Wikipedia:Reference desk/Archives/Science/2009 December 3

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December 3

Medical experiment that went terribly wrong

Resolved

I remember reading a news story from a few years ago about a medical experiment that went terribly wrong. My memory is foggy but I'll try as best I can to explain what I remember. The researchers were testing an experimental drug. It was the first trial on humans. The test subjects had a terrible reaction to the drug. I can't recall if any of the test subjects died, but a couple might have. I remember that part of the controversy was that the scientists administered the drug to the test subjects back to back, rather than waiting to make sure that the first person didn't have a negative reaction. They may have violated medical protocols. This happened maybe 2 or 3 years ago. It recieved some mainstream media attention. Again, my memory is foggy, but I think I read about it at BBC News. Does anyone know what I'm talking about? A Quest For Knowledge (talk) 05:16, 3 December 2009 (UTC)

Sounds a lot like the trials of TGN1412 — Zazou 05:34, 3 December 2009 (UTC)

• I think you've got it. It happened in England in March 2006; six patients got the drug at 10-minute intervals and it only took an hour before they began suffering one after the other. Nobody died, but they were all severely affected. --Anonymous, 08:28 UTC, December 3, 2009.

Presuming this is what you mean, and it sounds to me like it is, while the 10 minutes interval thing generated a lot of controversy amongst other things and did seem like a dumb thing to do to many, I don't believe it was a violation of protocols or particularly unusual. In fact, as this ref suggests [1] for example, giving sufficient time for a reaction to be observed is a new recommendation arising from the trial Nil Einne (talk) 10:40, 3 December 2009 (UTC)

They gave systemic doses of a previously untested drug instead of giving it topically to begin with. It was a drug designed to boost the immune system, they gave it to healthy patients, and it resulted in a cytokine storm. This was definitely predictable and as an immunologist noted "not rocket science". Fences&Windows 14:40, 3 December 2009 (UTC)

Maybe but that doesn't mean it violated the protocols of the time which was the point I was addressing. To put it a different way, they may have screwed up badly, but it doesn't mean they ignored established protocols, more that perhaps they didn't think properly whether the protocols were appropriate in the specific instance. On the other hand this [2] does suggest it's normal to try hazardous agents on one patient first so it may not have been uncommon as the earlier ref. However it isn't peer reviewed. There is of course still research ongoing as a result of the case. E.g. [3] [4] Nil Einne (talk) 15:44, 3 December 2009 (UTC)

The protocol-design issue is basically this: when you don't anticipate any problems, how long do you wait for problems to develop before you decide that it's enough? When they chose 10 minutes, they were probably imagining that the only possible rapidly manifesting problem would be something like anaphylactic shock, which comes on faster than that. In retrospect that was clearly a bad idea. But what if they'd waited an hour, only to find that after six hours people started getting sick? What if they'd waited a day, only to find that it took a week? With no data on the sort of problems to be expected, it really is a judgement call. Of course, if Fences is correct that this sort of reaction was to be expected, that's a different story. But that's not how it was reported in newspapers at the time, and I'm no immunologist, so I can't comment. --Anonymous, 08:55 UTC, December 5, 2009.

I was wondering about the case at the time in particular the final reports. It was one of those many things the media has forgotten about once the final report is release, and so have our editors so our article was never updated and it's difficult to find an overview of the final report. But the final report is [5] linked to from our article talk page and an interesting comment on this blog [6]

It’s worth pointing out that the final report of the Expert Scientific Group on Clinical trials published in November 2006 (http://www.dh.gov.uk/en/Publicationsandstatistics/Publications/PublicationsPolicyAndGuidance/DH_063117) found that the pre-clinical animal tests done by TeGenero were not adequate.

which then goes on to more detail. This is perhaps a key point. At the time, as with others, I don't really understand how this had happened since even as someone who hasn't done much immunology but did have some knowledge of molecular biology, it seemed to be something they should have antipated and properly tested for.

And the general impression I got was they had done what they thought was sufficient testing, including what they thought was adequete tests to account for the specific effects of their drugs on humans, according to established protocols etc. So my presumption was the protocols and testing were thought be adequete and would have been thought adequete by most in the field (but were not). Perhaps combined with hindsight being 20/20 and people focused on certain aspects and established practices sometimes losing sight of the bigger picture and common sense (whereas from an outsider looking in, it's easy to see things that you think should be obvious but aren't to the people actually doing the work).

All these may very well still be the case, but it appears they did screw up and not do their work properly.

BTW, from a quick skim of the report, it's still not clear to me that the time interval thing came under particular criticism. They did recommend the time interval be adequete for the reactions expected, so perhaps it's a moot point since they didn't test properly so didn't know what to expect. So I feel my point still stands, while they did make mistakes, it's not clear the time interval was a violation of the protocols. Re-reading my earlier comments, perhaps I didn't explain this very well. (My point was whatever they did or did not do wrong, it doesn't mean the time interval was a violation of the protocols or had they done proper testing and their information still the same, would the time interval have come under criticism from experts at the time.)

I also can't find any suggestion topical application was necessary or recommended (I'm not saying it wouldn't have helped). My impression from the blog comment and what I know suggests there are far better ways to test the drug which I had presumed they'd done but evidentally hadn't.

Nil Einne (talk) 14:59, 26 April 2010 (UTC)

Perhaps the X-linked severe combined immunodeficiency gene therapy trial? Or less likely the gene therapy trial that killed Jesse Gelsinger. 75.41.110.200 (talk) 06:40, 3 December 2009 (UTC)

Yes, that's it. Thanks! A Quest For Knowledge (talk) 23:44, 3 December 2009 (UTC)

Butterfly sensation from infatuation.

There's a girl I've recently become infatuated with and I think she reciprocates my affections at least to some degree. Sometimes, I'll go many minutes without thinking of her and then suddenly, in a flash, I'll remember her-- infectious laughter, her supple contour, her stellar character, her daring wit, & her infinite, limpid, brown eyes... Accompanying these thoughts, I often experience a sinking sensation in my stomach or heart -- butterflies, I think it's sometimes called. What is the cause of this delicious sinking feeling? What are the biological and physical reasons for it? —Preceding unsigned comment added by 66.210.182.8 (talk) 05:41, 3 December 2009 (UTC)

Wikipedia has an article on everything. Looking at that article, it seems that the main component is due to anxiety, possibly due to adrenalin. Vimescarrot (talk) 09:52, 3 December 2009 (UTC)

and good luck! --pma (talk) 13:31, 3 December 2009 (UTC)

Well, we really ought to have an article on the neurobiology of love; there is enough of a literature. In the absence of an article, here is a pointer to a recent paper with a lot of information, a bit technical though. Looie496 (talk) 17:22, 3 December 2009 (UTC)

Also Esch, Tobias (2005). "The Neurobiology of Love" (PDF). Neuroendocrinology Letters. 3 (26). {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help) Fences&Windows 23:25, 3 December 2009 (UTC)

And a video about how the key to love is oxytocin. Fences&Windows 23:29, 3 December 2009 (UTC)

This would somewhat overlap the existing article on limerence. 67.117.130.175 (talk) 06:58, 4 December 2009 (UTC)

Physical fallacies

Hi, I posted this question about speed of light calculations few months ago. Is there an article discussing such physical fallacies? If yes, can anyone volunteer to explain where the wrong use of physical laws was made in that website? I think such information should have the same interest as has been done to mathematical fallacy article.--Email4mobile (talk) 09:26, 3 December 2009 (UTC)

It seems to me you got a good answer last time. What else do you want to know? Second the paragraph "Variable Speed of Light" is not true. Not at all. It's completely contrary to the theory of relativity. And third scientists have NOT confirmed the existence of Dark Energy. Why do you want to learn anything at all from a website that does not understand science? If you want to theorize on changes to science go for it. But don't think for a second that what they say is correct by current theories. Unlike some, I don't mind speculating on changes to current thinking (historically the accepted scientific thinking of the day has been wrong quite often, I see no reason to believe we are in a unique period today) - but it's always important to note when your speculations differ from current understanding. Ariel. (talk) 11:07, 3 December 2009 (UTC)

I agree with Ariel, it is usually pretty pointless entering a scientific discussion with fundamentalists. The fundamentalist position starts from the premise that all truth emanates from their holy book (of whatever religion). It is intolerable to them that anyone else can obtain "truth" from another source, hence the strong desire to "prove" that their holy reference manual contains that truth, though it was previously somehow overlooked by everyone. I guarantee that no-one has previously interpreted that passage in the Koran as meaning the speed of light until long after science came up with an accurate measurement of it. Science starts from a radically different position, and mutually incompatible with the fundamentalist view. The scientific position is that truth (the laws of nature) is the simplest possible interpretation consistent with the experimetal results. This means that science will modify its laws in the light of new evidence. The fundamentalist can never do this, contradictory evidence will only cause the reasoning to become ever more contrived in order to make the holy book remain true.

I like the postulate on that site that Angels travel at the speed of light. If that is true, it means they are inside our own light cone and exist in our universe, not in some other ethereal existence. In principle then, they are scientifically detectable - but it is strange that no experiment, so far, has found them. SpinningSpark 14:03, 3 December 2009 (UTC)

Perhaps, but then we have never found any dark matter either. Googlemeister (talk) 14:22, 3 December 2009 (UTC)

Angels are photons, God is a singularity, and Satan is the heat death of the universe. Fences&Windows 14:31, 3 December 2009 (UTC)

That analogy doesn't work. In christian and jewish versions of the story, Satan is an angel who "turns to the dark side". I don't see how the heat death of the universe is also analogous to a photon. The information content of a singularity is restricted to it's mass and maybe it's spin...doesn't bode well for something that's supposed to be all-knowing and therefore containing an infinite amount of information!

Anyway - these kinds of websites are nonsense. It's very easy to come up with similar nonsense - it doesn't prove anything - the best you can do is ignore them. You can find approximate coincidences in ratios of numbers everywhere - it doesn't prove anything. Precise relationships are more interesting - but even then may not mean much. Let's look at one "fact" from that page:

"But 1400 years ago it was stated in the Quran (Koran, the book of Islam) that angels travel in one day the same distance that the moon travels in 1000 lunar years, that is, 12000 Lunar Orbits / Earth Day. Outside the gravitational field of the sun 12000 Lunar Orbits / Earth Day turned out to be the local speed of light!!!" - Well, how far does the moon travel in 1000 "lunar years"? What the heck is a "lunar year" anyway? If it's the time it takes the moon to orbit the sun - then that's almost exactly the same as a regular year - and the distance the moon travels over that time (relative to the earth) is 1.022km/s x 1000 x 365.25 x 24 x 60 x 60 = 32,251,000,000km - the distance light travels in a day is 1,079,000,000 km/hr x 24 = 25,896,000,000 km. So these supposed angels are travelling at about 25% faster than the speed of light. I'm not sure what the gravitational field of the sun has to do with it - the speed of light is constant and the sun's gravity can't change that, it can distort time a bit - but nothing like 25%. Now, you might consider the distance travelled by the moon relative to the sun...that's a bit tougher to calculate but it's got to be a lot more than it moves relative to the earth - so that just makes the situation worse. So this guy has an error of 25% in his calculations - that's simply not acceptable in any kind of scientific argument. The errors in our measurements of the speed of light and the speed of the moon are tiny TINY fractions of a percent. So this argument must be incorrect...period. SteveBaker (talk) 17:43, 3 December 2009 (UTC)

Not really related, but satan in jewish thought is NOT an angel that went to the dark side. Stan is more akin to a prosecutor, who works for god, has no free will! Ariel. (talk) 20:19, 3 December 2009 (UTC)

While I agree with Steve's overall sentiment, he is a bit overzealous with regard to numerical accuracy in astrophysics. For a lot of parameters, 25% error is acceptable in astrophysics... for example, look at some of the tolerances on the parameters of a typical exoplanet, CoRoT Exo B, as documented by the ESA. Its density is quoted with a 30% error bar. I've seen much more speculative numbers with worse uncertainty in other publications. Stellar physics publications are lucky if they can estimate some numbers to within a factor of 10. But these parameters are not the speed of light, which is well known to better than one part in a billion. In general, a "high level of accuracy" is context-specific. In any case, the above argument is making an outlandish claim, so a greater burden of proof is in order. While I can stomach a 50% uncertainty about whether an exoplanet is iron- or silicate-core, I don't have the same tolerance for the "angels are photons" argument. Because those claims are much more unbelievable, I would expect a much higher standard of accuracy before giving them even the slightest little bit of credibility. I guess my point can be summarized as follows: the above claims are false - but not simply because the numerical error is very large. Numerical error is acceptable, if the scientific claims are qualitatively correct. The above claims about "lunar years" are simply wrong, so it's useless to even bother analyzing their accuracy. Nimur (talk) 17:52, 3 December 2009 (UTC)

No, I'm not being overzealous. Errors that big are acceptable only when the data you're working from has error bars that big. The error bar on the speed of light is a very small fraction of a percent - and so is the speed of the moon, the length of a year and all of the other things that made up that calculation. The numbers I calculated for the distance travelled by the moon over 1000 years and the distance travelled by light in a day are accurate to within perhaps one part in a thousand. The discrepancy between them is 25%!! There is no way that those numbers back up that hypothesis - and no respectable scientist would say otherwise. Since our confidence in the speed of the moon, etc is very high - the hypothesis that the Koraan is correct about the nature of angels is busted. It flat out cannot be true. (Well, technically - the number "1000 years" has unspecified precision. I suppose that if the proponents of this theory are saying "1000 years plus or minus 50%" and therefore only quoting the number to one significant digit - then perhaps we have to grant that it is possible (not plausible - but possible). But I'm pretty darned certain that the proponents of this theory would tell us that when this holy book say 1000 - it means 1000.0000000000000000000000...not 803.2 - which would be the number required to make the hypothesis look a little more credible! Hence, probably, the necessity of muddying the water by dragging the sun's gravitational field into the fray - the hope being that anyone who tries the naive calculation above can be bamboozled into accepting the result as being 100% correct once general relativity has been accounted for...but sadly, that's not the case because none of the bits of the solar system involved are moving anything like fast enough relative to each other and the sun's gravitational field simply isn't that great.) SteveBaker (talk) 18:26, 3 December 2009 (UTC)

For the purposes of establishing the actual facts of this claim, I looked up the quoted passage and got;

He regulates the affair from the heaven to the earth; then shall it ascend to Him in a day the measure of which is a thousand years of what you count. (The Adoration 32:5)

I was going to post just the quote and leave it at that. However, I was intrigued by the lack of mention of the moon in the passage, or indeed, in the entire book (or chapter or whatever the Koran calls its subdivisions). Apparently we must read "the measure of what you count" as meaning a lunar year. So looking a bit further I found this;

To Him ascend the angels and the Spirit in a day the measure of which is fifty thousand years. (The Ways of Ascent 70:4)

Sooo, to be consistent we must interpret that the same way and now have angels travelling at 50C, and if the interpretation that angels travel at the speed of light or slower is to be maintained we must conclude that the Koran would have the speed of light to be at least 1.5x10¹⁰. I think that pretty much rules out the Koran as a potential reliable source for Wikipedia purposes. SpinningSpark 19:07, 3 December 2009 (UTC)

At the core of the issue, it's difficult/impossible to assess the scientific merits of an unscientific line of reasoning. This theory, and others like it, are very inconsistent, are not based on empirical observation, and do not draw logical conclusions from experimental data. Therefore any assertions that it makes are categorically unscientific. It doesn't matter what the error-bars are on its numeric results. A lot of numerology finds exact values via convoluted procedures. That "accuracy" does not mean the methods are sound or scientific. In the same way, the inaccuracy of the above numbers is irrelevant - the method is simply wrong. Nimur (talk) 19:09, 3 December 2009 (UTC)

Also, I object to SpinningSpark's comment, "that pretty much rules out the Koran as a potential reliable source for Wikipedia purposes." The Koran is a reliable source for information about Islam'. It is a very reliable source for Wikipedia's purposes when those purposes are related to Islam. It'd be hard to find a more reliable source for our article about Islam, for example. But, the Quran is not a scientific book, and sourcing scientific claims from it would be invalid. Since this is the science desk, we should never source our references from the Quran or any other "holy book;" nor should we source scientific claims from history books, poetry books, or other non-scientific references. However, that doesn't mean that these are unreliable sources - it's just the wrong source for the Science Desk or science-related issues. Nimur (talk) 19:16, 3 December 2009 (UTC)

Quite so, I had intended to qualify that with "...for scientific articles" or some such, but typed the more general "Wikipedia" instead. SpinningSpark 19:32, 3 December 2009 (UTC)

On second thoughts, no you cannot use the Koran as a reliable source about Islam, at least not on its own. The only thing it is a reliable source for is what the Koran says. SpinningSpark 09:03, 4 December 2009 (UTC)

The issue is not that people believe the Quran - that's entirely their own problem - it's that some people are attempting to portray what it says as somehow reliably relevant and applicable to modern science. Plainly, it's not...or at least not as that website explains it. But if he can't get his science right and he can't quote the Quran accurately then it's really no use to anyone. SteveBaker (talk) 19:44, 3 December 2009 (UTC)

A lunar year is 12 lunar months, which is about 354 days. That makes it a little closer than your calculation gave, but not by much. --Tango (talk) 22:37, 3 December 2009 (UTC)

Well, I'm an Arab and Muslim too; though I don't believe for any reason to connect between religion and Science. Unfortunately many Muslims believe. I'm afraid to say the one who tried to prove this fallacy was originally a professor as I heard. If I were just an engineer then how could I convince so may people who are spreading such information not only in that website but in the schools and universities. How can they believe me such information are totally mess unless I can verify that from reliable sources and I believe in Wikipedia because it either gives reliable sources or proofs. On the one hand, I still believe this problem is not just in Muslim countries but almost all religions have some extremist who would like to convince others by any means. Anyhow thank you very much for this wonderful interaction.--Email4mobile (talk) 20:38, 3 December 2009 (UTC)

I agree - it's certainly not just the Quran that makes these kinds of error. The Christian bible says that Pi is 3 and that bats are a species of bird. This is what happens when you try to take written material that's several thousands of years old and apply it to everything we've learned in the meantime. The fact is that we shouldn't expect this stuff to be halfway reasonable - the problem isn't the books - it's that people are still trying to apply it to modern situations. SteveBaker (talk) 00:53, 4 December 2009 (UTC)

Steve, I know you're not a big fan of the Bible, fine, but don't say nonsense about it. Nowhere does it say pi is 3. It says someone made a "molten of sea" that was 10 cubits across and 30 cubits round about. From there to "pi==3" there are a couple of large logical jumps. --Trovatore (talk) 00:59, 4 December 2009 (UTC)

The argument Steve mentions has indeed been made, but its main flaw (it seems to me) is to assume that exactly 10 and 30 (i.e. 10.0 and 30.0) cubits were meant. If the figures were actually rounded to the nearest cubit, which seems perfectly reasonable in the context, then the description is entirely consistent with the true value of pi: for example, 9⅔ and 30⅓ would come very close at 3.138. 87.81.230.195 (talk) 02:16, 4 December 2009 (UTC)

But that's the point! Did they mean 1000 lunar years or did they mean 1000 lunar years to one significant digit just like the "molten of sea" thing? If they really meant 803 lunar years - rounded to the nearest 1000...then this is indeed a valid "prediction" of the fastest speed anything can possibly move. But was it ever intended as a prediction of relativity? My bet is no. No more than the Bible is talking about geometry of circles. We're generally lead to believe that the words in these books are to be taken "as gospel". But we can't judge that by modern standards. Nobody measured the speed of an angel or the circumference of the "molten of sea" thing to modern precision levels. We must avoid dual-standard here. It's precisely as wrong to claim that the Quran predicts the speed of light as it is that the Bible predicts the value of pi - neither of those things were ever intended by the original authors - it's just modern hindsight trying to extract miracles where there is nothing but simple literary verbiage that's been blown out of all proportion. (Although it is pretty clear on that bat==bird thing - and on a whole bunch of other biological 'oopsies' in the dietary laws.) SteveBaker (talk) 04:08, 4 December 2009 (UTC)

What's the error with the bat bird thing? You define bird as creature with feathers. The bible doesn't, it defines the word in hebrew that is commonly translated as bird, as flying creature. During creation for example it even says flying creature[7][8]. And a bat flies, so what's the problem? And complaining about the basin is really stupid, since that part isn't even the word of god - it was a person recording what he saw - the basin was a physical object. You can't argue with that any more or any less than any other ancient document. And for the record the speed of light thing is nonsense. Ariel. (talk) 05:02, 4 December 2009 (UTC)

There seems to be some cherry picking going on here. My King James bible says,

And God said, Let the waters bring forth abundantly the moving creature that hath life, and fowl that may fly above the earth in the open firmament of heaven. (Genesis 1:20)

The American Standard Version does not say flying creature either. SpinningSpark 13:58, 4 December 2009 (UTC)

Back to Steve: A Lunar year is a year in the lunar calendar, i.e. in this case likely the Islamic calendar. It consist of 12 lunar months, i.e. 354 or 355 days, depending on how the fractions work out. That's how the original author arrives at the 12000 (12 months times 1000 years). So the error is about 3 percentage points worse than your result. --Stephan Schulz (talk) 20:50, 3 December 2009 (UTC)

Yes, Stephan, I think I've already mentioned that in the previous discussion but not sure it SteveBaker noticed that. To me I've accepted this step of calculations but was surprised when he again used another kind of conversions to achieve cos(26.92952225^o) in order to reach 0.01% error. That was the point I wanted to swallow, but couldn't understand how (See the details here).--Email4mobile (talk) 21:02, 3 December 2009 (UTC)

Apart from that other verse talking about 50,000 years a day, let's first verify the 1000 years a day calculation, Spinningspark.--Email4mobile (talk) 21:21, 3 December 2009 (UTC)

Lines of little circles of light on camera

How come when a camera shoots something very bright like a brief shot of the sun, you often see little circles, usually as if they were strung together along a line? 20.137.18.50 (talk) 12:56, 3 December 2009 (UTC)

See lens flare. Gandalf61 (talk) 13:01, 3 December 2009 (UTC)

It's caused by light reflecting back and forth between the surfaces of the lenses. Cameras with high quality lenses don't do it nearly so much. The dots you see in the 'flare' aren't always circles - sometimes they are pentagonal or hexagonal. In this photo they seem to be 7-sided. SteveBaker (talk) 17:16, 3 December 2009 (UTC)

Fixed your link. APL (talk) 17:22, 3 December 2009 (UTC)

Almost certainly images of the leaves of the lens aperture. See bokeh. --Phil Holmes (talk) 09:54, 4 December 2009 (UTC)

Rainbow ham?

What I'm talking about

What causes the rainbow color that I sometimes see in ham and other cured meats? This says it's a "chemical reaction" (not telling much more), this says it's birefringence, which is a nicer word, but our article on birefringence doesn't mention this effect at all. (If it is birefringence, this is probably one of the most common effects of birefringence encountered in the typical life of citizens of the western world. Probably deserves a mention.) Staecker (talk) 17:35, 3 December 2009 (UTC)

A lot of cured meats are soaked in a brine, saline solution, or other liquid to add volume and flavor to them. The birefringence or other optical effects are often the result of these saline liquids suspended in the interstitial spaces of the meat. Nimur (talk) 17:46, 3 December 2009 (UTC)

There are several possibilities - one is that we're seeing an "oil on water" effect because oils from the meat are mixing with water - another is that we're seeing some kind of Dichroism effect - yet another is some kind of coherent scattering - similar to the thing that makes the colorless scales of a butterfly's wing show up in such vivid, iridescent colors. There are a lot of related effects and this could easily be any one of them - or even some complicated combination of them. Without some kind of expert study - I don't think we should speculate. SteveBaker (talk) 18:07, 3 December 2009 (UTC)

We can, however, point to prior research, e.g. Prediction of texture and colour of dry-cured ham by visible and near infrared spectroscopy using a fiber optic probe, Journal of Meat Science, 2005. Virtually everything that can possibly be observed, and many things that can't, has already been studied and published somewhere. Nimur (talk) 18:10, 3 December 2009 (UTC)

Darn! How did I miss that? I'm such an avid reader of the Journal of Meat Science! SteveBaker (talk) 19:38, 3 December 2009 (UTC)

Does such a disease exist?

Is there a disease where the neurons of the brain spontaneously form synapses with all their neighboring neurons at an accelerated rate, essentially forming one very deeply interconnected mess? 20.137.18.50 (talk) 18:27, 3 December 2009 (UTC)

Never heard of anything like that. If there were a mutation that did that, it seems likely to me that it would be fatal at a pretty early stage of embryonic development. Looie496 (talk) 20:41, 3 December 2009 (UTC)

Relevant articles are Synaptogenesis and Synaptic pruning. Landau–Kleffner syndrome and continuous spikes and waves during slow sleep syndrome, related to epilepsy, both involve too much synaptogenesis during childhood due to electrical activity that strengthens the synapses.[9] Fences&Windows 23:12, 3 December 2009 (UTC)

There is a great variety of proteins that participate in axonal guidance and/or affect synaptogenesis. See, for example, FMR1, Thrombospondin, semaphorins, and Amyloid precursor protein. I am not familiar with the specific pathology you refer to, though. --Dr Dima (talk) 00:48, 4 December 2009 (UTC)

cheesewring stones

It does not say in the article, but is the Cheesewring a natural formation, or is it man made like Stonehenge? Googlemeister (talk) 20:26, 3 December 2009 (UTC)

Looks natural to me. In southern Arizona there are hundreds of rock formations that look like that -- made of sandstone rather than granite though. Looie496 (talk) 20:37, 3 December 2009 (UTC)

The article states "Geological formation" which implies natural rather than man made source. In Southwestern Utah there are formations called Hoodoos (you've seen them in the old Wile E. Coyote cartoons). Geology + psychology is capable of some remarkable looking formations. I remember taking some college friends to Northern New Hampshire to see the Old Man of the Mountain (RIP), and they kept asking "No really, who carved that? Was it the Indians?" I kept trying to tell them it was just a natural formation. Other fun natural formations which have been mistaken for manmade include the Giant's Causeway in Ireland, the Pingos of northern Canada, the Badlands Guardian of Alberta, the Cydonia face on Mars, etc. --Jayron32 21:07, 3 December 2009 (UTC)

Apparently we are lucky that it still exists. Looie496 (talk) 21:22, 3 December 2009 (UTC)

For interest, there is currently an artist in the UK who makes somewhat similar, though smaller, piles of rocks on public beaches, often featuring apparently impossible balancing. Google-searching turns up the name Ray Tomes who has done something similar but I don't think he's the artist I have previously encountered. 87.81.230.195 (talk) 02:00, 4 December 2009 (UTC)

I think you might be referring to Andy Goldsworthy. Richard Avery (talk) 10:30, 5 December 2009 (UTC)

Idol rock

Speaking of apparently impossible balancing, I have seen a lot of amazing stuff in Utah, but nothing as amazing as the picture on the right. Looie496 (talk) 17:52, 4 December 2009 (UTC)

Yes, the strength of that Millstone grit at Brimham Rocks is remarkable. This shape is supposed to be a result of natural sand-blasting of the somewhat softer layer at the base. Mikenorton (talk) 13:26, 5 December 2009 (UTC)

The Cheesewring is a rather extreme example of a tor, a type of rock outcrop that typically forms in granite. They are a result of weathering, which has acted particularly on pre-existing sub-horizontal joints to produce the unlikely shape (see Haytor for a less extreme example). Mikenorton (talk) 11:06, 4 December 2009 (UTC)

North Korea's closed-circuit speaker system

In this article and at least one other at the Wall Street Journal, they say that the North Korean authorities notified the citizenry of the replacement of the North Korean won by means of "a closed-circuit system that feeds into speakers in homes and on streets, but that can't be monitored outside North Korea."

Speakers in homes? Really? Do we have a Wikipedia article on this system? Is this cable TV but without the TV? How many homes are equipped with this technology? I have a raft of questions. Tempshill (talk) 21:54, 3 December 2009 (UTC)

Is this science? Anyhow... from the New York Times: "Every North Korean home has a speaker on the wall. This functions as a radio with just one station -- the voice of the Government -- and in rural areas speakers are hooked up outside so that peasants can toil to the top 40 propaganda slogans. Some of the speakers are hooked directly into the electrical wiring, so that residents have no way of turning them off; they get up when the broadcasts begin and go to sleep when the propaganda stops. In some homes, however, the speakers have a plug, and people pull the plug when they want some quiet."[10] Just like in 1984. Something similar but less scary in Australia: "loudspeakers are sprouting like mushrooms on Sydney streets, peering down from the tops of traffic lights. The State Government has begun to put in place a permanent public address network that will, in some unspecified emergency, tell people what to do."[11] Fences&Windows 22:47, 3 December 2009 (UTC)

You might find this: [12] link interesting. It has a photo of a similar hard wired radio(?) in russia. Ariel. (talk) 00:03, 4 December 2009 (UTC)

Back in the 70s and 80s -- and probably well before that -- there was a ubiquitous contraption called "radiotochka" (radio spot) in the USSR households. IIRC the radio signal was transmitted via the electric wires of the power grid and not by air. I do not know how the signal was modulated, but I am pretty sure it was separated in frequency from the 50 Hz AC current the wires were carrying. There was only one station. Yes, it was government-controlled, but so was the TV, anyway; and it could be turned off or unplugged any time you like, of course :) . I doubt it that it transmitted anything back, but in principle I guess it could double as a bug for the bolsheviks to eavesdrop on you. --Dr Dima (talk) 00:08, 4 December 2009 (UTC)

(I haven't seen Ariel's post when I edited mine, but I didn't get the EC screen either. Weird.) anyway, Ariel, yes, that's it in the picture. It had one station only, though, not three; or maybe it had three in some places. Or maybe the other two were added after I emigrated :). --Dr Dima (talk) 00:13, 4 December 2009 (UTC)

Would you mind creating an article on it? It's ok if you don't know everything about it, just get it started and put in what you do know. (I know nothing about it. But maybe I can ask the person who posted the photo to contribute.) Ariel. (talk) 00:34, 4 December 2009 (UTC)

Last time I've seen a radiotochka was about 20 years ago. I do not think my memory from back then is accurate enough for me to write a Wikipedia article about it now. Sorry. --Dr Dima (talk) 01:07, 4 December 2009 (UTC)

I don't think it's that weird. The software is getting better and better at resolving edit conflicts. It's obviously fairly annoying for editors when you make extensive edits to a page (or even fairly minor but spread out ones) and have an edit conflict then have to resolve that then try again and have another conflict etc. Particularly a problem for high traffic pages. I'm not sure but it's also possible that this page is treated like an article and the software is more fussy on talk pages in recognition of the fact that edit conflicts could in some instances lead to confusing discussions. This is of course the kind of thing that people don't tend to notice since unless you actually get an edit conflict, you may not realise people have edited while you were editing. But to use an example I just encountered see [13]. I didn't actually look at the time when I started editing but I'm pretty sure it was before the 2 Madman2001 edits maybe even before the Derlinus. These where not that hard to resolve for the software, but I strongly suspect several years ago I would have gotten an EC Nil Einne (talk) 07:09, 5 December 2009 (UTC)

Incidentally, there was a similar device in use in the 1950's in the US. It was to be used for civil defense, and would also get the signal through the electrical wiring. It would be always left on to sound the alarm in an emergency (even if the homeowners had the radio and TV turned off). It never really caught on, though, and the plan was canceled after a few years. StuRat (talk) 05:44, 4 December 2009 (UTC)

That US device was on a History's Mysteries segment I saw a week or two ago. Clever device, tested and worked for transmitting an alarm. But the system was scrapped when they recognized that there was just the alarm, no ensuing instructions on how to respond to the situation. DMacks (talk) 07:34, 4 December 2009 (UTC)

Correction: History Detectives. The webpage for that segment might have some good information for an article about this type of system. DMacks (talk) 07:52, 4 December 2009 (UTC)

For example, National Emergency Alarm Repeater. DMacks (talk) 07:54, 4 December 2009 (UTC)

In some places in the U.S. the emergency sirens can broadcast announcements as well as their really annoying screech. Which would be useful if that tornado ever happens to come at 1 o'clock on the first Saturday of any month (monthly system test time). Rmhermen (talk) 14:44, 4 December 2009 (UTC)

Thanks for the responses - I'll add "radiotchka" to Wikipedia:Requested articles. Tempshill (talk) 07:25, 5 December 2009 (UTC)

See also http://en.wikipedia.org/wiki/Cable_radio !

The system in NK is so pervasive it's also on trains. According to some references I read in 1970's NK books about the Great and Beloved Leaders, as a matter of course there was a tiny audio studio with a human speaker in every train. If radio is so mistrusted, this might well still be the case today.

Czechoslovakia had a nationwide PA system. It was used rather sparingly under communism. After all, everybody had radios and listened to western media anyway, they were definitely not completely shut out. Right after the Velvet Revolution it became a sort of public access system: you could informally ask authorities to let you tell people of innocuous community things like concerts or village parties. I don't know if the system is up yet and if it's being used.

The radiotochka system in Russia is better understood as a soft propaganda medium with a general interest program, more soothing than hypnotizing or inflammatory. It was not necessarily a wire system, and was generally radio-delivered over long distances, with often less than the last mile by wire. End-receivers in homes and offices had volume control. Very similar to local cable TV systems fed by satellite. You still find plenty of old, good quality, semi-professional broadcast receivers that were used to get a signal off the air and pipe it into wires. AFAIK it was not necessarily a single channel system either. Places like hotels, resorts etc. had a selection of channels. The main radio channel was indeed also put on the PA all day in many places of manual work, not totally unlike Muzak in the US or BRMB in Birmingham, but it did provide a degree of entertainment. After the fall of Communism many factories turned the system off - and there are reports that some workers complained. I wish someone could update us on that, and clarified whether there was ANY degree of wire transport other than from a local building/neighborhood/resort media office.

Switzerland pioneered audio wire-casting as cheaper-than-FM radio way of delivering the national radio and TV audio channels, and some extra contents, at medium-fidelity (up to 7kHz) into all tiny valleys: NF–TR = Niederfrequenz-Telefonrundspruch. It worked with AM carriers over phone wires in the frequency range where DSL now travels. The service was discontinued in the late 1980's. http://de.wikipedia.org/wiki/Telefonrundspruch

Italy still has a similar system called "filodiffusione" - literally wire-distribution.

http://it.wikipedia.org/wiki/Filodiffusione

http://www.radio.rai.it/filodiffusione/index.htm

It carries 6 channels, all from the national broadcaster RAI: three national on-air radio channels, plus one for light music, and 2 (stereo) for classical, with audio up to 10kHz, delivered by the quasi-monopolist Telecom Italia. On any given line if DLS is activated, wirecasting can't work. It is a pay-for system, the two wire-only programs are advertising free. Before the advent of private FM radio, satellite, and then internet, "filodiffusione" was often piped into retail outlets and sometimes in offices, just like Muzak.

As I personally don't care for music or stereo, I modded an early 1970's Italian filodiffusione receiver as a mono amplified computer speaker. It's the size of a large bible set on its side, and looks much like a larger mains-powered transistor radio from that period. It was used for some 15 years in an office.

I removed the radio-frequency board, which contained six separate sets of a 2 RF resonating circuits, one per channel, and two AM infinite-impedance (transistor) detectors - one for channels 1-5, the other for channel 6 only. Channels were selected by pushbuttons. For stereo you would press 5 and 6 together, and a complicated mechanism ensured that only the last 2 buttons could be depressed at the same time.

I left only the power supply and the audio amplifier with volume and tone controls. The unit contains a single mono audio amp and one speaker for receiving the 4 mono channels and the 2 stereo channels mixed into mono. A a line-level audio output socked was provided to feed audio from the two separate detectors to an external stereo amp.

It's the speaker connected to the PC I am writing from - I have a radiotochka right on my desk!

Spamhog (talk) 11:00, 25 May 2010 (UTC)

Environmental Impact of ebooks vs paper books

I've seen some e-book distributors advertising ebooks as environmentally friendlier than the 'dead tree' version. On the face of it this seemed reasonable; no trees, no chemicals for paper and ink making, no distribution of heavy books, no bricks and mortar stores (and all the energy to run them), but then I started thinking about the computing required to deliver ebooks. So, which is more environmentally friendly? I'll leave it to you to decide how much of the production / distribution / consumption chain to include, also what constitutes 'environmentally friendly'. Scrotal3838 (talk) 22:02, 3 December 2009 (UTC)

Hmm well this page and this page outline some perceived problems with paper. See also Pulp (paper). On the other hand Electronic waste is often portrayed as being bad fairly serious, and factories that produce Kindles or computers or whatever of course also pollute. On the balance, however, I'd say that electronic distribution is much more environmentally friendly. It could (theoretically) replace a huge amount of printed material, and I just don't think there's any way the pollution generated making a kindle could add up to the pollution generated making a piece of paper for every page a kindle electronically displays. As far as energy to run servers and the devices themselves, I really doubt you could quantify ebooks as being anything but a marginal energy use. I don't see why ebook distribution would take up any more energy than a regular website, which on an energy per unit of information basis is extremely efficient.

However, the argument should be taken with a grain of salt, in my opinion. People were predicting similar improvements with the advent of email replacing memos. But paper use over the period when email became widespread increased, due to it being much easier to produce documents with modern printers and (ironically?) people printing out their work emails to have a paper copy. I forget where I read that last bit, I think it was in the Economist. Regardless, I think ebooks could be portrayed as better for the environment if it can be demonstrated that the user in fact uses less paper, and doesn't just use the same amount of paper and an electronic device that has an environmental impact in its creation, operation and disposal. TastyCakes (talk) 23:26, 3 December 2009 (UTC)

To read an ebook you need to turn your computer on (assuming it was off), and that requires electric power which consumes energy producing CO2, CO, NO, NO2, SO2, etc... Dauto (talk) 01:50, 4 December 2009 (UTC)

Well first, you might live in an area that gets its electricity from hydro or nuclear or some other generator that doesn't produce pollution. And second, turning wood into paper requires significant electricity as well, along with chemicals and the logging of forests. And then you have to fuel the trucks that distribute books and other paper to stores or distribution centres, which also uses energy and produce pollution. I don't think anyone would argue that ebooks have zero environmental consequences. But again, taking everything in account it looks like they have less impact that printed books, which was the question. TastyCakes (talk) 02:43, 4 December 2009 (UTC)

I don't think there is much doubt that this is not a question of energy use. After all, the Kindle runs for a heck of a long time on battery power - and the 60 watt light bulb you are reading it by is consuming at least 100 times more energy than the eBook itself. It's more a question of environmental damage during manufacture and ultimate disposal. That comes down to how long books and eBook readers last. Books seem to be almost immortal. I don't think I know anyone who throws them away...it seems almost sacrilegious to do so - and burning a book is just such a taboo (especially for Ray Bradbury fans!) that I doubt anyone does it routinely. However, if eBook readers are going to be regularly obsoleted like laptops and fancy phones are - with a lifetime of just a few year - then dumped onto landfills - then we can probably say that the eBook is doing more environmental damage. Paper books lock in carbon - and if you dump them into landfill, the compost nicely and their carbon is sequestered - that's a net win if the manufacturing process wasn't too nasty. Most books are read by many people before they eventually go wherever it is they go. Since an eBook player has no moving parts (well, except, perhaps for the switches) - it could last a long time. If they aren't obsoleted, then all likelyhood, the battery will be the thing that finally kills them. Most batteries die because their lives get shorter and shorter over the years - and that's a real problem for an eBook which really needs to be cable-free and to run for MANY hours without a recharge. If things settle down enough technologically - and the battery life is good enough - then perhaps there is a chance of the eBook being a better choice - but I kinda doubt it right now.

(Dear Santa: Steve would like a Kindle for Xmas please - I have carefully sequestered the lump of carbon you sent me last year.)

SteveBaker (talk) 03:49, 4 December 2009 (UTC)

Who uses a 60 watt light bulb to read? A 15W or even 12W or heck even 8W CFL does fine Nil Einne (talk) 08:23, 4 December 2009 (UTC)

OK - even an 8W CFL uses vastly more power than a Kindle. The beautiful thing about ePaper is that the image stays there when you remove the power source. Hence a well-designed ePaper based eBook reader can turn itself completely off and consume literally zero power while you're actually reading. You wake it up by pushing a button to turn the page or something - the on-board computer grabs the next page, formats it, sends it to the ePaper - then turns itself off again about a tenth of a second later. They use truly microscopic amounts of power when you are using them as intended. Of course if you surf the web with them using the wireless link or continually flip back and forth between pages - then it's going to eat more power - but for simply reading a novel or something - their power consumption is almost completely negligable. SteveBaker (talk) 19:18, 4 December 2009 (UTC)

Also, how many of us read ebooks with the Kindle? I had never even heard of it. Most people will use a desktop computer or a laptop and these consume more energy than the Kindle. Most people don't turn the lights off when using a computer either so there realy isn't any savings. Finally, the environmental cost for the production of a paper book happens only once while the power consumption for reading an ebook happens every time you read it. 169.139.217.77 (talk) 14:27, 4 December 2009 (UTC)

See Amazon Kindle and electronic paper. It is true, at this point Kindle and other electronic paper readers have a negligible share of the overall book market. But the real question is whether the average Kindle owner's paper "usage" goes down enough to offset how much environmental damage the Kindle does through its creation, use and disposal. I don't know the numbers (I'm not sure anyone does), so I'll make them up to explain. Say the production of a kindle produces the same "environmental impact" or "environmental footprint" or whatever as 1000 books. I don't know if that's an accurate number or not. But if the owner of the Kindle only reads 100 books on the Kindle over the course of its life, the Kindle has not been better for the environment than the paper equivalent. If, however, they read 5000 books, it is a great improvement. As I state above, I suspect, on average, the Kindle is better for the environment than its paper equivalent over the course of its life, but that is just from a vague feeling of how much damage the paper industry causes compared to the electronic industry. TastyCakes (talk) 17:41, 4 December 2009 (UTC)

I'd like to agree with you - but the niggling problem I have is that paper books are often read by multiple people - when I'm done reading with my books, I either lend them to other people to read - or take them to my local "Half Price Books" store and sell them - or I give them away to some local charity or something. I can't ever recall tossing a book into the trash. Most of the books I read are second hand anyway - so I think it's possible that a typical book is read maybe a dozen times before it finally falls apart or something. That skews things in favor of paper books. If we assume that an average Kindle is used to read 1000 books (that seems like a very high number to me) - then if paper books are each read by 10 different people (or even by the same person 10 times) - then the Kindle has to be more environmentally friendly than 100 paper books - not 1000. I can't help suspecting that the average Kindle will only last at most maybe 10 years...probably more like 5. SteveBaker (talk) 19:18, 4 December 2009 (UTC)

Hmm that's true, multiple readers are left out on my simplistic calculation. And there is the added complication that the Barnes & Noble Nook allows users to lend e-books to others and this capability could become the norm. I guess the easiest (and fairest?) way to measure it would be if electronic readers became more commonplace (say, 10% of the market for new books) and then measure how much paper production per capita decreases in the same market over the same period. Then if you could get a reasonable estimate of how long the average Kindle will last (or how long until its obsolescence) you could estimate how much paper the average Kindle displaces over its lifetime. Of course that's making the big assumption that ebook readers are the only thing affecting paper sales per capita over that period, and it seems likely that a greater percentage of people will read a greater percentage of things on phones, computers and PCs over the same period... TastyCakes (talk) 01:27, 5 December 2009 (UTC)

Why would it so bad to take the carbon from trees and store it in a form (paper) that won't contribute to CO2 percentage for probably hundreds of years? I never understood why transforming trees to stored carbon should be bad, as long as trees are grown again afterwards. ----Ayacop (talk) 18:07, 4 December 2009 (UTC)

Oh that's not bad - it's good. But the environmental impact of printing a paper book is a lot more than just the wood pulp it's made from (which - as you say - is a positive benefit to the environment because it's sequestering carbon). But making paper from wood pulp requires diesel fuel to power the lumber trucks, gasoline for chainsaws, electricity for the pulp-making machine, water (lots of it). Most paper is also bleached - presumably with some nasty toxic chemicals. The ink is laced with antimony and other nasty heavy metals. There is glue in the binding. Many paperback thrillers have the title embossed and coated with a thin metal foil. More gasoline is burned in getting the book from the printer to the bookstore - and for the eventual purchaser to go to the bookstore and back. So paper books certainly do have an environmental footprint. We just don't have the information to compare the size of that footprint to an eBook reader. Gut feel says that a single book is much less destructive than a single eBook reader - but then we don't know how many books are replaced by that reader over it's lifetime - maybe it's a lot - maybe very few because books are so well recycled across many readers. That makes this a tough question to answer. SteveBaker (talk) 19:18, 4 December 2009 (UTC)

Stars

How are we able to see stars if they are so far away? jc iindyysgvxc (my contributions) 22:02, 3 December 2009 (UTC)

They are bright. --Jayron32 22:09, 3 December 2009 (UTC)

There's not a lot in the way. Light doesn't just fade away over long distances -- it has to go through plenty of interstellar dust before becoming indiscernible. Vranak (talk) 22:12, 3 December 2009 (UTC)

It does spread out, though. The brightness of nearby stars is determined more by the inverse square law than extinction. --Tango (talk) 22:15, 3 December 2009 (UTC)

A more interesting question might be: "How are we able to look at any of the night sky and not see stars?" See Olbers' paradox. Dragons flight (talk) 23:22, 3 December 2009 (UTC)

The previous answers are missing a critical point - and (sadly) it's a somewhat complicated explanation.

The sun is a star - a pretty normal, boring kind of star just like many others in the sky. It's so bright that you can't look at it for more than the briefest moment without wrecking your eyesight. Most of the other stars out there are at least that bright - and space is pretty empty - interstellar gasses and dust make very little difference. So the only real effect is that of distance.

As others have pointed out, that's driven by the "inverse square law" - when one thing is twice as far away as another similar thing - it's four times dimmer - four times further away means 16 times dimmer and so on. The sun is only 93 million miles away - that's 8 light-minutes. The nearest star is 4 light-years away. Let's consider Vega (which is one of the brightest stars in the sky) - if you were 93 million miles away from it - it would be about 37 times brighter than our sun and you'd need some pretty good sunglasses and a good dollop of SPF-50! But fortunately, it's 25 light years away. So, Vega is 25x365x24x60/8...about one and a half million times further away. Which means that even though it's 37 times brighter when you're up close, it's 1.5Mx1.5M/37 times dimmer from where we're standing (73 billion times dimmer) because of that inverse-square law thing.

Our eyes are able to see a range of brightnesses from the maximum (which is about where the sun's brightness is) to a minimum of about 10 billion times dimmer than that. On that basis, Vega ought to be about 7 times too dim for us to see - but it's not. It's actually pretty bright. So you can tell right away that that inverse square law that everyone is going on about ISN'T the whole story.

There is obviously something else going on - and that is that the total amount of light from the sun is spread over that large disk you see in the sky - and while Vega is 73 billion times dimmer, all of that light is collected into one tiny dot. It gets hard to calculate the effect that has - but it's actually rather significant because the apparent size of the sun compared to that of Vega is gargantuan. In fact, the apparent area of an object obeys the same inverse-square law as the brightness does - so when you double the distance to something, it looks four times smaller (in area, that is). That concentration of light from a perceptually large object into progressively smaller areas of our retina exactly counteracts the inverse-square law.

Someone's going to complain about that - but think about it...that's why you can see something quite clearly when it's 200 feet away and it's not 40,000 times dimmer than when it's 1 foot away!

That means that until you are so far away that the sun is just a speck that's comparable to the resolution of your retina - it's not really any dimmer to look at than it is up close. The total amount of light is much less - but the light coming hitting each cell in your retina is exactly the same - until the projected image of the sun on the back of your eye starts to get smaller than the size of a single cell. So if you were out at the orbit of (say) Pluto - where the sun casts almost no heat and very little light - staring at the sun's tiny disk would still ruin a very small patch of your eyeball.

But still, 73 billion is a big number - Vega is still a heck of a lot dimmer - as you'd expect. However: remember that the sun is bright enough to literally blind you - and that your eyes are really sensitive - we can see things that are 10 billion times dimmer than the sun - so it's actually quite easy to see Vega even in very light-polluted cities. Much dimmer stars are also visible to the naked eye.

SteveBaker (talk) 23:54, 3 December 2009 (UTC)

I understand that an interesting question is why the night sky is not bright white rather than black, as an infinite number of stars would lead to the former. 89.242.105.246 (talk) 01:13, 4 December 2009 (UTC)

I believe the answer to that question, known as Olbers' paradox (which remarkably was first hinted at by Edgar Allen Poe in his essay Eureka: A Prose Poem), is that the Universe is not infinitely old, so light from the more distant stars has not yet had time to reach us. Attenuation due to red shift may also play a part. 87.81.230.195 (talk) 01:44, 4 December 2009 (UTC)

The Olbers' paradox article is pretty good - it lays out all of the possible reasons for this. SteveBaker (talk) 03:32, 4 December 2009 (UTC)

Aha. I've actually caught the most excellent SteveBaker in a misstatement. In his first response to the OP, refering to brightness of the Sun, he stated, "Most of the other stars out there are at least that bright." In reality, the vast majority of stars are far dimmer than the Sun. They are, in fact, so dim that we don't see them. So what was meant was that of the stars we see, most are at least as bright as the Sun. (Just a tiny correction) B00P (talk) 08:17, 5 December 2009 (UTC)

Indeed - I believe about 90% of the stars in the galaxy are red dwarfs, few (if any) of which can be seen with the naked eye. --Tango (talk) 11:49, 5 December 2009 (UTC)

The most useless particle

Say you had to choose one type of subatomic particle to be completely rid of: every single particle of that kind would completely disappear and no process would ever produce them ever again. Which would make the least difference to the Universe? Vitriol (talk) 22:37, 3 December 2009 (UTC)

I strongly suspect there is no answer to this - they are all absolutely 100% necessary. Take any one away (if that's even possible - string theory says "No") then the universe would be a dramatically different place - probably life as we know it wouldn't exist. But there is no "marginally less useful" particle. SteveBaker (talk) 23:04, 3 December 2009 (UTC)

String theory in its current form doesn't say anything useful about the Standard Model. The current thinking that there are a huge number of string theory vacua with different effective physical laws in each one. There might be one that looks like the Standard Model with a particle missing. -- BenRG (talk) 02:46, 4 December 2009 (UTC)

Oh, I don't know. A universe without a top quark might not differ much. Top is very hard to create and decays in ~5×10⁻²⁵ s. Now there might be secondary effects on the rest of the standard model if one removed the top, and I'm not sure how to predict what modifications to the larger theory might be necessary, but the top by itself seems of little importance. Dragons flight (talk) 23:14, 3 December 2009 (UTC)

There is no particle that could be removed from the Standard Model without either making it inconsistent or making life impossible. However, we could remove a whole group of particles, such as the third generation of the standard model (which comprises the tau, tau neutrino, top quark, and bottom quark) This is the only of the three generations with no practical applications. 74.14.108.210 (talk) 23:13, 3 December 2009 (UTC)

Not to hijack the question but could you elaborate on that a little? Why would it be inconsistent or non-life sustaining if, for example, the top quark didn't exist? Maybe not so many pleasing symmetries would exist but where are the serious effects? 129.234.53.144 (talk) 23:56, 3 December 2009 (UTC)

In physics the math always balances. If the top quark was missing, some physical interaction would not balance which is impossible. So some other particle or effect would, nay MUST, happen instead. Which would then have implications, etc, etc. Make any change, and everything else changes too. Ariel. (talk) 00:01, 4 December 2009 (UTC)

The up-type and down-type quarks couple via the weak interaction, and I think there's a loss of unitarity if you don't have the same number of particles of each type. On the other hand, there are preon theories with nine quarks, four of one type and five of the other, that don't have unitarity problems as far as I know. The story is the same on the lepton side. I don't think there's any known reason why there have to be the same number of quarks as leptons, though, so you can get rid of just two quarks or just a charged lepton and a neutrino without trouble. (This is not quite "getting rid of the top and bottom" or "getting rid of the tauon and tau neutrino" because you would also have to rejigger the CKM matrix or PMNS matrix, which alters the nature of the leftover particles as well.) One problem with dropping a generation is that there can be no CP violation in the weak interaction with two generations, and CP violation of some kind is needed to explain why there's more matter than antimatter. But I don't think the CP violation in the weak force can be used to explain that anyway. My vote for the most useless particles goes to the right-handed neutrinos, unless they turn out to be an important component of dark matter. -- BenRG (talk) 02:46, 4 December 2009 (UTC)

BenRG, the symmetry between the number of leptons and quarks is necessary in order to cancel the gauge anomalies that would otherwise destroy gauge symmetry and spoil renormalization. Dauto (talk) 07:13, 4 December 2009 (UTC)

Oh. Oops. -- BenRG (talk) 17:53, 4 December 2009 (UTC)

More importantly, per Murray Gell-Mann, "that which is not forbidden is mandatory" in particle physics. The existance of the top and bottom quarks is necessitated by the symmetry in the Standard Model. The entire system predictes the existance of said particles, therefore they are ALL equally vital. We have a pschological sense that particles like electrons are more vital because we tend to work with them more often, but the entire system of particles is not seperable; you must take them all, because the laws that created the top quark also created the electron; you could not create a universe with one and not the other. You can think of the Standard Model like a house of cards. If you remove any part of it, the whole system does not stand. See also anthropic principle for more on this. --Jayron32 00:16, 4 December 2009 (UTC)

Here's an interesting article for you Weakless Universe, they imagine a universe where something is missing. But as you see they had to change various other things too to make it work. Ariel. (talk) 00:31, 4 December 2009 (UTC)

Excuse me, but that's totally nonsense answer. If there were no top quark, the standard model would be seriously broken, I agree. But that's still just a human model of physical reality. If the universe had no top quark, then that would imply physicists need to discover a theory of particle physics that is different from the standard model, and one in particular where top quark formation is forbidden. However, because the top quark is almost never involved in interactions at human scales, more likely than not one could invent a new theory (perhaps much less elegant) that still gave the same predictions for human life as we have now. The Standard Model might be a "house of cards", but physical reality need not adhere to your sense of aesthetic beauty in determining its laws. For another example, the Higgs boson has but long sought after and not yet found. Most physicists seem to believe the Higgs will eventually be found, but one can just as well replace the Standard Model with one of several Higgsless models and our physical reality would look the same. Dragons flight (talk) 00:35, 4 December 2009 (UTC)

The Standard Model doesn't predict the number of generations; there's no known reason why there should be three. I don't know of any anthropic reason either. "Everything not forbidden is compulsory" is not about particle content. It's a statement that any interaction or decay that's not forbidden by a conservation law has a nonzero probability of occurring in quantum mechanics (classically forbidden transitions can happen in quantum mechanics because of tunneling). -- BenRG (talk) 02:46, 4 December 2009 (UTC)

If string theory is to be believed - then all of these particles are just modes of vibration on a string - getting rid of one mode of vibration is an entirely unreasonable proposition - so it's very possible that these things are no more removable from the universe than the color yellow or objects weighing exactly 17.2kg. SteveBaker (talk) 03:29, 4 December 2009 (UTC)

Strings have vibrational modes (harmonics), and those vibrational modes are particles, but the modes are quantized in multiples of roughly the Planck mass. All observed particles have masses far smaller than that, so they all belong to the ground state of string vibration. They're supposed to be distinguished by their behavior in the extra dimensions, but there's no reason to believe that the shape of the extra dimensions is unique. You can say a similar thing about quantum field theory. "Particles are just vibrational modes of the vacuum" is an accurate enough statement about QFT. It doesn't make sense to get rid of one vibrational mode, so you're stuck with a certain set of particles—for a given vacuum. But this doesn't answer anything; it just rephrases the question about the particle content as a question about the vacuum.

There was some speculation in the earlier days of string theory that it would turn out to have a unique vacuum which would have the Standard Model as a low-energy approximation, but the current thinking is that there are lots of vacuum states and only some of them match the Standard Model. Whether there are vacuum states corresponding to slight variations of the Standard Model isn't known. It isn't even known that there's a vacuum state corresponding to the Standard Model, though obviously they hope that there is. -- BenRG (talk) 05:13, 4 December 2009 (UTC)

I could definitely do without [fat electrons] being sent down the electricity supply and clogging up my computer:) Dmcq (talk) 06:43, 4 December 2009 (UTC)