Wikipedia:Reference desk/Archives/Science/2010 June 25

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June 25

Probability distributions in Quantum Mechanics

How do scientists derive probability distributions in quantum mechanics? ? ––115.178.29.142 (talk) 03:09, 25 June 2010 (UTC)

Solve the Schrödinger equation. For one example see Particle in a box or List of quantum-mechanical systems with analytical solutions for others. Graeme Bartlett (talk) 03:57, 25 June 2010 (UTC)

To expand that answer somewhat: solving the Schrödinger equation gives the wavefunction of a system as a function of time, ψ(t). To find the probability distribution of an observable A at a given time t, you express the wavefunction ψ(t) as the sum of eigenstates of A; there will be an eigenstate ψ_a corresponding to each observable value a of A. The "co-ordinate" of ψ(t) along the "dimension" ψ_a will be a complex number φ(a, t) called a probability amplitude. The probability that a measurement of A at time t gives a value a is then the square of the magnitude of the probability amplitude, |φ(a, t)|². Gandalf61 (talk) 08:38, 25 June 2010 (UTC)

A 'perfect solution' is difficult, so sometimes iterative (but approximative) methods like Hartree-Fock are used. John Riemann Soong (talk) 20:38, 25 June 2010 (UTC)

scientific name of the plant( ?or substance?) called "Lapland sesame" in the Wikipedi- article about hand of glory

Please give me to know a botanical name of this thing, if it be a plant; if it be something else, please give me a reas'nably precise definition of that thing. In case past monetary support of {Wikipedia} be of any importance concernin' your-all decision, whether yeah or not to respond unto this query, i mention, that i donated ninety USDollars unto {Wikipedia} in May of this year. —Preceding unsigned comment added by Stig weard (talk • contribs) 04:54, 25 June 2010 (UTC)

Hmmm... Unless there are two Laplands, or some unrelated plant also called sesame, it seems unlikely that there is any sesame native to (or even grown in) Lapland. See sesame and this map which shows where Sesame is cultivated. Sesame is an exclusively tropical plant, while Lapland (northern Norway and Finland) is one of the coldest inhabited places on earth. I did a google search for Lapland Sesame, and turned up almost nothing other than references to the candle recipe already found in Wikipedia. --Jayron32 05:25, 25 June 2010 (UTC)

Agree. It seems that nobody really knows what this is supposed to be, but there is some speculation that it is a bad translation from a French original that meant "sesame and horse dung". Looie496 (talk) 05:28, 25 June 2010 (UTC)

I have corrected the links for you. this is one of those questions that shows just how useless Google can be. There are six hundred-odd links but they are almost circular in source with no answer evident. This seems to have been a 15th century scam but the real identity (if ever there was one) of the plant has been lost. Caesar's Daddy (talk) 15:52, 25 June 2010 (UTC)

I don't know if this is relavent here, but many alchemical/witchcraft recipes usually have ingredients that are either unobtainable, or the name obscured.77.86.123.157 (talk) 15:58, 25 June 2010 (UTC)

Measurment change by interacting

Hi. What's the name of the process, when we measure something, and by measuring we change the properties of this body or thing? 83.31.79.94 (talk) 12:23, 25 June 2010 (UTC)

Heisenberg uncertainty principle.

ALR (talk) 12:35, 25 June 2010 (UTC)

That is incorrect, the Uncertainty principle states that we can't know the exact location and vilocity of a particle at the same time, not that a measurement changes the particles properties, that is a seperate principle. —Preceding unsigned comment added by 74.67.89.61 (talk) 13:03, 25 June 2010 (UTC)

From a pure physics perspective you are indeed correct as it applies to sub-atomic entities. It is, however, used as the basis for a more practical problem in instrumentation and control, measurement impinges on the system and changes the characteristic.

I'd make the observation that I very rarely hear the issue described as observer effect, far more frequently we'll discuss uncertainty, although that does pre-suppose an understanding of the concepts in advance of the discussion.

ALR (talk) 17:42, 25 June 2010 (UTC)

Again, this is incorrect, uncertainty is a concept that limits the information available for two non-commuting observables, whereas the observer effect is merely the much simpler principle that measurement of a single observable forces a wave function to collapse into an eigenstate.

The correct principle is the observer effect. The uncertainty principle's got nothing to do with it. Dauto (talk) 13:37, 25 June 2010 (UTC)

Frequently the Heisenberg uncertainty principle is explained in terms of the observer effect. This is based on Heisenberg's original explanation of the principle (Heisenberg's microscope). However, recent interpretations of the uncertainty principle hold that the principle is a fundamental property of the universe and always valid, and is not simply a result of trying to measure the system. -- 140.142.20.229 (talk) 17:07, 25 June 2010 (UTC)

Yes, we do see that interpretation quite often but it is simply wrong. Dauto (talk) 17:35, 25 June 2010 (UTC)

DIY inspection camera

Is there a way to put together a home-made inspection camera using inexpensive parts? By "inspection camera" I mean something that can feed through a hole no more than an inch in diameter. You can use it to check the plumbing or wiring inside a wall, or to check the condition inside an an air duct. What can you adapt or repurpose for the camera component? --98.114.98.48 (talk) 12:40, 25 June 2010 (UTC)

This is a tiny $13.99 webcam - with LED lighting and infrared capability! All you need is a long enough USB cable and a laptop and you're in business. I'm pretty sure the case is under 1" - but it might be a tight fit. If that's a problem then you might need to remove the pretty plastic casing and make something smaller using electrical tape!

SteveBaker (talk) 13:39, 25 June 2010 (UTC)

Check the articles Borescope and Endoscopy. Cuddlyable3 (talk) 21:17, 25 June 2010 (UTC)

paint and primer in one

does Behr Ultra latex paint and primer in one contain surfactants such as sodium Lauryl sulfate to make the paint mix with the primer ?

the paint im talking about is seen here:

http://www.homedepot.com/Paint-Interior-Paint-Stain/Behr-Ultra/h_d1/N-5yc1vZ1xilZbbbpZ528/R-202182650/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053 —Preceding unsigned comment added by Alexsmith44 (talk • contribs) 14:26, 25 June 2010 (UTC)

It doesn't appear to be just a mixture of paint and primer, so the answer is no. Conventional paint and primer are similar enough to probably not required surfactants to mix (you can try this at home!). However surfactants are widely used in paints anyway.

The lack of requirement for a primer appears to be due to nanoparticles that reduce the porosity of the surface to be painted - I think, the company documentation is not that clear.77.86.123.157 (talk) 14:51, 25 June 2010 (UTC)

I'm guessing that the Aluminium hydroxide and diatomaceous earth are part of the active ingrediantes that make the paint an 'all in one' - mentioned on the MSDS [1], these should be carried by the acrylic (latex) binder just like the pigment. 77.86.123.157 (talk) 15:17, 25 June 2010 (UTC)

i thought oil and water dont mix? primer is oil based and latex paint is water based. does adding surfactants make them mix? —Preceding unsigned comment added by Alexsmith44 (talk • contribs) 15:16, 25 June 2010 (UTC)

No, primer can be water or oil based. If you were applying a water based paint you'd 100% certainly use a water based primer. ok maybe not, some people avoid oil based becuase of the solvents, bur water based still stinks, plus oil based paints are gradually being banned. An emulsion of oil/water based paints wouldn't work as planned though - there's no way for the oil component to know to be the undercoat. 77.86.123.157 (talk) 15:20, 25 June 2010 (UTC)

so does it have a water based primer in it ? —Preceding unsigned comment added by Alexsmith44 (talk • contribs) 18:16, 25 June 2010 (UTC)

Is the product water based or not? It depends what you mean by primer - a primer is just something that treats a surface before painting - this is a primer and paint in one: A primer is a product not an ingredient.77.86.123.157 (talk) 19:26, 25 June 2010 (UTC)

Is it possible to clean a pool with just Baking Soda and Bleach?

I heard a rumor about this. Anyone know anything about it? 148.168.127.10 (talk) 14:46, 25 June 2010 (UTC)

What sort of cleaning do you mean? (algae maybe?) - eg I can clean a pool with a scrubby, some cif and a bucket of water..77.86.123.157 (talk) 14:52, 25 June 2010 (UTC)

oh you must mean this http://wetheadmedia.com/how-to-clean-a-green-pool/ I thought you meant clean the sides.. Both chemicals are replacements for commercial formulations, but you need to know what you are doing, andwill probably still need test kits.77.86.123.157 (talk) 15:46, 25 June 2010 (UTC)

query regarding B.TECH

what does mechanical & electronic-communication{EC} engineering mean? —Preceding unsigned comment added by Spooky92 (talk • contribs) 16:45, 25 June 2010 (UTC)

Can you give more details, it might mean nothing. It might mean a combined course of two disciplines. Which BTECH? 77.86.123.157 (talk) 17:56, 25 June 2010 (UTC)

Big cases of correct theories largely ignored because they came from amateurs

What are some of the big cases where someone without status/credentials/contacts in the scientific community puts out a paper, the paper is largely ignored, and later it is discovered that the paper was right in what it stated? 20.137.18.50 (talk) 16:47, 25 June 2010 (UTC)

Marjorie Rice might qualify, though I don't know if she published her findings. --Sean 17:00, 25 June 2010 (UTC)

I don't think that one counts. Her discoveries were accepted by the main stream mathematitians as soon as they came to their knowlege. Dauto (talk) 17:06, 25 June 2010 (UTC)

I notice that Gregor Mendel wrote a paper describing what he is now known for that was ignored for 35 years. 20.137.18.50 (talk) 17:13, 25 June 2010 (UTC)

One of the best-known cases is John Garcia, who discovered the so-called Garcia Effect, also known as conditioned taste aversion. He had a Ph.D. and worked as a postdoc at Berkeley, but he didn't have any reputation, and his discovery, which now is considered a major part of the history of psychology, was at the time considered so bizarre that he was unable to publish it in any reputable journal. Looie496 (talk) 18:18, 25 June 2010 (UTC)

I have trouble imagining that the theory could be considered "bizarre" — it seems almost obvious. Is there anyone to whom this sort of taste aversion has not happened? Wouldn't you just say, "oh, yes, of course I know that; that happened to me when I was eight years old, even if I don't know why"? --Trovatore (talk) 01:25, 26 June 2010 (UTC)

Can someone with a PhD be considered an amateur? Dauto (talk) 21:28, 25 June 2010 (UTC)

Yes, sure (just having a PhD by itself does not actually make you a member of any particular academic community, much less the one you are innovating in), but probably not somebody working at a postdoc at a major research university. --Mr.98 (talk) 22:27, 25 June 2010 (UTC)

A similar case is Alfred Wegener, whose theory of continental drift was rejected by orthodox science for many years, but is now accepted as the basis of plate tectonics. Ghmyrtle (talk) 21:45, 25 June 2010 (UTC)

Wegener's theory was rejected because it was impossible. It is not the "the basis of plate tectonics"; it posited a different and impossible cause (mechanism) producing the same effects at the surface of the earth. (Cite: Asimov's New Guide to Science, p.174) It is true that scientists wrongly disbelieved that those effects existed, but that was because no possible mechanism was known. If Aristotle had encountered a radioactive substance and theorized that it was warm because it contained the element fire, that would not mean that his theories were "the basis of nuclear physics". Credit is due to Wegener for being partly right, but only for that. --Anonymous, 00:17 UTC, June 26, 2010.

Note, A. Wegener: The hypothesis of continental drift (ca. 1915), evolved to seafloor spreading (ca. 1962), and more recently to the theory of plate tectonics (ca. 1967). He based his publications on cartography, paleontology, glacial striations and old orogenic uplifts. But paleomagnetism, reflection seismology, sonar survey and gravity anomaly survey were needed to etablish the hypothesis. There was a lack of sound data... --Chris.urs-o (talk) 07:03, 26 June 2010 (UTC)

Keep in mind—as has been pointed out by the likes of Carl Sagan and others—that the cases of "amateurs who were totally wrong or actually just cranks" vastly overweighs the extremely limited number of times that an amateur was judged a crank and turned out to be brilliant. Quoth Sagan: "They laughed at Columbus, they laughed at Fulton, they laughed at the Wright Brothers. But they also laughed at Bozo the Clown."

Two really famous cases (depending on how you define "amateur") are Wegener and Albert Einstein (came up with the special theory of relativity while working at the Swiss patent office). If you go back historically, of course, the line between professional and amateur is quite blurry until the strong professionalization of science in the 19th century, and even then some fields (like astronomy) still often have a strong history of contributions from amateurs. (Even today, many astronomical discoveries—e.g. comet Hale-Bopp—are done by amateurs pointing telescopes at the sky.) --Mr.98 (talk) 22:27, 25 June 2010 (UTC)

It's worth noting that in Einstein's case his Annus Mirabilis papers were accepted for publication in a prestigious journal (Annalen der Physik), and that his work – particularly the special theory of relativity – were generally widely and rapidly accepted by the scientific community. TenOfAllTrades(talk) 22:43, 25 June 2010 (UTC)

Well, it's worth noting that the papers were accepted for publication largely through the influence of a single person (Max Planck), who acted as his sponsor, more or less. It was nothing like the expectations of modern peer review and there is little doubt that Einstein's papers would have been rejected had the standards been a bit higher. If you read his classic SR papers through the lens of what "physics in his time" was considered to be, they are extremely unusual, very amateurish in many ways (they read more like an exercise in logic than a work of physics, even theoretical physics, and have horrible citation practices). As an experiment give "On the Electrodynamics of Moving Bodies" a read without considering that the author is Einstein and obviously correct and you'll see what I mean—it's a very odd paper and if it had the name "Joe B. Crank" attached to the top of it you'd probably dismiss it as nonsense.

And to say that SR was rapidly accepted is an exaggeration. Most physicists did not regard it as "physics" at all in the traditional sense (they considered it philosophy or simply irrelevant), with the exception of the photoelectric effect, which they did find to be a rather convenient explanation. By the time Einstein put together GR it was considered something that needed to be known about but not at all unambiguously true. After the GR experiment of Eddington, relativity as a whole got a lot of attention but was still considered extremely scientifically controversial. Even after Einstein was generally recognized as a great scientist (say, in the 1920s and 1930s) by many (i.e. the newest physicists) it was still a pretty controversial theory. It was not until the 1940s and 1950s that it really became considered one of the gold standards of physics. Now one can say that many of the physicists we now consider to be the "winners" in history (e.g. Bohr and Eddington and even Planck) thought Einstein was pretty brilliant from the start. But they are not actually representative of the larger scientific community as a whole in Einstein's time, and depending on what one defines as your community, the up-take was really quite different (e.g. the physics communities in Germany, France, England, USA, Russia, and Japan all received relativity pretty differently). I'm not saying this to be pedantic, but studies on the reception of relativity are sort of a "canonical" topic amongst historians of physics and it was anything other than straightforward. (For a nice overview, Helge Kragh's Quantum Generations is great, and has an excellent graph of the early distribution of scientific publications on relativity and a great section discussing it, which you can see in Google Books. You'll notice it takes about 5 years for even the Germans to really start to get interested in the subject.) --Mr.98 (talk) 23:57, 25 June 2010 (UTC)

My aim here was mostly to respond to the original poster's question — specifically, to note that Einstein doesn't really qualify under the terms given. The fact that his work was supported and endorsed by Planck by itself suggests that he was not without academic contacts. And whatever else may be said about his papers, they certainly weren't 'largely ignored'. (To be fair, Einstein was far from the only scientist to benefit from the much laxer variety of peer review practiced a century ago.) I'll grant that his work wasn't universally and completely accepted for years (sometimes decades) and that there were geopolitical factors which hampered its acceptance in some countries (particularly France), but that's not unusual even for non-crank science published by well-known scientists. Consider the Higgs boson. It was first postulated in 1964, it's part of the Standard Model, but it's still not totally accepted — and it's still possible to have a career as a respectable scientist developing Higgs-less models. (One of those models might even be correct!)

The graph you've linked to is interesting. The figure legend observes that (on the subject of relativity) there is a "...decrease in the total number of publications between 1910 and 1915..." and notes that this feature "...probably reflects that, by 1911, the special theory of relativity was widely accepted among physicists and was no longer considered to be at the cutting edge of physics." I would tend to argue that five years is actually not a long time for a major new theory to gain prominence (if not predominance) in physics, particularly one for which experimental tests are difficult — and in an era when publications had to be distributed on paper and interpersonal communications tended to travel by snail mail. TenOfAllTrades(talk) 02:27, 26 June 2010 (UTC)

I think Einstein qualifies, even though he was shepherded in by someone "inside" the institution. I don't think "amateur" is meant to mean "totally ostracized". Einstein was an outsider. The only reason he got taken seriously at all is because an insider decided he wasn't a crackpot.

The graph and the accompanying chapter make it a bit more clear what is going on, especially if you recall that Einstein wasn't the first (or only) person talking about relativity theories (he was entering into a field already populated by the likes of Poincaré, Lorentz, etc.). Einstein's own specific take on things—that there is no such thing as universal time, for example—was really not accepted as true for quite a long time. By the time Einstein started work on GR, the idea of relativity and Einstein's contributions (again, because of Planck's sponsorship, in part) was enough of a topic that it warranted some attention from other theorists, but it was still a very, very minor part of how physics was thought of at the time, and considered irrelevant by most. It was not until 1919—for both scientific and political reasons—that it really became something that people had to grapple with (because of the immense attention given to it, and the huge implications saddled on it), and even then it was certainly still considered extremely controversial, often incorrect, by most "established" physicists.

Anyway, in the end, I don't think Einstein is a bad case study for this kind of question, even if he is obviously a rather singular historical figure. He's definitely an outsider, and he definitely had a struggle in getting his work accepted, in part because he was not in synch with the priorities or methods of the predominant physical community, and because the conclusions he proposed were seen as very out of step with how contemporary physics was developing. (Today we always refer to aether theory as the "classical" view, but this is quite ahistorical—it was considered a radical, unifying theory for the late-19th century and early-20th century, a real vanguard composed of really quite sophisticated mathematics. It was wrong, of course, but it was as "revolutionary" as what replaced it.) He also illustrates the way an outsider can get a "shortcut" into the mainstream discussions: get a major sponsor who can't be dismissed, weasel your way into mainstream journals, follow up some rather vague theories with really quite striking experimental reports. (And while you're at it, become a major international icon. ;-) --Mr.98 (talk) 12:12, 26 June 2010 (UTC)

As a chemist, my own favorites are John Dalton and Amadeo Avogadro. The former was excluded from university because of his religious beliefs; he wasn't exactly an "amateur", but he described atomic theory while earning his money as a schoolteacher and his theory would not be fully accepted for many decades. Avogadro is a more flamboyant character, an ecclesiastical lawyer but part-time revolutionary... still, he found the time to imagine Avogadro's Law, for which he never received credit during his lifetime: now, it is considered one of the bases of modern chemistry, hence the Avogadro constant named in his honour. Physchim62 (talk) 23:29, 25 June 2010 (UTC)

See http://www.environmentalgraffiti.com/sciencetech/the-5-most-important-amateur-scientists/940. I do not know how quickly their discoveries were accepted.—Wavelength (talk) 00:31, 26 June 2010 (UTC)

It's an interesting stab at a list, for something that gets caught up in real definitional issues, anyway. Faraday, for example, was certainly an outsider when he started, but he apprenticed under Davy before doing his really fundamental work. Does that make him an amateur? (Or just of low class in a highly stratified society? Is there a difference in 18th century British science?) Mendel was not so much an "amateur" as in a parallel profession, one that did value agricultural research and had cross-overs to mainstream academic biology (though Mendel himself was pretty much at the fringes). He wasn't denounced as a quack or anything, but he was ignored, mostly because his work just didn't have much exposure and even Mendel didn't think it was a general theory of heredity. His work was "rediscovered" many years later and translated into a somewhat different framework. Edison pushes that nice boundary between "inventor" and "scientist," wherever we want to try and draw that line. Evans and Leavitt I don't know enough about to comment, except that again there is a long, rich tradition of amateur astronomy, one that continues to this day. --Mr.98 (talk) 01:18, 26 June 2010 (UTC)

SeeHistory of radio. Discovery of the ability to transmit and detect high frequency electromagnetic radiation which Thomas Edison called "etheric force" in 1875, and which separately was discovered in 1878 by David Hughes, were rejected as "mere electromagnetic induction" by leading scientists of the day. When Hertz in 1886-1888 did similar experiments more mathematically based on Maxwell's theory the results were accepted. Hertz was better credentialled, and had a systematic mathematical and theoretical basis for the observations. Edison similarly discovered and wrote up Thermionic emission, the basis for diode vacuum tubes, but scientists of the 1880s rejected it as merely charged bits of carbon coming off the filament, and decades later Fleming used the same tubes with improvements to invent the diode valve or vacuum tube, with a better physical explanation, after the discovery of the electron by others circa 1897. Scientists of the era considered Thomas Edison and Hughes to some extent to be mere amateurs/tinkerers/inventors. Edison (talk) 04:23, 26 June 2010 (UTC)

In the 18th century, Kant realized that some of the "stars" are actually galaxies. In the 19th Century, a lot of bad science "discredited" this brilliant conclusion. Not till the 1920s was it established beyond doubt. 63.17.62.100 (talk) 06:53, 26 June 2010 (UTC)

Ants in my vacuum cleaner

If I use my vacuum cleaner to suck up an ant trail, will they survive the journey up the tube to the filter bag, or do I have to empty it to prevent further infestation? Hemoroid Agastordoff (talk) 17:04, 25 June 2010 (UTC)

The ants will survive (at least a good majority will). I remember reading that if you want to kill the ants, you could vacuum up some kind of dust right after you get the ants, but I can't remember what it was. Talc maybe? Or diatomaceous earth? Googlemeister (talk) 18:19, 25 June 2010 (UTC)

I think diatomaceous earth will work -- it has a dehydrating effect on insects (including ants). FWiW 67.170.215.166 (talk) 02:36, 26 June 2010 (UTC)

Disposing of the bag promptly is a good idea. Edison (talk) 04:07, 26 June 2010 (UTC)

Ant dust. Mitch Ames (talk) 13:17, 26 June 2010 (UTC)

Urologists

How many urologist are there in new jersey68.236.210.120 (talk) 17:19, 25 June 2010 (UTC)

I've added a section header for this question. Comet Tuttle (talk) 17:31, 25 June 2010 (UTC)

428 [2] 77.86.123.157 (talk) 17:51, 25 June 2010 (UTC)

How many urologists does it take to change a lamp bulb? Cuddlyable3 (talk) 14:17, 26 June 2010 (UTC)

Dunno. Tell us/--RampantHomo (talk) 20:15, 27 June 2010 (UTC)

One. S/he holds up the light bulb and the world revolves around them. (Works for any kind of medical doctor.) -Atmoz (talk) 20:29, 28 June 2010 (UTC)

Memory

I have heard there is one memory condition where one is unable to forget out anything and everything you experience is remembered forever. The advantages are obvious: One would never forget one's in-laws' birthdays for example ;). But What Would be some disadvatages to having such a permanent memory? Would it be harder to recall things? 76.229.149.7 (talk) 17:59, 25 June 2010 (UTC)

I think you're looking for hyperthymesia. An interview with the first identified case suggests that she doesn't find it harder to recall things; rather, things are recalled whether or not she wants to. She certainly expresses disadvantages to the condition in the interview. In particular, the inability to forget (and moreover, the inability to avoid remembering) tragedy is pretty lousy. Having a merely eidetic memory has a lot more practical upside. — Lomn 18:06, 25 June 2010 (UTC)

There is no such condition. There are people with extraordinary memory for events, but not perfect. There is however a well-known work of fiction by Jorge Luis Borges describing such a person, called Funes the Memorious. The most common problem for people with extraordinary event memory is difficulty in seeing patterns -- when somebody remembers every detail of every event, they have trouble seeing what the events have in common. The Russian psychologist Alexander Luria wrote a wonderful book called The Mind of a Mnemonist] about such a person. Looie496 (talk) 18:10, 25 June 2010 (UTC)

I've heard of people with such a "condition"...while not a medical condition, persay, the phenomenon does exist...I remember it being mentioned in a National Geographic article. [3] Ks0stm ^(T•C•G) 21:42, 25 June 2010 (UTC)

Perhaps not that relevant, but Gene Wolfe's The Book of the New Sun has a protagonist with an Eidetic Memory. The condition is a prevalent theme in the book, and is explored in several ways. Zigorney (talk) 19:14, 25 June 2010 (UTC)

You may want to read this book (http://www.amazon.co.uk/Delete-Virtue-Forgetting-Digital-Age/dp/0691138613) it is all about the virtue of forgetting and how useful it is (for society as well as individuals). It's an interesting area but whilst I have this book I must admit it's not the best read (a bit repetitive and a bit woolly in terms of their proposed solutions) but it has a lot about the disadvantages of never forgetting (that you wouldn't be able to escape ones past being a major issue). ny156uk (talk) 20:32, 25 June 2010 (UTC)

Some neurobiologists and cognitive psychologists think that once something makes it from short term memory into longterm memory (via attention being paid to it, through analysis and study, through rote rehearsal), it doesn't really go away, but we just lose the ability to access it. If I've forgotten someone's name, recognition is far better than recall. Same for "forgotten" addresses or phone numbers. The right prompt can cause it to be right there. But memory can be reconstructive, and we can be fooled into "remembering" things that never happened, by the right instruction [4]. An electrical stimulus in the temporal lobes of the brain during brain surgery, as reported by Wilder Penfield, can supposedly cause random forgotten incidents from the distant past to be relived in vivid detail in some individuals. Or maybe the "memories" are created out of fragments like dream experiences. Alexander Luria wrote "The Mind of the Mnemonist" about Solomon Shereshevsky, who could remember amazing amounts of detailed information. He sounds much like the mnemonist in The 39 Steps (1935 film). Some of us can probably recall a lifetime of factual information, but fail to recognize someone they were introduced to 5 minutes ago. Edison (talk) 23:15, 25 June 2010 (UTC)

since we're onto novels, try Black Milk by Robert Reed. interesting view on the topic.

The problems with excessively high retention are mostly social: (1) being able to remember accurately events which others have revised is uncomfortable (most people's memories are inaccurate and revised in various self-serving ways, and do not like being reminded that things were not as fun and noble as they remember them to be). (2) if the retention includes emotional states as well as simple factual recall, one may be left re-experiencing a lot of unpleasantness. consider being forced to remember how you felt (in full detail) whenever you think about high school. --Ludwigs2 03:56, 26 June 2010 (UTC)

It would be so easy to win at Trivial Pursuit and similar trivia games that either such a person would have to throw games by "not knowing the answer" or people would hate them. Edison (talk) 04:06, 26 June 2010 (UTC)

I think that it may be hard to focus on a task at hand if you are continually bombarded with vidid memories of yesteryear. Vranak (talk) 18:02, 26 June 2010 (UTC)

When you consider the numbers involved, remembering literally everything is quite impossible. Consider your eyes: Suppose we imagine that they take ten snapshots of the world per second - and at (let's be generous) 1000x1000 pixels of resolution and with (again, being generous) just 8 bits of color fidelity. 10 megabytes per second of data flows into the brain the entire you're awake - if you stay awake 10 hours a day then that's 130 terabytes of data per year...add in audio, touch, taste, smell, body positioning, pain, emotion, ideas we think up ourselves...we could probably double that number. Over a 70 year lifespan, that's 18 petabytes. We have about 33 billion neurons with about 10,000 synaptic connections each. It's hard to turn that into bits and bytes - but for sure, there isn't any possibility of storing more than around a terabyte. My home computer has more memory than that - but there aren't many places in the world where you can store 18 petabytes...WalMart's data storage center (which stores every credit card transaction ever made at one of their stores) has less than that. Google have more - but not a lot more!

The literal impossibility of storing that much information in a brain that's about 6" across means that we're simply incapable of storing that much data. Hence the brain has to do aggressively lossy data compression - and why it is vital to our ability to continue to function that we're able to forget unimportant things - or to simplify and 'soften' memories of more distant events. I can remember the day my son was born and the day I got married pretty well - but I have zero memory whatever of the 23rd of January 1964. The reason why we forget things is to make room for the new things we need to have memory of. Memories that you refer to a lot are strengthened - memories you don't use fade away. This isn't a flaw in the system, it's a very clever part of how evolution has 'designed' our brains to cope with vast data input and horribly limited data retention ability.

SteveBaker (talk) 13:08, 28 June 2010 (UTC)

Silicone solvent?

I'm trying to remove some 3-year old 100% silicone caulk from a textured glass panel. The textured glass prevents me from using razor blades. When I try to peel or rub the silicone off, it just comes off in bits. Is there any chemical method to removing silicone? —Preceding unsigned comment added by 70.167.58.6 (talk) 18:11, 25 June 2010 (UTC)

In short, no. There is no simple way to chemically remove silicones from glass. You can sometimes remove them physically, if you're lucky, but it's usually not worth the bother (as you seem to be discovering). What do you want to do with the glass afterwards? Physchim62 (talk) 18:26, 25 June 2010 (UTC)

It's glass from the 40's in an old office. The previous occupants thought it would be neat to affix acoustic foam to the windows using silicone glue. The foam was easy to tear down. But all these islands of silicone remain on the glass. Would a heat gun help to peel it off? Or would it just make a gooey mess? --70.167.58.6 (talk) 18:33, 25 June 2010 (UTC)

A heat gun might crack the glass, be careful.

My local DIY store sells silicone remover. Just Google it. --Heron (talk) 18:38, 25 June 2010 (UTC)

The problem with "silicone remover" is that it sticks to the glass itself, making it very difficult to get anything else to stick there. You can't see it, but it's there to prevent any other putty from sticking. If you must keep the glass plates, the best bet is patience and a judicious use of sandpaper (the cheapest works best, just don't scratch any visible bits of the glass) Otherwise, replace the glass. Physchim62 (talk) 18:58, 25 June 2010 (UTC)

Potentially, depending on how aged the sealant is you could used wd40/diesel/other oil (also consider nitromors or equiv) to try to soften it - it wont' remove it but it might make your job easier.

Disposable plastic knives (or even bluntish metal knives), as well as rotary brass brushes may be helpful tools in getting it off.77.86.123.157 (talk) 19:39, 25 June 2010 (UTC)

There's a technical paper here [5] it suggests

• tetramethylammonium hydroxide (TMAH) in alcohol - you probably can't get this
• solvents such as CH2Cl2 and DMF (again "nitromors" is a CH2Cl2/MeOH mixture - it might work)

as well as fluorides

A home grown version might be caustic soda in methanol, or isopropanol - but this also is very dangerous to work with in terms of burning your hands or face off.77.86.123.157 (talk) 19:50, 25 June 2010 (UTC)

You could also try DMSO. I had a professor that used to say "If it doesn't dissolve in DMSO, it wasn't meant to dissolve". Accodring to our article, it is safer than DMF and other similar compounds. --Jayron32 17:08, 26 June 2010 (UTC)

Silicones tend to form chemical bonds with glass (the tubes of silicon contain chemicals that polymerise) - that's why hydroxide or fluoride is needed to debond it. DMSO could make a good solvent for these, but probably won't work on its own. —Preceding unsigned comment added by 77.86.115.159 (talk) 17:19, 26 June 2010 (UTC)

A word of warning here: Fluoride in DMSO will enter the body via skin contact, and will have toxic effects similar to those of concentrated hydrofluoric acid (deep burns, etc.) So if this is what you plan on using, make ABSOLUTELY sure that you wear nitrile gloves and clothing (these are impervious to DMSO). Clear skies to you 67.170.215.166 (talk) 05:38, 27 June 2010 (UTC)

Why nitrile gloves? They will just dissolve. See Dimethyl_sulfoxide#Safety. --Chemicalinterest (talk) 18:23, 27 June 2010 (UTC)

Right, I meant neoprene, not nitrile. I stand corrected. 67.170.215.166 (talk) 01:29, 28 June 2010 (UTC)