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January 30

My Honda Accord will be 10 years old this year. Why no rust?

Some junked antique cars are coated with rust, and I've read that they've rusted rather quick.

Yet my 2001-model has almost 130,000 miles so how does it remain rust-free anyhow? --70.179.181.251 (talk) 00:12, 30 January 2011 (UTC)[reply]

There are lots of factors that cause different amounts of rusting. If you maintained your car very well, and didn't drive it on a lot of salted roads, I would not expect it to rust. All of our cars have been far older than that when we got rid of them, and other than a tiny spot, I can't remember any rust on any of them. Of course, it could be rusting in places that you don't see, but even that's not a guarantee. Basically: it depends on a lot of different things. I cannot tell you why your car specifically is not rusting, but I can surmise why a car might not rust after ten years. Falconus^{p t c} 03:14, 30 January 2011 (UTC)[reply]

At least in Germany, it's now standard for most new cars to have a fully zinc galvanized body, which makes rust a very rare occurrence. Toyota started the wide-spread use of galvanized steel in Europe in 1992, and seems to use it more or less universally since 2000. Car-makers now have the technology to nearly completely eliminate rust as a problem, although not all use it to the same degree (arguably, there is no reason for outstanding longevity if cars are retired for obsolescence reasons after 10 years anyways). --Stephan Schulz (talk) 09:19, 30 January 2011 (UTC)[reply]

Sorry, my mind misread Honda for Toyota. I don't know when exactly which Honda models started using galvanized steel, but from what I could find online it should be in a similar time frame.--Stephan Schulz (talk) 12:05, 30 January 2011 (UTC)[reply]

As above - modern cars rustproofing is a lot better than before. If you're driving in a dry climate without lots of rain, snow or ice the car's bodyshell will not degrade very much. Exxolon (talk) 16:38, 30 January 2011 (UTC)[reply]

Short answer: It's a Honda. :P Roger (talk) 17:38, 30 January 2011 (UTC)[reply]

How do I customize GPS navigation voices?

I think the voices that vehicles give through their embedded GPS navigation systems should reflect their ages and nationalities. At least the voices of the vehicles I plan to drive, anyway. Moreover, I'd also like some kind of subroutine that will "age"/deepen the voice of the navigation system as the vehicle ages.

For example, if I buy a used 2005 Volvo XC90 in 2013, how do I get the navigation program to voice out the directions sounding like a Swedish boy?

I think if I drive a Hyundai, the GPS voice should have a Korean accent. If I drive a Fiat, an Italian accent, etc. Moreover, their voices should reflect the date of the car's manufacture. (I won't have to worry too much about how silly they'd sound because I don't plan to buy vehicles newer than 5 years old anyway. It saves a bucketload of $$$ buying used.) --70.179.181.251 (talk) 00:12, 30 January 2011 (UTC)[reply]

I think most commercial GPS systems do not synthesize their voice phonemically; they simply play back a series of sampled words. So you would need to (1) pay a voice actor with your desired voice and accent to record a complete vocabulary for the navigation system, (2) rent a voice recording studio for him/her to do it in, (3) pay the manufacturer of the GPS system to help you get the new vocabulary into the box's firmware, as if it was a new language localization. The latter is not an off-the-shelf service; you could easily be looking at $10,000 or more here, and expect to pay in advance. Repeat everything whenever you think the voice ought to change due to the car aging.

Oh, and the GPS manufacturer may not even want to touch this unless you promise that they won't get sued if you let somebody borrow your car and they misunderstand the GPS directions and end up in a river and drown, and they may want you to back this promise with a bank guarantee or a fully paid up indemnity insurance policy, which isn't cheap either, and then you'll also want to pay a lawyer to go over the promise before you sign it, to make sure you're not accidentally signing away your firstborn.

It may be cheaper if you start out with an open-source navigation system running on off-the-shelf laptop or smartphone hardware, though in that case you'd need to hire a freelancer or consultant to do the heavy lifting (you can legally do it yourself, but if you had the skills to do so you wouldn't have to ask here), and that would still set you back at least several thousand dollars in addition to the actor's fee, and you'd risk getting a less stable and feature-rich system than a commercial GPS solution. –Henning Makholm (talk) 02:29, 30 January 2011 (UTC)[reply]

Henning is right about commercial sat nav systems, but there is an alternative: the free navigation app from Google, available on Android smartphones. It uses the Google text-to-speech (TTS) engine, which is customisable in principle since it's open source. How you would do it in practice, though, I have no idea. Also, it's currently only available in the USA and the UK. The British one sounds as you would expect the Bride of Frankenstein to sound. It tries to synthesise place names phonetically, often getting them wrong, but you can usually work out what it's trying to say. --Heron (talk)

Standalone GPS systems are easy to customise as long as you have voice samples in a compatible format and the master list that tells the system there's a voice there and which sample to play for each situation. If you could access the memory of an integrated system it should be possible to do the same. Exxolon (talk) 16:36, 30 January 2011 (UTC)[reply]

Vocal synthesizers, not voice actors.

Problem is, I'm not looking for actors' voice samples. I'm looking for vocal synthesis Aren't there vocal synthesizing programs that enable me to change any vocal recording to that of a desired age? Why can't I just convert the existing recordings to those instead?

(And if I do get a vocal synthesizer, how do I also change the accent to that of a desired country's?) --70.179.181.251 (talk) 17:08, 30 January 2011 (UTC)[reply]

This might be more of a question for the computer desk. Most SatNav vendors have a wide range of voices that can be downloaded from their website, some free, some purchased. The files are easy to install, simply copied to the SatNav flash drive. However, the data is not in a publicly published standard so it will not usually be possible to create your own without collaboration with the manufacturer. As Heron said, many devices use sampled voices rather than synthesis so there would be no way of programming in a variant synthesiser, there is just no facility. The best you could do would be to access the analogue audio going to the speaker (which will probably involve taking your satnav apart) and feeding it through a voice disguiser, suitably adjusted for the effect you are looking for. SpinningSpark 19:38, 30 January 2011 (UTC)[reply]

GPS satnav system are just not set up for this. If you connect one to your PC and browse it, you'll find a folder for the voices. Each subfolder contains all the samples needed to construct all the sentences ever needed and a file telling the satnav which sample to play when it needs to make that particular part of a sentence. Looking back at your original post it looks like you want the GPS to reflect the cars "personality" for want of a better term - an integrated SatNav with a voice that's appropiate for the car make, model and age - no manufacturer will bother doing this - it's a lot of expensive work for a demand that's just not there. It would be just about possible to do this manually assuming you could find or record samples in the relevant accent, timbre, elocution etc and access the satnav memory - you could then manually set the voice to match the car. However you'd have to do this manually for each make/model you wanted to do - there's no way to do it automatically. You'd also have to periodically replace the samples manually if you wanted to reflect the age of the car - there's no way for the satnav to switch samples based on the age of the car. This really isn't going anywhere. Exxolon (talk) 01:04, 31 January 2011 (UTC)[reply]

My sister's TomTom satnav has a range of different voices, accents and languages - I believe the feature was built in when she bought it. She prefers the Irish accent of "Sean" over the "posh English lady" :-) TomTom#Upgraded Voices suggests some of their products support the purchase(?) of celebrity voices. Astronaut (talk) 17:11, 31 January 2011 (UTC)[reply]

What's at the edge of a piece of diamond or graphite?

Or other lattice compounds, for that matter. Unlike molecular compounds, the atoms on the edge would have unpaired electrons, so what do they do? Do they just bond with random hydrogen or oxygen atoms from the air? --75.15.161.185 (talk) 03:17, 30 January 2011 (UTC)[reply]

Yes --Plasmic Physics (talk) 03:33, 30 January 2011 (UTC)[reply]

See in particular material properties of diamond, which contains some discussion of which terminators they typically end up with. Apparently we have nothing similar for graphite (I wonder whether it would be an acute problem there -- because the orbitals are hybridized throughout the graphite layer, the burden of lacking an electron could be shared among many more atoms than in a small radical. On the other hand, it appears that a phenyl anion is not considered aromatic, so perhaps the edge atoms are not allowed to just borrow their missing electron). –Henning Makholm (talk) 04:23, 30 January 2011 (UTC)[reply]

What if it's formed in a vacuum by vapor deposition? --75.15.161.185 (talk) 13:24, 30 January 2011 (UTC)[reply]

Then it would appear that the graphite has no choice but to grow with unpaired electrons at the edges, wouldn't it? As far as I can search, the most abundant molecules in carbon vapor are things like :C=C: and :C=C=C: which have more unpaired electrons than they have atoms, so it would still be a net win for them to join a growing graphite sheet, even if the sheet does not terminate nicely. –Henning Makholm (talk) 14:44, 30 January 2011 (UTC)[reply]

fruit

If a fruit falls from a tree and no animal eats it, will the fruit aid in the seed in growing? —Preceding unsigned comment added by 92.3.157.72 (talk) 03:35, 30 January 2011 (UTC)[reply]

If the fruit is not eaten by an animal, it's likely to rot before the growth season starts anyway. And even if it miraculously avoids rotting, the seedling would have to absorb the sugars from the fruit through its root, and it's far from clear that it would be up to that task -- the root epidermis would have to express specialized membrane transport proteins for this, and likely has no evolutionary reason to think trying that might be a good idea. It's even possible that the osmotic pressure of the sugar would make it difficult for the seedling to absorb enough water to grow. –Henning Makholm (talk) 04:55, 30 January 2011 (UTC)[reply]

Wait, surely the fruit rotting is a good thing, as now the seeds are sitting in a small amount of compost? I don't think any theory of fruits and seeds proposes that the seeds make use of the unrotted fruit. I'm sure many plants rely on animals eating the fruit to disperse the seeds, but that seems far from the only purpose of fruit in all non-cultivated plants: there are fruits with protective systems to prevent them being eaten, for example. And some apples, for instance, do rot where they sit without being eaten, and then the apple seed grows in the apple-enriched earth: there doesn't need to be only one benefit to something. 86.164.58.119 (talk) 10:33, 30 January 2011 (UTC)[reply]

This is a common misconception; the main purpose of fruits is not to provision seeds. Generally speaking, the purpose fruit serves a plant is to disperse the seeds via animals. This is a classic mutualistic interaction, because it benefits both the plant and the animal. SemanticMantis (talk) 05:33, 30 January 2011 (UTC)[reply]

And where fruits contain poison normally the poison is only present until the fruit is ripe or it is only in the nut or it is poisonous to some mammals rather than birds for instance so the seed gets widely dispersed. Dmcq (talk) 11:01, 30 January 2011 (UTC)[reply]

What is the point of the rough almost armoured coat on a lychee? This coat or rind seems "designed" to prevent animals from eating it. Thanks 92.29.125.152 (talk) 14:09, 30 January 2011 (UTC)[reply]

Plants often 'target' a certain animal to disperse their fruit. In the case of the lychee, the shell may keep out insects or mice, but allow a bird to eat the fruit and carry it farther. SemanticMantis (talk) 14:17, 30 January 2011 (UTC)[reply]

Dmcq mentioned something similar (before the OP's question) and there are also chillis and durians as other examples of targeting the right dispersal agent/animal. Nil Einne (talk) 15:14, 30 January 2011 (UTC)[reply]

Durians 'target' a handful of primates annually, resulting in several fatalities. -- 110.49.193.138 (talk) 17:22, 31 January 2011 (UTC)[reply]

the temperature of crab nebula

i had read any subject in scientific american that the temperature of nebula of such crab is 10⁴ degrees centigrade . i want to know if that is so or i have forgotten. --78.38.28.3 (talk) 06:22, 30 January 2011 (UTC)a.mohammadzade[reply]

I've fixed the formatting so that the question is more easily readable. Mitch Ames (talk) 06:27, 30 January 2011 (UTC)[reply]

According to our Crab Nebula article:

In visible light, the Crab Nebula consists of a broadly oval-shaped mass of filaments ... The filaments' temperatures are typically between 11,000 and 18,000 K ...

10⁴ degrees Centigrade is about 10,000 Kelvin, so the visible part of the nebula is about 10⁴ °C. Mitch Ames (talk) 06:35, 30 January 2011 (UTC)[reply]

ok thanks alot .then for recent observation the crab nebula is accelerating particles . is there any nucleic reaction in such clouds?--A.mohammadzade (talk) 06:57, 30 January 2011 (UTC) — Preceding unsigned comment added by A.mohammadzade (talk • contribs) 06:49, 30 January 2011 (UTC)Template:Unsigned -->[reply]

Note that "temperature" is fairly misleading in this setting. The crab nebula is a high-quality vaccum by our standards. So while the average energy of molecules in the nebula is high (that defines "temperature"), the energy density is extremely low. You could sit inside the nebula in a space suit forever, and still loose more energy from your thermal radiation at ~300K than you would take in from the rare interaction with one of the "hot" particles. The nebula is a recent supernova remnant. Supernovae often generate a lot of (in absolute terms) very heavy radioactive elements. So I'm fairly certain that there still is a measurable amount of nuclear fission going on in the nebula. I don't think there is an appreciable amount of fusion, though. --Stephan Schulz (talk) 09:27, 30 January 2011 (UTC)[reply]

Tidal Locking Formula

Dear Wikipedia

I emailed Dr. Burns at Cornell University (e-mail address removed). He said that he had a quick look for formula 2 [which has 10 to the 10 years on the end of it] and it is not in the book cited on the wiki page. http://en.wikipedia.org/wiki/Tidal_locking#Timescale

Would Dr. Peale know? (e-mail address removed)

I have removed e-mail addresses in the above, as per the policy at the top of this page. Red Act (talk) 09:35, 30 January 2011 (UTC)[reply]

The formula you seem to be referring to is not cited to a book at all. Which book is it missing from? Do you contend that the formula is wrong? –Henning Makholm (talk) 11:34, 30 January 2011 (UTC)[reply]

Can anyone provide clear, simple answers to these Mandelbrot Set questions needed

1. I’ve heard that the Set is connected I gather this means it has no islands. Does that mean you could go from any point on it to any other point without lifting your pencil? But could you do it without crossing any other line?

2. I see great electric lightning type tendrils coming from the main body. Are these lines or do they have have some kind of width? With the tendrils, I have seen images where they extend many times further than the diameter of the main body. How far is the longest one/

3. Also on tendrils coming from the main body, I notice that they seem to be more violent and extensive at the poles of the three main bodies, and that more sub MD sets are clustered there. Is this true, or do I just imagine that there are areas more conducive for such activity?

4. On the tendrils, sometimes a sub-MD appears. How does this happen? Why does a tendril go on normally and then suddenly explode into a full MD. Is there some value in the code which, when it is encountered, explodes it into a whole new set?

5. It says in the article that the MD is self-similar, but unlike Koch’s snowflake and others, you can’t make a priori predictions as to what will be happening down levels deeper. I’m told that this means that the volume enclosed by the set can’t be calculated except within limits. Is this true?

6.There seems to be no shape or line in this set which looks like anything in Nature, expect superficially. There are no circles or lines. I noticed in images that the lance of the MD seems to have something like a straight line, or gradually curved one, and that the fractal activity there appears less complex. Are there areas of the Set where complexity is reduced compared to other areas? Can this complexity scale be measured? Myles325a (talk) 11:57, 30 January 2011 (UTC)[reply]

1: Yes, when we say it is connected, it means you could (in principle) draw a line from one point in the set to any other point in the set, without leaving the set or lifting your pencil. SemanticMantis (talk) 14:55, 30 January 2011 (UTC)[reply]

5: Basically, yes. Note that the Mandelbrot set is not self-similar in the same strong sense that the Koch curve is. There is at the moment no exact area known for the Mandelbrot set, but we can (in principle) calculate it as precisely as we choose. Related is the idea of the Coastline problem, which is often paraphrased as "The length you get when measuring a coastline depends on the length of your measuring stick". SemanticMantis (talk) 16:18, 30 January 2011 (UTC)[reply]

6: It is interesting you say no shapes that look like 'nature', and then mention circles and lines. It is true there are no perfect circles or lines in the (boundary of) the Mandelbrot set, but there are also very few circles or lines in nature (i.e. the physical world). In fact, many sources mention that things like clouds, mountains, or islands are better described by fractal geometry than Euclidean. SemanticMantis (talk) 14:14, 30 January 2011 (UTC)[reply]

4: There is no why. The set is what it is. There is no secret input value hidden in the code. In fact, the code is incredibly simple. 71.101.41.73 (talk) 16:34, 30 January 2011 (UTC)[reply]

2: These filaments do have width, a program such as fractint will let you zoom in to see more detail. Also note that all the pretty colors are outside of the set, and colored by 'escape speed'. For the questions you are asking, you want to focus on the second, black-and-white picture in our mandelbrot set article. SemanticMantis (talk) 21:11, 31 January 2011 (UTC)[reply]

Delivery

during the delivery of a child the child does not get harrased or injured while passing through the pelvic girdle? — Preceding unsigned comment added by Joshuki (talk • contribs) 12:15, 30 January 2011 (UTC)[reply]

See Birth trauma (physical) for some types of physical injury that the child can sustain during delivery. As for harassment, I think the risk is low. Staecker (talk) 13:56, 30 January 2011 (UTC)[reply]

What do nebulae look like in visible light?

What would a nebula look like if you were inside it on a spaceship? --75.15.161.185 (talk) 13:26, 30 January 2011 (UTC)[reply]

It depends on the nebula. For interstellar clouds, in most cases, it would be invisible. Matter is very diffuse in these nebulae. The Great Andromeda Nebula would presumably look a lot like the Milky Way from the inside. --Stephan Schulz (talk) 13:35, 30 January 2011 (UTC)[reply]

Would it ever look like the dense, glowing fog/clouds used in TV shows like Star Trek? --75.15.161.185 (talk) 15:11, 30 January 2011 (UTC)[reply]

Only if you use a positronic scan with reversed polarity. --Stephan Schulz (talk) 15:43, 30 January 2011 (UTC)[reply]

Make it so, Mr. Broccoli. --Anonymous, 03:52, January 31, 2011.

This wasn't really answered satisfactorily, and I can't do it properly either, but consider that the Crab Nebula has absolute magnitude of −3.1 ± 0.5, compared to 4.83 for the Sun - in other words, it is much, much brighter from a given distance. Our close neighbor Sirius has magnitude 1.42, and it's the brightest, flashiest star in the sky - though admittedly, all that brightness is in one dot rather than in a large cloud. I think something like the Crab Nebula should be spectacularly visible from neighboring stars, but I wish an astronomical expert would chime in with details. Wnt (talk) 02:28, 2 February 2011 (UTC)[reply]

This does need a better answer, but a rough calculation tells me it will remain invisible to unassisted human vision at any distance. From 6500 light years away it subtends an area of about 5 by 7 arc minutes, that is about 4 percent of the area subtended by the Moon. Move 5 times closer to 1125 light years away and it will appear as large as the Moon does from Earth, but its apparent magnitude has only risen to about 5. This would be the same as a very short-sighted person such as myself trying to see a magnitude 5 star without glasses. I have difficulty even seeing magnitude 2 stars without glasses! -84user (talk) 11:51, 2 February 2011 (UTC)[reply]

Actually I was thinking of being just a few light-years away, like Sirius, and the OP was asking about how it looked from inside. While the increase in brightness is initially cancelled out by the increase in size as one gets closer to an object, I don't think this applies when it fills a large portion of the sky. Wnt (talk) 21:33, 3 February 2011 (UTC)[reply]

cell sonicator

is there any other cell distruption method, other than sonicator ? —Preceding unsigned comment added by 115.242.140.78 (talk) 15:24, 30 January 2011 (UTC)[reply]

Yes, there are a number of different options. The optimal method will depend a lot on your ultimate goal and what you want to do with your cell lysate. As it turns out, we have a very interesting article entitled cell disruption that would be a good place to start. --- Medical geneticist (talk) 15:38, 30 January 2011 (UTC)[reply]

I'm surprised that this article doesn't mention old standbys like a Dounce homogenizer or freezing in liquid nitrogen and grinding in a mortar and pestle. (See e.g. [1] and [2] for description) Wnt (talk) 21:42, 3 February 2011 (UTC)[reply]

A scientific test to determine if Blacks are dumber than Whites

If we wanted to design an thorough scientific experiment (and ignoring all ethical considerations) to determine if Blacks are dumber than Whites for purely GENETIC reasons alone, how would we design the experiment? I came up with the following experiment, please tell me if this is a good experiment (ignoring ethical considerations) with proper controls.

The sample size of each group is unclear to me at this point. Suggestions on minimum sample size would be helpful.

1 group of newborn Blacks with at least 90% of their DNA can be traced to Sub Saharan Africa. Divided into two subgroups, one half is intact, the other half has their skin bleached. Half of the intact newborns, and half of the bleached newborns are placed into adoptive parents that live in upper class society. The race of all the parents should be white. The other half of intact and bleached newborns should be placed into adoptive parents that live in lower class society in the inner city. The race of all the parents should be black.

1 group of newborn Whites with at least 90% of their DNA can be traced to Europe. Divided into two subgroups, one half is intact, the other half has their skin darkened (not sure how this can be accomplished, but lets assume that it can be). Half of the intact newborns, and half of the darkened newborns are placed into adoptive parents that live in upper class society in the suburbs. The race of all the parents should be white. The other half of intact and darkened newborns should be placed into adoptive parents that live in lower class society in the inner city. The race of all the parents should be black.

As they all grow up, they should be given IQ tests at different time intervals, and their academic performance should be measured. This experiment would last for several decades.

The bleached and darkened newborns are there as controls. If the bleached Black newborns performed as well as intact Whites in their respective socio-economic levels, it would prove that intelligence is determined from purely external factors, and not determined by genetics.

How is my experiment? Suggestions? Are there any unnecessary groups? What should be changed? Etc ScienceApe (talk) 16:53, 30 January 2011 (UTC)[reply]

Well (gritting my teeth and trying to ignore the offensive wording of parts of the question), to have a properly controlled experiment, the participants need to be blind to the status of the subjects. You can't make a person from sub-Saharan Africa look caucasian, or vice versa, merely by bleaching or darkening skin, so I don't see how that would be possible. Going beyond this, the fact that sub-Saharan Africa comprises more human genetic variability than the entire rest of the world put together makes experiments of this sort a bit silly, in my opinion. It's like asking whether mammals are smarter than dogs. Looie496 (talk) 17:58, 30 January 2011 (UTC)[reply]

(edit conflict) Here at the RD/S we routinely rebuff, for good reason, "scientific" questions built on speculative assumptions ("what if you traveled at 1.5 times c for 5 years in an elliptical path, returning to your starting point..."). This one is in that category for multiple reasons, aside from the patently offensive premise and wording on which it's built (the hypothesis, as stated, is clearly one-sided). We have insufficient scientific basis for (i) how representative these study groups would be of the overall population on which you build the premise, (ii) that the groups could be sufficiently blinded to the study assignments, (iii) that there are "bleaching"/"darkening" procedures that would eliminate racial characteristics giving rise to bias, (iv) that adoption itself does not fundamentally alter linkages among key variables - thus making the adoptive placements an invalid surrogate for race reversal, (v) IQ tests and current measures of "academic performance" are valid measures of intelligence. More importantly, we do not have a basis for believing that these children would not be harmed in the course of this research, so it's unethical as proposed. Bottom line, this proposal is offensive, unethical, and unscientific. -- Scray (talk) 18:06, 30 January 2011 (UTC)[reply]

I've put a hat on this, a better idea would be to propose something without the given variables, but the same idea. Tofutwitch11 ^(TALK) 18:11, 30 January 2011 (UTC)[reply]

What are "blacks"? What are "whites"? We need a much better definition of terminology before we can proceed. Bus stop (talk) 18:11, 30 January 2011 (UTC)[reply]

I have hatted it. Tofutwitch11 ^(TALK) 18:12, 30 January 2011 (UTC)[reply]

In the world of science, is there anything that is as taboo as this subject? 88.112.59.31 (talk) 18:45, 30 January 2011 (UTC)[reply]

I don't think the word "taboo" is perfectly applicable here. The fundamental problem, IMHO, is that "race" is a social construct, and "intelligence" as broadly defined is impossible to measure (currently). So, science is a very poor domain in which to address the intersection of race and intelligence, and the attempts to do so end up embroiled in meta-discussion. -- Scray (talk) 18:55, 30 January 2011 (UTC)[reply]

It's not "taboo". It requires definition. What are we trying to find out? "Blacks" and "whites" are meaningless terms. "Intelligence"—what is "intelligence"? Bus stop (talk) 18:56, 30 January 2011 (UTC)[reply]

Interracial cookie. Bus stop (talk) 19:00, 30 January 2011 (UTC)[reply]

See Race and intelligence. Further discussion in this realm is unlikely to be fruitful. --Jayron32 19:14, 30 January 2011 (UTC)[reply]

I'm unclear as to why this has been hatted, except for the idea that any discussion of the topic is verboten. The OP has clearly indicated that the experiment is fanciful — he is just asking whether it would actually be useful to ferreting out the answers, or if there are methodological problems. I think there are methodological problems (the entire thing is reliant on a 19th-century vision of both race and the nature/nurture debate). But I don't see why we can't talk about that. I suppose it could be viewed as troll food, but I'm wary about preemptively labeling topics that just because they are controversial. --Mr.98 (talk) 20:39, 30 January 2011 (UTC)[reply]

But the OP labelled it in the section title with the hypothesis of Blacks are dumber than Whites. That's not a good start. I'd like to see the objective reasoning behind that. And, as Looie496 said, we need this to be a double blind experiment. I would need to hear a lot more about how that was going to happen. HiLo48 (talk) 21:00, 30 January 2011 (UTC)[reply]

It's a HYPOTHESIS. A hypothesis isn't meant to be true; it's meant to be tested, and possibly refuted, by the experiment. If a hypothesis is known to be true, it wouldn't be a hypothesis, and there would be no point in performing the experiment. --99.237.234.245 (talk) 21:04, 30 January 2011 (UTC)[reply]

Have fun! --Jayron32 20:51, 30 January 2011 (UTC)[reply]

Yes, but he could have titled the question as "A scientific test to determine if Whites are dumber than Blacks" as well, but he didn't. Why not? Clearly there is some underlining bigotry here. I agree that instead of hatting it we should discuss it openly and show why such a study (even as a hypothetical study) is unlikely to prove anything useful. Dauto (talk) 21:10, 30 January 2011 (UTC)[reply]

What about if we reformulate the question into correlation between IQ and skin color? The second can be measured, and if someone manages to measure the first, we can plot the data... Quest09 (talk) 21:16, 30 January 2011 (UTC)[reply]

Take young children from their parents and have them raised by adoptive parents? It has been done before, many times, with tragic consequences for which the Australian parliament has apologised. See Stolen Generations#Australian federal parliament apology. Dolphin (t) 21:42, 30 January 2011 (UTC)[reply]

Just a reminder - Jayron32 provided a useful link to our article Race and intelligence, which provides a thoughtful treatment of many of the issues. That would be a great starting point, if this discussion is to be fruitful at all. I'm sure that article could be improved, as well, if someone has lots of energy. -- Scray (talk) 21:46, 30 January 2011 (UTC)[reply]

The answer is that no valid scientific experiments can be done on this, because neither race nor intelligence have useful operational definitions. You could perhaps perform a study to compare the performance on standardized tests of people with various amounts of certain skin pigments, and see if there is some correlation. However, this scientific dead-end was abandoned at the beginning of the 20th century, and I don't see why one would want to waste their time with it. I'm not sure why one would suspect that skin pigments would affect test performance. As people have suggested, you might want to take a look at Race and intelligence, where you can learn more about experiments that have been done, as well as allof the bad science that's been done by people trying to prove that "Blacks are dumber than whites". -- Mesoderm (talk) 21:56, 30 January 2011 (UTC)[reply]

BTW, A lot of the responses above have been predicated on the fact that race can not be found in DNA, or that race is a social construct. This is not true, see here: http://blogs.discovermagazine.com/gnxp/2010/12/to-classify-humanity-is-not-that-hard/ Ariel. (talk) 22:53, 30 January 2011 (UTC)[reply]

It is certainly possible to classify humans based on genetics, however those classifications would not correspond with the usual concept of "race". The article you link to mentioned this: "The various phenotypically “black” peoples of the world, Africans, Melanesians, and some South Asians, do not cluster together. Rather, all non-Africans are separated from Africans by the largest component of variance within the data set." --Tango (talk) 23:17, 30 January 2011 (UTC)[reply]

Why are you only using upper class white parents and poor black parents? If you want to eliminate the effect of wealth from your study (which you need to do), you need to have white and black parents with a wide range of wealths. --Tango (talk) 23:17, 30 January 2011 (UTC)[reply]

Yikes, I didn't think I would be accused of being a racist. If it makes any difference to anyone, I have dark skin myself and I was sick of racist bigots claiming that black people are dumber than whites. They kept saying how there isn't a black nation on the planet that is modern, that the bell curve for black's performance on IQ tests is worse, that Africa isn't as technologically advanced as white nations because they are inferior, etc, etc. Just awful things, and I was so sick of it, I wanted to at least conceive of a real scientific test that would at least provide some evidence that what they are saying simply is not true. But I want it to be as accurate as possible with proper controlls, so please try to indulge me for the sake of argument. How would I do this if we had no ethical considerations stopping us? ScienceApe (talk) 00:13, 31 January 2011 (UTC)[reply]

You would begin with an operational definition for both race and for intelligence. After that, the experiment would be trivial to conduct. The difficult part is creating an operational definition that other people agree on, because science is subject to peer review. As you have been informed many times, both concepts - race and intelligence - are poorly defined, and therefore difficult to use in straightforward experiment. Nimur (talk) 18:33, 31 January 2011 (UTC)[reply]

I want to expand on someone's concern above about IQ tests. They do not measure smartness and dumbness. They measure the ability to score well on IQ tests. HiLo48 (talk) 00:34, 31 January 2011 (UTC)[reply]

Then we can't use terms like race and intelligence since they aren't well defined. I'm having trouble phrasing a testable hypothesis with terms that have well defined definitions, but here's my attempt,

"Americans with at least 90% of their ancestry descended from Subsaharan Africans have comparable IQ and academic performance to Americans with at least 90% of their ancestry descended from Europeans based on genetics alone" ScienceApe (talk) 19:21, 31 January 2011 (UTC)[reply]

All humans descend from a common ancestor. So your definition fails to specify a meaning for "90% of their ancestry descended from (blank)." That leaves an enormous ambiguity subject to interpretation, meta-debate, and so on. As I said, meaningful and scientifically acceptable construction of definitions will be the hard part of your experiment. Nimur (talk) 19:51, 31 January 2011 (UTC)[reply]

Well I remember this American researcher coming to Nigeria saying he was researching to show blacks had the same IQ as whites and being asked was that American whites or European whites. Went off in a huff he did. :) Dmcq (talk) 20:37, 31 January 2011 (UTC)[reply]

Any suggestions would be helpful Nimur. ScienceApe (talk) 04:07, 1 February 2011 (UTC)[reply]

Personally, I don't believe there is any meaningful scientifically valid definition of human race. I think that emphasizing race in scientific and sociological literature solidifies the position of race as an established social norm, indirectly validating all of the social ills associated with racial discrimination. I believe race is just one of many weakly-defined social institutions that are constructed by the gentry with the intent to isolate, divide, and weaken the proletariat; and that when we all finally unite as a species, instead of quibbling over insignificant differences of language, gender, color-tone, and eye-shape, we will be unstoppable. But my opinion isn't at issue here. You can read all about other viewpoints at our article, Race (classification of humans); you can also read scientific racism for perspective. Regarding the definition of intelligence, I think IQ is a pretty darned good indicator of how smart you are, albeit with some well-known flaws; but again, my opinion isn't at issue here. You can read about intelligence, intelligence quotient, and standardized testing to see what professional psychologists and other researchers have previously concluded; and you can make up your own mind. If you really want my opinion, though, I will direct you to this archive from August 24 of last year where I posted several long paragraphs about intelligence in response to another IQ-related question. If you would like references for specific books on human intelligence, or various books expressing different viewpoints about the sociology of human racialism, I can recommend those too. Nimur (talk) 04:40, 1 February 2011 (UTC)[reply]

Well that's exactly what I want to prove here, that race is just a social construct. But just asserting that without evidence doesn't say much. There has to be a scientific test to back up that claim with evidence. ScienceApe (talk) 17:48, 1 February 2011 (UTC)[reply]

Better add "operational definition of social construct" to your to-do list, then. As well as a meaningful semantic effect of just. –Henning Makholm (talk) 19:59, 1 February 2011 (UTC)[reply]

Well that's not my hypothesis, that's just my opinion as it is Nimur's. I don't know what is a good hypothesis. I think this can be tested, I need a testable hypothesis. ScienceApe (talk) 21:24, 1 February 2011 (UTC)[reply]

Above, I have tried to differentiate between opinion and scientific fact. I do not believe you can apply the scientific method to test or disprove opinions. Nimur (talk) 19:43, 2 February 2011 (UTC)[reply]

If it's a valid hypothesis, sure you can. A hypothesis is an educated guess. That guess can be an opinion. ScienceApe (talk) 19:50, 2 February 2011 (UTC)[reply]

The first problem in this experiment is one of definitions. What is "black" and what is "white"? Bear in mind that the usual taxonomic way of defining species or races is cladistic - it assumes that you can say with certainty that two groups are more related to one another than a third group. But within a species, cladistics breaks down. According to ideas I read some years ago, which don't seem to be as popular of late, modern Homo sapiens diverged into three main subpopulations, one of which came to populate western Africa near its connections to Asia minor, and left Africa and colonized all the other continents before the others. But this cladistics is threatened by reports that modern humans, especially outside Africa, may contain a small proportion of genes from Homo erectus^[3] and Homo sapiens neanderthalensis. This would technically make some people, especially whites, a crossbreed of more than one species, though only to a small extent, and perhaps variably between individuals. Who then is more related to who? It gets complicated. And the problem is, these estimates of cross-breeding are all statistical in nature - it's not like a scientist can actually point to your gene sequence and say that you're 3.1% Neanderthal and these are the genes you inherited from them.

Of course there are less technical obstacles of definition. Some people, for example, wouldn't class Egyptians as black, even though they are Africans, or wouldn't class Hispanics and Asians as white, even though they are light skinned, and so forth. Social factors and irrational beliefs determine what people are lumped into a race more than any science.

Another problem that comes up is the issue of what defines intelligence. Some races have a larger proportion of people with weak catechol O-methyltransferase activity than others, and those with the right genotype are reported to do a whole 4% better at a card sorting test than those without. Well, actually, on examination, they do it faster but with more errors (PMID 17689985). So do you define the test as important? Does it matter more to get it done fast or get it done right? I suspect that the race that writes the IQ test will tend to do the best at it.

Now the "newborn" criterion sounds like a nice, clean start - but it clearly is not. A newborn could come from a crack mother or one who plays Mozart to her unborn fetus. It might have received prenatal vitamins or been subjected to amniocentesis and was allowed to survive only because it was healthy. Beyond this, the fetus may carry epigenetic traces of the lives of its parents and grandparents, which potentially might direct it to build (for example) a bigger brain as directed by epigenetic marks on (maybe) insulin-like growth factor target chromatin regions, committing irrevocably to the body's expectation that more nutritional resources will be available throughout the child's life. So you don't have a clean start, and it's very difficult to get one.

Philosophically, one might even question whether a per-individual basis, which favors the largest, most resource-intensive humans, is really the accurate criterion. In a future human species, perhaps people will be smaller, the descendants of African "pigmies", with perhaps a fraction of a percent of their maximum computation rate shaved off on account of fewer neurons, but capable of supporting twice as many in an interstellar ship using the same amount of resources. Is that truly a stupid way to design a human being? Wnt (talk) 02:01, 2 February 2011 (UTC)[reply]

Well the the methods to find significant latent variables are getting better so we shouldn't need definitions so much and fast gene sequencing should help with finding groupings. I don't doubt that some group differences will be found that aren't due to deprivation or disease or upbringing but it seems pretty certain they are not very significant compared to the general variability that occurs anyway. As to the original question I guess it would eventually work out as has the contribution of Neanderthal genes contributed significantly to intelligence because there probably hasn't been enough time for a large drift or mutation factor - though of course evolution is affecting intelligence today just as it always has. That would have to be compared to the much larger variation between peoples in Africa, so which particular blacks would one choose? In fact it is perfectly possible that some tribe in Africa will turn out to have the highest innate intelligence by most measures of that. So I'd say if you were doing an experiment like this you'd need to take a large random sample and just try and find what you are measuring from them rather than define it to start with. Dmcq (talk) 10:41, 2 February 2011 (UTC)[reply]

How to remove glue?

I was building a Heller Ariane 5 model rocket when, due to defective assembly instructions, I glued together the two halves of the fuel tank before I was supposed to. Now I need to unglue them without risking damage to the structure, so ideally I'd like to remove the glue without applying force on the model. Is it OK to submerge the model in hot water and wait for the glue to decompose?

I am using standard tube glue. Thanks everyone. Leptictidium (mt) 18:01, 30 January 2011 (UTC)[reply]

"standard tube glue" is not very specific, but in context I assume you're referring to the glue generally used for plastic models, i.e. butanone-based adhesive. There are de-bonding agents sold in hobby stores for this purpose; I'm not confident that hot water will achieve the results you want because butanone works by dissolving a bit of the polystyrene and allowing the two parts to fuse, but if it won't damage your model then you could try it. -- Scray (talk) 18:33, 30 January 2011 (UTC)[reply]

I am not sure what the best way to proceed would be. One thing that comes to mind is to allow the two glued halves to remain glued together, and then to cut them apart with a tool like a Dremel rotary tool. Of course this is a very expensive approach, so you will probably want to consider other alternatives. But I just thought I'd mention the possibility of this. I really don't know much about the exact situation. But I know sometimes glues can be difficult to reverse once they have set. Bus stop (talk) 18:40, 30 January 2011 (UTC)[reply]

You can possibly try to carefully pry them apart with an old style plain razor blade. Be careful with the remaining 9 fingers! --Stephan Schulz (talk) 19:27, 30 January 2011 (UTC)[reply]

Acetone (i.e. nail polish remover) is often useful for dissolving glues. Use a cotton swab to spread some (liberally) over the glued area, and then after it's had a few minutes to work, take a razorblade to it. It might only dissolve partway through the glue the first time -- if so, cut in as deep into the glue as you can, and then apply more acetone and repeat. -- Mesoderm (talk) 19:34, 30 January 2011 (UTC)[reply]

Note that if we're talking about a welding glue like butanone, which is really a solvent as I noted above, then any solvent that can dissolve the joint may damage, weaken, or at least deface the material with which you're working. Any "liberal" application might be tested on a throw-away piece of the same material to ensure you get the results you desire. -- Scray (talk) 21:20, 30 January 2011 (UTC)[reply]

To answer your question properly you're going to have to tell us what "standard tube glue" is. Ariel. (talk) 22:45, 30 January 2011 (UTC)[reply]

EEK! I would be especially careful of acetone as it could dissolve more then just the glue! Solvents can soak into the plastic and melt them or soften them to the point where they become impossible to set. I would try the very careful razor approach. Vespine (talk) 01:23, 31 January 2011 (UTC)[reply]

Thanks to all for pointing this out -- I've used acetone to remove glue in the past without problems, but I'll definitely be more careful in the future. What types of plastics specifically do you have to worry about? -- Mesoderm (talk) 02:23, 31 January 2011 (UTC)[reply]

Actually, I found the answer to that question. Here is a list of plastics that can/can't be used w/ acetone:

Acetone-Plastic Compatibility List

Acetone, pure - Ketone, Aliphatic

LDPE at 20C ..... Little or no damage after 30 days of constant exposure.

HDPE at 20C ..... Some effect after 7 days of constant exposure.

PP at 20C ..... Some effect after 7 days of constant exposure.

PPCO at 20C ..... Immediate damage may occur. Not recommended for continuous use.

PMP at 20C ..... No damage after 30 days of constant exposure.

PETG at 20C ..... Immediate damage may occur. Not recommended for continuous use.

FEP at 20C ..... No damage after 30 days of constant exposure.

TFE at 20C ..... No damage after 30 days of constant exposure.

PFA at 20C ..... No damage after 30 days of constant exposure.

ECTFE at 20C ..... No damage after 30 days of constant exposure.

ETFE at 20C ..... No damage after 30 days of constant exposure.

PC at 20C ..... Immediate damage may occur. Not recommended for continuous use.

RPVC at 20C ..... Immediate damage may occur. Not recommended for continuous use.

PVCT at 20C ..... Immediate damage may occur. Not recommended for continuous use.

PSF at 20C ..... Some effect after 7 days of constant exposure.

PS at 20C ..... Immediate damage may occur. Not recommended for continuous use.

PVDF at 20C ..... Immediate damage may occur. Not recommended for continuous use.

PMX at 20C ..... No damage after 30 days of constant exposure.

TMX at 20C ..... Some effect after 7 days of constant exposure.

PET at 20C ..... Some effect after 7 days of constant exposure.

PMMA at 20C ..... Immediate damage may occur. Not recommended for continuous use.

SAN at 20C ..... Immediate damage may occur. Not recommended for continuous use.

PK at 20C ..... Data not available.

FLPE at 20C ..... No damage after 30 days of constant exposure.

TPE at 20C ..... Immediate damage may occur. Not recommended for continuous use.

SILI at 20C ..... Immediate damage may occur. Not recommended for continuous use.

XLPE at 20C ..... Immediate damage may occur. Not recommended for continuous use.

NYL at 20C ..... No damage after 30 days of constant exposure.

LDPE at 50C ..... Immediate damage may occur. Not recommended for continuous use.

HDPE at 50C ..... Immediate damage may occur. Not recommended for continuous use.

PP at 50C ..... Immediate damage may occur. Not recommended for continuous use.

PPCO at 50C ..... Immediate damage may occur. Not recommended for continuous use.

PMP at 50C ..... No damage after 30 days of constant exposure.

PETG at 50C ..... Immediate damage may occur. Not recommended for continuous use.

FEP at 50C ..... No damage after 30 days of constant exposure.

TFE at 50C ..... No damage after 30 days of constant exposure.

PFA at 50C ..... No damage after 30 days of constant exposure.

ECTFE at 50C ..... Little or no damage after 30 days of constant exposure.

ETFE at 50C ..... Little or no damage after 30 days of constant exposure.

PC at 50C ..... Immediate damage may occur. Not recommended for continuous use.

RPVC at 50C ..... Immediate damage may occur. Not recommended for continuous use.

PVCT at 50C ..... Immediate damage may occur. Not recommended for continuous use.

PSF at 50C ..... Immediate damage may occur. Not recommended for continuous use.

PS at 50C ..... Immediate damage may occur. Not recommended for continuous use.

PVDF at 50C ..... Immediate damage may occur. Not recommended for continuous use.

PMX at 50C ..... No damage after 30 days of constant exposure.

TMX at 50C ..... Immediate damage may occur. Not recommended for continuous use.

PET at 50C ..... Immediate damage may occur. Not recommended for continuous use.

PMMA at 50C ..... Immediate damage may occur. Not recommended for continuous use.

SAN at 50C ..... Immediate damage may occur. Not recommended for continuous use.

PK at 50C ..... Data not available.

FLPE at 50C ..... Little or no damage after 30 days of constant exposure.

TPE at 50C ..... Immediate damage may occur. Not recommended for continuous use.

SILI at 50C ..... Immediate damage may occur. Not recommended for continuous use.

XLPE at 50C ..... Immediate damage may occur. Not recommended for continuous use.

NYL at 50C ..... No damage after 30 days of constant exposure.

So basically, if you know what type of plastic the model is, you could check this list and see if it's safe to use acetone.Mesoderm (talk) 18:12, 31 January 2011 (UTC)[reply]

I have rolled your list up for convenience. Can you provide a reference citation for that list? Nimur (talk) 21:00, 31 January 2011 (UTC)[reply]

Just to be on the safe side, you can always "patch test" the solvent first on the inconspicuous inside of a part or on the disposable frames that hold the pieces. Vespine (talk) 22:04, 31 January 2011 (UTC)[reply]

@Nimur: Thanks for collapsing the list -- sorry I didn't think about doing that. I got the information from here (Select "Acetone, pure" and "All materials/resins", and don't select anything from "chemical class"). -- Mesoderm (talk) 02:15, 1 February 2011 (UTC)[reply]

Codeine and its counterparts

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page. If you have a question about drugs to take if you have an allergy, please ask a physician or pharmacist.

I have taken this discussion to the Ref Desk talk page. Bielle (talk) 22:14, 30 January 2011 (UTC)[reply]

Highbeam's offer of scientific magazines

Does Highbeam have many top scientific magazines among its offer? Quest09 (talk) 21:04, 30 January 2011 (UTC)[reply]

Here's a list of the science magazines they have. Red Act (talk) 21:12, 30 January 2011 (UTC)[reply]

Well, I can't seem to find any which is really highly prestigious.Quest09 (talk) 21:18, 30 January 2011 (UTC)[reply]

Agree - no first-tier journals. The latter are a bit hard to define dogmatically, but ScienceWatch, Eigenfactor, and Science Gateway have lists that might be relevant. -- Scray (talk) 21:40, 30 January 2011 (UTC)[reply]

Big alignment

I heard that our solar system and all the planets and the sun will be aligned with the center of the milky way galaxy in next year if so will this be noticeable. --93.107.73.219 (talk) 21:11, 30 January 2011 (UTC)[reply]

It's not the case, and it wouldn't be noticeable everyday effects even if it were. After the moon and the sun, the gravitational effect of heavenly bodies on the Earth is basically negligible. Jupiter is the next most significant, and you've never been affected by its gravity nor observed the effects of such, and we align with Jupiter roughly once a year. — Lomn 21:45, 30 January 2011 (UTC)[reply]
This is just part of the 2012 Hoax. A large part of the sordid story is at 2012_phenomenon#Galactic_alignment. In short, there is no particularly exciting multiple conjunction in 2012. The Earth, the Sun, and the galactic center line up roughly once per year. --Stephan Schulz (talk) 21:52, 30 January 2011 (UTC)[reply]

If you use a telescope and check the position of the planets, you will notice where they are, but why would it matter? --Lgriot (talk) 13:27, 31 January 2011 (UTC)[reply]

It's much easier to photograph planets when they're nearby. Stunning and artistic photographs, such as this one, featured at NASA's Astronomy Photo of the Day in April 2000, are only possible during syzygy or near-syzygy. Here's a nice gallery of December 1, 2008 Moon Venus Jupiter alignment, photographed throughout the world. A few scientific observations are possible during planetary occultations; radio shadow, atmospheric refraction spectroscopy, and other scientific measurements are possible as a one object traverse across the limb of another object. Otherwise, planetary alignments have no special significance. Nimur (talk) 22:12, 31 January 2011 (UTC)[reply]

An approximate planetary alignment can also help make it possible to use the slingshot effect to have a spacecraft efficiently do a planetary flyby of multiple planets, as in the Planetary Grand Tour of Voyager 2. Red Act (talk) 23:14, 31 January 2011 (UTC)[reply]

Subterranean flows of water (contains spoiler of Philip Pullman's The Tiger in the Well)

Starting on page 265 of Philip Pullman's The Tiger in the Well is talk of subterranean rivers and springs and whatnot. Mentions of houses crumbling into such bodies of water (and sewage and other wastes) after storms seem to be based on historical fact. Where can I read more about this phenomenon, both as a matter of fact and of history. Thanks. 66.108.223.179 (talk) 23:06, 30 January 2011 (UTC)[reply]

See Underground river, Sinkhole, Cenote and be sure to follow the "See Also" links from those articles. Ariel. (talk) 02:03, 31 January 2011 (UTC)[reply]

Following one such link: Subterranean rivers of London. 66.108.223.179 (talk) 01:42, 2 February 2011 (UTC)[reply]

January 31

Star formation

Is it right that stars can blow up and their remains recondense to form new stars? Is it also right that this cycle cannot continue forever but must gradually wind down? —Preceding unsigned comment added by 86.135.27.52 (talk) 00:03, 31 January 2011 (UTC)[reply]

In two words, yes and yes. in more words, i'm not sure where to start, perhaps with Stellar evolution and entropy.. feel free to come back if you have any more specific questions. Vespine (talk) 00:19, 31 January 2011 (UTC)[reply]

Also take a look at Metallicity. As stars age, they burn Hydrogen into heavier elements. When they "blow up" (into red giants, or even supernovae), some or all of the material of the star is ejected from the star. This can become part of a later population of stars. But not all of the ejected material is Hydrogen. The heavy elements have a number of interesting effects (they catalyse different fusion processes in the star), but, in particular, they cannot themselves fuse in the same way Hydrogen does. Eventually, a region of space will run out of Hydrogen to form stars from. --Stephan Schulz (talk) 00:32, 31 January 2011 (UTC)[reply]

(Edit Conflicts) Yes to both questions.

As is detailed in Star formation (surprise!), stars form from condensing clouds of interstellar gases and dust. Some of the gases are left over from the initial creation of the universe in the Big Bang, but this only made Hydrogen (H) and Helium (He) (and maybe a little Lithium (Li)): all other gases and (non H/He) dust have been created by nuclear fusion processes within stars (see Stellar nucleosynthesis) and then dispersed when they exploded as novae or supernovae; some of the H and He will also have been cycled through those stars without being consumed in nuclear fusion.

However, only a small proportion of stars explode. Most (see Stellar evolution) simply use up all their nuclear fuel and then gradually cool down (although the Universe has not yet existed long enough for any of the resultant white dwarfs to stop glowing from their fusion-created heat). Also, some of the material forms not stars but planets and associated materials, which do not get redispersed much. Even when a star does explode, some of its material usually remain concentrated as a white dwarf, neutron star or black hole.

Because these processes 'lock up' some of the universe's material, the amount available for forming new generations of stars is continually diminishing, and will (presumably) eventually run out. When that happens no new stars will form, no fusion will occur, and all the white dwarfs, planetary material, and so on will gradually cool down by radiation which will heat up the colder interstellar (and intergalactic) clouds until everything in the universe is at a uniform (very low) temperature - this is called the Heat death of the universe.

However, the Heat death scenario assumes that the universe eventually stops its expansion and becomes static. If it continues to expand indefinitely, the result may instead be what is called the 'Big Freeze', which may not look much different. If however the universe stops expanding and begins to contract, it may be able to restart star formation for a while before eventually coalescing into a Big Crunch, after which the prognosis is unclear. 87.81.230.195 (talk) 00:43, 31 January 2011 (UTC)[reply]

Thanks for the great answers! I have one more question... does anyone have any clue about the maximum number of times that any material will be recycled through different stars? I'm not expecting an exact answer, but something more along the lines of whether the answer is 3 or one million... 86.135.27.52 (talk) 00:56, 31 January 2011 (UTC)[reply]

Depending on how you define "material", closer to 3 (I'd put it somewhere from 10 to 100). The percentage of hydrogen fused by a star varies based on the mass of a star. The sun will fuse, ballpark, 10-20% of its hydrogen, with larger stars fusing less and smaller ones fusing more (red dwarfs, being convective, fuse nearly all of their hydrogen, albeit on much longer time frames). As for the "depending" -- well, a good chunk of that fused hydrogen, now helium, will get fused later on, either in that star or reconstituted in another future star. Is it still the same material? Still, though, there is a finite number of fusion progressions available before net energy becomes negative. Much of those heavy elements end up as the starting mass for black holes. Now, granted, at the end of all this, you can still have the material out and about somewhere (Earth's heavy elements are basically all supernova ash), and so you can get outlier cases where a bit of material cycles as unburnable stellar ash over and over and over, but odds are that a black hole will vacuum it up sooner or later. — Lomn 02:15, 31 January 2011 (UTC)[reply]

Considering the age of the Universe and the time it takes for stars to form, live, and die, most stars are either first or second generation (i.e. either formed from the initial material from the Big Bang or from the direct result of those stars "dying"). Our sun is a second-generation star, IIRC. There are likely some third or fourth generation stars out there, but with each successive generation there are probably orders or magnitude fewer stars to be found. --Jayron32 15:38, 31 January 2011 (UTC)[reply]

No, this is something of a confusion. Our sun is a Population I (or "metal-rich") star, as are most stars in our vicinity. Population II stars are metal-poor stars that formed earlier. The hypothesized Population III stars would be the very first stars, formed before the interstellar medium had been enriched by an earlier generation of stars. Since "metals" (for astronomers, everything except for Hydrogen and Helium) catalyze certain fusion processes, population III stars could become extremely large before fusion became strong enough to generate enough light pressures to stop the further increase in size. Such large stars have a very short lifetime (compared to the universe, or our sun - Hypergiants like Eta Carinae live only a few million years), so the PI-PIII classification does not correspond directly to the number of generations. --Stephan Schulz (talk) 16:32, 31 January 2011 (UTC)[reply]

color changing mug

A Chemical Engineering org I worked with gave me this wonderful mug. It's black but when you pour hot coffee in it, it changes color and reveals the group's logo. Any idea how it works? --Lenticel ^(talk) 01:31, 31 January 2011 (UTC)[reply]

My guess is the mug uses thermochromic liquid crystals, making it a kind of liquid crystal thermometer, similar to a mood ring. Red Act (talk) 01:47, 31 January 2011 (UTC)[reply]

Thanks for the explanation--Lenticel ^(talk) 02:39, 31 January 2011 (UTC)[reply]

By the way, if it's like the ones my wife and I bought about 20 years ago, be careful how you wash it. We found that the thermochromic layer was not well bonded to the mug and was very easily damaged. Of course, the technology may have improved since then. Incidentally, on ours that layer was black at room temperature and turned clear with heat, revealing the pattern painted underneath. --Anonymous, 04:00 UTC, January 31, 2011.

Identify unknown mineral

Hi. I have a very small sample of a mineral, and need some help in identifying it. I have discerned the following properties:

Type: Non-metallic
Colour: Red to reddish-brown
Crystal shape: Nearly amorphous, some flat sides, slightly irregular
Morphology: Tar-like appearance, may have layers, smooth with creases
Rock form: Igneous appearance, two 'parallelogram' sides (opposite at angle), two long nearly 'triangular' sides (opposite), one rhombus-like 'trapezoidial' side, one small 'triangle' side (opposite aforementioned)
Angles: 50° to 130°
Other minerals: At least two, one may be quartz, other mineral is greenish-brownish-black and earthy striated appearance
Mohs hardness: >6.0 (scratches stainless steel and glass)
Lustre: Waxy or resinous
Diaphaneity: Translucent to opaque
Specific gravity: ~3 - 5 (imprecise method)
Reactions: No visible reaction w/ brown vinegar

Any idea what the mineral might be? Thanks. ~A H 1^(TCU) 03:30, 31 January 2011 (UTC)[reply]

I have uploaded an image. For the other lower-quality images, see here and here. ~A H 1^(TCU) 19:33, 31 January 2011 (UTC)[reply]

I would suggest Jasper from the colour and hardness, although the S.G. would be less than you measured, any idea where it came from? Mikenorton (talk) 19:46, 31 January 2011 (UTC)[reply]

First, u must know is streak, it is very important if it's not white.--Chris.urs-o (talk) 20:02, 31 January 2011 (UTC)[reply]

I found the mineral sample as a piece of gravel on a paved road surface near a river. When I measured the specific gravity, I used a floating container in water and compared the volume displaced by the "rock" to the water-volume-equivalent (mass) displaced by the rock, thus it is an extremely imprecise method. I am unable to test the streak as I do not have an "unglazed porcelain tile" handy, though attempting to crush the rock produced a white powdery surface and pinkish edges. ~A H 1^(TCU) 20:11, 31 January 2011 (UTC)[reply]

Something must scratch the mineral, just tell me the colour of the streak. The characteristics of the streak (mineralogy) and of the cleavage (crystal) (angle n surface, if u could use a hammer), would be nice. --Chris.urs-o (talk) 20:33, 31 January 2011 (UTC)[reply]

I tried using tools such as a clamp and a hammer to create powder from the mineral, and it appears noticeably white, at least compared to the mineral itself. Any cleavage of the mineral is likely not distinct, but may come in roughly rhombus-shaped thin layers. However, I unfortunately lost the sample down the drain when attempting to wash it, so any further tests will at least momentarily be unlikely verifiable. By the way, the sample itself could have originated almost anywhere. The actual geographical location where I found it though, is Southern Ontario. ~A H 1^(TCU) 19:42, 1 February 2011 (UTC)[reply]

There are few minerals that don't have a white streak. There are few minerals with Mohs above 6.0. Lemon juice (citric acid) is better than vinegar (acetic acid). Wheathering changes the colour surface, a macro picture of the cleaved surface is better. The density is not precise enough; streak, mohs and density identify at least the mineral family/ mineral group. We'r at Mikenorton's suggestion: Jasper (SiO₂, Commons:Category: Heliotrop). Try Mindat.org, Rhodonite MnSiO₃, Orthoclase KAlSi₃O₈ ?--Chris.urs-o (talk) 05:46, 5 February 2011 (UTC)[reply]

Damiana

does Damiana lower testosterone like weed does — Preceding unsigned comment added by Tommy35750 (talk • contribs) 04:34, 31 January 2011 (UTC)[reply]

According to most of the sources here, many herbalists claim that it stimulates testosterone production, and acts as an aphrodisiac [4]. On the other hand, one author has stated that the claims of aphrodisiac qualities are an "herbal hoax"[5]. Either way, I'm certainly not seeing anything claiming that it reduces testosterone levels. -- Mesoderm (talk) 05:17, 31 January 2011 (UTC)[reply]

Paternity

Hello, i had sexual intercouse with a woman 10 months ago. I ejaculated in her oral cavity, not in her vagina. Now she has had a baby and claims i am the father, which i can't as i disposed no jizz in her vagina. Am i the father and what can i do?—Preceding unsigned comment added by 77.17.27.62 (talk) 10:22, 31 January 2011

It's easier to become a father than you might think. While it's not very likely in the individual case, sperm can get into the vagina from other ways of intercourse. You can request a paternity test (but try to be diplomatic about it). If its yours, you'd better cherish and support it. --Stephan Schulz (talk) 10:33, 31 January 2011 (UTC)[reply]

Even with perfect use, coitus interruptus has a failure rate of about 4% per year, i.e., out of 100 couples who use coitus interruptus correctly every time they have sex for a year, 4 women will become pregnant. It is thought that the primary cause of failure in the case of perfect use is preseminal fluid picking up some sperm from a previous ejaculation. So this is not necessarily a case of paternity fraud. Red Act (talk) 15:10, 31 January 2011 (UTC)[reply]

In her mouth? Kittybrewster ☎ 17:07, 31 January 2011 (UTC)[reply]

It is possible she either accidentaly or deliberately transferred it. SpinningSpark 17:39, 31 January 2011 (UTC)[reply]

I had thought something similar initially but a careful reading suggests the OP's described scenario is ambigious. He said 'i had sexual intercouse with a woman 10 months ago. I ejaculated in her oral cavity.' This may mean he solely had receptive oral sex and his penis never went anywhere near his partner's vagina, it may also mean he had vaginal intercourse (which is a common meaning for sexual intercourse) but withdrew before ejaculation (i.e. coitus interruptus) to ejaculate in his partner's mouth. In the later scenario, Red Act's reply is clearly relevant Nil Einne (talk) 18:13, 31 January 2011 (UTC)[reply]

Yes, my interpretation of the question is that vaginal sex occurred prior to the oral ejaculation. Red Act (talk) 02:42, 1 February 2011 (UTC)[reply]

You sound very much like Boris Becker after his intercourse with Ermakowa. He accused here that she stole his sperm and impregnated herself later. The whole thing was a big hype and was called the "Samenraub" Afair.--Stone (talk) 19:33, 31 January 2011 (UTC)[reply]

In theory, simple tooth brushing can cause bacteremia, so I suppose that human microorganisms might also penetrate to the bloodstream by this means. And bleeding occurs normally during ovulation, at least briefly within the ovary as it ruptures, and perhaps for a longer duration in unusual cases. This makes me think that it is theoretically possible to have a conception which, though not immaculate, is certainly unexpected. However, the odds of this probably rank up there with getting hit by a meteor - I'd need to look up the original bacteremia data to make even a wild guess. Of course in practice, I expect a paternity test is what is needed to find the truth. Wnt (talk) 00:12, 1 February 2011 (UTC)[reply]

Wnt, it seems like you are pushing way past the boundaries of "theoretically". That scenario is not even remotely possible; others have given much more plausible answers above. Let's stick with relevant references and not wild guesses. --- Medical geneticist (talk) 01:06, 1 February 2011 (UTC)[reply]

But science is supposed to be fun.... ;) Wnt (talk) 01:17, 2 February 2011 (UTC)[reply]

The OP's statement that the "Had sexual intercourse" with the paramour before "ejaculating in her mouth" provides ample possibility of introduction of his sperm in her vagina. Genetic testing might be informative. (This does not constitute medical advice, but I once watched the Jerry Springer Show). Edison (talk)

Monatomic elements?

Is there such a thing in nature? [6] <-- Is there any truth to this or is it all basically pseudo-science? -- œ ^™ 10:52, 31 January 2011 (UTC)[reply]

The noble gases are monatomic gases, but the idea that there are macroscopic amounts of precious metals in a stable monatomic form at normal temperatures and pressures makes no sense. The article that you link to is definitely pseudo-science. Gandalf61 (talk) 11:27, 31 January 2011 (UTC)[reply]

This was discussed recently; see Wikipedia:Reference desk/Archives/Science/2011 January 27#ORME Orbitally Rearranged Monoatomic Elements. –Henning Makholm (talk)

Most of that site is pure balderdash, but nuclear isomers including superdeformation and hyperdeformation of nuclei are real. And I do think that this phenomenon one day will be the basis of some very important technology... Wnt (talk) 00:23, 1 February 2011 (UTC)[reply]

However, the idea that nuclear isomers would have a different enough electron structure be relevant for chemical bonding sounds firmly like balderdash. There's the isomeric shift, but that's rather more subtle. –Henning Makholm (talk) 02:02, 1 February 2011 (UTC)[reply]

WiFi laptop or home PC amateur radio packet network equivalent

I know that armature radio has a packet radio relay system which can serve as a network with each station becoming essentially a switch. Is there a way for home computers and laptops with WiFi to set up such a network as well? I ask because even in my neighborhood whenever I try to set up my WiFi I get a list of connections I might log onto. --Inning (talk) 13:04, 31 January 2011 (UTC)[reply]

Yes, the general term for such is a wireless ad hoc network, and WiFi supports such capability. Note, though, that those connections you're seeing (almost certainly) aren't configured for that purpose. — Lomn 14:15, 31 January 2011 (UTC)[reply]

How might one configure those connections for such a purpose in the event of an emergency? 19:43, 31 January 2011 (UTC) — Preceding unsigned comment added by Inning (talk • contribs)

You might be better asking these questions on the computing/IT ref des. CS Miller (talk) 19:59, 31 January 2011 (UTC)[reply]

With wifi, the short answer is "you won't". Wifi is a very short-range network type intended to transfer data between computers -- it's not capable of cross-linking into a ham radio system or other useful emergency response system. Additionally, the hardware to run a standard no-config-needed wifi network is dirt cheap and readily available -- just grab any $50 router off the shelf at a store and plug it in. Ad hoc wifi has very little real purpose or utility. — Lomn 21:05, 31 January 2011 (UTC)[reply]

That said, your search engine of choice (or your operating system help files) will readily tell you how to use ad hoc networking for your particular system. — Lomn 21:07, 31 January 2011 (UTC)[reply]

...so you are saying I can not log onto my neighbors WiFi and in turn have him log onto one down the street , etc until a link of WiFi's make up a network that reaches across town and eventually to the next town, county, state and country? --Inning (talk) 02:10, 1 February 2011 (UTC)[reply]

In principle, I see no reason that you couldn't, provided you've got enough suitably equipped computers to bridge the inevitable network gaps. The effort and cooperation needed, however, is unlikely to ever materialize, nor is there any compelling use case beyond "to see if it can be done" (a motivation which has a rich tradition on the internet, to be sure). But if you want wireless computer communication in the event of emergency, plan on some combination of data-rich mobile service or satellite internet -- protocols designed for the purpose at hand. — Lomn 04:21, 1 February 2011 (UTC)[reply]

You may be interested in today's news stories about the Open Mesh Project (wireless mesh networking, mesh network)^{[7], [8]}. It sounds like this idea - which I should say grumpily, should have been a major focus by somebody somewhere before major protests and internet blackouts broke out - may finally get the attention it needs. Wnt (talk) 01:25, 2 February 2011 (UTC)[reply]

Brace, brace

I've noticed that the advised position to brace for impact on cheap flights (e.g. Ryanair or Easyjet) would place my head hard against the seat in front, with tension in my neck. I'm just under six feet tall, which I suppose is about average height for a 26 year old male in the UK. Could the intention be that a quick cervical dislocation would reduce/prevent my suffering in the event of a collision? --129.215.47.59 (talk) 16:55, 31 January 2011 (UTC)[reply]

I think the idea is to protect you from injuries like whiplash in the case of light impacts. Of course, if your plane ploughs headlong into the side of a mountain, there is not much you can do. Also, it's not just cheap providers who offer this advice - it's standard across industry. I don't have any references for this, but I can tell you I have never flown on the providers you mention and I have seen this advice on pretty much every flight I have been on. --KägeTorä - (影虎) (TALK) 17:03, 31 January 2011 (UTC)[reply]

We do have an article about it: Brace for impact. --KägeTorä - (影虎) (TALK) 17:07, 31 January 2011 (UTC)[reply]

The general idea with a brace position is: you're going to end up in that position anyway in a hard deceleration. By pre-positioning yourself in that position, you reduce blunt head trauma and whiplash involved with getting your head into that position from the crash. Whatever then happens, was going to happen anyway. Arakunem^Talk 17:08, 31 January 2011 (UTC)[reply]

The brace position will soon be adapted to the air-bags used in some planes.--Stone (talk) 19:04, 31 January 2011 (UTC)[reply]

Incidentally, some people seem to believe that the brace position was designed to kill you (to lessen the insurance payout). Mythbusters did an episode on it, finding this not true, and that the position does really help reduce neck and head injury: [9]. Buddy431 (talk) 04:38, 1 February 2011 (UTC)[reply]

I understand that passengers would be better off if all the seats faced backwards, which I whjat I'd prefer. 92.28.247.121 (talk) 18:42, 1 February 2011 (UTC)[reply]

The proposal for rear-facing airplane seats was discussed somewhere and the conclusion seemed to be that the only way to get passengers to accept it would be to replace the windows with TV screens showing moving clouds, and have a dummy cockpit door at the back wall of the plane. Cuddlyable3 (talk) 20:48, 1 February 2011 (UTC)[reply]

About half the passengers in trains are happy going backwards. Actually what I would prefer would be something like bunks that you could lie flat on. I think you could squeeze as many or more in if they were stacked zig-zagged and in alternate directions so that everyone got a double height above their cheast and head. 2.97.220.121 (talk) 20:26, 2 February 2011 (UTC)[reply]

Forward facing seats are simply what people have become used to by not being given a choice. The first commercial aircraft, such as the Boeing 307, often had seats facing in both directions, similar to a train. Some even had bars with barstools so you could swivel around and face whichever way you liked - including face down on the floor when the plane hit turbulence. -- kainaw ™ 20:42, 2 February 2011 (UTC)[reply]

The difference between aircraft and train seats is that aircraft frequently operate with a significant pitch angle. The RAF passenger VC10s used to operate with rearward facing passenger seating and I can confirm from personal experience of several transatlantic crossings courtesy of Crab Air that the sensation of being about to fall forward out the seat the whole time quickly gets quite wearing. Zeusfaber (talk) 23:03, 2 February 2011 (UTC)[reply]

But unless you are taking-off and landing at different altitudes, don't you have as much up-pitch as down-pitch? 92.15.14.91 (talk) 17:31, 3 February 2011 (UTC)[reply]

ear piercing (2)

A follow up to semi-archived discussion above: (copied text removed) –Henning Makholm (talk) 19:48, 31 January 2011 (UTC)[reply]

Also, is the a time when closing of the piercing is impossible?Accdude92 (talk) 11:26 am, Today (UTC−6)

Could you try asking your question with more detail? I don't understand. Comet Tuttle (talk) 18:43, 31 January 2011 (UTC)[reply]

Insulated windows

I am not sure if this question has been answered before, but here goes:

My parents built a new house last spring/summer. They had energy efficuent windows installed. Several times over the course of this winter (central Ontario, Canada), they have noted frost (sometimes significant amounts) on the insides of all of the windows. When they enquired about this, the builder told them that there was too much moisture in the air. Personally, I don't buy this. I have had new windows installed in my home (several years ago) and while there may be some condensation at times (eg. after a hot shower), there has never been any kind of frost. So, while there may, indeed, be excessive moisture in the air of my parent's home, there is no way that I can think of that frost would develop unless there was something wrong with the windows construction and/or installation. The cold air from outside needs to somehow get inside to freeze the condensed moisture; properly built and installed windows should not do this. What do others think? Physics is not my forte . . . 76.75.136.254 (talk) 17:40, 31 January 2011 (UTC)[reply]

Googling for "condenstation windows", I found this guy, who claims that the condensation might be a sign that they did a good job, because it means the house is properly sealed up and thus trapping all of the moisture inside. Drafty houses let in the dry winter air, which lowers the relative humidity, making condensation less of a problem. It sounds like they sealed up your windows properly, and your parents need to get a dehumidifier. -- Mesoderm (talk) 18:04, 31 January 2011 (UTC)[reply]

I think the OP is implying that the windows are sub-standard because they are letting heat out (hence the frost), not because of the condensation per se. But I have no idea whether or not this would be normal at Canadian temperatures. SpinningSpark 18:42, 31 January 2011 (UTC)[reply]

Oh, yes. I see that now. Sorry. -- Mesoderm (talk) 18:50, 31 January 2011 (UTC)[reply]

This is very odd. We had -26°C last winter and no more than -10°C during the day and the 20 year old double glass isolation windows showed a lot of condensation but no ice not even in the bedroom where the heating was very low at that time.--Stone (talk) 19:01, 31 January 2011 (UTC)[reply]

It really does depend on the temperature gradient between outside and inside. If you keep the room very cool, and it is extremely cold outside, then frost would be normal. I regularly get quite a thickness of internal frost in single-glazed unheated rooms, but frost on the inside shouldn't happen in a heated room with efficient double glazing except in really extreme conditions. Drawing curtains across at night might make frost more likely. Do you have a guarantee on the windows, or any specification on their insulation rating? Are they sealed units? It sounds as if there is some convection of freezing air somewhere. Dbfirs 19:53, 31 January 2011 (UTC)[reply]

Thanks for the feedback everyone. All of the rooms are well heated but there is frost formation whether or not the curtins are drawn. A dehumidifier was recommended but, as I note, nothing should be frosting over (in my opinion). Frost develops not only where the upper and lower window meet but also on the glass and sil itself. Is there a way to measure or determine if there is a problem with the window construction or installation? 76.75.136.254 (talk) 21:12, 31 January 2011 (UTC)[reply]

Just feel the temperature with your hand. Compare the temperature of various windows, and also compare it to some external walls. A double paned window should be somewhat colder than the walls if the walls are insulated, and about the same temperature as uninsulated walls. Feel also for drafts near the window, and feel the edges of the window (not the glass, the frame), because maybe they didn't insulate the edges. Make sure they actually used double paned glass (it's easy to tell, just look inside the window at the edge). Ariel. (talk) 03:08, 1 February 2011 (UTC)[reply]

If the frame and sills are frosting first, it sounds like they are the cheaper ones without the hollow cavities having been filled with polyurethane foam; See diagram. Between the frames and sill, where they meet the walls, lintels and so on, there should also be foam sealant (often bright yellow), to keep out moisture and draughts. Also, the optimum air gap is 16 mm and with two sheets of glass -that's 24 mm total. The paper work that your parents signed (contract), agreeing to have them installed, should give details as to who's frames (or Window System) they are. From that, you can find out from the manufacture, what specifications and standards they meet. They also need to know the manufacture, in case they need to order new parts for repairs.--Aspro (talk) 14:07, 1 February 2011 (UTC)[reply]

Often the coldest part of a window is the frame. Glass can be made relatively efficient in terms of thermal efficiency, although there are limits. The frames are harder to make energy-efficient do while retaining sufficient stiffness to support the glass and to seal, since stiff materials tend to also be conductive. Single-pane glass has a U-value of about 1.3 (lower is better). Plain double-pane glass, U= about 0.49, triple clear about 0.34 and double glazing with low-e coating and argon fill about 0.30. Super-efficiency windows might reach 0.15. This is in contrast with normal wall construction, which in Canada should have a U value of about 0.05, so even efficient windows are the cold spot. The temperature of a glass or frame surface is related to the temperature gradient through the assembly, and the right combination of temperature and relative humidity might produce condensation or frost, so the answer is: it depends. Frame construction, glazing options and construction details all play a part. Acroterion _(talk) 16:07, 1 February 2011 (UTC)[reply]

Handheld missile/rocket launchers with multiple missiles

Are there any handheld rocket/missile launchers that can carry multiple missiles/rockets? ScienceApe (talk) 18:38, 31 January 2011 (UTC)[reply]

The M202 FLASH fits that description. --Daniel 18:40, 31 January 2011 (UTC)[reply]

While not a missile/rocket launcher, there is also the M32 Multiple Grenade Launcher, as well as others. --KägeTorä - (影虎) (TALK) 18:47, 31 January 2011 (UTC)[reply]

Fliegerfaust qualifies if "effectiveness" isn't one of the requirements ;) . Vespine (talk) 21:34, 31 January 2011 (UTC)[reply]

what the species name?

hi. i found a funny pic of a baby monkey online. here is the link: http://www.superlaugh.com/pets/babymonkey.jpg please, could you tell what species that baby belong to? —Preceding unsigned comment added by 62.0.34.93 (talk) 20:38, 31 January 2011 (UTC)[reply]

It's a macaque. I'm not sure about the specific species, but possibly a Toque Macaque. CS Miller (talk) 22:41, 31 January 2011 (UTC)[reply]

Processing of metals: casting

When using a pattern for hot metal casting, which kind of pattern volatilizes when the metal is poured? —Preceding unsigned comment added by 208.54.5.54 (talk) 21:22, 31 January 2011 (UTC)[reply]

Usually a pattern is used to make one or more moulds, and the molten metal is then poured into the moulds and allowed to cool. In many applications, each mould is then destroyed to allow removal of the cast object. I have not heard of volatile moulds or patterns. You could investigate investment casting and the lost-wax casting process. Dolphin (t) 21:31, 31 January 2011 (UTC)[reply]

When I was at school we used expanded polystyrene to make a shape, then formed damp sand around this. We poured aluminium into the mould and the polystyrene vapourized, leaving an aluminium shape. Whether this is still considered safe, I'm not qualified to comment. --Phil Holmes (talk) 22:03, 31 January 2011 (UTC)[reply]

See also evaporative-pattern casting. Our entire article on casting (metalworking) has lots of interesting stuff, actually. TenOfAllTrades(talk) 03:59, 1 February 2011 (UTC)[reply]

Parachutes

Why do parachutes have holes in them? 74.15.137.130 (talk) 22:25, 31 January 2011 (UTC)[reply]

See Parachute#Round types. Basically, it reduces flapping around. I think it also increases drag by forcing the air to flow around the interior of the chute, rather than creating a high-pressure cell. --T H F S W (T · C · E) 22:33, 31 January 2011 (UTC)[reply]

How does it reduce oscillations? 74.15.137.130 (talk) 00:13, 1 February 2011 (UTC)[reply]

If you drop a piece of paper it slides back and forth as the air spills first from one side then the other. By putting a hole in the middle all the air spills from there instead of the sides, which stops it from doing that. Ariel. (talk) 03:02, 1 February 2011 (UTC)[reply]

To clarify a bit, the holes help the parachute keep its shape. It is simplest to explain with the round "WWII" style parachutes. If you just have a closed fabric "cup", inverted, the air rushing into the parachute from the bottom needs a way to get out. If you don't have a hole in the middle, it gets out by tipping the entire cup shape on its side, which does a pretty terrible job of actually slowing you down. By putting a hole in the middle, the inrushing air is "funneled" out the hole in the center, which prevents the chute from tipping over or collapsing. Now, with all of the inrushing air escaping out the top, the chute is able to maintain its inverted cup shape, and thus help to trap most of the air, and thus slow you down. The same principles apply to the rectangular shaped parachutes, but its just organized a bit differently. --Jayron32 05:37, 1 February 2011 (UTC)[reply]

And you can tug on a pair of handles just before you hit the ground which close the holes and slow you down. Alansplodge (talk) 09:24, 1 February 2011 (UTC)[reply]

Also, per the article, vents enable a certain amount of steering.--Shantavira|^{feed me} 10:25, 1 February 2011 (UTC)[reply]

February 1

Levitation material

Back in the mid 80's, I recall that a group (probably some university students) had mixed some compounds together which was then shaped into a disk. As I remember it, I believed that they needed to heat this compound in a kiln as part of the process. Later, they were then able to have this disk suspend over some sort of gas, perhaps liquid nitrogen or it could have possible have even been dry ice - I am not sure. It became an interesting science fair project and was repeated often (certainly at that time). Other than being able to get the compound to suspend or levitate - I can not recall what use it may have eventually became of it. Certainly, ideas of high speed trains utilizing this discovery were at the forefront. I do recall however that Omni magazine had a contest which was to determine the best practical use of this discovery and challenged its readers to submit idea/designs towards that end. Would anyone recall what I am referring to and how the Omni contest turned out?24.89.210.71 (talk) 02:24, 1 February 2011 (UTC)[reply]

The only thing that comes to mind for me is the Meissner effect. --Mr.98 (talk) 02:35, 1 February 2011 (UTC)[reply]

I agree, a levitating superconductor seems like the best explanation. Ariel. (talk) 03:00, 1 February 2011 (UTC)[reply]

That is exactly right. To be more specific, high-temperature superconductivity was discovered in the mid 80s. Low temperature surperconductors had been known for many decades previous to that time. Dauto (talk) 03:12, 1 February 2011 (UTC)[reply]

It was probably a demonstration of a YBCO (yttrium barium copper oxide) superconductor. It's sometimes called 123 or Y123, both because of the ratio of its metal ingredients (1:2:3 Y:Ba:Cu) and because it's a straightforward synthesis (as easy as 1-2-3...). The raw ingredients are sintered at around a thousand degrees to make the final product; that would be the kiln step you remember. I don't have a reference for the Omni contest, but mayhaps you'll have more luck given the material name. TenOfAllTrades(talk) 03:54, 1 February 2011 (UTC)[reply]

Lockout Hasps

what r Lockout Hasps used 4 — Preceding unsigned comment added by Tommy35750 (talk • contribs) 03:15, 1 February 2011 (UTC)[reply]

Sounds like Lockout-Tagout. Note that many readers here do not speak English fluently and are not teenagers, so text-message-abbreviations are not a great way to communicate. DMacks (talk) 03:49, 1 February 2011 (UTC)[reply]

They are used for teaching how to hack the man in the middle attack in a classroom demonstration. One student uses a lockout hasp and padlock to safely lock a message in a box. He leaves. Another student comes in and sees a padlock on the box and agrees to place his lock on the box. He leaves. The original student returns and sees two locks, so removes his lock. He leaves. The second student returns and removes his lock to get the message. Secure, right? No. -- kainaw ™ 03:57, 1 February 2011 (UTC)[reply]

Something about igniting salt water with radio waves - our energy savior?

I heard or read long ago about an experimenter shooting radio waves at a beaker of salt water, therefore igniting it.

How come I haven't heard anything else? If igniting salt water produces more energy than what it takes to ignite it, then wouldn't that be our energy savior once and for all?

If it truly works as hoped, we could shut down all the dirty power plants and refit all motor vehicles to run on salt water instead. To expend salt water would be an EPIC civic duty because we might stem the tide of rising sea levels just from burning it off.

Moreover, the source of energy should be epically cheap. How much $ per gallon would salt water sell for?

Anyway, if the energy expenditure-to-energy generation ratio isn't efficient enough, why not improve the tools and methods to make the process more efficient?

^{PS: I wonder what the emissions would be, and if it'd be detrimental.} --70.179.181.251 (talk) 05:01, 1 February 2011 (UTC)[reply]

How do you get the energy to generate the radio waves? I'll give you a hint: It probably invoves burning something that is the compressed remains of dead algae... --Jayron32 05:05, 1 February 2011 (UTC)[reply]

(ec) That's a lot of wondering to do about something that is total nonsense. Looie496 (talk) 05:07, 1 February 2011 (UTC)[reply]

Could someone supply the chemical equation for the combustion of saltwater, or prove that it is utter nonsense? Edison (talk) 05:12, 1 February 2011 (UTC)[reply]

It isn't combustion. If you take wet salt (or molten salt, but wet salt is easier to obtain) not salt water, but rather slightly moisten salt, and blast the shit out of it with a powerful electric current, you will electrolyze it into sodium metal and chlorine gas. The deal is, their's more than enough ambient energy in the air to provide the activation energy to cause the sodium and chlorine to pretty much instantly re-react again, creating a rather impressive fireworks show. You get lots of brightly colored flames when you do it. If you have a carefully controlled set up, you can isolate the chlorine gas (it will form at the cathodic electrode) and prevent it from recombining with the sodium. But if you basicly just jam the leads from an stripped extension cord into a pile of wet salt, you get some pretty awesome flames. (note to kids: DO NOT DO THIS AT HOME). This isn't actually combustion per se, its just the tiny bit of sodium and chlorine gas you just formed via electrolysis reacting to reform the salt. --Jayron32 05:25, 1 February 2011 (UTC)[reply]

...and it should go without saying – though I'll say explicitly it here anyway – that the heat and light energy released by the recombination of the chlorine and sodium will never exceed the amount of electrical energy that you put in to separate them in the first place. (This will be true regardless of the energy source used, actually—there's nothing special about radio waves versus electric current.) If it were possible to extract additional energy from the process, it would be a perpetual motion machine of the first kind. If you prefer to think of it in terms of combustion, sodium chloride is just the 'ash' you get when you burn metallic sodium in a chlorine atmosphere; it's the waste product you get after you've extracted very nearly all the available chemical energy. TenOfAllTrades(talk) 14:04, 1 February 2011 (UTC)[reply]

See the video here. The relevant part starts about at about 1:20. But yes, as Jaron implies, it's bullcrap. Specifically, bullcrap that a bunch of ignorant reporters decided to pass off as news years ago. Someguy1221 (talk) 05:32, 1 February 2011 (UTC)[reply]

Getting arsenic out of water

How does one purify arsenic out of groundwater.--128.54.15.47 (talk) 06:07, 1 February 2011 (UTC)[reply]

With ion exchange. --T H F S W (T · C · E) 06:39, 1 February 2011 (UTC)[reply]

See Arsenic contamination of groundwater. The sourcing is terrible, but it will provide you some good terms to Google for. Also, see the books listed here. -- Mesoderm (talk) 07:01, 1 February 2011 (UTC)[reply]

OP here (probably a different IP though). Anyone know the cheapest option on filtering arsenic out? If so, know the cost? I'm trying to compile a budget for a project and it would be a great help.--128.54.224.231 (talk) 07:50, 1 February 2011 (UTC)[reply]

It really depends on the scale. For a small scale - for one or a few households - reverse osmosis would probably be the cheapest however disposal of the "filtrate" and used filter cartridges will be a serious concern. Roger (talk) 07:55, 1 February 2011 (UTC)[reply]

I'm trying to develop a proposal for rural Bangladesh so it can't be anything too complicated I imagine. Specifically I'm responsible for the budget. I'm thinking a community scale of sorts. Household can work too. I know this is an odd question.--128.54.224.231 (talk) 08:02, 1 February 2011 (UTC)[reply]

I'd consider asking an expert at a school of public health, like Allan Smith at Cal Berkeley. Researchers at schools of public health usually have their heart in the right place, and will certainly know the data and many of the options. Looks like Bangladesh is on his list, too. -- Scray (talk) 12:55, 1 February 2011 (UTC)[reply]

Study what already works localy. [10]--Aspro (talk) 13:12, 1 February 2011 (UTC)[reply]

Planetary Satellites Book

Dear Wikipedia I emailed Dr. Burns at Cornell University (email redacted) and he does not think that Tidal Locking [11] timescale formula number 2 is in the book "Planetary Satellites." It is not in the Gladman article http://audiophile.tam.cornell.edu/randpdf/gladman.pdf. Formula 2 has 10 to the 10 years at the end of it. Would Professor Peale at University of California Santa Barbara (email redacted) who wrote the chapter have the answer?PaulNethercott (talk) 09:28, 1 February 2011 (UTC)[reply]

The answer to what? And how should we know whether some particular person can answer whatever? This is an encyclopedia, not an oracle. –Henning Makholm (talk) 10:04, 1 February 2011 (UTC)[reply]

A discussion about the formulae quoted in the article Tidal locking was started here and should be continued on the article talk page. The OP seems to have investigated the reference sources (no. 4) quoted in the article. To investigate further, one can look through the article history to find who has edited the article and try contacting them on their talk pages. Cuddlyable3 (talk) 11:38, 1 February 2011 (UTC)[reply]

Please don't repeat your question here after only 2 days. Cuddlyable3 (talk) 21:41, 1 February 2011 (UTC)[reply]

Using lasers to melt snow

Anything like this exist yet? ScienceApe (talk) 15:20, 1 February 2011 (UTC)[reply]

Why would you want to? A hair drier is likely to be more efficient than a laser would be for that purpose... --Jayron32 15:26, 1 February 2011 (UTC)[reply]

Possibly, unless it actually isn't very good at melting snow. Doesn't seem like it would require that much technological know how, so why don't we have these? Well I mean a device that blows hot air for the sole purpose of melting snow I mean. ScienceApe (talk) 15:36, 1 February 2011 (UTC)[reply]

Because melting snow requires a lot more energy than shoveling it out of the way. --Stephan Schulz (talk) 15:44, 1 February 2011 (UTC)[reply]

For roads maybe, but I had drive ways in mind mostly. ScienceApe (talk) 17:53, 1 February 2011 (UTC)[reply]

Why would there be a difference? --Stephan Schulz (talk) 17:56, 1 February 2011 (UTC)[reply]

Because on a driveway, you're breaking your back to shovel it! You're not using a truck. ScienceApe (talk) 18:10, 1 February 2011 (UTC)[reply]

This [12] doesn't use lasers, but it apparently uses a dragon. Acroterion _(talk) 15:50, 1 February 2011 (UTC)[reply]

As Acroterion say's. If you look at the Enthalpy of fusion you will see that it take about 333 kJ of energy. One only needs about 4KJ to then bring it to boiling. In other words, melting ice consumes a lot of energy , almost as much as boiling it. Might be cheaper to compress it, load it onto a bulk-carrier and sale it to Arabia. There exchange it for oil, which is costs less than bottled water.--Aspro (talk) 15:52, 1 February 2011 (UTC)[reply]

It's actually somewhat more efficient to collect the snow and melt it in a purpose-built device — just blowing hot air means wasting a lot of energy (not all of the heat is efficiently transferred to the snow; a lot of warm air would escape). See Winter service vehicle#Snow melter and Metromelt. In areas which receive sufficient snow, the only way to clear the roads can be to melt it in place and dispose of the runoff through the sewer system; there just isn't enough space available to store the snow locally, and carrying it long distances to the suburbs is cost-prohibitive. TenOfAllTrades(talk) 16:57, 1 February 2011 (UTC)[reply]

There is such a thing as a heated driveway, sidewalk, or roadway. Usually, it takes the form of a fluid heat-exchanger running through specially-constructed plumbing pipes underneath the pavement. This maximizes the energy-efficiency of the heat-transfer to the snow; heating from above with a "hair-dryer" or hot-air machine would result in huge losses to convection and warming the air. (Though, to call a heated driveway "energy-efficient" is being generous, at least). I have seen radiant heat lamps, but lasers, by their very nature, are extremely focused/collimated - so you'd be melting tiny millimeter-sized holes of snow at a time. If you had a special need, I imagine you could probably use a cutting laser, but there would be great potential risks of high-power reflections, in random directions, off the specular snow-surface. This would be an unpredictable and incredible safety hazard.Nimur (talk) 18:27, 1 February 2011 (UTC)[reply]

Well, the whole point is that, being a tightly focused beam of light, a laser is actually markedly worse for melting snow than just about anything, even the completely shitty hair-drier. The point wasn't that the hair drier would be a good idea, it was just that, as completely terrible a job as a hair drier would do, the laser would be even worse. --Jayron32 19:20, 1 February 2011 (UTC)[reply]

What's stopping you from adjusting the focus of the laser so it becomes more diffuse or focused? We have lasers that can do that. ScienceApe (talk) 19:48, 1 February 2011 (UTC)[reply]

Diffusing it reduces the power; if you make it wide enough to be effective, you reduce the heating power to the point where it becomes equally as ineffective. You can't get something for nothing. --Jayron32 19:51, 1 February 2011 (UTC)[reply]

I'm willing to bet that it's more efficient than a hair dryer though. ScienceApe (talk) 20:08, 1 February 2011 (UTC)[reply]

I doubt it. You know how snow is white? That means that it reflects optical light. In fact, the albedo of snow is about 0.9 - even if it's a little dirty. So almost 90% of the light intensity (that is, 90% of the energy) is wasted as reflected light. This says nothing of the energy loss in powering the laser - so we're talking about a process that is at best converting a small fraction of the input energy into thermal heating of snow. Nimur (talk) 20:53, 1 February 2011 (UTC)[reply]

That doesn't sound right... It's well known that mirrors don't work as armor against directed-energy weapons, I don't see how this would be different. Hell, if what you were saying is true, using snow to focus a diffuse laser might work better than a mirror. ScienceApe (talk) 21:19, 1 February 2011 (UTC)[reply]

Precision mirrors have reflection coefficients approaching 5 nines (99.999%). That would be a much higher albedo than snow. Energy reflected is, by definition, not absorbed as heat. A very tiny percentage of energy is absorbed by snow as heat; an even smaller percentage would be absorbed by a mirror. Whether such a small percentage of the incident energy is great enough to cause damage (or melt the snow) depends only on the quantity of incident radiation. A small percentage of a very large amount of incident energy may still be significant enough to heat, melt, or damage a substrate. But that doesn't make the process efficient. Nimur (talk) 23:51, 1 February 2011 (UTC)[reply]

Shining a laser pointer into the snow demonstrates how poorly this would work. The beam spreads out as soon as it hits the surface. The result is about a couple square inches of snow that's glowing p You'd need a very dangerous laser to melt the snow. APL (talk) 01:26, 2 February 2011 (UTC)[reply]

Even if that's true, there are other frequencies that can be used. The MTHEL uses infrared light. ScienceApe (talk) 02:30, 2 February 2011 (UTC)[reply]

That's great but how well is that frequency asborbed by snow? Or to put it a different way what's the frequency you intend to use and how efficient is the laser that makes it. Nil Einne (talk) 03:43, 2 February 2011 (UTC)[reply]

No idea, just saying that visible light is not the only frequency of light that can be used in a laser. ScienceApe (talk) 14:29, 2 February 2011 (UTC)[reply]

I think we all know that. It doesn't seem particularly useful in this discussion though unless you are actually proposing a frequency you feel can be used... Nil Einne (talk) 18:51, 2 February 2011 (UTC)[reply]

Actually I think it's very useful because the statement about snow reflecting 90% of a laser's light (assuming it is true) is not true at different frequencies of light. You can theoretically make a laser using any frequency so you can run the entire gamut of frequencies and state how much light is being reflected for each. ScienceApe (talk) 19:48, 2 February 2011 (UTC)[reply]

One practical consideration is that the small volume of tepid water produced by melting snow with a low-power heat source is much easier to deal with and dispose of than the much larger volume of super-heated steam that you will get if you flash boil the snow with a laser. Gandalf61 (talk) 20:01, 1 February 2011 (UTC)[reply]

What about flamethrowers, wiki's article says they were used to melt snow on JFK's inauguration. More efficient at removing snow? ScienceApe (talk) 20:16, 1 February 2011 (UTC)[reply]

More efficient then what? Lasers? Hair dryers? Vehicles that collect snow and melt it? Heated driveway/etc? Nil Einne (talk) 21:07, 1 February 2011 (UTC)[reply]

All of the above. ScienceApe (talk) 21:11, 1 February 2011 (UTC)[reply]

Have you heard of a device called a snowblower? APL (talk) 01:26, 2 February 2011 (UTC)[reply]

Yes I have, but I'm asking about more exotic methods of snow removal. ScienceApe (talk) 02:28, 2 February 2011 (UTC)[reply]

Lasers probably since as several people have pointed out they're a poor choice. At a random guess probably none of the others though. Nil Einne (talk) 03:41, 2 February 2011 (UTC)[reply]

Just sprinkle salt on the snow. Cuddlyable3 (talk) 20:35, 1 February 2011 (UTC)[reply]

That can be a less-than-ideal solution, especially for large scale applications. The salt doesn't disappear after the snow melts—it ends up in the soil (poisoning plants and nearby agricultural land); it makes its way down to groundwater (poisoning aquifers); it runs into nearby bodies of water (directly or through sewers, poisoning aquatic plant and animal life). It ends up damaging clothing and rusting automobiles. It corrodes iron rebar, damaging bridgeworks. Salt may need frequent reapplication if lots of snow is falling, and it becomes less effective as the mercury drops. (Below -18°C, sodium chloride brine freezes.) Salt's miserable stuff. TenOfAllTrades(talk) 20:46, 1 February 2011 (UTC)[reply]

You could perhaps think of building roads that have microwave emitters built into them... Count Iblis (talk) 01:32, 2 February 2011 (UTC)[reply]

Actually, the lasers have one point in their favor: conceivably, you could focus them on a very small faction of some ice on the ground, physically breaking it up so it could be pushed out of the way.

It makes me wonder, though: is there a way to make a microwave or more likely terahertz heating ray, calibrated so that it can pass straight through all snow and ice without absorption, but the moment it hits blacktop it is intensely absorbed, so that it creates a hot layer right at the surface of the driveway that physically severs the ice from the road? Terahertz has such complicated absorption spectra that I can readily believe several such frequencies exist. Once the ice is severed from the road, you run over it with some uneven roller or break it up with a heavy shovel, and slide it all aside. (for simple snow, you might do this twice, once to deliberately create a shell of ice at the road and the second to dislodge it, so that rafts of ice would make it easier to slide the snow out of the way)

I wish someone had implemented Meta:WikiPatents, which seemed an outstanding idea. The current system rewards only the people who are ready to plunk down $10,000 every time they think of some random idea like this, and everyone else just pays royalties. Wnt (talk) 02:13, 2 February 2011 (UTC)[reply]

This may be of interest: [13] 10draftsdeep (talk) 15:01, 2 February 2011 (UTC)[reply]

Laser dazzlers

The dazzler article has an unsourced mention of an "alleged use of a Soviet dazzler against a Space Shuttle in 1984". This seems very unlikely to me; how could this have been effected? And why? Googling the key terms turns up little more than Wikipedia forks and mirrors. Was this actually possible and where are these allegations?--Shantavira|^{feed me} 17:27, 1 February 2011 (UTC)[reply]

It was the Terra-3 complex that did it. The atmosphere straight up is very transparent - in other words, the laser power under goes little attenuation. More than enought to upset delicate sensors.--Aspro (talk) 18:12, 1 February 2011 (UTC)[reply]

Some discussion of this at Sary Shagan. Apparently the reason was just to bug the Americans, in response to Reagan's stubbornness on SDI. It's not the most brilliant thing to have done, but not out of character for the pre-Gorbachev USSR. Incidentally for years afterwards the US over-estimated the Soviet SDI work going on at Sary Shagan, which was in fact pretty primitive. Not sure if that's connected with this incident or not. --Mr.98 (talk) 18:34, 1 February 2011 (UTC)[reply]

Dreams

I saw this on a few blogs, but I can't find a source for it, is it true? "Fact: we only dream of what we know. Our dreams are frequently full of strangers who play out certain parts – did you know that your mind is not inventing those faces – they are real faces of real people that you have seen during your life but may not know or remember? The evil killer in your latest dream may be the guy who pumped petrol into your dad’s car when you were just a little kid. We have all seen hundreds of thousands of faces throughout our lives, so we have an endless supply of characters for our brain to utilize during our dreams." -112.213.219.56 (talk) 17:59, 1 February 2011 (UTC)[reply]

I can't confirm or refute, but I think the claim is untestable. Even careful experiments like the one mentioned here [14] wouldn't be able to determine whether a face was known to a dreamer prior to dreaming. SemanticMantis (talk) 18:20, 1 February 2011 (UTC)[reply]

Sounds unlikely to me. Why is it that we can imagine unique faces for fictional characters in the books we read or write but our brains wouldn't be able to generate new fictional faces while dreaming? Abyssal (talk) 18:22, 1 February 2011 (UTC)[reply]

You get faces in your dreams? For me I either "know" who the person is (by name), or I just get a general idea of them (gender, age) basically an archetype, but no distinct or recognizable face. Ariel. (talk) 19:43, 1 February 2011 (UTC)[reply]

It's nonsense, or at best an unverified theory. 82.43.92.41 (talk) 20:59, 1 February 2011 (UTC)[reply]

Fact: You should be wary of things labeled as facts that don't have supporting citations. --Mr.98 (talk) 21:25, 1 February 2011 (UTC)[reply]

Your wish is my command! ⇈^{[citation needed]}⇈ Nil Einne (talk) 23:52, 1 February 2011 (UTC)[reply]

Sounds unlikely. The mind is perfectly capable of creating new and novel ideas both awake and in sleep, so I don't see why it couldn't create new faces and even modified existing faces. ~A H 1^(TCU) 21:50, 2 February 2011 (UTC)[reply]

A few months ago I dreamed I was (among other characters) a little girl in the far future, and I had three pets, red blue and yellow, which looked like 3-D 3-letter acronyms about two feet long, but I could call out to them "molybdenum, aluminum, uranium" and they would uncoil into colorful taffy-ish pets faintly reminiscent of dogs or cats, and assist me in my adventure to track down Silvio Berlescui's secret wormhole to a limitless supply of gemstones, including such things as sneaking around on a space-yacht with artificial gravity on both sides of the main deck. I mean, there are elements of the dream which are preposterously unfamiliar, and others that were preposterously familiar. When there are so many aliens in my dreams, why should all the human faces be genuine? Wnt (talk) 07:20, 3 February 2011 (UTC)[reply]

water

where can i get a jug that has a valve like this http://www.youtube.com/watch?v=LimbOdetYeM — Preceding unsigned comment added by Tommy35750 (talk • contribs) 19:45, 1 February 2011 (UTC)[reply]

Here are some links: http://www.shopwiki.com/Spigot+Jug Search for "water jug spout" and "water jug spigot" (without the quotes). Ariel. (talk) 19:48, 1 February 2011 (UTC)[reply]

the jug in the vid is a water cooler jug it is pre-filled with water where can i buy this — Preceding unsigned comment added by Tommy35750 (talk • contribs) 21:24, 1 February 2011 (UTC)[reply]

Forgetting the fact that you pretty much make it impossible for someone to help you, even if they wanted to, by not even bothering to mention where on the planet you are; the wikipedia science reference desk is really not the best place to ask for advice on where to do your shopping. Vespine (talk) 23:59, 1 February 2011 (UTC)[reply]

While agreeding with the sentiments, from memory the OP is from New York Nil Einne (talk) 03:39, 2 February 2011 (UTC)[reply]

Most bottled water companies offer it in those big bottles. Just go to their websites. You can usually set up a regular delivery if you drink enough of it. (Of course, most bottled water companies are just bottling tap water, so you really just need the bottle.) APL (talk) 00:53, 2 February 2011 (UTC

it dosent have that valve in it thou. i need it to have the valve

See this, for example. Most springwater companies will stock something like that. But I agree with above, you really just need the bottle. If you really are keen on having pure water, getting a home purifier is cheaper and probably better than buying springwater. Someguy1221 (talk) 06:09, 2 February 2011 (UTC)[reply]

Unknown bullet case

I don't know if this is the right place to ask, but anyway I have a bullet case that has exactly the same measurements of the 8x57mm IS (rim, base, neck diameter, caliber etc.) if not for the length, that is precisely 56 mm, instead of 57 mm, do you think it's the same cartridge case? Other thing, I have a case that is very probably from the Askoriya AMR (same length, colour and shape), but I can't tell, because it has been made into a screwdriver (not my fault). Considering that it is quite dinged up, would it be useful to have a photo of it on Commons or is it superfluous? Thanks, --Amendola90 (talk) 19:53, 1 February 2011 (UTC)[reply]

Why can neurons only use glucose as an energy source?

Like the title states. Why can neurons only use glucose as an energy source? —Preceding unsigned comment added by 137.224.252.10 (talk) 20:34, 1 February 2011 (UTC)[reply]

As I understand it, the restriction to Glucose applies to all forms of cellular respiration in all cell types - not only in neurons. Other forms of energy extraction from more complex molecules, like protein metabolism, fat metabolism, and complex carbohydrate metabolism, occur outside the cytoplasm, as part of the process of macroscopic digestion and metabolism (occurring in humans using acids, enzymes, proteins, and other bio-chemicals made in the pancreas, intestine, stomach, and so on). Nimur (talk) 21:05, 1 February 2011 (UTC)[reply]

Fatty acid metabolism disagrees with you: The enzymes used in fatty acid oxidation in animal cells are located in the mitochondrial matrix. However, Free fatty acid chains of more than 12 carbons require the help of membrane transporters to cross into the membrane into the mitochondria; I presume that neurons just don't express those transporter proteins. –Henning Makholm (talk) 21:45, 1 February 2011 (UTC)[reply]

Nimur, I think you are referring to digestion, which is just the beginning of the process. The cellular metabolism of proteins, fat, and carbohydrates does occur within the cytoplasm, with many of those pathways utilizing the mitochondria and other organelles. This is the basis of biochemistry and cell biology. --- Medical geneticist (talk) 03:35, 2 February 2011 (UTC)[reply]

My error, sorry. I was not aware that those other biochemicals were metabolized inside any cells. So are neurons unique in this respect, in that they lack the metabolism capabilities of other human cells? Nimur (talk) 19:24, 3 February 2011 (UTC)[reply]

One reason why neurons do not like to burn proteins might be that the breakdown of amino acids uses glutamate as a nitrogen sink. Glutamate also happens to be an important neurotransmitter. If neurons were to start producing lots of metabolic glutamate depending on the available nutrients, it would be a problem to get rid of it without disrupting their signaling functions. Simply releasing it into the cerebrospinal fluid to find its way towards the liver is not going to be a good idea.. –Henning Makholm (talk) 22:22, 1 February 2011 (UTC)[reply]

Neurons use glucose as their primary energy source but under certain conditions they can utilize ketone bodies derived from fatty acid oxidation. --- Medical geneticist (talk) 03:35, 2 February 2011 (UTC)[reply]

Bread-maker diagnosis

Recently my bread-maker has started making "bread" which does not rise much if at all, and the upper part of which is crumbly. What might be the cause of this? I'm not sure if this started after I switched to another brand of bread-flour. Thanks. 92.28.247.121 (talk) 22:14, 1 February 2011 (UTC)[reply]

It could be dead or old yeast, try proofing the yeast (basically add some warm water and sugar and see if it foams). Or it could be a low gluten flour, make sure to use bread flour - not pastry flour (and all purpose flour is not so great either). (If you are not in the US those flour terms may not be familiar to you, hopefully someone will translate.) Ariel. (talk) 00:43, 2 February 2011 (UTC)[reply]

Based on my experience, old yeast is the most likely but another possibility is that the bread-maker has a mechanical fault resulting in poor kneading. If the mixing/kneading blade is not turning, the result will be more like pastry than bread (you can get a similar effect by forgetting to put the blade into the machine after cleaning it) - most breadmakers can be opened while they're running so you should be able to check this. You could also try another brand of bread flour. --Colapeninsula (talk) 10:58, 2 February 2011 (UTC)[reply]

I opened a new sachet of dried yeast and put twice the recommended amount in, and now I've got normal bread. I thought it could be because all the ingredients were cold, it being winter. Thanks 2.97.220.121 (talk) 20:08, 2 February 2011 (UTC)[reply]

Depending on how your breadmaker works, that could indeed be the problem. If you're baking by hand, you can start with a tiny amount of yeast even in cold conditions and the bread will eventually rise all the way: you just give it more time. Obviously, the breadmaker isn't able to do that because it is working by the clock, not by the volume of the dough. Solutions are to increase the quantity of starting yeast (as you have done), or pre-warm the flour (and mixing bowl?) in a very low/switched off oven. The first risks making the bread taste more 'yeasty', the second takes a little extra preparation time and an oven. 86.164.58.119 (talk) 21:02, 2 February 2011 (UTC)[reply]

Try adjusting the amount of sugar and salt. More sugar will increase the leavening of the bread while too much salt will impede the yeast action. ~A H 1^(TCU) 21:48, 2 February 2011 (UTC)[reply]

February 2

How do microorganisms cause mutations?

I do not understand how the different microorganisms can cause mutations. I know that viruses attach to a cell and insert their dna in, but how do fungi, protists and bacteria infect cells and cause mutations. —Preceding unsigned comment added by 206.116.124.140 (talk) 03:06, 2 February 2011 (UTC)[reply]

The simplest answer is that microorganisms usually do not "cause" mutations. Perhaps you could explain where you got that notion from? Yes, there are some examples of retroviruses whose replication cycle involves insertion of copies of their genetic material into the host's genome (which can sometimes interrupt a gene thus causing a "mutation" of sorts), but this is not generally the infective strategy of other viruses, fungi, protists, and bacteria. Some microorganisms are intracellular pathogens, which means that they enter the cell, hijack its replication machinery to make copies, and then destroy the cell in the process -- others are extracellular pathogens that cause problems through production of toxins. Unfortunately, our microbiology article isn't particularly great. The pathogen article and the separate articles on viruses, bacteria, protists and fungi are probably a good place to start. --- Medical geneticist (talk) 03:27, 2 February 2011 (UTC)[reply]

(ec)It's not guaranteed that they do cause mutations. There are specific cases such as aflatoxin where microbial products are mutagenic or carcinogenic. Persistent infections might also increase the rate of cell division and tissue regeneration, potentially leading to cancer, as in Helicobacter pylori infection in stomach ulcers. I'm sure I'm neglecting other examples. Wnt (talk) 03:29, 2 February 2011 (UTC)[reply]

Prions can also cause mutations. See bovine spongiform encephalopathy and NDM-1. ~A H 1^(TCU) 21:41, 2 February 2011 (UTC)[reply]

No, they don't. Dauto (talk) 00:26, 3 February 2011 (UTC)[reply]

Snowstorm

We are currently having a snowstorm here in WIsconsin (grr.... shoveling ): WHy is it that it is very rare for snowstorms to have thunderr and lightneing? Thanks. 24.92.70.160 (talk) 05:32, 2 February 2011 (UTC)[reply]

Thunderstorms usually form in the warm summer months where there is a very steep temperature gradient between the ground and the atmosphere above the ground. This sharp temperature gradient coupled with a strong area of low pressure generates rapid lift of warm, moist air (known as Vertical draft) into a much colder area just above it. This causes the air to rapidly recondense, generating fast, heavy rains and the necessary electric charge seperation between the clouds and the ground necessary to form lightning. In the winter, it is rare that these conditions will exist because there just isn't the same temperature profile of warm, moist air near the surface and colder air just above it (i.e. its cold everywhere, so the lack of a steep gradient in temperature inhibits thunderstorm formation). The article Thundersnow does describe the necessary conditions for this rare (but not unheard of) event to occur. --Jayron32 05:41, 2 February 2011 (UTC)[reply]

It happened in (old) England this winter on several occasions. Dbfirs 19:01, 2 February 2011 (UTC)[reply]

Opaque universe

At the beginning, the universe was too opaque to let light through, but as density decreased, light was able to start shining through. What is the cutoff density point at which the universe loses its opacity?--Leptictidium (mt) 07:05, 2 February 2011 (UTC)[reply]

As far as I understand it, the critical parameter was not as much density as temperature. The early universe was a plasma of charged particles, which interacts strongly with electromagnetic radiation. Once the temperature dropped enough, most of the matter condensed into neutral atoms which are much more transparent. See, Recombination (cosmology). –Henning Makholm (talk) 11:19, 2 February 2011 (UTC)[reply]

Is there any way of knowing the density of the universe towards that period? Leptictidium (mt) 14:08, 2 February 2011 (UTC)[reply]

Recombination happened at redshift z=1100. The densities of ordinary (and dark) matter scale as (1+z)³, so the density was a factor of a billion (10⁹) higher than today. This applies to the mean density in the Universe, which is a few times 10^-27 g/cm³ today. The (energy) density of radiation scales as (1+z)⁴, so it was a factor 10¹² higher than today. (the density of dark energy is constant, it was the same then as it is now). --Wrongfilter (talk) 17:50, 2 February 2011 (UTC)[reply]

Do we also know the volume of the universe back then? Leptictidium (mt) 21:01, 2 February 2011 (UTC)[reply]

No. We don't even know the size of the entire universe now, only the size of the visible universe. We don't even know the shape of the universe, which includes consideration of the universe's size (like finite vs. infinite). The infinite flat model is currently the most popular model among cosmologists, but there are other models that also fit the available data. Red Act (talk) 21:47, 2 February 2011 (UTC)[reply]

How can one know the density of something without knowing the volume????? —Preceding unsigned comment added by 165.212.189.187 (talk) 14:32, 3 February 2011 (UTC)[reply]

That's easy, as long as the "something" is homogeneous, which at least the observable universe appears to be remarkably close to being on the largest of scales. The volume and mass (and energy) of the observable universe can be determined, so the density of the observable universe can be calculated. And then it's reasonable to assume that the density of the unobservable portion of the universe is about the same as the density of the observable portion, if you assume that the observed homogeneity of the observable universe extends to the rest of the universe. It's sort of like how you can measure the density of seawater to within a few percent by taking measurements on just a small sample of seawater, even if you don't know the volume of the world's oceans. Red Act (talk) 15:36, 3 February 2011 (UTC)[reply]

That is a pretty big ASSumption! Its funny that we dare assume what happens beyond the event horizon of a black hole, but it epidemically OK to assume that the entire universe, the extent of which we don't know since it's also beyond a so-called "event horizon", is homogeneous! —Preceding unsigned comment added by 165.212.189.187 (talk) 19:26, 3 February 2011 (UTC)[reply]

I don't think there's a whole lot of science that relies on an assumption of homogeneity outside of the observable universe. I think calculations pertaining to the expansion rate, composition, age, local geometry etc. of the universe all basically really just care about the observable universe. So you could just mentally insert the word "observable" before every occurrence of the word "universe" in any discussion of the density of the universe, if that makes you feel more comfortable. That being said, I don't think there's any evidence that would suggest that some parts of the universe outside of the observable universe might not be homogeneous, so it's simplest to just figure that the rest of the universe is probably a lot like the observable portion, unless and until there's some evidence that would suggest otherwise. Red Act (talk) 20:56, 3 February 2011 (UTC)[reply]

Ever hear of a black hole?? Look it up. —Preceding unsigned comment added by 165.212.189.187 (talk) 21:12, 3 February 2011 (UTC) Then lets make similar assumptions about black hole event horizons, while we're at it, right? I thought an event horizon is an event horizon, now I realize its just a green curtain. —Preceding unsigned comment added by 165.212.189.187 (talk) 21:10, 3 February 2011 (UTC)[reply]

Fast cold

Wanting to see whether the rapid cooling feat in this video works, I tried it and it works like a charm: fill a bowl with icewater, pour salt in, dunk a warm soda in it, stir, and you get an ice cold soda in about two minutes. I understand that salt lowers the freezing point, but I don't understand why it makes the soda cool so rapidly. Can you explain this to me?--141.155.143.65 (talk) 07:09, 2 February 2011 (UTC) P.S. Some of the other stuff they show in the video is rather neat, but I should add that the particular phenomenon I am here about is shown at 4:36 minutes in.--141.155.143.65 (talk) 07:14, 2 February 2011 (UTC)[reply]

Salt makes ice melt faster by lowering its melting point. That also allows the water in the bowl to get colder than it would normally, which I'm going to assume is at least partly why salty icewater works better than plain old icewater; most of the heat transfer is going to be between the can and water, rather than directly between the can and the ice. Someguy1221 (talk) 07:26, 2 February 2011 (UTC)[reply]

From Freezing-point depression "This phenomenon is effective in quickly lowering the temperature of a beverage placed in an ice bath containing salt; it is commonly used to make ice cream or cool beers rapidly." Try the same thing but using something besides salt like sugar. CambridgeBayWeather (talk) 07:42, 2 February 2011 (UTC)[reply]

It's not just a matter of "allowing" the water to get cold; adding salt actively lowers the temperature by forcing the ice to melt (you could look at this as a kind of osmotic pressure gradient across the saltwater/ice boundary that sucks water out of the ice). The melting ice still has to pay the heat of fusion cost, and the only place to take that energy from is the heat energy. –Henning Makholm (talk) 11:26, 2 February 2011 (UTC)[reply]

For reference, here's a plot of freezing point versus salt concentration (for an aqueous solution of sodium chloride). For a fairly concentrated brine solution (about 20% salt by weight) the freezing point can be reduced by about 20 degrees Celsius. To a passable approximation, the rate of heat transfer out of the can of soda is proportional to the difference in temperature between the can and its surroundings. Consider a can at 10°C (cool, but not quite refrigerator 'cold'). Immersed in a plain icewater bath at 0°C, you get one-third the temperature difference and therefore one-third the rate of cooling that you'd see with a -20°C brine bath. (I'll note that either method will still cool your beverage faster than just sticking in the fridge; the air in the refrigerator is going to be even warmer – around 4°C – and the air's lower heat capacity means a much less efficient transfer of heat than you'd see with liquid immersion.) TenOfAllTrades(talk) 14:31, 2 February 2011 (UTC)[reply]

You're roughly correct, but I think your math is wrong. Maybe I am mistaken here, but the difference in cooling rates between the ice bath at 0C and the salt-ice bath at -20C is 273/253 or about an 8% increase in cooling rate. I think you need to use an absolute temperature scale like Kelvin, not celsius, which is an arbitrary scale and has no connection to the physical behavior of the matter involved. Assuming two cans at the same temperature are placed into those baths, the two cans will reach arbitrary identical temperatures at a rate difference of about 8%; that is the can in the cooler bath may take 100 seconds to drop 1 degree, the can in the warmer bath should then take about about 108 seconds to also drop 1 degree. This is, of course, a different question than asking how long each can takes to achieve equilibrium with the bath. It also ignores the fact that the specific heat of the salt water bath will be different than that of pure water, and of course that to be scrupulously correct specific heat itself is temperature dependent, and so some calculus will need to be done to find the exact comparison. But I think that as a back-of-the-envelope sort of calculation, it should come out to a roughly 8% difference. --Jayron32 16:48, 2 February 2011 (UTC)[reply]

No, you're mistaken. The rate of heat transfer depends on the magnitude of the temperature difference between the source and the sink, not on their absolute values: Newton's law of cooling. (Consider the implications of your math. If a -20°C bath will always draw off heat 8% faster than a 0°C bath, does this still make sense when the can is at 1°C? What if we start with a can at -5°C?) Yes, I agree that differences in heat capacity between water and brine will modify the answer somewhat – not to mention differences in viscosity, which I suspect may be more important for convective heat transfer here – but that's why I described my response as an approximation. TenOfAllTrades(talk) 17:30, 2 February 2011 (UTC)[reply]

Thanks for the link. Once again, my physics knowledge is just good enough to be dangerously wrong. Sorry for drawing the wrong conclusions. It makes much more sense now; of course the ΔT which matters, not the absolute temperature, and ΔT works the same in any temperature scale. Thanks again for clarifying and providing an article link. --Jayron32 17:45, 2 February 2011 (UTC)[reply]

See Mpemba effect. ~A H 1^(TCU) 21:22, 2 February 2011 (UTC)[reply]

No, the Mpemba effect is completely irrelevent in this case. The Mpemba effect is mainly an effect that occurs during the interaction between fluid dynamics and thermodynamics, and has absolutely no bearing on the current discussion, which is more about the effect of adding salt to ice. --Jayron32 21:28, 2 February 2011 (UTC)[reply]

The problem with all your explanations is that you're stating that the ice-salt-water bath has a lower temperature than a plain ice-water bath. That's definitely not true. What I think happens is that the melting of ice is an endothermic reaction, thus pulling heat out of its environment (similar to how the evaporation of sweat cools you down). The salt lowers the melting point, causing ice to melt easier, causing more heat to be sucked in from the environment, i.e. whatever is conducting heat outside of the ice-salt-bath system, i.e. the soda can or ice cream bag. SamuelRiv (talk) 03:24, 3 February 2011 (UTC)[reply]

No. The ice-salt-water bath definitely has a lower temperature than a plain ice-water bath. It's a standard experiment for kids to do. Also see cooling bath. --Stephan Schulz (talk) 03:38, 3 February 2011 (UTC)[reply]

Legend of the frogurt's curse

I recently acquired six large tubs of plain soy yogurt. Or "soygurt", as the package insists on calling it. It will take me a year to finish it. In the meantime, I worry that it might spoil, but I hesitate to freeze it. I'm afraid that freezing it might kill the bacteria. I've been getting conflicting advice on the matter. On the one hand, I've been told that freezing the yogurt will indeed obliterate its probiotic properties. I've also been told that my fears are groundless, and that the bacteria are merely rendered dormant by freezing. My own knowledge of bacteria is too scanty to be of any use. Intuitively, I would be surprised to discover that frozen yogurt retains the same probiotic properties as unfrozen yogurt, but I really don't know. LANTZY ^TALK 08:16, 2 February 2011 (UTC)[reply]

There's actually an amazing amount of research on this (see here). Most of those are paywalled, but I gather the jist of it is that 50-90% of the bacteria may die during the freezing process, and this may depend on what is being frozen, what bacteria are in it, and how it is frozen. Papers from over fifteen years ago seem to say that there was no evidence that the naturally occuring bacteria in milk are sensitive to cold, so this may be a somewhat recent finding, although repeated several times. Someguy1221 (talk) 09:21, 2 February 2011 (UTC)[reply]

Although anyway, it stands to reason you shouldn't care about the bacteria. No significant metabolic activity is going to happen while it's frozen; a more significant concern is how the texture of the yogurt might be affected by freezing. Someguy1221 (talk) 09:23, 2 February 2011 (UTC)[reply]

... but killing 90% might affect the "probiotic" properties, though the stomach does a pretty good job of killing most bacteria anyway. Dbfirs 09:31, 2 February 2011 (UTC)[reply]

Cynics like me would say that a) "soygurt" is spoiled at the concept level, and b) that the evidence for benefits from probiotics in general is fairly scant, and what benefit there is is most likely not due to the living microorganisms (as the stomach kills them anyways), but doe to the presence of their metabolic products. --Stephan Schulz (talk) 09:40, 2 February 2011 (UTC)[reply]

That sounds reasonable. But why the automatic scorn for soy yogurt? It has a longer shelf life, and it tastes especially good with lemon juice. Maybe you're confusing being a cynic with being a puke. LANTZY ^TALK 15:25, 2 February 2011 (UTC)[reply]

The problem I have with "soy milk" products like soygurt is that soybeans don't have teats. They are clearly soy juice products, and calling something milk when it clearly has never been inside of a mammal is misleading... --Jayron32 13:26, 2 February 2011 (UTC)[reply]

It's not even soya juice. As our article soya milk says "Soy milk can be made from whole soybeans or full-fat soy flour. The dry beans are soaked in water overnight or for a minimum of 3 hours or more depending on the temperature of the water. The rehydrated beans then undergo wet grinding with enough added water to give the desired solids content to the final product. The ratio of water to beans on a weight basis should be about 10:1. The resulting slurry or purée is brought to a boil in order to improve its nutritional value by heat inactivating soybean trypsin inhibitor, improve its flavor and to sterilize the product. Heating at or near the boiling point is continued for a period of time, 15–20 minutes, followed by the removal of an insoluble residue (soy pulp fiber or okara) by filtration." It's an industrial slurry. DuncanHill (talk) 13:42, 2 February 2011 (UTC)[reply]

Coconuts, pigeons, and magnesium hydroxide all produce milk, so why shouldn't soy? Do you lack the milk of human kindness? --Colapeninsula (talk) 14:15, 2 February 2011 (UTC)[reply]

The word "milk" is never used by soy milk manufacturers in my part of the world. They call it "soy drink". I don't really understand such superstitions about etymology. Who's afraid of a little semantic drift? LANTZY ^TALK 15:25, 2 February 2011 (UTC)[reply]

A web search turned up this research draft, Is Soy Milk? The Economics of the Soy Milk Market. Apparently, economists, agronomists, marketers, and government regulators are all a bit afraid of semantic drift: "Many of the major US dairy producer organizations have lobbied to have soy beverages banned from using the moniker “milk”. Much of the relevance of this debate hinges on whether soy milk competes against cow’s milk or serves a separate consumer market." ... "Understanding the interactions between these milk types will improve our ability to determine of whether trade in both milk markets exhibits the hallmarks of anti-competitive behavior." The paper goes on to analyze marketability of "soy drink" and the impact of the phrase "milk" on price-economics. Nimur (talk) 19:20, 2 February 2011 (UTC)[reply]

The free frogurt is cursed... but it comes with choice of topping! Note the toppings contain potassium benzoate. That's bad. SamuelRiv (talk) 03:27, 3 February 2011 (UTC)[reply]

@ Stephan Schultz - The benefits of "probiotic" yoghurt are financially hugely successful, nutritionally I agree with you! Richard Avery (talk) 13:48, 3 February 2011 (UTC)[reply]

Schizophrenia with catatonia

Are people suffering from Schizophrenia with catatonic excitement capable of living normal lives at least in some situations...i.e while continuing to suffer from such bouts occasionally? —Preceding unsigned comment added by 1.23.10.106 (talk) 18:10, 2 February 2011 (UTC)[reply]

Yes, many treatments can be very effective, but of course depends on the individual case. Management of schizophrenia explains some of the widely-recognized treatments, including medication, that can ease the burden and minimize the symptoms. Schizophrenia can be a very serious psychiatric condition, so any patient should be under the care of a psychiatrist to make sure that they are receiving the treatment they need and obtaining the results that make their life most comfortable and normal. Nimur (talk) 19:03, 2 February 2011 (UTC)[reply]

See catatonia, persistent vegetative state and anhedonia. ~A H 1^(TCU) 21:20, 2 February 2011 (UTC)[reply]

Actually I wanted to ask that whether a person still suffering from catatonia can behave as a normal person while erupting once in a while? Sorry for wrong questioning. —Preceding unsigned comment added by 1.23.10.106 (talk) 01:05, 3 February 2011 (UTC)[reply]

Catatonia is simply an observed behaviour. If such a person in this state, suddenly gets up and goes off to do some shopping, they are no longer in that state. However, it depends on why they entered this state. Neuroleptic malignant syndrome and a few other causes might mean that it is persistent. They may not even eat. Or, they might slip in and out of it. When out of it, they may appear and act -like you or I.--Aspro (talk) 01:26, 3 February 2011 (UTC)[reply]

Scientist Qualifications

What is the scientific attitude and what attitudes and characteristics define a good scientist? -GlennRichardAllison ^{Mr. 900 Jr.} bowling —Preceding undated comment added 19:02, 2 February 2011 (UTC).[reply]

First, "scientists" is a very large and vastly diverse group of people. There is no way to answer with one attitude. Second, you must define "good". How you define good is purely up to you and will drastically change what the question means. For example: A good scientist is one who gets published often. ...or... A good scientist is one who never makes mistakes during calculations. ...or... A good scientist is one who gets a lot of research funding. etc. etc. etc. -- kainaw ™ 19:05, 2 February 2011 (UTC)[reply]

There are a lot of different ways to answer this, and people have put forward many different opinions over the years. I suspect the ones that most scientists today would self-identify with (even if it doesn't quite cover the gamut in terms of actual practices) are the Mertonian norms put forward by the sociologist Robert K. Merton in 1942. But it's a big question and a big topic, depending on, as Kainaw notes, different measures of "good". You could contrast this with, say, the model put forward by Thomas Kuhn in The Structure of Scientific Revolutions, where "good" scientists (working under "normal science") are actually not pushing the envelope every day, but producing dogmatic "stability" of theories, and only once in awhile get swept up into a "revolutionary" confusion that leads to creating new theories. Or you could contrast both of these with the views of a radical like Paul Feyerabend, who essentially said there was no scientific method whatsoever, and no "good" scientists whatsoever — just different people using totally different methods to come up with knowledge. --Mr.98 (talk) 19:14, 2 February 2011 (UTC)[reply]

It is perhaps easier to say what is good science than who is a good scientist. That is, a certain work can be critiqued and assessed for scientific quality, this is the goal of peer review. As for characteristics that define a 'good scientist', this is tantamount to asking for characteristics that define a 'good person'. Scientists are people; it's easier to objectively judge the quality of their work than the quality of their personhood. SemanticMantis (talk) 19:26, 2 February 2011 (UTC)[reply]

I'm not sure they're judging personhood. I can say somebody is "good scientist" but a "lousy person," the same way I could say someone is a "good cop" or a "good fireman" without passing judgment on whether they are "good people" or not. I think most scientists would identify "good scientists" are being those who adhere to or embody Mertonian norms — they are "disinterested" and share their data and participate in "organized skepticism" and measure worth by objective terms and so on. A "good cop" would be one who caught the bad guys without accidentally harming the good guys and so on, whether he was a good person or not. A "good fireman" saves lives and puts out fires and retrieves cats from trees and so on, even if he's actually a jerk in all other respects. --Mr.98 (talk) 20:56, 2 February 2011 (UTC)[reply]

I think a main primary attribute of "good scientists" is critical thinker. Not all scientists are good critical thinkers, but I'd argue all good scientists are. Vespine (talk) 22:02, 2 February 2011 (UTC)[reply]

I wholly agree, Vespine. A good scientist is one who thinks scientifically, and makes no compromises. Science is a way of thought. Mac Davis (talk) 23:24, 2 February 2011 (UTC)[reply]

Saying: "a good scientist thinks scientifically" is a circular definition. Ariel. (talk) 01:27, 3 February 2011 (UTC)[reply]

Maybe Mac meant to write a good scientist is one who thinks critically? While critical and scientific thinking aren't too far off being synonyms, I think critical thinking is a subset of scientific thinking. Critical thinking can, in a fairly well defined way, be applied by people who are not scientists, however it takes more then 'just' critical thinking to successfully apply the scientific method, but critical thinking would play a part all along the way. Vespine (talk) 02:29, 3 February 2011 (UTC)[reply]

I like your example Mr. 98. A "good cop" might not be a "good person", but it is certainly a person who does cop stuff well. Thus, we can say a "good scientist" is a person who performs good scientific work. This is not circular, because we have (relatively) objective ways of assessing the latter. Not to diminish the Mertonion norms; they are great guidelines, and I profess them. But one can certainly be a great scientist and not follow any of the norms. We just promote them because we think good science is more likely to occur under these practices. I'm sure we can find famous scientists of the past who did not believe in openness, were not detached, but still produced amazing work that qualifies them as "good scientists". SemanticMantis (talk) 16:48, 3 February 2011 (UTC)[reply]

SS United States

It is generally accepted that the SS United States was subsidized in large part by the US because it could be converted to a troop ship.

As a teenager, my neighbor who was Chief Stewart, hosted my family while the ship was berthed in NYC. He confided that the ship was not designed to be converted to a troop carrier but an aircraft carrier. He explained to me that the elevators were designed so that multiple elevators could be yoked together to move airplanes to the flight deck.

Is there any evidence or suggestion that indeed the SS United States was secretly designed to be converted to an aircraft carrier (not a troop ship) and that the government and builders were dealing in disinformation? —Preceding unsigned comment added by 70.125.52.217 (talk) 20:13, 2 February 2011 (UTC)[reply]

It was designed as a troop carrier in the sense that it has a design specifically to quickly load and unload troops. By "converted" in this sense, it merely means that it will be used for a different purpose. To "convert" into an aircraft carrier, it would have to be lengthened by about 100 feet, have the entire bridge removed and replaced, and then have numerous other alterations made for the actual service requirements of an aircraft carrier. So, it could be converted into an aircraft carrier by changing the ship itself, but no changes are necessary to use it as a troop carrier. -- kainaw ™ 20:24, 2 February 2011 (UTC)[reply]

A secret aircraft carrier design seems highly unlikely, but note that the cancelled USS United States (CVA-58) was under construction at approximately the same time, which could lead to confusion. A cruise ship is not built with the vast open spaces needed to support a hangar deck, nor the vast fuel stores to support an aviation wing, nor any of the armor or other protective measures needed for a ship intended to sail in harm's way. Note that a troop ship needs none of those things, but does need vast spaces for holding, feeding, and (dis)embarking personnel -- right up a cruise ship's alley. Note also the case of the Lexington class battlecruisers, successful conversions to aircraft carriers. Those conversions were performed early in construction (a case of fitting carrier equipment into a given hull's dimensions), not post-completion as the supposed SS United States conversion would entail. Note also that the budgeted cost of the conversion was higher than that of keel-up new construction, and was undertaken only because (a) some money had already been sunk into the project and (b) naval treaty limits applied, which wouldn't have been the case in the SS US timeframe. — Lomn 21:27, 2 February 2011 (UTC)[reply]

I will point out that civilian service ships are regularly under contract to the United States Government, including the Department of Defense, with very little need for secrecy or covertness. We have an article on the United States Merchant Marine, which is the total set of civilian-owned ships that can be called upon as part of the Navy Auxiliary if needed. Here in the United States, we also have Military Sealift Command and the National Defense Reserve Fleet, not to mention the prepositioned strategic fleet. There seems to be zero reason to "hide" the fact that one extra ship might have a role for military service if the time and need arises. So it's very unlikely that the ship would have such a "hidden" purpose. Nimur (talk) 21:31, 2 February 2011 (UTC)[reply]

Concur with Lomn: it's a confusion between SS United States and the quite real, but ultimately canceled aircraft carrier USS United States (CVA-58). The name is something of a jinx in the Navy - there have been three projects since the original USS United States (1797), none of which have been launched except for CVN-75, which was renamed USS Harry S. Truman (CVN-75). Acroterion _(talk) 04:46, 3 February 2011 (UTC)[reply]

gravity was not the only force that formed the universe

Notice to the shape of galaxies they don’t show the spiral formation because of the rotation and Thermo dynamical interactions with gravity . if there was only gravity cased to shape the galaxies they could condensed in all around the central mass . we know some of galaxies are so, with gathering comas in outer zones .also for the solar system we have planetary surface with sun with lens shaped placement .after finding out the properties of sun and planets , that appears to us the rule and mechanism of creation of this system . the gravity cases to create general force and movements in space and also it case general weightless in all over the world for galaxies and stars . --78.38.28.3 (talk) 09:11, 3 February 2011 (UTC) this means that. however the space objects have inertial and gravitational mass . a. mohammadzade[reply]

Hi. This page is for questions about science. Do you have a question?--Shantavira|^{feed me} 09:22, 3 February 2011 (UTC)[reply]

February 3

Help identifying mineral

Any suggestions about what the blue (or blue-green) mineral shown in this photo might be? There is an outcropping of this stuff in the East Bay hills behind Berkeley. I have no reason to suspect that it's anything remarkable, just would like to figure out what it actually is. Looie496 (talk) 00:20, 3 February 2011 (UTC)[reply]

A close-up photo, of a freshly chipped of piece would help. The sparseness of veg looks like the soil suffers from metal poisoning.--Aspro (talk) 01:04, 3 February 2011 (UTC)[reply]

I have some smaller pieces, but it's difficult to take a useful photo -- basically the blue stuff looks powdery and nonreflective -- however it also sometimes seems to associate with what looks like very dark blue or dark brown quartz. The lack of veg is a consequence of the fact that this rock lies in the middle of a fire road. Much of the road looks the same. Looie496 (talk) 01:41, 3 February 2011 (UTC)[reply]

Sorry if I'm stating the obvious here but I thought 'copper' as soon as I saw it. Is this some kind of cuprous salt? Is the rock blue inside or just the surface? Richard Avery (talk) 13:43, 3 February 2011 (UTC)[reply]

Insoluble sodium compounds

Are there any insoluble sodium ionic compounds? --75.15.161.185 (talk) 00:33, 3 February 2011 (UTC)[reply]

Uranyl zinc acetate is usually highlighted in qualitative inorganic analysis texts as perhaps the only way to precipitate Na⁺ from aqueous solution. DMacks (talk) 00:44, 3 February 2011 (UTC)[reply]

Sodium#Compounds lists a few, but all the compounds I can find include other metals in addition to sodium. (As our article notes, the insoluble precipitate formed with uranyl zinc acetate is uranyl zinc sodium acetate – UO₂)₂ZnNa(CH₃COO)-6H₂O – which contains uranium and zinc in addition to sodium.) If you're restricting your search to compounds which contain sodium as the only metal, you're probably out of luck; if you're willing to accept more than one metal, then you have a lot of choices. TenOfAllTrades(talk) 02:34, 3 February 2011 (UTC)[reply]

Tesla Roadster

About how much does it cost to fully recharge the Tesla Roadster? ScienceApe (talk) 03:00, 3 February 2011 (UTC)[reply]

The cost of electricity varies considerably across the world, so we'll need a bit more information about where you are. Perhaps first one should ask "how much electricity" is required to recharge? And even that may vary depending on the circumstances. Mitch Ames (talk) 03:48, 3 February 2011 (UTC)[reply]

$10.04 US dollars[15], using the average US price of 11.62 cents/KwH[16]. Ariel. (talk) 03:50, 3 February 2011 (UTC)[reply]

(EC) The 135 Wh/km usage times 393 km range would imply a full charge of 53.055 kWh. I don't know where you live, but I pay my electric company $0.1064 USD per kWh during off-peak hours, so it would cost me $5.65 USD to fully recharge a Roadster from empty during off-peak hours. Red Act (talk) 03:53, 3 February 2011 (UTC)[reply]

Oops, my calculation was based on the 135 Wh/km battery-to-wheel efficiency, but I should have used the plug-to-wheel efficiency, which is around 174 Wh/km. That would change my answer to $7.28 USD. Red Act (talk) 04:00, 3 February 2011 (UTC)[reply]

(ec) From Tesla Roadster#Battery system: "A full recharge of the battery system requires 3½ hours using the High Power Connector which supplies 70 amp, 240 volt electricity..."; that's 58.8 kWh to charge. (The actual amount of available juice is given in the article as roughly 53 kWh; losing about 10% in charging/discharging doesn't sound too unreasonable.) If you're paying the $0.1162/kWh provided in Ariel's response, it will set you back just shy of $7 per 'tank'. The actual answer will depend on your local electricity price; in some jurisdictions you may receive a significant discount late at night and very early in the morning—just when your car is most likely to be in the garage. TenOfAllTrades(talk) 04:06, 3 February 2011 (UTC)[reply]

The section "Recharging" in article says 4 hours and 90A not 3½ hours and 70A, so the article contradicts itself. (The 48hours for 120V and 15A works out to the same amount of energy.) Ariel. (talk) 04:29, 3 February 2011 (UTC)[reply]

The section you're looking at indicates that the high-power charger is connected to a circuit with a 90-amp breaker, but the actual current drawn is the lower 70 amps: [17]. TenOfAllTrades(talk) 13:21, 3 February 2011 (UTC)[reply]

What is the Emergency oxygen system bag for?

Hi - Concerning Emergency oxygen system

What is the plastic bag for? The standard demonstration says 'bag will not inflate during normal operation'

Thanks — Preceding unsigned comment added by InverseSubstance (talk • contribs) 04:01, 3 February 2011 (UTC)[reply]

It serves as an oxygen reservoir -- see the fourth paragraph in this section: Bag_valve_mask#Components. DRosenbach ^{(Talk | Contribs)} 05:09, 3 February 2011 (UTC)[reply]

The Straight Dope : When you wear an airline oxygen mask, why doesn't the plastic bag inflate? Hope this helps. APL (talk) 06:30, 3 February 2011 (UTC)[reply]

The trick is, they want to blow oxygen at you, as fast as possible, but not so fast that it could be hazardous. So, we need a pressure regulator of some sort. SCBA and SCUBA, (two other cases of breathing air out of a "tube") solve this problem by including a pressure regulator valve. A quick look at the diagrams in types of diving regulator readily demonstrate how sophisticated those systems are: the valves are multiple stages, they have many moving parts, and the breathing apparatus is actually a bit tricky to use (well, you just breathe in and out - but if you've ever used one, you'll know that it feels a little weird breathing over a pressure-differential between inhalation and exhalation - and you must make a tight pressure seal with the air supply, or else the intake valve won't actuate). So, the "bag" on an aircraft is much simpler - it allows for reasonably high-pressure oxygen to be jetted at your lungs without popping them (by acting as a pressure "reservoir"), and also allows gas to flow without requiring a pressure seal. It's the safest, fewest-moving-parts, fewest-things-that-could-break, easiest-to-operate, way to get air out of a hose and into your lungs. Nimur (talk) 17:32, 3 February 2011 (UTC)[reply]

I2Cl6

What is the shape and structure of I2Cl6? —Preceding unsigned comment added by 122.169.220.58 (talk) 06:30, 3 February 2011 (UTC)[reply]

See iodine trichloride. Someguy1221 (talk) 06:33, 3 February 2011 (UTC)[reply]

Strongest Allergy Medicine

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page.

Hamilton, Ichthyologist, active in 1822

Hi all,
The usual. One Hamilton (possibly Robert) is the binomial authority for Gagata cenia. According to the ITIS, went on a bit of a taxonomic spree in 1822. Who is this guy?
--Shirt58 (talk) 09:45, 3 February 2011 (UTC)[reply]

Francis Buchanan-Hamilton, maybe? Apparently the Hamilton, 1822 notation is used for him. Although there are a surprising number of Hamiltons associated with fish, so... --Kateshortforbob _talk 11:34, 3 February 2011 (UTC)[reply]

<JHS cigar> "I love it when a plan comes together" </JHS cigar>--Shirt58 (talk) 14:01, 3 February 2011 (UTC)[reply]

single hydrogen atom emitting light

constructive interference (and destructive interference) make much more sense to the eye than to the brain!

when the e- falls it emits one photon. another jump up, then down, another photon. so, we get successive distinct portions of emitted energy. how can this become a wave with a wave front and continuous (harmonic) variation in intensity? (don't tell me about duality right now) should we have many sources (atoms) that have to emit in perfect phase to get a spatial wave front? should we consider many sources nearly in phase that by superposition give continuity? — Preceding unsigned comment added by M121121121 (talk • contribs) 11:32, 3 February 2011 (UTC)[reply]

A single hydrogen atom only emits single photons, but a real-world light source emits A LOT of photons. A photon of red light has energy of 2.84 x 10^-19 joules[18]. A one-watt light source will emit one joule per second, or around 3.5x10¹⁸ photons per second. At this sort of level, light appears to be smooth and continuous. A 40W incandescent bulb emits about 4W light (source: Incandescent light bulb). --Colapeninsula (talk) 11:52, 3 February 2011 (UTC)[reply]

When you drop a stone into a pond, you get more than one wave. Same, for different reasons, with the electron dropping down a shell of an atom. (Don't read that rigth now: Wave–particle duality). 95.112.210.107 (talk) 13:20, 3 February 2011 (UTC)[reply]

Also relevent, quantum mechanical properties are best understood only in bulk, not in isolation. Understanding the quantum behavior of electrons and photons in atoms makes much more sense than trying to work out the quantum behavior of an electron and a photon in a atom. Indeed, you can't even definitively say where one electron is located around an atom. You can say how electrons will behave when the atoms of a material are subjected to a light source. But talking about what happens to one electron as a result of one photon strike is only useful as an illustrative model, not as an accurate one. --Jayron32 13:46, 3 February 2011 (UTC)[reply]

Jayron, bite your tongue before you start talking about things you don't fully understand. There is nothing wrong with talking about the behavior of a single isolate atom. Dauto (talk) 15:53, 3 February 2011 (UTC)[reply]

In good faith, Jayron's comments are consistent with the ensemble interpretation. Perhaps not the currently most popular interpretation, but still reasonable. SemanticMantis (talk) 17:15, 3 February 2011 (UTC)[reply]

What makes you think there is always going to be a perfectly smooth in phase wave front? Dauto (talk) 15:56, 3 February 2011 (UTC)[reply]

You might find Coherence (physics) useful. Dauto (talk) 15:58, 3 February 2011 (UTC)[reply]

If I understand correctly, I think that the original poster is confused as to why a given emission adds up (constructive interference) with previous emissions. After all, you'd think that there would be a 50/50 chance it would be out of phase with the existing light and cancel it out. But light is typically incoherent, coming from many sources and going in many directions. It is like tossing two pebbles into a pool - even though you'd think that the waves could as easily interfere destructively as constructively, the net result is still a bigger commotion. Now the reasons for this are complicated and involve actual math, but the video I've added above should show you the basics: wherever the two sources interfere destructively, they are still adding up constructively somewhere else. There's simply no way for destructive interference of waves to squirrel away energy under the carpet and forget about it - it always comes out somewhere. Wnt (talk) 18:38, 3 February 2011 (UTC)[reply]

Magnets- where's the potential energy?

This probably sounds like a homework problem, but it's not. It's just an example I concocted with which to form my question about a concept. Imagine the following setup: a strong magnet with mass m is connected to a horizontally rolling trolley hanging from the ceiling at a height of h. Just for the sake of simplicity, imagine the wheels of the trolley are frictionless. A block of iron of mass M sits on the ground but far enough from the magnet that it stays on the ground. The total energy apparent to me is just the mechanical potential energy because of the magnet at height h, or mgh. Now you move the magnet to where it's above the block (which didn't take energy to do because of the frictionless wheels and no change in height). Suddenly the block jumps up to the height h' so that the total energy is mgh + Mgh'. So where was the potential energy in the amount of Mgh' in the before case? Did the energy to jump up come from slight slowing down of all the jiggling of the electrons in the iron as it aligned with the magnetic field or something? As much layman's terms and simplification without losing the essential information to explain this would be greatly appreciated. Thanks. 20.137.18.50 (talk) 15:35, 3 February 2011 (UTC)[reply]

The final configuration has some (negative!) magnetic potential energy that must be included in the energy budget equation. Potential energy can often be negative. Dauto (talk) 15:46, 3 February 2011 (UTC)[reply]

As in 'in the before case, the iron block has the potential to align with any given magnetic field that comes its way, but in the after case, it doesn't have as much potential to do so because it's already used much of that potential to wrap up with m'? 20.137.18.50 (talk) 15:55, 3 February 2011 (UTC)[reply]

Just to correct one thing: It does take energy to move the stationary magnet from one location to another even if the wheels are frictionless. As long as the magnet has mass, it will take a force to move it, and Work = Force * Distance. Not sure how it affects the final answer, but thats something that needs to be fixed. Even in my self-admitedly retarded understanding of physics, I am pretty sure that you cannot move a real object without some energy, even in a frictionless environment. --Jayron32 16:09, 3 February 2011 (UTC)[reply]

You only need a force to accelerate it, but in the end you decelerate it, hence you can regain the kinetic energy transferred to the magnet. You can also move it arbitrarily slowly. How you do that in practice is another matter (in practice there is no frictionless environment), but in theory there's no problem. --Wrongfilter (talk) 16:37, 3 February 2011 (UTC)[reply]

(ec) Under the usual physics approximations (frictionless, vacuum, etc.) you can have a displacement of a mass without any net energy consumption. Force and displacement are actually properly treated as vector quantities (see Work (physics)), so you counter the work done to start the object moving with an equal amount of 'negative' work in the opposite direction to bring it to a halt in its new location. The object starts and finishes with the same amount of energy (kinetic and gravitational), so no net work is done.

(I will note parenthetically that the particular case the original poster describes is a bit more complicated. One has to account for the change in potential energy due to the motion of a ferromagnetic block relative to a magnetic field and so there is work done there, but this is a separate consideration from the 'horizontal displacement on a frictionless track' issue.) TenOfAllTrades(talk) 16:41, 3 February 2011 (UTC)[reply]

The fact that the magnet is "above" the track is irrelevant. The potential-energy due to gravity, plus the potential energy due to the magnetic field, result in a local minimum of energy at that location. This question is essentially equivalent to asking "if a ball rolls down a hill, where did it get the energy from?" Well, it took energy to put the ball at the top of the hill in the first place. Similarly, the fact that the iron block was far away from the magnet means that it started with potential energy, and used that energy to counteract gravity, and is now stuck at the bottom of the potential energy well (the "bottom" of the well happens to be physically located above ground-level). To get the magnet back down, you'll have to do work! It may seem a little strange, but it will require a force to pull the iron box back downward, even though we typically like to think that gravity causes things to fall down by themselves. In this case, gravity alone isn't strong enough, so you'd have to do work to counteract the magnetic potential energy. Nimur (talk) 17:44, 3 February 2011 (UTC)[reply]

I think I see, thanks for that explanation. How would one represent that potential energy which is equal in magnitude to Mgh' in the before case? In some kind of inverse squared thing in terms of the linear distance from the block to the magnet, the flux density of the magnetic field, and some properties of the iron block? 20.137.18.50 (talk) 18:11, 3 February 2011 (UTC)[reply]

Concocting a model of magnetic potential energy that is both theoretically valid and also experimentally useful is difficult; (it is for this reason that most introductory physics courses gloss over the notion of magnetic potential energy). Magnetic potential is a vector quantity; and to make matters worse, ferromagnetism is pretty non-ideal in that ferromagnetic materials have a very nonlinear magnetic permeability (in other words, they interact with the magnetic field - which we expect - but it's hard to write a simple equation describing how they react, because so many statistical processes are happening with all the crystal lattices and electrons in atomic-orbitals). But here's a rough paintbrush stroke of how we would do it: we could assume the magnetic field is caused by a perfect magnetic dipole; and we could model the field B at all points (x,y,z). And we could assume we have a block of iron with a straightforward, effective (constant-value) μ. Then we could estimate an effective magnetic vector potential A by inverting the equation-set:

\mathbf {B} =\nabla \times \mathbf {A} ,

\mathbf {E} =-\nabla \phi -{\frac {\partial \mathbf {A} }{\partial t}},

\mathbf {B} =\mu \mathbf {H}

And we could estimate a potential energy with value equal to magnitude of |A|. All of this is possible; it is reasonable to expect that a moderately intelligent physics student could figure out how to do this; but the math is very hard, and the resulting answer depends on how well our field is modeled with a dipole, and how close the ferromagnetism is to a "constant" permeability (... neither of which are good assumptions - in fact, μ is a nonlinear function of B). Attempting a better model would require more complicated (probably numerical) inversion of those equations. Or, we could perform a simple experiment and measure the force required; but because magnetism is described by a vector field, the orientation and velocity of approach can change the effective force felt. So it's not easy to give a "straightforward" answer to "how much" magnetic potential energy is present. Nimur (talk) 18:28, 3 February 2011 (UTC)[reply]

Land

copied from [[WP:RDH|humanities reference desk. Itsmejudith (talk) 16:35, 3 February 2011 (UTC)[reply]

Hi, you know every land mass on earth like Eurasia, Africa, The Americas etc are they all like embedded in the seabed or do they just bob like a cork so they can move gradually?— Preceding unsigned comment added by Hadseys (talk • contribs)

Plate tectonics has the explanation. Moving this to science reference desk. Itsmejudith (talk) 16:32, 3 February 2011 (UTC) Copying it there, look for answers there not here. Itsmejudith (talk) 16:35, 3 February 2011 (UTC)[reply]

Plate tectonics go deeper than the seabed. From the point of view of plates, land and seabed are the same thing; the only difference is that one is above the waterline. —Preceding unsigned comment added by 205.193.96.10 (talk) 17:02, 3 February 2011 (UTC)[reply]

Actually, I've been wondering something about this myself in the context of the Appalachian mountains. According to what I've read, there is a sole thrust fault at the level of weak Cambrian strata which has displaced the land by kilometers relative to the underlying strata, folding up the upper layers. (See e.g. [19] - I could redraw a figure following an offline source I have lying around somewhere if need be) It is like "continental drift" on a continent! What I don't get is, where did the "excess" of pre-Cambrian strata go? Was it subducted, did it replace ocean crust - it couldn't have emerged out the far side with nothing on top of it, right? - it just confuses me. (Note that whatever goes on with that, it is only a very minor effect relative to the thousands of miles that continents and oceans move as single plates on top of the mantle) Wnt (talk) 18:51, 3 February 2011 (UTC)[reply]

At least one scientist seems to believe the "excess" crust is now buried underneath the overburden: Thin-skinned tectonics in the crystalline southern Appalachians... (with seismic profiling pictures, if you have access to the full article). Some of the crust has steeply dipped and is thus subducted; much of the crust is simply lateral with new material on top. The effects of erosion in the Appalachians should not be understated - they are very old, geologically, and a lot of crust material has been removed by wind, water, and other erosive forces. Nimur (talk) 19:31, 3 February 2011 (UTC)[reply]

Slimming tip

I keep reading "Cutting down a bit of the belly each day is easy by simply using this 1 weird old tip. Click here to see what it is...". What is it all about? Kittybrewster ☎ 17:10, 3 February 2011 (UTC)[reply]

"There's a sucker born every minute." The tip in question is just "buy lots of acai berry, it's a miracle food! You'll lose weight, instantly!" It's patent nonsense and the FDA has issued warnings to many of these websites for claiming miraculous health and diet effects that are entirely unproven. --Mr.98 (talk) 17:27, 3 February 2011 (UTC)[reply]

Thank you. I knew you would know. I won't buy any. Kittybrewster ☎ 18:11, 3 February 2011 (UTC)[reply]

"WHY" does diamond form out of graphite?

It's a stupid question,I know.But I don't understand it "thermodynamically", because diamond has a higher enthalpy level than graphite and -seemingly- less entropy.Does diamond have a higher entropy than graphite or the Gibbs free energy equation does not work in conditions in which diamond is formed?--Sina-chemo (talk) 19:05, 3 February 2011 (UTC)[reply]

This "gem" of thermodynamic wisdom may help: "The nucleation and growth of a crystal are under kinetic, rather than thermodynamic, control." Here's a whole textbook on the subject, too: Crystals: growth, morphology, and perfection by Ichirō Sunagawa. From Chapter 3 of that book, excerpts of which are available online, it is evident that to thermodynamically consider crystal nucleation, you have to consider the kinetic processes as well - you can characterize these kinetic behaviors statistically (thermodynamically) by constructing an effective surface free energy potential for nucleation sites. Lattice thermodynamics is a huge ongoing area of research in materials and solid-state physics. Nimur (talk) 19:10, 3 February 2011 (UTC)[reply]

Note that enthalpy is equal to internal energy + pressure*volume. Now because diamond has density 3.52 whereas graphite has density 2.1-2.2, the volume will be a lot different for the two. The higher the pressure, the lower the enthalpy of diamond relative to graphite. Wnt (talk) 19:14, 3 February 2011 (UTC)[reply]

@@ Line 364: / Line 364: @@
 == Strongest Allergy Medicine ==
+{{RD-deleted}}
-I am having a hard time finding out what the strongest allergy pill is, both over the counter and prescription. Does anyone know?  <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/76.169.33.234|76.169.33.234]] ([[User talk:76.169.33.234|talk]]) 07:42, 3 February 2011 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
-: That sounds suspiciously like a request for medical advice. We don't do that here. You probably have 10 to 20 minutes to claim that you're researching medicobabble for your next screenplay, before someone summarily deletes your question... –[[User:Henning Makholm|Henning Makholm]] ([[User talk:Henning Makholm|talk]]) 10:03, 3 February 2011 (UTC)
-::It's also a question that does not have a good answer. Different pharmacological substances have different effects for different people and different allergies. There very likely is not "the" strongest pill. --[[User:Stephan Schulz|Stephan Schulz]] ([[User talk:Stephan Schulz|talk]]) 11:00, 3 February 2011 (UTC)
-:::Any particular reason you can't go to a pharmacy and ask? Seems like the best way. Especially since they'll also be able to limit their answers to what they have in stock. [[Special:Contributions/90.193.232.171|90.193.232.171]] ([[User talk:90.193.232.171|talk]]) 11:06, 3 February 2011 (UTC)
-::::Agree on this. I've done this very thing with pharmacies — shown up and said, "hey, this other thing isn't working for me, what else you got?" and they found me something that did what I wanted it to. This is exactly the sort of thing a pharmacist is good at, potentially better even than a general practitioner. --[[User:Mr.98|Mr.98]] ([[User talk:Mr.98|talk]]) 13:30, 3 February 2011 (UTC)
 == Hamilton, [[Ichthyology|Ichthyologist]], active in 1822 ==