gives $F=\gamma ^{3}ma$. If you insist on using relativistic mass (which is ugly because coordinate-dependent), then that is $F=\gamma ^{2}m_{\mathrm {rel} }a$. You forgot to take into account that relativistic mass also changes when the dumbbell is accelerated. At v- (c-1)m/s, $\gamma =12243$, hence a= 5.45⋅10⁻¹³ m/s².--Wrongfilter (talk) 11:10, 24 January 2011 (UTC)

So what if I applied that very same force to an object with relativistic mass = 1 kg? --Leptictidium (mt) 11:17, 24 January 2011 (UTC)

Well, I gave the equation. You've absorbed one factor of γ into your relativistic mass (rest mass is 1/γ kg), hence the acceleration is larger by that factor, i.e. 6.7⋅10⁻⁹. --Wrongfilter (talk) 11:24, 24 January 2011 (UTC)

Then you'd get closer to the speed of light a little quicker, but the energy (AKA weight/mass) you are expending will transfer to your object making it heavier, and the acceleration will slow down. Objects getting heavier as they reach the speed of light isn't from magic. The energy contained in their velocity has mass, and that is what makes them heavier, and since they are heavier, you need even more energy to speed them up, but that extra energy makes then even heavier than before, etc, etc. till you have a runaway effect. Ariel. (talk) 11:30, 24 January 2011 (UTC)

You mean "more massive" not heavier. Cuddlyable3 (talk) 12:03, 24 January 2011 (UTC)

I do, but I will often say heavier so people understand it's not some sort of weird relativity thing, but that it really does weigh more (if you were to bring it near a planet or something). Ariel. (talk) 12:10, 24 January 2011 (UTC)

It is a "weird" relativity thing anyway, isn't it? And even in that pseudo-Newtonian understanding of relativity, it's not weight that matters here, but inertia. --Wrongfilter (talk) 12:22, 24 January 2011 (UTC)

By weird I mean some kind of mathematical thing used for calculations but not "real". And no one has ever found a difference between inertia and weight (aka gravitational mass) - that equivalence is a cornerstone of relativity. Ariel. (talk) 12:32, 24 January 2011 (UTC)

Phenomenologically, they are different effects, even if in general relativity they can be unified. --Wrongfilter (talk) 12:55, 24 January 2011 (UTC)

It doesn't really make any difference if the mass is 1kg or 1/12g (which it would need to be to have a relativistic mass of 1kg), you just multiply or divide the final answer by 12,000. --Tango (talk) 19:46, 24 January 2011 (UTC)

Would it exert gravity as if it weighed 12,000 kg? —Preceding unsigned comment added by 205.193.96.10 (talk) 17:21, 24 January 2011 (UTC)

Tricky. That would seem to make gravity frame-dependent. In a comoving frame, the dumbbell clearly exerts gravity as fits a 1kg rest mass. With the dumbbell zooming past, you would feel a time-dependent gravitational field. Taking into account the required coordinate transformations gravity might be pretty strong for a short time. There certainly is no reference frame where gravity acts like that created by a stationary dumbbell of 12,000 kg. --Wrongfilter (talk) 17:56, 24 January 2011 (UTC)

In its own reference frame, the dumbbell still weighs only 1 kg and exerts only one kg-worth of gravity on its surrounding objects. Also, it is still accelerating at 1 m/s by its own measurements. Only the observer in a different reference frame sees the situation differently. Dbfirs 19:32, 24 January 2011 (UTC)

The force is a vector, so you have to specify in which reference frame the (3-)force is given. That's why I wrote "Assuming that you measure the force in your restframe". If the force is measured in the rest frame of the dumbbell instead of that of the observer, then things are a little different and you get a couple of factors γ in different places. --Wrongfilter (talk) 19:53, 24 January 2011 (UTC)

Also, the 3-force components are three members of the 4-force which also include power as a fourth member which means that the force will have different magnitudes depending on the observer. Dauto (talk) 20:35, 24 January 2011 (UTC)

So, in its own reference frame, the dumbbell has accelerated to c, Dbfirs? Leptictidium (mt) 20:06, 24 January 2011 (UTC)

In its own reference frame the dumbbell is always at rest (duh). Dauto (talk) 20:23, 24 January 2011 (UTC)

Yes, the dumbbell can measure only its speed relative to something else, but in its own reference a measured force of one Newton will produce a continuous acceleration of 1 m/s/s using the length and time of that reference frame. Adding an increase of 1 m/s in speed to a speed of "c-1" in the other direction does not give a speed of "c" by the relativistic addition law of speeds. As others explain, the interpretation in other frames depends on how the observations are taken. Dbfirs 13:05, 25 January 2011 (UTC)

Even in Newtonian mechanics, you need to specify a force and a duration of time to estimate a velocity-change. Special relativity is very nice, because duration of time will also be Lorentz-contracted. So if you exert a 1 newton force for one second, you need to specify in which reference frame you have exerted that force. If you press on the object for 1 second, measured in the "stationary" (laboratory) coordinate frame, the effective force experienced by the moving object will be much more instantaneous; and the momentum transferred will be much smaller. The coordinates all work out using a lorentz transform and you just have to keep your coordinates straight. Convenient, eh? The paradoxes of paradoxical nature of measurements in different coordinate systems, with high velocities relative to each other, have been thoroughly explored: see Ladder paradox for a start. Nimur (talk) 21:10, 24 January 2011 (UTC)

Herpes virus

I was wondering how long the herpes virus stays around outside the body. I had a customer touch her lip and touch some of my book at work she was looking through. Now I am afraid to even touch the books. I can't really spray lysol on the books or clean them. So what else can I do? How long will the virus stay around? —Preceding unsigned comment added by 76.169.33.234 (talk) 08:12, 24 January 2011 (UTC)

Our article on Herpes simplex says "Herpes is contracted through direct contact with an active lesion or body fluid of an infected person." It seems you really need skin to skin contact for transmission. Get back to those books! HiLo48 (talk) 08:34, 24 January 2011 (UTC)

This says that under ideal conditions (temperature and humidity), it can survive a couple of hours. Ariel. (talk) 09:07, 24 January 2011 (UTC)

Inside a mirrored sphere

If you found yourself inside a mirrored sphere with a diameter of twice your eye level height from the ground and a source of light above your head, what would you see around you? How would the view change if you moved around? TheFutureAwaits (talk) 09:18, 24 January 2011 (UTC)

Mostly you would see yourself, but upside down. Your own body will block most of the reflections from other parts of the sphere. Your body will also absorb light, so it won't get constantly brighter and brighter (plus no mirror reflects all light, so some is lost). It looks like Japanese TV actually tried it but someone took down the video. Supposing you had a perfect point source light and a perfect mirror, and you placed the light in the exact center of the sphere, then you would see almost nothing because except for the light reflecting off of the top of your head, all of it would reflect right back into the light and none would reach you. Even if the light was not in the center, all of it would end up focused on one spot, lighting that spot but nothing around it. Just how perfect a mirror and light are we talking about here? Are you making use of reflected light from your clothing? It would be cool to model this with PovRay and it's pretty likely someone already did. Ariel. (talk) 09:47, 24 January 2011 (UTC)

We had a big parabolic mirror at school, over a meter in diameter, and I used to love starting into that thing. It had a tiny spot to mark the very center, if you walked towards the mirror with your eye right in line with the spot eventually, when your eye was right at the focal point, the whole mirror would be a reflection of just your pupil, it was really cool! Obviously even slight imperfections in the mirror make this effect not "flawless" but it was certainly impressive enough for me:) Vespine (talk) 00:52, 25 January 2011 (UTC)

Your eye was twice as far from the mirror as the focal point. 71.101.41.73 (talk) 09:11, 26 January 2011 (UTC)

Yeah good pick up, incorrect assumption on my part. i hadn't actually thought it through completely. Vespine (talk) 01:17, 27 January 2011 (UTC)

Actually, you will only appear upside down (and left/right reversed) if the center of the sphere is in front of your eye. If the center of the sphere is behind your head, you will appear right-side up. And if your pupil is in the exact center of the sphere, all you will see is the blackness reflected from your pupil. Red Act (talk) 00:49, 28 January 2011 (UTC)

Parts of a horses skull

I would like to know and cannot find out the name of the small holes on a horses skull on both sides just above the nasal bone and below the eye socket and what is it's use —Preceding unsigned comment added by 216.218.29.249 (talk) 16:31, 24 January 2011 (UTC)

The word for this type of hole in other animals seems to be "temporal fenestra" [5], but our skull article also says "Mammals, which are synapsids, possess no fenestral openings in the skull". SemanticMantis (talk) 16:44, 24 January 2011 (UTC)

(edit conflict)I believe these are some type of fenestra, See Skull. Mammals characteristicly seem to have these fenestra, located under the eye sockets. You can see small ones on the chimpanzee skull, and they really stand out on the bulldog skull. I am pretty sure that most of the fenestra act as conduits for nerves and blood vessels to get through the skull and other bones that have them, our article on fenestra is woefully weak in this regard, and I am remembering back to the last anatomy class I had, sometime in the fall of 1994. Perhaps someone with more anatomy knowledge can fill in the gaps. Post EC answer after SemanticMantis: I don't think these are temporal fenestra, the article synapsid has a picture which shows the temporal fenestra at the back of the skull, between the postorbital and squamous bones, no where near the nasal bone. If you look at the other skulls of mammals, you can see a fenestra of various sizes in the location described by the OP. This isn't the temporal fenestra. --Jayron32 16:49, 24 January 2011 (UTC)

Correct myself. These are not fenestra, these are foramen, see File:Gray190.png where the human analog to these holes is called the "infraorbital foramen", and according to foramen, serve exactly the purpose I describe above. I knew it was an "f" word, and got my foramens and fenestra confused. --Jayron32 16:53, 24 January 2011 (UTC)

Addendum to the correction: We even have an article titled Infraorbital foramen which describes the exact purpose of those holes. --Jayron32 16:54, 24 January 2011 (UTC)

Also, fenestra is singular; the plural is fenestrae. Not a big deal, but just kind of obvious if you speak Italian, where fenestra is the everyday word for "window". --Trovatore (talk) 00:22, 25 January 2011 (UTC)

(Oh, actually I think it's finestra now that I think about it.) --Trovatore (talk) 00:23, 25 January 2011 (UTC)

Which is of course also the origin of one of my favorite words: Defenestration. Vespine (talk) 00:45, 25 January 2011 (UTC)

Eye bone

What is the name of the bone in the eye of some reptiles? I can't find the article anywhere. Here are some examples: It is a torus shape with radial lines. -Craig Pemberton 17:10, 24 January 2011 (UTC)

• 
• 
• 
• 

Sclerotic ring. LANTZY^TALK 17:20, 24 January 2011 (UTC)

Thank you!-Craig Pemberton 17:34, 24 January 2011 (UTC)

Registering a new rock

My Dad found a rock which he sent to an organization (which I'm trying to find) and they told him it was indeed a newfound rock and should be registered with them. He has died since and I don't know if he registered it or not. What is the organization I go to, and how do I go about it (will ask them if necessary)? Thanks —Preceding unsigned comment added by 4.240.78.111 (talk) 18:22, 24 January 2011 (UTC)

Your IP address geolocates to New Mexico, so the organization could either be the Mineralogical Society of America or the CNMNC (part of the International Mineralogical Association). Physchim62 (talk) 19:08, 24 January 2011 (UTC)

Pure proteins

I'm looking for suggestions for proteins that can be obtained in a relatively pure form (maybe >95%). I'm look for things that I could purchase for research in quantities of about a gram for a reasonable price, say < US$200. I need to identify as many as possible. I'm not asking for specific commercial recommendations or prices, just names of proteins.

So far I've found:

• BSA
• beta-casein
• Lysozyme
• Hemoglobin
• gamma-globulin

Thanks for the suggestions! ike9898 (talk) 20:42, 24 January 2011 (UTC)

Even suggestions on how to search for such things would be helpful. ike9898 (talk) 21:18, 24 January 2011 (UTC)

Pepsin is a cheap enzyme, cheap enough to be used in UK high schools 25 years ago to demonstrate enzyme kinetics. I just checked the price for pharmaceutical grade from a supplier who's known not to be the cheapest, and it's less than €1/g. Physchim62 (talk) 21:29, 24 January 2011 (UTC)

Do you have any requirements other than price, like size, function, species, etc.? I'm not a biochemist so I don't know the specialty-companies in this arena, but one way to search is to pick a chemical/biochemical company and search its catalog. For example, I just poked the Sigma-Aldrich online catalog and found a whole Proteins and Derivatives section. In it are several you did not list. DMacks (talk) 21:34, 24 January 2011 (UTC)

Actually, what I need is variety. I want to study the relationship between various protein characteristics (MW, amino acid composition, secondary structure, ...) and a their activity in a particular practical application I'm interested in. I need them to be soluble under mild, aqueous conditions (keratin and zein won't work). I think ideally I want plain-vanilla proteins, rather than things like glycoproteins, but I'll take what I can get. Thanks! ike9898 (talk) 21:46, 24 January 2011 (UTC)

If you want a big enzyme, then I know you can buy rubisco from spinach. Might you be able to hint at the "particular practical application" that you're interested in? It might help us think of more suitable proteins. SmartSE (talk) 22:26, 24 January 2011 (UTC)

Check over the contact lens cleaning tablets - depending on the store you go to, you might find a variety. Pancreatin and subtilisin are the two most common, I think. Wnt (talk) 20:53, 25 January 2011 (UTC)

Hypothetical question

If all of the illnesses in the world were cure, would human beings still die naturally? --Thanks, Hadseys 22:09, 24 January 2011 (UTC)

It's kind of begging the question. If you define illness as "something that can go wrong with us" then the answer is obviously no. However, these days if you don't die of a specific thing like heat attack or cancer or stroke, then you will still eventually die from the very fact that your chromosomes don't copy perfectly when your cells split. You might find Telomeres interesting. However, you don't actually "die" of this, you die of liver failure (sure you can replace a liver, but not so easy to replace a spine or a brain) or something else which is caused by this, so eventually, excessive telomere shortening might be defined as an illness. Vespine (talk) 23:19, 24 January 2011 (UTC)

Actually our Death by natural causes article also seems to address your question. Vespine (talk) 23:24, 24 January 2011 (UTC)

Even if you somehow could evade death and live forever (assume that the universe will go on forever without a heat death), you would still effectively die, because there are only a finite number of states your brain can be in. You cannot go on to store more and more information in the brain, at some point you have to erase old information to make room for new information. Since you can only be in one of a finite number of states, you will eventually return to some old state you were previously in, meaning that you will have erased all of the information that you had accumulated since you were in that state the last time. Count Iblis (talk) 01:33, 25 January 2011 (UTC)

I'm struggling to reconcile your interpretation with the actual definition of death.. As far as I can tell death has nothing to do with what information is in your brain, i might have forgotten everything that happened to me before the age of 5 but by no rational definition am I "dead". Vespine (talk) 02:35, 25 January 2011 (UTC)

I suppose a philosopher might posit that your 4 year old self is now dead, but that's pretty tortured.

Also, I think the "finite number of states" is a red herring, I wouldn't be surprised if you could survive all the way to the heat death without duplicating states. APL (talk) 04:11, 25 January 2011 (UTC)

lol yes, by adding rational i was attempting to exclude the philosophical "out", maybe I should have said airy fairy ;) Vespine (talk) 05:42, 25 January 2011 (UTC)

Well, the heat death or the big rip would imply mortality, so you have to assume that this doesn't happen and that the universe goes on forever. Then we apply a similar reasoning as in the Poincare recurrence theorem. Count Iblis (talk) 13:44, 25 January 2011 (UTC)

The traditional Four Horsemen of the Apocalypse idea divides up the ways of dying into oppression, war, famine, and pestilence. (I suppose crime, terrorism, ignorance, and suicide or old age also fit roughly into these categories) Curing all diseases (including old age and mental diseases) would cut off one of the exits, but the question is whether the others are always defined by the reader as "natural death". Wnt (talk) 05:14, 25 January 2011 (UTC)

How broadly do you define 'all illnesses' and 'natural causes'? Do accidental deaths count? (Car accidents, falls, drownings, and the like?) The all-ages all-causes rate of accidental deaths in the United States in 1996 was 35 per 100,000 per year: about 0.03%. Assuming that value remains constant, one would have a half-life of about two thousand years. In practice, that risk peaks twice — a bump in late adolescence (ages 15-24) and very sharply in old age (65 and up). So the question is, will our otherwise-immortal humans have the reflexes and durability of early middle age, or will they be frail and fragile geriatric patients? The over-75 risk is actually about four times the average, at 140 per 100,000. (Those numbers also don't include homicides, ranging from the individual crime of passion to the global thermonuclear war.) TenOfAllTrades(talk) 14:34, 25 January 2011 (UTC)

even without diseases, which I'll take as viral, bacterial and parasitic infections for the sake of simplicity, the human body has a certain lifespan. The article on Telomeres explains rather well, but to put it in layman's terms: every time DNA is replicated not all of it can be duplicated, because it is copied at an "angle" (a gross oversimplification of 5' to 3' copying for the sake of a simple explanation). To prevent this there are protective "caps" on the end of chromosomes, these caps become shorter over time, and this is thought to be a reason for biological aging. Lengthening these caps can result in cancer, and all known 'immortal' cell lines are derived from a cancerous growth of some form. 65.29.47.55 (talk) 03:45, 26 January 2011 (UTC)

See biological immortality. Humans do not seem to naturally posess this ability. ~AH1^(TCU) 23:19, 26 January 2011 (UTC)

It is very true that transgenic human beings might well be immortal, however eliminating diseases does not automatically confer biological immortality and experiments with telomere lengthening in animals have usually lead to cancer. It's uncertain if a complex mammalian organism could ever achieve biological immortality without tumor formation. 65.29.47.55 (talk) 09:07, 27 January 2011 (UTC)

Taraxacum

The Taraxacum article says people eat them, but does not say if preparation is required. Can people just eat them raw? 82.44.55.25 (talk) 23:20, 24 January 2011 (UTC)

In fact it does: under 'Classification: Cultivars' it mentions some varieties that are suitable for blanching, and others mild enough (in taste) not to require it, which implies that they can be eaten raw as salad leaves. Further on under 'Properties and Uses: Culinary use' it mentions boiling or eating raw the leaves and buds, and also preparation of the petals for dandelion wine and the roots for dandelion coffee (or tea), with links to more detailed articles on those topics. 87.81.230.195 (talk) 23:47, 24 January 2011 (UTC)

The leaves of the young (pre-flowering) plants are very widely used as a salad green. Once they get more mature, they are too bitter. The flowers are also very bitter. Looie496 (talk) 02:45, 25 January 2011 (UTC)

I eat them every spring, in salad. You pick the leaves early on before the flower blooms or and just make salad with a vinegar and oil dressing, preferably with slices of warm cooked potatoes, because the leaves are somewhat hard and the heat from the potatoes softens them. TomorrowTime (talk) 20:34, 25 January 2011 (UTC)

Just a warning: the flower (yellow type) tastes awful and has no resemblence to the nectar taste. ~AH1^(TCU) 22:47, 26 January 2011 (UTC)

Moon

If you look at pictures such as this or this, you can still see some light on the back of the moon. This light is reflected from Earth, correct? And if not, where from? --T H F S W (T · C · E) 23:59, 24 January 2011 (UTC)

Yes, it's earthlight. HiLo48 (talk) 00:10, 25 January 2011 (UTC)

Starlight would also be a small component of any light reflected by the moon that does not originate from the Sun. WikiDao ☯ 00:15, 25 January 2011 (UTC)

As I have pointed out on this desk in another post a few weeks ago, the image File:Lunar libration with phase2.gif is a synthetic image stitched together from many thousand individual photographs from the Clementine (spacecraft). The photos were stitched into a moon image, and then accurately animated to mimic the time-lapse behavior as if viewed from Earth. Any "earthshine" in those photos should be considered synthetic. The image meta-data even explains: the moon was rendered with an ambient illumination of 1% intensity of the solar illumination - much brighter and more isotropic than actual earthshine. Earthshine is a real phenomenon, though, and you can easily see it tonight, even with the naked eye, if you look beyond the sunlit portion toward the lunar limb. This evening, the lunar sunset will be visible from the Apollo 17 landing site. If you photograph the moon, you can compare it to the synthetic image and see for yourself - the luminosity contrast is much greater than 100 to 1. Our article on Apparent Magnitude lists a full- to new-moon contrast ratio of 10 magnitudes - about 1000x - but apparent magnitude is measured in nonlinear units of luminous intensity, designed to match human perceptions of brightness. If you can manually set exposure on your camera, you can measure the actual luminous intensity difference. Have a look at the exposure chart in this guide to lunar photography. Nimur (talk) 00:16, 25 January 2011 (UTC)

Let's note also that File:Luna Nuova.jpg is no better. Such a view of the moon (no sunlit portion, dark sky) is effectively impossible, as the new moon only occurs when the sun and moon are aligned from Earth. We note that the image is an edit of this one, which displays no earthshine. As such, it's just a darkening of a picture of a full moon. — Lomn 14:09, 25 January 2011 (UTC)

The ballad of Sir Patrick Spens contains the lines (with slight variants in different versions) "Late late yestreen I saw the new moone, / Wi the auld moone in hir arme, / And I feir, I feir, my deir master, / That we will cum to harm." Apparently, "the new moon with the old moon in her arm(s)" was a common idiom referring to a thin (waxing) crescent moon with the rest of the disk dimly visible by earthshine. I've seen it many times myself and only rarely come to harm thereafter. Deor (talk) 04:17, 25 January 2011 (UTC)

You might like to read planetshine which is a little more complete than earthlight, I fancy there may be a case to merge the articles. Richard Avery (talk) 07:23, 25 January 2011 (UTC)

Light also reaches the Moon from Earth during a lunar eclipse, but the light is refracted through Earth's atmosphere rather than reflected. ~AH1^(TCU) 22:44, 26 January 2011 (UTC)

January 25

minerls

How is a mineral inoganic but yet found in natere?♠ — Preceding unsigned comment added by Dwight peru (talk • contribs) 01:52, 25 January 2011 (UTC)

There is no contradiction, maybe your difficulty is in the meanings of the words. Organic in this definition usually means either Organic compound or Organic matter while the definition of Nature can be found there. Vespine (talk) 02:15, 25 January 2011 (UTC)

To be a bit more precise, in the nomenclature of chemistry, "organic" means that it contains carbon as the key element. Inorganic means carbon is not a key component. Thus a "Mineral Acid" (a slightly archaic term) is an acid without carbon as a key component of its stoichiometry. Hydrochloric Acid (HCl) exists in nature but is a mineral acid based on the fact it contains no carbon. 65.29.47.55 (talk) 08:59, 25 January 2011 (UTC)

Furthermore, the "natural" sense of the word "organic" doesn't just mean "found in nature". Uranium is found in nature, after all, but you won't see "with 99.28% natural ²³⁸U!" on your granola bars anytime soon. --Sean 14:16, 25 January 2011 (UTC)

99.28% 238 would be a poor granola bar but an excellent kinetic penetrator for an antitank shell!

Organic food#Meaning and origin of the term states:

In 1939, Lord Northbourne coined the term organic farming in his book Look to the Land (1940), out of his conception of "the farm as organism," to describe a holistic, ecologically-balanced approach to farming—in contrast to what he called chemical farming, which relied on "imported fertility" and "cannot be self-sufficient nor an organic whole." This is different from the scientific use of the term "organic," to refer to a class of molecules that contain carbon, especially those involved in the chemistry of life.

A list of articles related to the various uses of the term organic is at our Organic disambiguation page. -- 119.31.126.68 (talk) 00:31, 26 January 2011 (UTC)

Minerals like calcite, however, can sometimes have an "organic" origin. Any sedimentary rock not considered organic is clastic, though even some new igneous rocks and minerals could have an ultimately organic origin when subducted limestone, coral or the fossil fuel substances return through volcanic activity. ~AH1^(TCU) 22:42, 26 January 2011 (UTC)

Lip cells

Hi. How often do the different layers of lip cells usually replace themselves through cellular division? Is this rate faster or slower than for regular skin epidermis? This is neither homework nor a request for medical/legal advice. Thanks. ~AH1^(TCU) 02:57, 25 January 2011 (UTC)

Epithelial surface cells, in general, will be replaced every 7-10 days. Lips can be divided into keratinized and unkeratinized sections (by the lip wet/dry line) and the unkeratinized (which is contiguous with the lining of the lips and cheeks inside the oral cavity) will be moist, decreasing friction and reducing cell shedding due to mechanical insult. Then again, a quick, sturdy rub of the lips against the teeth will remove cells at a much faster rate than normal -- it's like rubbing a dull knife over your skin. So if you do that 5 times a day every day, which most people do, and then you may bite or pick at the lips, even more cells will be removed. So I'd go for faster rate of superficial layer loss. This is all educated guess-timation, but a derm or dental textbook would likely not take into account the tooth scraping, and it seems as though that should play an overwhelming role. DRosenbach ^{(Talk | Contribs)} 07:00, 25 January 2011 (UTC)

Loss of cabin pressure / oxygen at high altitude flight

I looked at Effects of high altitude on humans, but I have some lingering questions. Obviously losing cabin pressure at high altitude is a problem, but it's my understanding that standard procedure is to descend quickly to a lower altitude. What altitude is that generally? My other question is whether or not this is a substantial problem or not. Obviously it's not beneficial, but humans have been known to survive at 26,000+ feet for hours at a time (mountain climbers of course) and for considerably longer at lesser altitudes. I guess I wonder if emergency oxygen systems are placed out of an abundance of caution, or if there's some other factor that exacerbates the problem when the loss of oxygen is quick... or something similar. Shadowjams (talk) 03:37, 25 January 2011 (UTC)

We have quite good articles on Cabin pressurization and Uncontrolled decompression. Vespine (talk) 03:43, 25 January 2011 (UTC)

Here's a topical answer - "A Qantas airliner carrying 99 passengers from Adelaide to Melbourne was forced rapidly to descend 26,000 feet after a sudden cabin depressurisation this morning... Oxygen masks dropped from the overhead consoles on the Boeing 737-400 as the pilots of flight QF670 announced that they would have to make a rapid descent from a cruising altitude of 36,000 feet to just 10,000 feet." From here. HiLo48 (talk) 03:53, 25 January 2011 (UTC)

Immediately after complete loss of cabin pressure the crew of a civil aircraft will descend quickly to an altitude around 10,000 to 12,000 feet. Trained athletes are capable of considerable exertion at altitudes above 20,000 feet, but the passengers of an airline aircraft are not trained athletes and it must be assumed some of them will be particularly vulnerable to inadequate pressure.

Supplemental oxygen systems are provided in high-flying aircraft to provide support to the passengers during the descent from cruise altitude (typically 30,000 to 45,000 feet) down to below 20,000 feet. Pressurised propeller-driven aircraft, and other aircraft that don't fly higher than 20,000 feet, usually don't have supplemental oxygen systems for the passengers because they can descend to 12,000 feet quickly enough. All aircraft that fly above 10,000 feet have supplemental oxygen systems for the pilots. Dolphin (t) 04:01, 25 January 2011 (UTC)

It's interesting that the article said it took a full 10 minutes to go from 36,000 to 10,000 feet. That's a surprisingly long time. --Sean 14:21, 25 January 2011 (UTC)

Thank you all. I especially found the Time of useful consciousness article helpful, although again, I'm surprised that the TUC limit at Everest style heights is on the order of minutes, when clearly some individuals are able to withstand it for longer. I suppose it only highlights how remarkable a feat that is. Shadowjams (talk) 04:41, 25 January 2011 (UTC)

It does indeed, though it should be added that at such altitudes humans do suffer from effects of altitude, it is common practice for teams making a bid for very high peaks to carry and use oxygen, though at partial pressures not as their only breathing gas. Mishandling of such cylinders due to the effects of oxygen deprivation have been implicated in peak casualties and near-casualties. 65.29.47.55 (talk) 09:03, 25 January 2011 (UTC)

The TUC will be for someone that has not acclimatised. People climbing Everest will do so over several days and will be starting from a pretty high altitude (Everest Base Camp is at around 18,000ft) where they will have spent days, if not weeks, acclimatising before they even start their ascent. That makes a big difference compared with rapid decompression on a malfunctioning aeroplane. The body's abilty to acclimatise to high altitude is pretty remarkable, indeed. --Tango (talk) 23:49, 25 January 2011 (UTC)

As for "surprisingly long time", descending 2600 feet per minute at a forward speed of 800 km/h corresponds to a downwards slope of about 1:19. It appears believable that the 737's lift-to-drag ratio is in about that range, so that would be consistent with the pilots reducing thrust to idle and letting the plane glide downwards at constant speed. Going down faster than this would require some additional drag to avoid exceeding the maximal rated airspeed. It is probably SOP not to deploy spoilers in this situation unless particularly necessary. In the event of sudden trouble (and remember there's a problem of unknown nature unfolding somewhere on the aircraft) it would be preferable not to start dealing with it from a deliberate high-drag/low-lift configuration. –Henning Makholm (talk) 15:35, 25 January 2011 (UTC)

The problem is increasingly difficult to solve as the airplane's cruising altitude increases. The highest-flying airliner is (was) Concorde which cruised around 60,000 feet, almost twice as high as other types of jet airliner of the day. (Time of useful consciousness at 60,000 feet is not long enough for passengers to react and don their supplemental oxygen masks.) The maximum credible cause of sudden decompression was loss of one complete window in the passenger compartment. It was possible for Concorde's engines to supply sufficient compressed air into the cabin to maintain cabin pressure at a survivable level during the deceleration and descent to 10,000 feet, even with one complete passenger window missing and air pouring out the resulting hole. However, it necessitated smaller windows in the passenger cabin than windows in other types of jet airliner of the day. See Concorde#Cabin pressurisation. Dolphin (t) 06:14, 26 January 2011 (UTC)

Exoatmospheric Warefare

Hypothetically, would an airtight bulkhead be of any use when applied to an exoatmospheric vessel intended for warefare? Would the bulkhead be at all effective in minimising the loss of atmosphere due to explosive decompression, like what could result from an explosive ordinance strike?

Conditions:

1. The vessel has a large internal volume, approximately seven million cubic meters.
2. The bulkheads doors are normally in the open position, they take 3 seconds to seal.
3. The doors are approximately 14 square meters in area.

--Plasmic Physics (talk) 10:16, 27 January 2011 (UTC)

Independence Day

Hello.

  I refer to the 1996 film Independence Day, in which during a missile tipped with a nuclear warhead is used to destroy the alien mothership. The alien mothership is said to be 550 kilometers long, with a mass one-quarter that of the Moon; so how can a single nuclear warhead completely destroy such a huge vessel? I'm quite familiar with the scene where anti-ship Harpoon missiles were fired at a 15mi-wide destroyer ship floating in the air, but obliterating a 550km-long mothership with one single nuclear warhead would require new spans of imagination, as I estimate that the equivalent of around 14,600,000,000 tons of TNT would be needed to blow up something that big. Even the world's most powerful nuclear bomb ever made, the Soviet Tsar Bomba, had a maximum yield of 100,000,000 tons. So atleast 146 Tsar Bomba warheads would be needed to obliterate a 550km-long alien mothership. Are my calculations correct?

  Thanks, everyone. Rocketshiporion♫ 03:54, 25 January 2011 (UTC)

Maybe they hit the armory. APL (talk) 04:06, 25 January 2011 (UTC)

Could you share your calculations? Taking your numbers (which sound familiar, so I'll assume they're correct), the gravitational binding energy of the ship (which I further assume, incorrectly, to be spherical) is on the order of 9 x 10³¹ joules, or about 2 x 10¹⁶ megatons of TNT. You could certainly destroy a ship with less, but I'm assuming you're going for the "explodes into a million tiny pieces and leaves no large wreckage" level of destruction that was seen in the movie, which although it leaves Earth being pelted with a considerable amount of debris, is better than being pelted with a moon-sized spaceship. I'm willing to chalk up the epicness of that destruction to secondary explosions - maybe there was antimatter onboard. Someguy1221 (talk) 04:12, 25 January 2011 (UTC)

This really counts as an entertainment question rather than a science question - there's no doubt that such a ship could blow up, if designed in a highly unstable way. In the movie, as I recall, the big saucers over the cities could be blown up with a single 9/11 style attack on their main weapon, and the main ship was attacked with a bomb brought near to a central reactor. Wnt (talk) 04:24, 25 January 2011 (UTC)

I thought the big saucers over the cities were destroyed because the "9/11 style attack" damaged their one and only engine? (Or at least, their one and only glowing bit.) and they fell down onto the city. Not really the best strategy on the part of the saucers. Very intimidating, but it seems like an engines-on hover like that leaves them at their most vulnerable. APL (talk) 06:14, 25 January 2011 (UTC)

gravitational binding energy is not the right way to measure this since no ship would be held together this way. But lets ignore that. The ship massed 1/4 of earth's moon, i.e. 1.836×10^22 kg. The Tsar Bomba has an energy of 420PJ. Put those together and you can accelerate the ship to the amazing velocity of 6.8 mm/s! So yah, a nuclear bomb would do absolutely nothing to it. It would barely be able to move it much less destroy it. Ariel. (talk) 04:37, 25 January 2011 (UTC)

I used GBE not because it was what held the ship together, but because the level of destruction showed that GBE was probably exceeded. Someguy1221 (talk) 04:43, 25 January 2011 (UTC)

The writers and creative directors of Independence Day probably didn't worry too much about the technical merits of the plot. So, suspension of disbelief is called for. But anyway - the energy of explosion is not only from the bomb. Consider another issue: overpressure. The mothership was floating in space; its material construction (or energy beam shielding or whatever) had to keep the air inside in, across a pressure differential with the vacuum of space. A slight increase in the pressure (such as we'd expect, at least locally, when the bomb explodes) would increase the internal pressure, presumably above the yield strength of the ship's walls and superstructure, and boom. All that air - which was not gravitationally bound - serves as an energy reservoir of pressure-volume work. One slight disruption breaks the external containment, and boom. This is one reason why space combat is a very bad idea. You don't need to obliterate a ship - you just have to pop its pressure hull like a balloon. Nimur (talk) 05:31, 25 January 2011 (UTC)

of all the myriad issues with the rigors of science and Independence Day I find the question of how an off-the-shelf apple computer could hack an alien mainframe that might not even use binary logic far more pressing... however it is noted well above and I concur that it has been proven in real-life naval combat that a single blow to a vital section can destroy a ship, assuming an alien energy reactor was poorly designed in such a way it might release energy explosively if tampered with, the real cause of destruction would be the xenos own personal Chernobyl happening in the middle of the ship, not the bomb itself. 65.29.47.55 (talk) 09:07, 25 January 2011 (UTC)

The most unlikely part of that film was the RAF officers saying "Thank God for the Americans" - "It's the Americans - take cover!" is much more likely ;-) Alansplodge (talk) 09:56, 25 January 2011 (UTC)

IMO, destroying a 550km-long spaceship (really more like an artificial moon, given its sheer size and mass) with a single nuclear warhead would be equivalent in scale to blowing up an aircraft-carrier with a single hand-grenade. A well-aimed thermite hand-grenade tossed into one of the jet fuel reserves on an aircraft-carrier would cause the entire ship to explode, but the hull would still mostly be in one piece - there's still be a pretty large wreck. As for my calculations, they are quite crude. Using the Little Boy, which had a blast radius of around 3km, as a yardstick, I calculated as follows.

 3km blast radius - 20kT yield, hence 275km / 3km = 91.6666666667 and 20kT * 91.6666666667^3 = 15,405,092.592kT
 for simplicity (albeit not accuracy) I rounded it off to 20kT * 90^3 ≈ 14,600,000kT

Rocketshiporion♫ 11:31, 25 January 2011 (UTC)

A ship of that size and mass would have a density of about 65 times that of the Moon (and that's assuming the ship is spherical, any other shape would increase the density further). That's denser than the core of the sun! I don't know of any was of constructing a space ship that would give such a high density, so we must assume it is something completely beyond our science. In that case, we cannot predict how it would respond to a nuke. --Tango (talk) 00:07, 26 January 2011 (UTC)

Energy as a measure of damage?

Have there been any studies on how the kinetic energy of a bullet or the thermal energy of an explosive device relates to the number of shots or blasts it takes to kill a person or destroy a vehicle, if accuracy is held constant? NeonMerlin 04:22, 25 January 2011 (UTC)

You'll have to define "destroy". Or even kill. News reports demonstrate a properly aimed Q-tip can kill a man given the right circumstances. Now, as for vehicles, I'm certain you would clasify "hitting a tank so hard the turret comes off" as destroy, but what about simply taking the treads off the wheels? Or what about a weapon that burns a tiny hole through the armor and then incinerates everyone inside? You'd have to not only define destruction, but also hold constant the way the weapon works. Someguy1221 (talk) 04:38, 25 January 2011 (UTC)

You may find Impact depth interesting as it gives a direct relationship. Ariel. (talk) 04:43, 25 January 2011 (UTC)

Possibly the science used to answer this question would be Terminal ballistics. Vespine (talk) 05:37, 25 January 2011 (UTC)

Absolutely yes. Conservation of energy is widely used in the study of weaponry, in both design and operation. If you peruse our various articles on military firearms and heavy artillery, you'll see the term muzzle energy pop up very often. This energy term has huge impact on the stopping power of a handheld firearm, and on the damage of an artillery, cannon, or other heavy weapon; energy can be a more useful parameter than muzzle velocity because it also accounts for the mass of the projectile. Downrange energy is a little harder to be precise about, because it depends on how far down range your projectile ends up; how much air resistance, and the trajectory it took. Have a start at our ballistics article, and our terminal ballistics article, and let us know if you need help finding anything more specific. Nimur (talk) 05:38, 25 January 2011 (UTC)

h (home depot)

does home depot have a basement — Preceding unsigned comment added by Tommy35750 (talk • contribs) 04:27, 25 January 2011 (UTC)

The one near me doesn't. Unless you find a home depot with a second story, it's pretty safe to assume it doesn't have a basement. Why do you ask? Ariel. (talk) 04:41, 25 January 2011 (UTC)

A basement is generally opposed to the idea of a "big box store" (hmmm, that's an American sense - apparently the UK has two story "big box stores", but having to take everything up an elevator is just the sort of labor that an American big box store is trying to cut out), but I would be surprised if they don't have at least some sort of crawlspace for their plumbing, and a "penthouse" on the roof for some of their HVAC equipment. Wnt (talk) 05:46, 25 January 2011 (UTC)

We are lazy, aren't we? My own observation is that the big box stores (not Walmart, but Target and such) have second floors where land is too expensive to have a profitable one-floor outlet. But then high land prices tend to ruin the whole "low low prices" strategy, which is why they're still pretty rare. Someguy1221 (talk) 09:21, 25 January 2011 (UTC)

They put all the plumbing around the sides, and nothing in the middle. It would be too expensive to make a strong elevated floor (the loading levels are much higher than in a residence or office) rather than just placing in on grade. And even if they put something in the middle it would just be a buried pipe without a crawlspace. Ariel. (talk) 07:07, 25 January 2011 (UTC)

Home Depot in Manhattan is the lower levels of a large building. I can't remember if anything except the entrance is as high as ground level--just a small space to get to the escalators/elevators, and I think most of the major actual store floorspace is on the lowest below-ground level (at least among those open to the public). It was built into an existing building IIRC, so this is definitely a large store in a multilevel construction, not "expand exoskeleton to fill the land" as typical "big-box". DMacks (talk) 09:28, 25 January 2011 (UTC)

• I think that everyone has missed the OP's question completely. I think they are trying to ask if the Home Depot runs a bargain basement; which is the term for a store which sells damaged/old/out of style items for a main store. In the past, the "bargain basement" used to literally be in the basement of large, multistory downtown department stores; though they eventually got spun off as independent chains for selling remainders from the main store. In the U.S. northeast, prior to the 1990's department store consolidation, many people will remember Filene's Basement, which was spun off from the higher-end Filene's. I take the OP's question to mean "Does the Home Depot maintain any 'bargain basement' stores for selling its damaged/old/remaindered items." I don't know the answer, per se, but it does give us an extra place to search... --Jayron32 15:47, 25 January 2011 (UTC)

what I wanted no is why A does in the concrete not crack. in my basement there are cracks in flour — Preceding unsigned comment added by Tommy35750 (talk • contribs) 21:58, 25 January 2011 (UTC)

If there are cracks in your foundation, you need to contact a business that repairs them or ameliorates their effects. Look up "foundation repair" to find someone to come out and inspect your situation. If you live in an area with a high water table you may also need to install a sump pump to keep your basement dry. Cracked foundation is generally not a good thing. --Jayron32 04:10, 26 January 2011 (UTC)

The Target store nearest me has two full shopping floors. It has a amusing four-lane escalator. The outer lanes are, as usual, for customers, while the center two are fitted to handle shopping carts. PhGustaf (talk) 22:43, 26 January 2011 (UTC)

Genomic DNA in northern blot

Ummm... is it necessary to remove genomic DNA before performing a northern blotty blot blot? --129.215.47.59 (talk) 10:47, 25 January 2011 (UTC)

According to Northern_blot#Procedure - yes. SmartSE (talk) 10:54, 25 January 2011 (UTC)

You probably should consider a more technical how-to forum like this one (there are many others). In general what you would usually like (though it could be different for specialized situations) is a known amount of polyadenylated RNA in each well, pure as the driven snow. If you have genomic DNA mixed in with your samples, for example, who knows how much you're really loading? And of course there is always the dread of RNAse in less-pure preparations (though then again there's also the dread of contaminating the RNA or letting it get chopped up while you're messing with it).

That said, at least in theory, the emphasis on doing Northerns with poly(A) rather than total RNA does impose a certain bias, because who knows if the RNA you're interested in really follows all the standard rules about how RNA is supposed to be processed in the cell? For all you know, for example, the removal of the last intron is a crucial regulatory step for your gene. Wnt (talk) 20:12, 25 January 2011 (UTC)

What comes after Blu-Ray?

There was VHS --> DVD --> HD-DVD --> Blu-Ray. What's after? --70.179.181.251 (talk) 14:08, 25 January 2011 (UTC)

Internet TV? I know we already have it, but it does seem as though the time will come when having a physical copy of something will be a bit pointless. If everywhere was to have a high speed broadband connection then you could hire/buy an electronic film in HD and have it streamed to you as and when you want. (Oh and the HD-DVD --> Blu-Ray isn't quite accurate as both are the same step, it's just that Blu-Ray won the format war, like the VHS over Betamax.) SmartSE (talk) 14:27, 25 January 2011 (UTC)

Blu-Ray#Ongoing_development covers some future directions. --Sean 14:29, 25 January 2011 (UTC)

Smartse is probably correct in that the future is fully digital (i.e. physical-copy-less) media. Music is already going that way. Future advances will go towards speeding delivery methods and improving resolution and quality of digital streaming, but given the trends in other media (cloud computing, MP3 and iTunes, etc.) the days of maintaining a hardcopy of anything are fading. In fact, given the trend towards cloud computing, you may not even have a locally stored copy of your media. You simply buy the rights to play a song/movie/video game and then you have the ability to listen/view/play the media anywhere you want, using any of your connected devices. We're already almost there now, there's just the inertia attached to the old media and attitudes. Give it a few decades, and we'll all be wondering why people in past generations felt the need to keep a personal copy of anything... --Jayron32 15:05, 25 January 2011 (UTC)

Your list conflates physical formats with resolution upgrades. You need to split them. I agree that it's likely that the next physical format won't exist, and it will be internet. But a resolution upgrade is certainly possible, and is likely to be 4K resolution, after that comes Ultra High Definition Television (but given how technology works we may skip 4K and go directly to UHDT). Ariel. (talk) 15:16, 25 January 2011 (UTC)

Stereo blu-rays may be "next". They're not a new media, but they're a reason to buy all your movies again if you're into that. It'll be a hard sell, though. 5-10% of the market is stereo blind, (or stereo-blind enough that they don't care about 3d) and the most of rest aren't going to want it until someone invents an auto-stereo TV that can be seen from any angle.

Personally, I'd like to see movies at a higher frame-rate, but I believe that blu-ray disks could handle that as well.

Blu-ray may be the end for a while. Physical collections of movies may become the domain of a small market of enthusiasts and collectors. That's probably not enough of a market to support a new standard every decade. APL (talk) 15:40, 25 January 2011 (UTC)

I stream high definition TV from the internet via Netflix and "Hulu plus" using a Roku wireless connection box. It is a much more satisfying experience than watching Netflix discs or discs from the library or rental place, since most discs which have circulated a few times have scratches causing the program to skip ahead or back, with some bits utterly unwatchable. Only new CDs seem to play reliably without the need to clean the disc and polish out scratches. The only benefit for physical media right now is the larger selection: Netflix still has far more titles on CD than on Internet. I suppose that in the future one might rent or borrow from the library a video program stored on a solid state memory chip. That would get past the problems of a device trying to read a spinning disc optically through jammy thumbprints and deep scratches. Moving media belong in the scrapheap of technology. Edison (talk) 16:33, 25 January 2011 (UTC)

I would like to suggest that your disk player has a problem. Over the years I have rented literally hundreds of disks from Netflix, both DVDs and Blu-Rays and I have received exactly two that were damaged in any way that had the slightest impact on my viewing experience. (They were both snapped in half by the postal service.) Not once has a scratch caused even the slightest problem for me. Nor have I ever felt the need to "clean" a disk before putting it in my player, because I know from experience that any number of thumbprints will not effect playback.

On the other hand I find that compression artifacts are very noticeable in Netflix's streaming service, especially since they changed it about two years back. And that's if you have as much bandwidth as Netflix is willing to give you. If your network connection has problems that day (For example, if it's a school snowday and your local cable-provider is over-stressed.) then you'll get even worse quality and the skipping and stuttering you're so afraid of.

(I'll grant that my sensitivity to compression artifacts may be because I watch movies through a projector that lights up my entire wall, and not a small computer screen.)

I'm not complaining, I love both halves of Netflix's service, but for movies that are a "visual feast", there's still no substitute for a blu-ray. Or even a DVD if there's no blu-ray available. APL (talk) 17:14, 25 January 2011 (UTC)

Sadly, the problem is scuffs and scratches on the DVD, (as well as sometimes dirt) since 2 DVD players and a computer DVD drive all have problems with the same DVDs. I would rather have compression artifacts I cannot see rather than have the playback stop, the skip back or forward several minutes. Then I try cleaning the disc, with a soft cloth, which usually does not fix the problem. Then I spend some time cleaning the disc with a device sold for that purpose, if I still want to watch it at that point. Sometimes I try reversing back to as close to the scratched sport as I can, but it always takes out part of some scene I would like to watch without all the fiddling around. You might have a more modern or sophisticated player with more error correction. Edison (talk) 01:00, 26 January 2011 (UTC)

Well, OK, I believe you, but I have rented huge number of Netflix disks (In the three digits) and have honestly never had that problem. I pop the disk into my Playstation3 and it works every single time. I mean that literally. This is not an exaggeration. APL (talk) 03:46, 26 January 2011 (UTC)

Maybe the number of my bad experiences stands out in disproportion to its mathematical exactitude, and the good disc experiences fade into the background. Edison (talk) 18:36, 26 January 2011 (UTC)

I think that the rumors of the death of physical media in the way you are predicting are greatly exaggerated. There will always be people who want to hold physical copies of something, if nothing else, to have possession of it once its DRM authentication server gives up the ghost. Titoxd^{(?!? - cool stuff)} 17:17, 25 January 2011 (UTC)

Based on reports that Blu-Ray requires censorship from anyone allowed to mass-produce the disks [6] I would say that it is not actually a storage medium at all, but a publisher with some proprietary format. But it appears that the company is creating some ambiguity on the issue, and I can't say for sure what the full truth is. Wnt (talk) 20:24, 25 January 2011 (UTC)

Note that if you read the linked article carefully, it's only Sony who refused to work with porn. And while Sony may have been a key part of Blu-ray, the Blu-ray group themselves said they would work with anyone. And even before they won the format wars (and everyone else who wasn't part of Blu-ray joined so Sony's influence diminished even more) people were already making Blu-ray porn [7] and there is plenty of porn on Blu-ray porn now [8] (store link, if you are at work and they aren't extremely liberal with what you can do you may want to consider what we're discussing and look at the link name before clicking on it) including of course 3D porn [9] (discussion of a specific title, again think of what we're discussing). On the other hand even while the format wars were ongoing plenty of people mentioned that it didn't really matter much unlike it allegedly was in the Betamax-VHS fight since the porn market was moving on from physical mediums which was what would happen with other movies and shows, and that hasn't died down [10]. Nil Einne (talk) 21:55, 25 January 2011 (UTC)

In fact, the fact the LA porn industry endorsed blu-ray and not HD-DVD was a major deciding factor in the format war. 65.29.47.55 (talk) 01:46, 26 January 2011 (UTC)

I know the Porn-Drives-All-Media has a grain of truth to it, but it can't claim credit this time. Blu-ray's success was almost entirely due to Sony's efforts. Both their strong advertising campaign (Much stronger than the HDDVD one), movies from Sony Pictures were big factors, but most importantly the Playstation3 solved the chicken-egg adoption issue by putting millions of blu-ray players into the homes of people who weren't necessarily looking for a new movie player. APL (talk) 03:58, 26 January 2011 (UTC)

All true I will admit, but the choice by the LA-based porn industry to back blu-ray was a significant coup for the format. If porn decided to back HD-DVD it would have made HD-DVD a potent contender instead of a distant also-ran 65.29.47.55 (talk) 09:10, 27 January 2011 (UTC)

Jupiter," Posibly a furter STAR ?"

I have heard that the core of Jupter is a metalic Hydrygen , posible because of the extreme presure,not posible here on Earth. When our Sun novas and explodes is it posible the core of metalic Hydrgen will ignite and start a new star? ( If you have seen Magneseum burn and the brightness of that, and know the explosive forces of Hydrogen ,with the Sun as a flame or catalist to ignite the metalic hydrogen I wonder if it could become a new Star?" My questioncomes from the artical on "Nova posible from Hydogen" —Preceding unsigned comment added by 71.190.254.93 (talk) 17:15, 25 January 2011 (UTC)

It already happened in 2010. Staecker (talk) 17:27, 25 January 2011 (UTC)

Most planetary scientists do not believe that the pressures and conditions inside Jupiter are anywhere close to sufficient to sustain nuclear fusion - so the short answer is "no." If you're interested, I recommend this article, Formation of Giant Planets and Brown Dwarfs, written by a leading NASA planetary scientist, that explores the practical observational facts that we have collected on the formation of large planets - there are many similarities and differences from small stars. For the slightly less technical reader, here is a 2002 Nature article, Extrasolar planets, by the same author, that discusses Jupiter structure, comparatively to other celestial observations of stars and star-like objects. That article also states that Jupiter is about 13x too small for deuterium fusion to occur. Nimur (talk) 17:37, 25 January 2011 (UTC)

Stars are not on fire. See fusion. --Sean 18:08, 25 January 2011 (UTC)

Our Jupiter article, in the section "Mass", says that Jupiter might ignite if it were 75 times its current mass. Comet Tuttle (talk) 19:08, 25 January 2011 (UTC)

The chemical reaction of magnesium with oxygen, or hydrogen with oxygen, is completely unrelated to proton-proton fusion. What is more surprising is that fusion is actually a very weak energy source, which our article on the Sun compares to the amount of heat generated by a compost heap! What is difficult to grasp is that the Sun is very, very, very big, and all the heat from the core of the Sun has to come out of the surface. It's as if a "compost pile" the diameter of the Earth were perfectly insulated except for the very top and all the heat just adds up. (See square-cube law if you want a really technical description of that) The funny thing is, hydrogen in the Sun wouldn't even burn with oxygen - in stars that are big enough, just before supernova, the oxygen sinks to the core instead of forming water. That's because the Sun is so hot that it is made up of a "plasma (physics)" where all the electrons are stripped away from the atoms - they're transcended beyond burning. Wnt (talk) 20:35, 25 January 2011 (UTC)

I thought our sun wasn't the right size to even qualify for a supernova death? TomorrowTime (talk) 20:37, 25 January 2011 (UTC)

Sorry about the confusion, I wasn't saying it was - just if it were. Wnt (talk) 20:46, 25 January 2011 (UTC)

This post does pose an interesting question, though: how much matter could Jupiter be expected to capture and accrete while the Sun is shedding its outer layers into a planetary nebula? Titoxd^{(?!? - cool stuff)} 21:13, 25 January 2011 (UTC)

Apply the inverted formula of Jean's Escape to compute a rate of gravitational-capture. The answer depends on the gas temperature. You can estimate an effective "capture cross section" for Jupiter to describe the percentage of gas particles that will pass close enough to Jupiter to be captured (assuming they are ejected from the sun isotropically - a zeroth-order model that you could improve on as you so desire). Over astronomical time-scales, I doubt it even matters which direction or trajectory an individual ejected gas particle follows - eventually, the nebula will reach thermal/gravitational equilibrium; and angular momentum will be conserved. Nimur (talk) 23:15, 25 January 2011 (UTC)

To order of magnitude, if Jupiter captures everything that comes within a few Jupiter radii and the sun ejects matter isotropically then you have a factor that is ((radius of Jupiter) / (orbital distance of Jupiter))^2 = 8×10⁻⁹. Which basically guarantees it won't make a big difference in Jupiter's life cycle. Dragons flight (talk) 23:27, 25 January 2011 (UTC)

The gases that produce a planetary nebula at the end of the Sun's life would be ejected from the outer layers of the red giant sun with enough force to blow away most of Jupiter's atmosphere, leaving perhaps only its metallic core and possibly an outer layer of metallic hydrogen cooling over time despite the core's incredible density. Even to produce a brown dwarf, Jupiter would need to be roughly the same size it is now but at least 13 times more massive, which still is not enough to initiate nuclear fusion. See also formation and evolution of the solar system. ~AH1^(TCU) 22:37, 26 January 2011 (UTC)

I swear we used to have an article on Lucifer project. Vespine (talk) 00:11, 27 January 2011 (UTC)

Orbit

What is the name of the object a satellite orbits around? Our article on Kepler's Laws just uses the phrase "sun", but obviously one would not refer to a planet or a black hole as a "sun". --T H F S W (T · C · E) 20:05, 25 January 2011 (UTC)

Perhaps "focus" (of the orbit) or "barycentre" or "centre of mass"? Dbfirs 20:12, 25 January 2011 (UTC)

Focus_(geometry) seems appropriate, but Barycenter seems incorrect, i.e. the focus around which an object rotates is not the center of mass of the system. From our article on Kepler's laws "The Sun is not in the center but in a focal point". The focal point is the abstract point in space though, not the object. SemanticMantis (talk) 20:18, 25 January 2011 (UTC)

... but the focus of the orbit is the barycentre (and the centre of mass of the two objects). The centre of mass is not at the centre of the ellipse, and the rotation is not around the centre of the ellipse. Dbfirs 00:03, 26 January 2011 (UTC)

I would use primary, although the article says that it has yet to obtain currency for extrasolar orbits. --Tardis (talk) 21:51, 25 January 2011 (UTC)

Yes, that's a better answer to the question, since it does ask for the object, and the focus is not necessarily within the object. Dbfirs 01:09, 26 January 2011 (UTC)

I agree that "primary" is a good term, and another description could be that the satellite orbits the centre of a Hill sphere. ~AH1^(TCU) 22:31, 26 January 2011 (UTC)

Autoclaving a bottle of liquid

Suppose you want to autoclave a bottle of medium, to make it sterile, and suppose the medium actually contains bacteria or bacterial spores at the beginning. If I understand correctly, the autoclave's mode of action is to utilise the latent heat of vapourisation of water to sterilise by subjecting things to steam. However, the liquid medium, whose primary component is water, will not benefit from this because steam will not permeate the liquid - it would be no more sterile than if it were boiled, and if any spores remain after boiling, then they would surely remain after autoclaving? Also, how loose should a lid be? Completely, and just resting on top, or..? --129.215.5.255 (talk) 20:24, 25 January 2011 (UTC)

The heat of vaporization has little to do with it. The main point of autoclaving liquids is that it makes them hotter than boiling them under typical room air pressure. For example, the typical lab autoclave will bring liquids to 121 C instead of 100 C. Now in order to do this, you need to do two things:

• Pressurize the chamber. Because water not under pressure boils at 100C, and it would boil out entirely.
• Saturate the chamber with water. Because if boiling water is not in equilibrium with steam, it still loses volume, and you have things in the chamber a fairly long time. (In practice the volume of solutions coming out of an autoclave still tends to be reduced a little, because the air isn't perfectly flushed out, etc.)

The easiest way to do these two things is with highly pressurized steam.

The lid has to be loose enough that there is no way, despite expansion/contraction, that it can possibly stick and form a tight seal, or else SOMETHING is going to give when the pressure changes. Wnt (talk) 20:43, 25 January 2011 (UTC)

(edit conflict) No, autoclaves usually use high pressure steam. I'm not sure what pressure is typical, but I recall autoclaves that were labeled for 2 atmospheres total pressure. The advantage of the high pressure when autoclaving water-based liquids is that it allows the liquid to be heated above 100 C without boiling away. So the media will reach an elevated temperature (e.g. 120-135 C) that is more effective at killing organisms than boiling (at 100 C) would be. Autoclaves intended for this purpose generally have a "liquid-cycle" that controls the pressure in a way that minimizes boiling during the cool-down phase. One also generally needs to run the cycle longer to ensure the whole volume of the liquid is effectively heated when compared with sterilizing empty containers. A rule of thumb with caps is that if you fill the bottle with water then the cap should be loose enough that the water will flow quickly past it and continue flowing easily even if you press down or pull up on the cap. One way to accomplish this is to simply leave the cap resting on top (and that's pretty common), though it is also common to see caps partially threaded, provided they don't create an effective seal. With liquids most of the heat will be conducted through the walls of the container (rather than through the top), but you need to avoid creating a seal that would lead the container to be at a different pressure than the outside since that could lead the container to explode (or implode). Dragons flight (talk) 20:56, 25 January 2011 (UTC)

The science classic "Microbe Hunters" (1926) says that Lazzaro Spallanzani, in the 18th century, sealed flasks of water or broth and left them in containers of boiling water for hours to kill off microorganisms. How was he able to do that without the flasks exploding? There is no mention of using a pressure cooker, and they were glass flasks of thin enough material he could pull the neck down to a thin tube and flame seal it. I have tried boiling a container full of water in a boiling water bath, and the water in the smaller vessel turned to steam. I have no idea how to calculate the pressure which would have resulted had the small vessel been sealed in an open bath of boiling water, but I expect there could have been an extreme pressure rise. Edison (talk) 00:54, 26 January 2011 (UTC)

I don't understand why there should be an extreme pressure rise in the sealed vessel. Provided that the vessel is surrounded by water at 100 degrees, the very slight pressure rise inside the sealed vessel will increase the boiling point of the water it contains above 100 degrees, so only a limited amount of steam can form and the water in the sealed vessel will stop boiling. Of course, if the sealed vessel contains alcohol or some liquid with a boiling point below that of the surrounding water, then pressure will rise higher. In an autoclave, a sealed vessel will perhaps need to be slightly stronger to withstand pressures both ways during heating and cooling, but, with a small expansion space, I still don't see how there will be extremes of pressure, because, once equilibrium is reached, the pressure (up to two atmospheres?) will be the same inside and out. The best way to test this would be to try it with a sealed aluminium can which will show the deformation either way.Dbfirs 08:24, 26 January 2011 (UTC)

In water bath canning, where the water bath boils at atmospheric pressure, a lid with a rubber ring is screwed onto the jar to be canned, which is filled with any fruit, veg, or juice, some of which would be so watery (low in salt, sugar or other solute as to have about the same boiling point as water. Other recipes would have enough salt or sugar that the boiling point would be elevated a bit. (One could always can distilled water, I suppose, for experiment's sake). Only a small airspace is left. Although the lid is on fairly tight, secured by a screw ring, the steam pressure from within forces out steam, and the water level may drop a cm or two more with normal processing times due to steam production. When the boiling stops, pressure drop inside causes the lid to "pop" downward and stay indented. I have always wondered how high the pressure inside would rise if the lid were very tightly shut, and conjectured that the jar might explode. Would higher pressure inside somehow mean higher temperature inside the jar? There has to be higher pressure for the steam to escape during the processing. Edison (talk) 18:32, 26 January 2011 (UTC)

This mostly has to do with the partial pressure of water vapor. Consider if you have a can of liquid water inside a container of boiling water. You wouldn't expect the water to squirt out of the can, or generate steam, just because you have some of it inside a can. (Excepting minor thermal expansion of liquid water) But when you have a can with an air pocket at the top, the water (which after all is at the boiling point) dissolves into the air pocket. The added vapor exerts extra pressure, and makes the air pocket larger or under more pressure. Wnt (talk) 18:43, 26 January 2011 (UTC)

All that seems clear, but could the pressure rise significantly in a sealed jar in a boiling water bath, if no steam at all could escape, assuming some air space to allow for thermal expansion of the water, like to several atmospheres, or only to a small percentage above atmospheric? (If the water bath boiled away, then a steam explosion would be assured after a bit, so don't try this experiment at home). Edison (talk) 22:24, 26 January 2011 (UTC)

Yes, I'm not sure whether a mixture of gases will exert a higher pressure than either of the gases separately. My intuition says that when the pressure rises just slightly, the water will stop boiling and some of the water vapour will condense back into the water, maintaining equilibrium at marginally above the pressure outside, but I haven't tested this out. It should be easy to test safely with just basic equipment, even in a school lab, using a manometer. Dbfirs 08:39, 27 January 2011 (UTC)

January 26

What's the difference between van der Waals forces and London forces?

My chemistry textbook claims that they're different names for the same force, but Wikipedia has separate articles for them. --75.15.161.185 (talk) 00:28, 26 January 2011 (UTC)

Have you read the intros to the respective articles? The London dispersion force is a component of the van der Waals force, which is itself a sum of many forces. We note in the former article that "dispersion forces are usually dominant of the three van der Waals forces", with the other two being orientation and induction forces. Small polar molecules like water are a notable exception to this trend. — Lomn 00:42, 26 January 2011 (UTC)

Forces stronger than London dispersion forces that are also van der Waals include Debye forces, Keesom forces, hydrogen bonds, ionic bonds and induced ion forces; see intermolecular force. The "London forces" are dominant in nonpolar molecules that do not have the stronger forces, as they lack permanent dipoles, and increase in strength given larger molecules and thus more atoms for temporary charge induction. ~AH1^(TCU) 22:27, 26 January 2011 (UTC)

The amount of energy in houshold rubbish

How much energy would a typical household expect to get from burning all their burnable rubbish and using it for heating? Thanks 92.24.182.244 (talk) 02:02, 26 January 2011 (UTC)

More than enough to heat their home, in most locations. But the technology to do it cleanly enough is not feasable on a household scale. And in most developed countries, it would be illegal to try to do this in a crude way yourself. Some cities do this to some of their garbage not just for energy, but to reduce landfills. Some of the remaining matterial (black "nuggets" formed) that doesn't go up in smoke can be collected and used as a raw material (for road pavement is one common application). Roberto75780 (talk) 02:20, 26 January 2011 (UTC)

Well my household does not produce enough rubbish to provide even a twentieth of the heating cost, even with super-efficient combustion, but perhaps some households produce tons of rubbish. Dbfirs 08:18, 26 January 2011 (UTC)

The article Incineration has good information on waste incineration. It says one metric tonne of garbage can produce 0.67 MWh of electricity and 2 MWh of heating. A person produces on average 726 kg garbage per year[11] Taking the average US household size as 2.6[12] that's 1890 kg per household, which will give 1.3 MWh electricity and 3.8 MWh heating.

For comparison, domestic energy consumption is around 100 million BTU or 29 MWh per household [13]. Energy in the United States says 45% of domestic energy is used for heating water, which assuming the figures match would be 13 MWh. Big shortfall. --Colapeninsula (talk) 10:55, 26 January 2011 (UTC)

Energy in the United States actually says "Residential Living quarters for private households: 13% water heating" - not 45%. Living in a mild weather area in the U.S. Midwest which is currently on day 45 of 57 to fail to reach a daily high temperature above 0°C (32°F), 45% of energy just for water heating sounds like optimism. Rmhermen (talk) 14:45, 26 January 2011 (UTC)

For many years I had the job of burning my family's trash in an old 55 gallon drum. It flared up to a high temperature, but burned down quickly, and would have been far too little to heat the home in the winter. For a time, we used coal, so I had a direct comparison of the mass of coal versus the mass of trash, and the heat produced by the coal stove versus the trash fire. There was no trash collection service at that time in that location. Edison (talk) 18:17, 26 January 2011 (UTC)

Methane capture is another method of making energy from trash, and incineration often works best given combustable (ie. organic-based) garbage. ~AH1^(TCU) 22:20, 26 January 2011 (UTC)

Rubbish Island

a) It was a quite frequent trope of 1950s-1970s films set in New York, or elsewhere, to see as a finale the hero ending up on a large barge or 'scow' taking rubbish out to sea. Where did this rubbish in actuality go to? Does this practise still continue?

b) Is there any reason why it would not be a good idea to use rubbish for land reclamation? In Britain the dogger bank is crying out to have an island built on it, and would be a great place to put all the things that nimbys do not like. Thanks 92.15.10.209 (talk) 14:47, 26 January 2011 (UTC)

Fresh Kills Landfill is now closed but the location is used to repackage New York garbage for rail shipment to South Carolina. Also not an island. Rmhermen (talk) 15:03, 26 January 2011 (UTC)

Fresh Kills Landfill is not an island, but it is on an island -- Staten Island. Indeed, it forms a rather large portion of the island. --M@rēino 20:02, 26 January 2011 (UTC)

The trash heaps occupy 2.6% (990 acres) of the 37,400-acre island and the entire site occupies about 6%. Not "a rather large portion". 75.41.110.200 (talk) 21:41, 26 January 2011 (UTC)

I believe your numbers are accurate. I'd still say that's a rather large portion of the island. --M@rēino 17:56, 27 January 2011 (UTC)

The annual volume and mass of NYC garbage must be impressive. How much trash (excluding recycled materials) has to be disposed of from that one city each year? Does SC or other victim states build Mount Trashmores out of it, or what? Edison (talk) 18:10, 26 January 2011 (UTC)

Environmental issues in New York City#Garbage disposal says the city produces 12,000 tons of (landfill) garbage per day (confirmed by this article). This totals more than 4 million tons annually. -- Finlay McWalter ☻ Talk 18:26, 26 January 2011 (UTC)

(edit conflict)New York has shipped its garbage to various places, including Fresh Kills Landfill, Philly, and North Carolina (cf Mobro 4000). Building islands is very expensive; regular garbage, and miscellaneous landfill in general, isn't a stable engineering material. High-value properties like Kansai International Airport have been constructed in shallow water, but it takes a lot of concrete to make something that doesn't just wash away. Moreover, post-consumer waste yields for lots of problems to anyone planning on building, farming, or living on top of it. Firstly it's not compact, so structures built on fill subside - the Japanese airport solution (which I think Changi uses too) is to build structures on jacks, and jack the sagging end of the building up as they subside. Secondly is methane offgassing due to biodegradation in the waste. And third is contamination - the waste stream contains (whether it should or not) all kinds of nasty stuff like paint, motor oil, medical waste, dioxins, asbestos, and heavy metals. So you'd spend a fortune constructing an island that couldn't be used. -- Finlay McWalter ☻ Talk 15:08, 26 January 2011 (UTC)

(edit conflict) The Mobro 4000 article is a very interesting read in this regard. --Jayron32 15:17, 26 January 2011 (UTC)

See also Great_Pacific_Garbage_Patch. Kittybrewster ☎ 15:35, 26 January 2011 (UTC)

I get the impression that some people think the sheer volume of garbage is a problem (see the opening of Wall-E, or of Sex, Lies and Videotape, where I think she's specifically reacting to the Mobro 4000 story). There just isn't that much garbage. Pollutants leaching from garbage into water is a problem, methane from rotting garbage is a problem, but the simple volume occupied by garbage is not a problem. If you want to reduce the environmental impact of garbage, dumping it in the middle of a body of water probably isn't the best idea. Also, if you're upset that Manhattan exports its garbage, remember that it imports the stuff that becomes the garbage. There are advantages to concentrating people in one location and putting the support systems elsewhere -- BenRG (talk) 20:52, 26 January 2011 (UTC)

Some floating islands could be constructed from garbage. ~AH1^(TCU) 22:19, 26 January 2011 (UTC)

Submarine speed

Why do submarines go faster underwater than on the surface? Example: German Type XXIII submarine. When underwater, would they not have more drag and more displacement of water to overcome? Thanks 92.15.10.209 (talk) 14:54, 26 January 2011 (UTC)

Turbulence. Cuddlyable3 (talk) 14:57, 26 January 2011 (UTC)

See diagram. The prop-shafts and therefore thrust is generally in-line with the central axis. If the vessel was to go too fast, the water level behind the vessels would drop further than it does at max surface speed, until the blades of the screws would experience rapid changes in the forces acting upon them as they first left, then re-entered the water. This would lead to early failure. As it is, some screws are only just covered by water when cruising on the surface. Also, and which needs to be mentioned. The deeper a sub goes, the less likely the screw is to experience cavitation but that is a bit secondary to the much faster damage caused by the atmospheric air ventilating the screw.--Aspro (talk) 15:37, 26 January 2011 (UTC)

A significant part of the drag of a surface ship is due to creation of a bow-wave and other signs of disturbance on the surface of the water. See Wave making resistance. A submerged streamlined body, such as a submarine, does not make any disturbance on the surface of the water so this form of drag is avoided.

After a diving entry, competition swimmers remain underwater as long as possible in the hope of maximising their average speed. It seems to work. Dolphin (t) 21:31, 26 January 2011 (UTC)

A Discovery Channel TV documentary I just happened to watch attributed the speed increase to water density. Go deeper, denser water, more stuff for the propeller to push against. 88.112.59.31 (talk) 22:32, 26 January 2011 (UTC)

Untrue! The pressure of water increases with depth but the density is almost constant throughout the ocean. The density of the atmosphere changes significantly with height above the Earth's surface because air is a gas. Water is a liquid and its density does not change (significantly) with changes in pressure. Dolphin (t) 01:41, 27 January 2011 (UTC)

Water does not compress as gasses do, so the density is mostly the same (as the appropriately named Dolphin51 mentioned), and even if it did increased moved mass would be offset by increased density of the medium you were pushing through, to a point. I would also suspect that a significant factor is that submarine hulls are optimized for travel at depth, not surface travel (this is especially true of the modern hull, less so I'd imagine of WWI and II-era hulls that were more closely adapted from surface ships). The article on Teardrop Hulls confirms this. Oddly the article makes no mention of the modern "Albacore" Hull, so named for the ship that first used it, which is the standard more or less today. This hull is strongly optimized for travel sub-surface and highly suboptimal for surface travel. 65.29.47.55 (talk) 09:20, 27 January 2011 (UTC)

First lets dispel the landlubber's myth that submerged vessels do not create bow waves. The sea is a viscous medium and as such, the hydrodynamic force will raise the sea's surface, above the vessel, to a hight over the mean. Although, this hight diminishes with the vessel's depth, its surface area increases. The American Fleet understood bow waves and so by the 1970's had become alarmed to discover the capabilities of synthetic aperture radar satellite technology and its ability to resolve alimentary delta information to millimetre resolutions and thus its possible potential to expose the position of its nuclear launch subs. (Note: and the difference in most cases is only in the order of millimetres.) Quote: The bow wave from submerged submarines could thus show up in radar images of the ocean's surface unquote. Page 97 Therefore, the 'wave making resistance' can not account for the slower surface speed because it exists in both situations. Indeed, if we go here to calculate the approximate displacement hull speed, we find that for this submarine's length it is about 14.3 knots rather than 9.7 or almost half as fast again and this is without the added frictional increases when submerged. Therefore, perhaps a better understanding of the danger of the screw ventilating and the way chosen to prevent it, can be had by looking at photographs of this sub on the surface, both in the article itself and again here. Compare those to the line drawing of this sub and you will see that is surface attitude is trimmed to keep the bow high. The line drawing also shows that if it was to sail without this raised forward pitch, although it would go faster, the trough formed at the rear would quickly allow the screw to suck down air as the speed increases. This would hammer the bearings, fatigue the blades of the screw and create vibrations throughout the vessel. Marine architecture is, like many other engineering structures, an assemblage of compromises. --Aspro (talk) 18:33, 27 January 2011 (UTC)

Endosome/endocytic vesicle

Is there any difference between these two terms? I have read endosome and the Gene Ontology entries [14][15] but I'm still not wiser. Is an endosome an organelle and an endocytic vesicle not (as GO suggests)? But why, both have a lipid bilayer. Can you help? -- Ayacop (talk) 16:45, 26 January 2011 (UTC)

It gets a bit semantic, but the term "endocytic vesicle" tends to be used to describe the structure that pinches off during endocytosis. This vesicle then fuses with an endosome where sorting of different receptors takes place and then allows for trafficking of those consituents to different locations. One way to think of it is that the endocytic vesicle comes directly from the plasma membrane and carries something from outside to inside. The endosomal compartment (not one organelle but a very dynamic collection of membrane-bound structures) is a bit more murky, with different compartments handling flow of materials from inside to outside, outside to inside, into the lysosomes for degradation, etc. --- Medical geneticist (talk) 16:57, 26 January 2011 (UTC)

Ah, thanks. Followup: so a phagosome would be a kind-of endosome (both can mature)? -- Ayacop (talk) 17:01, 26 January 2011 (UTC)

Why the "Coma" Cluster?

The article on the Coma Cluster gives no hint of why it is called that. Was it named after a person or a place? Was it named after the medical condition Coma, or did it somehow look like the galaxies were in a deep sleep? Is it pronounced like the medical condition? Edison (talk) 18:04, 26 January 2011 (UTC)

It's named after the constellation Coma Berenices. Info found on the Coma supercluster article. 90.193.232.5 (talk) 18:26, 26 January 2011 (UTC)

Coma is also a type of optical aberration in telescopes. That could possibly be related to the etymology of the Coma Cluster. On the other hand, coma is also used to refer to any sort of nebulous blurring, whether an artifact of instrumentation or actually due to the characteristics of the astronomical object. The word root is "coma (from the Greek κόμη, "hair")" - not from Ancient Greek κῶμα (kōma, “deep sleep”). See the wikt:coma etymologies. Nimur (talk) 18:28, 26 January 2011 (UTC)

The Latin term "coma", according to the OED, derives from the Greek κόμη, meaning "hair of the head, also applied to foliage, etc., and to the tail of a comet". As the Coma Berenice article points out, in Latin the term means "Berenice's Hair". It's of note that the use of the term "coma" for a comet's tail dates only from the late 18th century, and the use of "coma" to mean aberrations caused by lenses is from the 1860s. So there's the same metaphor here, but it's not that the name of the constellation came from the previous astronomical terms. --Mr.98 (talk) 18:45, 26 January 2011 (UTC)

I've added that piece of information to the article - many nearby clusters are named after the constellation they're in, e.g. Virgo, Fornax etc. --Wrongfilter (talk) 20:52, 26 January 2011 (UTC)

Thanks for the explanation. Someone laughed when I was talking about late 20th century cosmology/astronomy and the importance of the "Coma Cluster" observations, and asked where the name came from, and Wikipedia provided no guidance. In American English, how is this "Coma" pronounced? Like "Coma," or like "comma," or otherwise? The responses above list two differently spelled Greek words, but Wiktionary has one pronunciation. The article Greek alphabet shows the letter ο or Omicron but the one shown above was "ό." The article Omicron says nothing about accents on the letter. Apparently F. Scott Fitzgerald's story Bernice Bobs Her Hair (1920) derives from this ancient Coma Berenices legend of Berenice II cutting her hair off. Edison (talk) 05:09, 27 January 2011 (UTC)

KBOs and TNOs

KBOs, a detached object and the inner Oort Cloud.

Is there any difference between Kuiper belt objects and Trans-Neptunian objects? Or are KBOs a subclass of TNOs? --T H F S W (T · C · E) 20:00, 26 January 2011 (UTC)

Our article Transneptunian object says

"The Kuiper belt, scattered disk, and Oort cloud are three divisions of this volume of space [where TNO reside]."

As I understand this quote, all KBOs are TNOs. But there is a difference between the classes: members of the Oort cloud are TNOs but not KBOs. SemanticMantis (talk) 20:45, 26 January 2011 (UTC)

(edit conflict) Other members of the TNO class that are not KBOs include Scattered disk objects and detached objects. The Oort cloud is thought to lie much farther than the Kuiper Belt and even objects that have great eccentricities in non-parabolic orbits are thought to be unable to reach it, however. Also, the Kuiper Belt seems to cut off almost abruptly at 50 AU. ~AH1^(TCU) 22:15, 26 January 2011 (UTC)

Proton spheres

I have a question which has been left unanswered by our article on photon spheres: are photonic orbits around neutron stars more stable than photonic orbits around black holes? Why/why not? Thank you in advance. --Leptictidium (mt) 22:13, 26 January 2011 (UTC)

No difference because the space around a neutron star has the same metric (space-time shape) as the space around a blackhole. 71.101.41.73 (talk) 02:46, 27 January 2011 (UTC)

January 27

Best way to dissolve methane in a liquid that mixes with scintillation fluid

Hi,

I'd like to be able to "trap" 14-C methane in some kind of solvent so that I can mix that solvent with scintillation fluid and be able to determine radioactivity. What would be the ideal solvent for this situation? Ideally, I'd like a liquid that can trap all of the methane in the tube but also mixes with the scintillation fluid.

Thanks a lot for your help.

Ccarlst (talk) 03:50, 27 January 2011 (UTC)

Methane isn't going to be soluble to a great extent in any liquid (it is arguably more soluble in a nonpolar solvent like benzene than in water, but only in relative terms. Its not terribly soluble in either). Furthermore, even soluble gases will never completely dissolve in a liquid. Your best option is to react the methane with something, preserving its carbon, but making that carbon now bound to be part of a liquid compound rather than gaseous methane. I'm not sure how feasible it is based on the equipment you have availible, but something like Free radical halogenation would work; the article lists free radical halogenation as a method used most commonly to create chlorinated methanes like dichloromethane (methylene chloride) and trichloromethane (chloroform) both of which are actual liquids. --Jayron32 04:12, 27 January 2011 (UTC)

Try converting the methane to a methanide salt, which is soluble in polar anhydrous solvents. --Plasmic Physics (talk) 09:07, 27 January 2011 (UTC)

Yeah, but methanide salts would be much more difficult to work with than methyl halides. Alkyl salts are metastabile at best, I would expect all of them to be so highly alkaline as to be pyrophoric in air. The nice thing about methylene chloride is that it is fairly easy to work with (it is a low-boiling liquid, so you'd have to work in a cool room, but otherwise is very unreactive). --Jayron32 14:00, 27 January 2011 (UTC)

What's the source of the methane? Does the gas also contain other methane (not containing C-14) and is there anything else that does contain C-14? Google gives lots of literature hits for liquid scintillation of C-14 methane over the past few decades (sample search: 14c methane scintillation). Doesn't necessarily answer your direct question (as others have noted, it's "hard"), trying to figure out solutions to the larger situation. DMacks (talk) 09:36, 27 January 2011 (UTC)

Geographic center of the world

Hi. I know that the geographic center of the contiguous United States is near Lebanon, Kansas {{coord|39.828175|-98.5795}} Could you, please, tell me the coordinates of the geographic center of the whole world? I searched the internet but couldn't find anything. If you don't know, could a science geek calculate the coordinates using a world map such as File:BlankMap-World6.svg and a good piece of software? --41.178.235.216 (talk) 03:50, 27 January 2011 (UTC)

To my admittedly sometimes muddled mind it seems there is no centre of the surface of a sphere. HiLo48 (talk) 03:54, 27 January 2011 (UTC)

There is, but it's not on the sphere. The center of mass of the earth is located, unsurprisingly, at the center of that sphere, not on its surface. The geographic center is defined as the center of mass of a uniform, two-dimensional cut out of the section of land in question. However, as you correctly note, it makes no sense when dealing with a sphere, only with the (planar approximation) of parts of that sphere does it make sense. --Jayron32 03:57, 27 January 2011 (UTC)

(edit conflict) I mean the center as if the whole world was flat (projected on a surface). It is probably some point in the Middle East but I need the exact coordinates. --41.178.235.216 (talk) 03:59, 27 January 2011 (UTC)

That involves some arbitrary map borders. To make the world appear flat on a map involves choosing edges, which don't actually exist, and flattening curved bits. HiLo48 (talk) 04:02, 27 January 2011 (UTC)

To expand, while a lot of maps do seem to have the Americas on the left, and Asia on the right, this one gives another perspective. HiLo48 (talk) 04:27, 27 January 2011 (UTC)

The proper way to calculate it over the whole globe is to use the (two-dimensional) circular mean. See also land hemisphere, which is nearly synonymous. --Tardis (talk) 05:02, 27 January 2011 (UTC)

For the centre of a conventionally made "flat" map, you're asking for the intersection of the prime meridian and the equator, this article has a story and pictures of a visit there (it's far out at sea off the coast of West Africa). Many world maps show more of the Northern than the Southern hemisphere, for such maps, the centre would be further north. I guess you could also calculate the centre of all the land masses in the world, this is maybe what's described in Tardis' post above. Jørgen (talk) 08:55, 27 January 2011 (UTC)

Further reading at Extreme_points_of_Earth#Center and geographical center.--Shantavira|^{feed me} 09:01, 27 January 2011 (UTC)

Greenwich, Mecca, or Jerusalem have been regarded as being the centre points of the world. At Greenwich you can stand astride the piece of metal the marks the boundry between the eastern and western hemispheres, and its where GMT comes from. 92.24.187.66 (talk) 12:21, 27 January 2011 (UTC)

Surely, the answer is wherever you are at that particular moment? --Dweller (talk) 14:25, 27 January 2011 (UTC)

Actually, the answer is wherever I am at that particular moment! --Stephan Schulz (talk) 17:17, 27 January 2011 (UTC)

I assume DWeller meant where you are. DMacks (talk) 17:25, 27 January 2011 (UTC)

Actually, I suspect it has something to do with the barycenter of the planet. Damn you, chocolate! --Stephan Schulz (talk) 17:33, 27 January 2011 (UTC)

Hmmm, despite the absurdity of it, this question is theoretically answerable. Imagine you make a globe where all the world's land surface is accurately represented by a homogeneous layer of material. Wrap it in a much lighter layer over the whole sphere to hold it together. Now put it on a smooth floor and let it roll to a stop. The point on the bottom should be "the center point of all land on earth", and the point on top should be "the center of all Earth's oceans". An industrious person could probably do this on a computer in a jiffy, but alas... Wnt (talk) 18:01, 27 January 2011 (UTC)

ORME Orbitally Rearranged Monoatomic Elements

There is some ideas on the web, but what is actually "Orbitally Rearranged Monoatomic Elements (ORME)"?, there is no information on english Wikipedia, usually it the best place to serch, would you explain please?Ghrmsn (talk) 06:23, 27 January 2011 (UTC)

It looks like it's not something real. One user attempted to write an article about it: User:Sloth_monkey/ORMEs and was deleted : Wikipedia:Articles_for_deletion/ORMEs and Wikipedia:Articles for deletion/Monatomic elements. Maybe you can glean some information from the deletion comments and the article draft. Ariel. (talk) 08:59, 27 January 2011 (UTC)

Mean distance in a square

Maths have always been my Achilles' heel, so I'm having trouble trying to figure out a problem with a square.

Let's imagine a big 100 sq. ft box divided into one hundred 1 sq. ft boxes. In the centre of each small box there is a candle. If I were to calculate the average distance from each candle to all other candles, would I get the same result for all the candles, or would there be a divergence depending on the location of the candles within the big box? Intuitively, I think candles located along the edges would have a greater average distance to all other candles, but I can't find a way to prove it mathematically.

Thanks to whoever can help. Leptictidium (mt) 08:55, 27 January 2011 (UTC)

When you have a problem like this simplify it. Imagine a line with just 3 squares in it, and calculate the average distance for each of those 3 candles. Ariel. (talk) 09:04, 27 January 2011 (UTC)

It would be ideal for a simple Basic program, such as SmallBasic. 92.24.187.66 (talk) 12:54, 27 January 2011 (UTC)

It's not clear from your phrasing what geometry you mean, but you will get different answers for a 1X100 rectangle of boxes compared to 10X10. The issue at play here is the perimeter to area ratio, and more generally the notion of boundary_(topology). For instance, if you put the small boxes on the surface of a sphere (and measure distance along the same surface), then all candles would share the same mean distance to the others. SemanticMantis (talk) 15:06, 27 January 2011 (UTC)

First, it has been noted that there are 100x100 10x10 1 square foot boxes in a 100 square foot box. Regardless, this is a very simple program to write. The output for a 5x5 box is:

3.31  2.83  2.67  2.83  3.31 
2.83  2.31  2.14  2.31  2.83 
2.67  2.14  1.95  2.14  2.67 
2.83  2.31  2.14  2.31  2.83 
3.31  2.83  2.67  2.83  3.31

As you can see, the mean distance to all other candles is not constant. -- kainaw™ 15:19, 27 January 2011 (UTC)

It is interesting to see the calculations, thanks. Also, I think you mean 10X10 1 square foot boxes in a 100 square foot box :-) SemanticMantis (talk) 18:29, 27 January 2011 (UTC)

Religion, mental health and education

Is religion correlated more positively with mental health in people with higher education? I ask this because it would test my hypothesis that approaching the ultimate nature of humanity or the universe is hazardous to a person's mental health, and that religion is a way of defending against that hazard. (I agree with Richard Dawkins' assertion that religion itself is a mental illness, but I'm not sure I agree that it's a more severe mental illness than the alternative.) NeonMerlin 11:05, 27 January 2011 (UTC)

Who's to say what the "ultimate nature of humanity or the universe" is? I don't think physicists are more crazy than other people, except in cartoons. 92.24.187.66 (talk) 12:56, 27 January 2011 (UTC)

Is this the religious version of "You can't handle the truth"? HiLo48 (talk) 14:03, 27 January 2011 (UTC)

I read an article about this in the last few weeks; the author claimed that religion (particularly the fervent, born-again type) is measurably more popular among undergraduates at Britain's most prestigious universities than at other, less rarefied institutions. His interpretation was that unusually bright people under intellectual stress are more likely to turn to religion. Anecdotal and unscientific, but it did strike a chord. It could have been in The Guardian or maybe the Financial Times; I can't find anything online ATM but I'll try to dig up a reference for you. Karenjc 16:04, 27 January 2011 (UTC)

Interesting comments regarding "unusually bright" students turning more to religion. From what I've seen, most studies show a strong negative correlation between "intelligence" (as measured by IQ) and religious faith. -- Mesoderm (talk) 16:16, 27 January 2011 (UTC)

Yes, given the strong negative correlation between religiousness and intelligence, it presumably isn't those students' intelligence that's causing them to turn to religion, so much as their highly competitive, high-stress environment. And a high-stress environment does increase a person's risk for developing other forms of mental illness (see Causes of mental disorders), so a stress/religiousness correlation would seem to fit Dawkins' religion-as-mental-illness paradigm in at least that regard. Red Act (talk) 17:36, 27 January 2011 (UTC)

Correlation is not causation (Propter hoc fallacy), and doubly so when dealing in false syllogisms. If I say "I love you, and I love cheese, therefore you are cheese" you can see the rediculous leaps of logic needed to reach that conclusion. However, I have no idea why, replacing random nouns and verbs in that statement, it suddenly becomes a reasonable proposition. Lets try it "Stress causes religiousity, and stress causes mental illness, therefore religiousity is mental illness." Nope, its still a patently stupid conclusion to reach. --Jayron32 18:05, 27 January 2011 (UTC)

There is a strong correlation between citing studies linking low IQ to a group of people 'and' your personal dislike of these groups. Quest09 (talk) 18:10, 27 January 2011 (UTC)

This isn't quite what you asked for, but I did stumble across this study that attempted to measure the effect of religion on physical (rather than mental) health while also controlling for the effects of age, income, education, etc. They found that religious practice had a positive and statistically significant association with health even after controlling for other variables. (Probably not surprising.) However, they also found that those holding self-reported "conservative" ideologies were on average less healthy than those with moderate / liberal religious beliefs, even after controlling for other variables. They speculated that religious conservatives may be more reluctant to seek out medical treatment when problems arise. They also found that people with higher levels of education where more likely to engage in regular religious practices (e.g. praying, going to services, etc.), but paradoxically less likely to report feeling "closeness to God". Dragons flight (talk) 18:16, 27 January 2011 (UTC)

Anal sex in the 1800s

I watched Total Eclipse (film) the other day and was confused about something. When Verlaine is in court and a doctor tests whether he was having anal sex, the doctor says there was proof that he was having both active and passive sex. I understand how the doctor could tell that Verlaine was having passive sex, but how could he ever know that Verlaine was also having active sex? Or were they just saying that to further incriminate him...? Thanks, this has been bothering me for some time! 129.3.178.228 (talk) 14:06, 27 January 2011 (UTC)

Was something like syphilis involved? (Which was common enough at the time) Wnt (talk) 18:11, 27 January 2011 (UTC)

I can't find anything saying he ever had syphilis, no. 129.3.151.117 (talk) 18:45, 27 January 2011 (UTC)

Sky photography

I stumbled upon this image during one of my Wikipedia strolls, and I was surprised to learn that it was a photograph. It looked like a negative or even a diagram to me. To what purpose would an astronomer use such a picture as opposed to a more usual (to my lay eyes) photograph such as this one ? What are those "negative" images useful for ? Thank you, have a nice day. 130.79.160.112 (talk) 15:33, 27 January 2011 (UTC)

Many astronomers would find it simpler to pick faint black specks out of a white background than vice versa, particularly if you're working by hand rather than with digital photo processing equipment. — Lomn 15:47, 27 January 2011 (UTC)

Technically, it is the negative (or a print of a photograph of the original plate); the 'raw' image collected on film at the telescope would look exactly like that, as bright stars would create dark spots. From the standpoint of working with the image, it's usually easier to pick out a small dark spot on a white (or clear, on the original film/plate) background than it is to pick out a slightly-less-dark spot on a black background. (This applies both to manual examination and to automated discrimination.) When printed non-photographically, the negative version uses less toner (or ink), and is more forgiving of printing flaws. When annotating the image, it's much easier to add dark text and symbols to the clear background (particularly when dealing with physical copies of the image) than it would be with a positive image. TenOfAllTrades(talk) 16:32, 27 January 2011 (UTC)

When I was measuring faint structures in deformed minerals on electron micrographs (more decades ago than I care to remember) I always used the negatives directly - you always lose some information when you print. Mikenorton (talk) 18:11, 27 January 2011 (UTC)

(Edit Conflict) In addition to the previous answers, an important factor is that every time a non-digital image is processed (such as when making a positive print from an original negative) degredation of the image occurs. Similarly, every extra lens that an image has to pass through will reduce the inherent quality of the image. For these reasons, professional astronomers from the earliest use of telescopes and of astrophotography generally did not add an extra lens into their eyepieces usually necessary to convert the inverted image into an upright one, and worked with original negative plates (film tended to distort more so was not used for astrometry). Thus astronomers have always been used to dealing with such images, which also have the advantages previously described. 87.81.230.195 (talk) 18:16, 27 January 2011 (UTC)

incipient fusion

A google search suggests that in geology or materials science or something like that, there is a concept called "incipient fusion". But Wikipedia has no article with that title. Can someone say what it is?

There is a joke I heard many years ago, in which a school principal visits a class and tries to ascertain what they're learning. He asks the pupils what they would expect to find if they dug down to 4000 miles below the ground. Nobody could say anything. Then the teacher assisted. He asked them:

"What is the state of the center of the earth?"

They all responded in perfect unison:

"The center of the earth is in a state of incipient fusion."

Michael Hardy (talk) 19:10, 27 January 2011 (UTC)

Practicality of experimental procedure for measuring microwave wattage

Is there anything about the following procedure that in actual practice would make its results significantly inaccurate? Thanks in advance.

Procedure for finding the wattage of a microwave with no labeling whatsoever:

1) Place 0.1 kg (100 mL) of water in a beaker and measure the initial temperature T1.

2) Heat water in the microwave for 10 s.

3) Quickly measure temperature of water T2 and find dT = T2 - T1.

4) Calculate energy transferred to water Q = m*c*dT using c = 4.187e+3 J/kgK.

5) Divide Q by 10 to get wattage (J/s).

76.27.175.80 (talk) 19:15, 27 January 2011 (UTC)