Science desk
< February 26	<< Jan \| February \| Mar >>	February 28 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

February 27

Alcohol Rub

What is the gelling agent that is used in Alcohol rubs?? (My guess is a carbohydrate of some sort) --Shniken1 (talk) 00:19, 27 February 2008 (UTC)[reply]

From Hand_washing#Medical_hand_washing: "Most are based on isopropyl alcohol or ethanol formulated together with a humectant such as glycerin into a gel, liquid, or foam for ease of use and to decrease the drying effect of the alcohol." AlmostReadytoFly (talk) 14:28, 27 February 2008 (UTC)[reply]

Thanks, but I don't think that anwsers my questions. The glycerine seems to be used as a moisturiser. "Glycerol is used in medical and pharmaceutical and personal care preparations, mainly as a means of improving smoothness, providing lubrication and as a humectant". I certainly can't see any chemical reason how this could form an alcohol gel...--Shniken1 (talk) 00:11, 28 February 2008 (UTC)[reply]

An ingredient check of two leading brands [1][2] shows Carbomers (a trade name for polyacrylic acid) are used for this purpose. An example: [3]. These belong to the acrylate polymers. Dforest (talk) 06:14, 28 February 2008 (UTC)[reply]

How deep

How deep is the ocean? —Preceding unsigned comment added by 79.76.241.79 (talk) 00:30, 27 February 2008 (UTC)[reply]

It depends. The ocean is obviously near 0 m deep close to the shore, but its deepest point is the Mariana trench at 11 km. --Bowlhover (talk) 00:58, 27 February 2008 (UTC)[reply]

Unidentified ocean animals

What is this thing: http://i29.photobucket.com/albums/c282/rOll3r_cOast3r_lOv3r/lobb.jpg ? I know it's a lobster, but what kind? —Lowellian (reply) 01:23, 27 February 2008 (UTC)[reply]

Kiwa hirsuta. --Milkbreath (talk) 01:51, 27 February 2008 (UTC)[reply]

What is the bizarre-looking animal in the image at http://www.mbari.org/expeditions/hawaii/Leg2/apr11images/apr11_10_10_12_08.jpg, taken in the ocean near Hawaii? I know the image caption says Holothuroidea (sea cucumbers), but not only is that very vague, but the people taking the photograph were actually very doubtful about this identification themselves (if it's a sea cucumber, then why does it look so much like a swimmer as opposed to a crawler?), which is why they put a question mark in front of "Holothuroidea" in the image caption. Can someone either confirm that it is a sea cucumber and give a more specific identification, or confirm that it is not a sea cucumber but something else? —Lowellian (reply) 01:01, 27 February 2008 (UTC)[reply]

I've seen a lot of real holothuroidea on the east and north-west coast of Oz, so to my mind, it ain't a sea cuke an I ain't goin ocean swimmin no mo'. As for that other hairy thing... mother! Julia Rossi (talk) 08:28, 27 February 2008 (UTC)[reply]

I'd be more likely to put it in Opisthobranchia, because they are somewhat more diverse in form, and some, like Gymnosomata look somewhat similar. --Cynops3 (talk) 21:52, 27 February 2008 (UTC)[reply]

Hmm, it doesn't really look that much like a sea angel to me, though it does certainly look more like a sea angel than it does a sea cucumber. Can anybody else also weigh in? (Especially if you're a marine biologists frequenting the Reference Desk, but I'd be glad to have input from anybody else knowledgeable about marine life.) (Heh, it would be funny if this was in some new previously-never-identified taxon.) —Lowellian (reply) 19:01, 28 February 2008 (UTC)[reply]

Kiwa hirsuta for sure. I recognize it.

Jourdy288 (talk) 00:54, 4 March 2008 (UTC)[reply]

Yes, we know the first animal is a kiwa hirsuta, and someone already said so above a week before your answer. The problem is the second animal, which no one seems to be able to identify. —Lowellian (reply) 14:06, 5 March 2008 (UTC)[reply]

How high is the sky?

How high is the sky? —Preceding unsigned comment added by 79.76.241.79 (talk) 01:05, 27 February 2008 (UTC)[reply]

From zero to infinity (not inclusive). — Lomn 01:29, 27 February 2008 (UTC)[reply]

You sounds like Buzz Lightyear --Dweller (talk) 11:03, 27 February 2008 (UTC)[reply]

See atmosphere. Most clouds are in the atmosphere, a few kilometres up; artificial satellites usually orbit a few hundred to 40 000 km above the ground; the solar system's other planets are hundreds of millions of kilometres away; we'll talk about the distance to stars in the next question. --Bowlhover (talk) 01:41, 27 February 2008 (UTC)[reply]

The sky itself doesn't really exist, you cannot touch it. You can see it during the day because of oxygen in the atmosphere (mainly the troposphere, approx. 0-16 km altitude) diffracts the blue, and at night you can see the sky because of particulate matter or clouds reflectin off light pollution, and the stars appear glued to a sphere but aren't, the farthest naked-eye individual star is maybe about 10 000 light-years away, the farthest star contributing to the milky way glow is maybe about 50 000 light-years away, and the farthest star contributing to a naked-eye galaxy is maybe about 5 000 000 light years away. If you count fog as part of the sky because you can see it when you look up on a foggy day, maybe from ground level, or perhaps you might count it as the visibility. On most good days sea-level visibility is 24 km if transparency is good. Also, the visible universe only extends about 17 billion light-years from us, after that telescopes cannot pick up galaxies because they are seeing farther into the past than the big bang. Also, remember it's possible to stand in a cloud, but it looks more like fog or mist. Hope this helps. Thanks. ~A H 1^(TCU) 23:05, 28 February 2008 (UTC)[reply]

Well, it's possible to stand in a cloud, but you'll fall through it and onto the ground if you try. --Bowlhover (talk) 00:31, 1 March 2008 (UTC)[reply]

How far to a star?

How far is the journey from here to a star? —Preceding unsigned comment added by 79.76.241.79 (talk) 01:25, 27 February 2008 (UTC)[reply]

The nearest star (the sun) is 8 light-minutes away, about 150 million kilometers. The nearest extra-solar star (Proxima Centauri) is 4.22 light years away, 275,000 times further. — Lomn 01:32, 27 February 2008 (UTC)[reply]

Ah then you know how much I love you! —Preceding unsigned comment added by 79.76.241.79 (talk) 01:34, 27 February 2008 (UTC)[reply]

You love me 1.3 parsecs? Is that a lot? — Lomn 14:10, 27 February 2008 (UTC)[reply]

I wish Valentine's day hadn't just passed. I know some people who would swoon over that. 199.67.16.60 (talk) 14:54, 27 February 2008 (UTC)[reply]

Well, I once told a girlfriend that I would love her forever, but that was before I heard about proton decay.

How to clean up acid/base spills.

Let's say that I spill a strong acid/base, what is the safest way to clean it up? Could someone answer really fast? Thank you. 99.226.26.154 (talk) 01:38, 27 February 2008 (UTC)[reply]

Which is it, an acid or base? How concentrated is it? What is it spilt on?--Shniken1 (talk) 01:43, 27 February 2008 (UTC)[reply]

Let's say Car Battery acid...On...Well...Concrete, or whatever they use to pave the floor of garages. 99.226.26.154 (talk) 01:46, 27 February 2008 (UTC)[reply]

If you spill an acid, neutralize it with copious amounts of a weak base -- baking soda is the canonical example. Contrariwise, if you spill a base, neutralize it with vinegar or another weak acid.

If you work with acids and bases frequently, it's strongly recommended that you keep baking soda and vinegar on hand, so you won't have to go scrambling around looking for some when you have a spill. —Steve Summit (talk) 01:49, 27 February 2008 (UTC)[reply]

(ec) Sodium bicarbonate or sodium carbonate are the common materials used to neutralize acid spills, these are found in commercially available "spill kits". Boric acid or citric acid is typically used for neutralizing alkali spills. However, check the Material Safety Data Sheet first and, if there is large amounts and/or you are notable to determine the effects of those compounds on your particular spill, contact the fire brigade or the appropriate safety personnel. Rockpocket 01:50, 27 February 2008 (UTC)[reply]

Is it good to dilute it with water? Does that work well? —Preceding unsigned comment added by 99.226.26.154 (talk) 01:52, 27 February 2008 (UTC)[reply]

No. According to the MSDS for battery acid "EPA and Superfund reportable discharge is 1000 lbs. Stop flow if possible. Use appropriate protective equipment during clean up. Soak up small spills with dry sand, clay or diatomaceous earth. Dike large spills, and cautiously dilute and neutralize with lime or soda ash, and transfer to waste water treatment system. Prevent liquid from entering sewers, waterways or low areas. Comply with Federal, State and local regulations. Do not dilute it with water. Rockpocket 01:54, 27 February 2008 (UTC)[reply]

Note that battery acid (if it came out of a battery, as opposed to a refill bottle) contains large amounts of lead sulfate, and is therefore highly toxic even after the acidity has been neutralized. --169.230.94.28 (talk) 02:00, 27 February 2008 (UTC)[reply]

Hm...Just curious, but if it gets on skin, can you wash it off with water? Just in case this happens next time. 99.226.26.154 (talk) 02:02, 27 February 2008 (UTC)[reply]

I would say wear (acid resistant) gloves so it doesn't happen. But yes you can wash it off with water. And just to clarify how to clean up said spill. Use lots baking soda to mop up the liquid and neutralise the acid. Then collect the powder and dispose of it through a chemical waste company..--Shniken1 (talk) 02:06, 27 February 2008 (UTC)[reply]

Would about one bottle do for a puddle about the size of a sink? Or do I have to get some more? —Preceding unsigned comment added by 99.226.26.154 (talk) 02:08, 27 February 2008 (UTC)[reply]

What exactly may you clarify happened "This Time"? --99.237.101.48 (talk) 02:10, 27 February 2008 (UTC)[reply]

Nothing...Nothing at all... 99.226.26.154 (talk) 02:18, 27 February 2008 (UTC)[reply]

Thank you for your help! I could not have done this without you. 99.226.26.154 (talk) 02:30, 27 February 2008 (UTC)[reply]

Sorry but isn't it pretty clear that what happened "this time" is that 99.226 spilled some car battery acid on the concrete floor of their garage? (and by the way, I think the singular they is grammatically fine) 81.96.160.6 (talk) 16:24, 27 February 2008 (UTC)[reply]

Next to do...Gunpowder. 99.226.39.245 (talk) 21:49, 28 February 2008 (UTC)[reply]

My invention

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.

A question asking about how to go about protecting your intellectual property rights for your inventions is a rather clear-cut case of asking for legal advice. Rather than asking us, please consult with a patent attorney. MrRedact (talk) 05:42, 27 February 2008 (UTC)[reply]

well Mr.redact respectfully, why is it that someone who doese not even know of what proper channels to go through cant ask for a little guidance? as you saw people just pointed to me where i should go.

Respectfully Inutasha De Fallen —Preceding unsigned comment added by Inutasha De Fallen (talk • contribs) 06:18, 27 February 2008 (UTC)[reply]

Welcome to the refdesk Inutasha De Fallen. You might find these helpful links in the pedia such as Inventor (patent), Patent, List of patent legal concepts, patent application, patent pending, First to file and first to invent, United States Statutory Invention Registration, and more here[4]. Then in the refdesk archives you can pick from among these answers[5]. BTW I read the guidelines as guidance and "may be" rather than sure-fire will be removed, so please MrRedact, let's just open up what's in wiki so a person can get themselves orientated before they pay for specific legal advice. Cheers Julia Rossi (talk) 09:21, 27 February 2008 (UTC)[reply]

If you are a first-time inventor you should probably get a patent lawyer. They will look at your claims and give you an honest assessment of how good they think they are. They can also do a search of the prior art and see if your invention is really novel or not. They cost money, but if your inventions are legit it is probably worth it. It's not impossible for someone who is not a patent lawyer to do these things, but if you don't know what you are doing you will probably screw something up and not get the patent. --98.217.18.109 (talk) 13:42, 27 February 2008 (UTC)[reply]

Before paying for a patent attorney, you can research whether your invention is novel by searching through old patents yourself. For example, US patents can be searched for free here, and there is much useful information at the patent and trademark office's web site. --mglg_(talk) 16:47, 27 February 2008 (UTC)[reply]

It's actually a lot easier to search patents using Google Patents (much better than the USPTO website, in terms of searchability, usability, and even total scope), but I just want to note that unless you know what you are looking for it can be very hard to just search patents and expect to make sense of whether or not your invention has been patented before or whether or not you might still have a patentable claim. Patents are, as the name suggests, supposed to be easy for anybody to see and understand, but in reality there is a very specific way of writing and reading them required. It's not impossible to learn how to do this, obviously, but it takes some training and practice. A patent attorney would be able to do this much more reliably than one would be able to one's self, assuming one is not at all trained in such things. You can get some indication of this by just looking at the few "recognizable" patents that Google Patents always has on its front page—something as apparently simple as a Christmas tree stand is actually quite complicated when it comes down to the specific patent claims. --98.217.18.109 (talk) 17:23, 27 February 2008 (UTC)[reply]

Who discovered or invented rock candy?

I searched the internet and I keep running into dead ends, or the same information on alot of sites, but nothing to what I was looking for. I was hoping you could give me the history information on rock candy. Who discovered or invented rock candy? —Preceding unsigned comment added by Gblueproductions (talk • contribs) 05:49, 27 February 2008 (UTC)[reply]

Haven't found who first made hard candy but found roughly when and where as in India and Persia, noted by 9th century Arab writers. Thanks for pointing to an article that needs more help. Julia Rossi (talk) 08:54, 27 February 2008 (UTC)[reply]

Role of sweat and body odor in Human attraction

I was reading an article in the sci section of the NY times that showcased a new idea that encouraged potential partners to smell each others odors as a test for compatibility even before they met in person. This made me wonder, is natural body odor attractive? And if so, are purfumes counterproductive? If pheromones and odor are natural ways to attract the other sex, why is are odor masking techniques so prevalent today? —Preceding unsigned comment added by 76.25.201.104 (talk) 06:20, 27 February 2008 (UTC)[reply]

here's a link to the article i read by the way:

http://www.nytimes.com/2008/02/26/science/26elas.html?ref=science —Preceding unsigned comment added by 76.25.201.104 (talk) 06:24, 27 February 2008 (UTC)[reply]

Reasons people most likely use perfumes to cover these natural odors are because they are very self concious and dont like the way they smell, or they like how the perfume smells so they are trying to make themselves happy. Also most people proably dont know that little tidbit your asking —Preceding unsigned comment added by Inutasha De Fallen (talk • contribs) 06:27, 27 February 2008 (UTC)[reply]

Human sweat can be attractive, because we associate the smell of body odor with something we find attractive (bodies). Whether sweat is innately or inherently attractive is a question of scientific debate. This would make them a pheromone, which is something that has been widely demonstrated to be important in sexual behavior in many animals, but not in humans. Thus, despite what people who wish to sell you sex pheromones might say, there is no proof that humans react to human odors in an innate manner. Rockpocket 06:47, 27 February 2008 (UTC)[reply]

Question about that Rocket cant people start attraction from scent which leads to sexual attraction? —Preceding unsigned comment added by Inutasha De Fallen (talk • contribs) 06:50, 27 February 2008 (UTC)[reply]

There might be a difference in appeal between fresh sweat, stale sweat and sweat that leaves clothes standing up by themselves. Apocrine glands secrete more than moisture and salt which might knock off the initial signal FWIW. Whatever happened to that pheromone perfume people were touting awhile back? OR but here goes: peer pressure can result in using body sprays even if beforehand a person felt quite comfortable not to. I like the bit about feeling happy with perfume. Yeh. Julia Rossi (talk) 08:43, 27 February 2008 (UTC)[reply]

I can only comment on your first question, "This made me wonder, is natural body odor attractive?"

It has been known for a long time, that mice prefer mates which have different Major histocompatibility complex (MHC) genes than their own, and that they can tell whether a mate is similar or different from themselves from the smell of their urine. If pregnant with a mate that is MHC-identical to herself, a female mouse may abort sponaneously if an MHC-different male becomes available. MHC molecules play an important role in the immune system, and it is advantageous to be heterozygous. This is assumed to be the primary reason for this phenomenon. In addition, the mechanism protects against inbreeding. To answer your question directly, go to pubmed, and type

MCH sweat

in the search box. You will get a lot of hits, one of the first is this paper: Santos PS, Schinemann JA, Gabardo J, Bicalho Mda G. New evidence that the MHC influences odor perception in humans: a study with 58 Southern Brazilian students. Horm Behav. 2005 Apr;47(4):384-8. When you click on it, you can read the abstract of the paper. To the right of the abstract itself, you will find a box labelled "Related Links". There you will find related papers. This "Related links" tool in pubmed is excellent, the links tend to be highly relevant. To learn more about this, I suggest you do a similar search using the key words

MCH urine

Happy reading, it's a fascinating story. --NorwegianBlue^talk 10:54, 27 February 2008 (UTC)[reply]

Note that mammals detect pheromones with a specialized organ, the vomeronasal organ, and that in humans this organ regresses during fetal development and is either vestigial or entirely absent in adults. It is therefore unlikely that pheromones play a major role in human sexual attraction. --mglg_(talk) 18:04, 27 February 2008 (UTC)[reply]

Except there is a problem with that reasoning. The MHC class molecules described above are actually detected by the main olfactory epithelium in mice, not the vomeronasal organ (vomeronasalectomized mice can still detect odor-types among conspecifics). Rockpocket 23:42, 27 February 2008 (UTC)[reply]

Re the further question above. I'm sure there are people that fall in love at first sniff. It might even be a recognized paraphilia (I seem to remember a character in A Fish Called Wanda seems to get turned on by the smell of his own sweat!) But, from a technical point of view, its important to distinguish between associating a smell with something attractive and a smell that is itself inherently attractive. With animals we differentiate between these things in controlled conditions (we ensure an animal has never before been exposed to a smell before we test its reaction to it). We can't do these experiments on humans, so its very difficult to distinguished between learned/conditioned and innate responses.

The study NorwegianBlue cites above is an interesting case in point. The authors wanted to determine whether MHC class influenced odor preference in humans. The found "a significant correlation only when female smellers evaluated male sweat odors" (but not male to female). This doesn't tell you that body odor is naturally attractive, though, as it is possible, probable even, that we can can be conditioned to the smell of sweat with prior experience. This research would seem to suggest that humans have odor-types that are, at least in some part, genetically influenced (but considering the differences in odor between male and female sweat, that isn't really surprising).

From a practical point of view, this distinction may not be that important, since it suggests people can show a preference based on the smell of sweat only (irrespective of the mechanism behind it). But compared to other animals, the importance of smell in overall partner choice is likely to very very, very minimal. The evolution of trichomatic colour vision in primates is co-incident with the loss of many of the genes involved in pheromonal communication. In short, in the human world you can smell hot, but that doesn't count for much if you looks like a horses arse.

The other thing to remember is that we can also be conditioned to perfume. I'll bet there are few people who have not detected a whiff of a distinctive perfume that they strong associate with an ex-partner or loved one and felt a visceral reaction. Perhaps this is why we use perfumes, because they are much more distinctive than the subtle differences in natural body odor. Rockpocket 19:18, 27 February 2008 (UTC)[reply]

At the speed of sound

If something is moving at, or faster than the speed of sound--say any of those fancy jet planes, can sound be heard by the people inside them?

My understanding (however limited) of relativity would tell me that the sound waves inside the planes would be traveling at 1,120 ft/s PLUS the rate of plane, so i think the answer is yes. BUT if that's the case, then I don't think I understand how we measure the speed of sound...

(it is also my understanding that light does not work that way, its speed is constant) —Preceding unsigned comment added by 76.118.184.59 (talk) 07:17, 27 February 2008 (UTC)[reply]

The speed of sound is measured relative to the motion of the air. Since the plane carries its own air with it, sound within travels at 343m/s relative to the plane, and everyone inside hears it just as well as if the plane were sitting still on the tarmac. If that doesn't seem right to you, keep in mind that the Earth is spinning quite fast (over 400m/s at the equator), and is hurtling around the sun even faster. We can still hear because air near the ground is relatively slow with respect to us (and the ground), and that's what's important. Someguy1221 (talk) 07:34, 27 February 2008 (UTC)[reply]

The speed of sound and the speed of light have a lot in common: like all waves, they are independent of the speed of the emitter (hence you can get something like a sonic boom on the outside of the aircraft). Sound, however, is just a compression of the air itself, so if the air is pressurized then it's going to be the same inside whatever that frame of reference is. You can't do that with light. --98.217.18.109 (talk) 13:45, 27 February 2008 (UTC)[reply]

Wires

How much copper would it take to run a hundred miles of telegraph line? --12.169.167.154 (talk) 09:57, 27 February 2008 (UTC)[reply]

At the time of the US Civil War, wire plus insulation was about 75 pounds per mile, putting the copper content around 40 to 50 pounds per mile (about 13 kg/km). This corresponds roughly with 16 AWG, and 100 miles would be around 4500 pounds of copper. — Lomn 14:06, 27 February 2008 (UTC)[reply]

Telegraph wire was not typically insulated. Air was the dielectric, with wires spaced apart from one another, and with glass insulators to insulate the wires from the crossarms of the poles. A layer of insulation would have increased the weight, requiring stronger and more closely spaced poles, and would have increased the buildup of ice, and would have increased the whipping due to wind, because of the larger cross sectional area. Insulated wire would have made sense in locations with tree limbs near the wire, and certainly cables in couduit or direct buried, as in British practice. Perhaps the Signal Corps made insulated wire standard because they did lots of temporary runs with the insulators attached directly to trees and wire run through the branches. Galvanized iron wire was strong and cheap, but heavy, high resistance, and prone to corrosion. Copper was high conductivity and light, but weak and expensive. An 1869 book [6] discusses various wire use in 1860's telegraph practice in the US and elsewhere."Compound wire," or steel core wire with a copper outer layer was liked, because the steel gave it superior strength compared to galvanized iron or copper, while the copper gave high conductivity and corrosion resistance. They mention compound wire weighing 80 to 175 pounds per mile as a good choice. Strong wire means fewer poles per mile, and fewer insulators to drain off signal strength. A 1903 book [7] says iron wire was used through much of the 19th century for telegraphe runs overland, but that galvanized iron corroded and failed in 10 or 12 years, and that soft copper was too weak to run from pole to pole, because it sagged under its own weight. It says that compound wire lost out to hard drawn copper wire, which was stronger than soft copper. This book says (p532) that 35 to 40 poles per mile was typical. P 542 mentions #14 copper (British Wire Gauge) as a typical conductor. Page 555 says the hard drawn copper wire, if 12 gauge weighs 170 pounds per mile, and if 14 gauge weighs 110 pounds per mile. Edison (talk) 16:25, 27 February 2008 (UTC)[reply]

Gain in a transistor

In genral what factors affect the gain of a transistor?Bastard Soap (talk) 11:13, 27 February 2008 (UTC)[reply]

From our Bipolar junction transistor article, the common-emitter current gain is represented by

\beta _{F}

or h_fe which is an intrinsic characteristic of a given transistor. Increasing the amplitude and frequency of the input signal will have an impact in reducing the gain of a transistor. --hydnjo talk 15:04, 27 February 2008 (UTC)[reply]

Mental illness in children

The newspapers in Britain seem to mention every week how more children are being diagnosed with mental illnesses, or are more stressed or anxious etc. Is this actually due to an increase in these problems amongst children or is it just increased diagnosis? Have any studies been done about this? Thanks a lot 81.96.160.6 (talk) 16:20, 27 February 2008 (UTC)[reply]

A pediatrician's opinion and some experts discussing a study. The bottom line is no-one really knows. And, depending on which axe one has to grind, it may be due to increase in drug use, stress, over-medication by the pharmaceutical industry, vaccines, better diagnoses, worse diagnoses, psychiatry, bad parenting or a sign of the degeneration of society leading to the second coming. Rockpocket 19:37, 27 February 2008 (UTC)[reply]

And don't forget the old saw, the medicalization of basic human behaviors (whereby something that in a previous generation would just be considered part of being a kid is suddenly and somewhat arbitrarily determined to be a disorder, or, for the less cynical, whereby the borders between genuine disorders become so lax that they start to impinge on the border of "regular" behavior). --98.217.18.109 (talk) 00:43, 28 February 2008 (UTC)[reply]

Thanks a lot guys! Rockpocket, those links were great! 81.96.160.6 (talk) 03:11, 28 February 2008 (UTC)[reply]

Thermodynamics and antimatter

If the second law of thermodynamics is correct and the total entropy in the universe is constantly increasing with time, why isn't our world full of relatively equal amounts of matter and antimatter? Shouldn't the two have become more disordered with time? Wrad (talk) 17:03, 27 February 2008 (UTC)[reply]

It is currently one of the Great Big Questions in Physics as to why there is not more or equal amounts of antimatter in the universe. See our article on Baryogenesis. To answer your question more specifically: very early on in the Big Bang matter ended up dominating over antimatter, and since then there have never been significant quantities of antimatter in the universe. --98.217.18.109 (talk) 17:14, 27 February 2008 (UTC)[reply]

(ec)You've touched on one of the most significant unsolved problems in physics—why is our observable Universe made almost entirely of matter? Where did the 'missing' antimatter go? Our articles on baryogenesis (the formation of matter in the Universe) and baryon asymmetry (why there's so little antimatter) discuss the issue in some detail.

To approach the question of 'equilibration' between matter and antimatter (the idea that some sort of 'settling' process would drive an early imbalance in matter/antimatter ratio to an equilibrium) one must note that there is no known process that allows the conversion of matter to antimatter. We can convert energy (reversibly) into equal parts matter and antimatter, but we can't bias the process to generate more antimatter (or matter). Pair production – as far as we know – always produces a matter and an antimatter particle. TenOfAllTrades(talk) 17:17, 27 February 2008 (UTC)[reply]

Maybe I'm being obtuse here, but what does the second law of thermodynamics have to do with the mystery of the imbalance between matter and anti-matter in the observable universe?--Eriastrum (talk) 18:06, 27 February 2008 (UTC)[reply]

From what I know about it, experiments seem to show that the universe began with equal amounts of matter and antimatter. The second law of thermodynamics states that things to become less ordered over time, yet somehow all of the antimatter has been separated from the matter in our universe. If things were following the second law, it would be a more uniform mix of matter and antimatter. Wrad (talk) 18:31, 27 February 2008 (UTC)[reply]

My understanding is slightly different. The problem is not that matter and antimatter were originally intermixed in equal quantities and have somehow (improbably) separated, but that there seems to have been more matter than antimatter synthesized immediately following the Big Bang. We effectively started with more matter than antimatter, which both explains why antimatter is still so rare today, and is something that makes cosmologists pull their hair out. TenOfAllTrades(talk) 19:01, 27 February 2008 (UTC)[reply]

Ten, your understanding is incorrect/incomplete. The usual assumptions in cosmology call for a universe that begins with equal quantities of matter and antimatter, and then evolves into a matter dominated universe within the first fraction of a second due to some poorly specified process that favors matter over antimatter. By the time the Quark epoch ended, the universe had acquired a 1 part in 10^10 preference for matter over anti-matter (i.e. for every 10^10 quarks, there was one too few anti-quarks). Then, once the universe cooled below the temperature for quark pair production, all the quarks and anti-quarks annihilated and left a residual of extra matter lying around that created the universe as we know it.

This can happen if there is some physical process that creates matter more often antimatter. We already know of such CP-violating processes that favor matter over antimatter. In essence, we already have experimental proof that the weak interaction can create matter/antimatter imbalances (a Nobel prize was awarded for that work). The problem is that weak interactions are so inefficient that it appears they could never create a large enough imbalance during that first fraction of the second in order to explain the abundance of matter. In fact, no known physical process can create an imbalance fast enough to explain the observed abundance of matter. Hence one either needs to posit new physics (beyond the Standard Model) that allows asymmetry to arise more quickly, or one has to accept the aesthetically displeasing notion that universe was simply created with a tiny excess of matter. Dragons flight (talk) 04:25, 28 February 2008 (UTC)[reply]

On that note... The baryon asymmetry states that "As of May, 2007, no helium atom (or larger atom) made of anti-matter, either in nature, or created synthetically, has ever been scientifically observed.". However, the Antimatter article says that indeed, a few synthetic antihelium-3 atoms have been produced (source). Should the article be corrected or am I missing something? -- Aeluwas (talk) 18:56, 27 February 2008 (UTC)[reply]

I think the cited article is referring to production of an antihelium-3 nucleus, not a complete atom (with positrons). -- Coneslayer (talk) 19:41, 27 February 2008 (UTC)[reply]

My understanding of the situation is what Tenofalltrades said--that we started with far more matter than antimatter, and thus entropy could have nothing to do with it.--Eriastrum (talk) 20:56, 27 February 2008 (UTC)[reply]

It's not correct to say that there was "far more" matter than antimatter. While the excess matter represents the entire baryonic mass of our universe (which is big, I admit), the matter excess was very small in relative terms. Kolb & Turner estimate the matter excess to have been only 1 part in 30,000,000. -- Coneslayer (talk) 14:36, 28 February 2008 (UTC)[reply]

Also, entropy is a probabilistic statement, which predicts which equilibrium state (out of a set of otherwise equivalent states) a system will tend to over time. Having matter and antimatter together is generally not a state of equilibrium, as opposed to the alternative of them annihilating each other and replacing it with photons. Confusing Manifestation(Say hi!) 22:42, 27 February 2008 (UTC)[reply]

Given what a footnote to the composition of the universe we baryonic types apparently are (see image), the matter-antimatter split seems like fighting over scraps. --Sean 13:33, 28 February 2008 (UTC)[reply]

Temperature sensation

Is there a difference in physiological response to the sensation of extreme temperature as stimulated by actual temperature changes and as stimulated by chemical means? More specifically, would there be a difference in response to an actual cold stimulus (which for this example we will assume is not of sufficient duration or intensity to cause clinically appreciable tissue damage) and a stimulus which chemically imitates the same degree of "coldness" ( I realize this is an ambiguous term, and am just as interested in discussion of this topic as I am in a clear answer). Would these two stimuli send identical signals through the spinothalamic tract? Would the efferent signals be identical? Without any way to measure temperature, would there be any way to distinguish between the temp. cold area and the chem. cold area? Does a chemical cold stimulus cause an increase in temperature of the affected tissue? And finally, is the situation reversed for temperature and chemical heat stimuli? Sorry for the compound question! Tuckerekcut (talk) 18:00, 27 February 2008 (UTC)[reply]

The exact mechanism through which thermosensors are activated is not fully understood, but the proteins themselves are known to be in the Transient receptor potential channel family. For example, TRPM8 has been shown to be a cold sensor [8]. On a decrease in temperature from 32°C to cold temperatures ranging from 23°C to 10°C TRPM8 is activated, permitting the influx of cations (which will eventually result in an action potential along the Dorsal root ganglion neuron). The scientists demonstrated that menthol activated the same channel, resulting in the same cellular consequence, which is why we perceive menthol to be cold. There is no difference in cellular response to cold or menthol, once the channel opens the downstream signal is the same, though the kinetics of receptor activation are likely different (but since we don't yet know exactly how cold activates the channel, it is difficult to measure this).

Note, however, that there are likely other cold receptors, since there are neurons that are activated by colder temperatures (4°C–15°C) and others that respond to temperatures below 0°C. Menthol probably doesn't activate these, which is why we perceive menthol as being "innocuous" cold, rather than "noxious" cold. However, since there is a range of different neurons sensitive do different temperature ranges, its possible that the combined output of these is sufficient to distinguish between cold and chemical cold, but at the level of the single TRPM8 neuron, there does not appear to be a difference. There is a similar situation with the noxious heat/Capsaicin receptor TRPV1. Rockpocket 20:09, 27 February 2008 (UTC)[reply]

Evolution

Is it at all possible that a plant could one day evolve into an animal? What would be the intermeddiate steps? If not, why not? Thank you very much 81.96.160.6 (talk) 19:32, 27 February 2008 (UTC)[reply]

It's not very likely but it depends on which theory of evolution you believe. The most widely accepted theory is that plants and animals evolved in parallel, however, another theory says that animals evolved from algae (microscopic plants). If you believe this theory then, yes, it is possible. As for the intermediate steps, I cannot offer any help there. George D. Watson (Dendodge).Talk^Help 19:56, 27 February 2008 (UTC)[reply]

It's always possible in some arbitrary environment, but that arbitrary environment may be unlikely or impossible to ever exist. For plants (either multicellular or algae, whose classification is still not agreed upon), there would need to be a selective pressure to have animal-like characteristics, and this pressure must drive the plants to fill an ecological niche that's not already occupied by something else (or else they have to "invade" the niche and outcompete what's already there). The problem is that every species on Earth is the result of billions of years of evolution, and as a result is very well adapted to its own niche with respect to all organisms in the same environment. And so it would be very difficult for a plant to radically mutate and then successfully invade a niche normally associated with animals. Someguy1221 (talk) 20:07, 27 February 2008 (UTC)[reply]

No, plants cannot evolve into animals, because plants and animals diverged as separate species long ago, and anything a plant evolved into, even if it walked around on four legs, would not be an "animal", that is, a member of the kingdom Animalia, it would be a descendant of the kingdom Plantae. If by "animal" you simply meant something that moves around like an animal, then it would probably have to either evolve a great deal from something simple like unicellular algae (mimicking animal evolution), or evolve from some rapidly moving plant like a Venus Flytrap. Anything that had evolved that much from plants that it moved around like an animal would probably be deserving of its own kingdom though. -- Hi Ev 20:26, 27 February 2008 (UTC)[reply]

As a speculative look at what such an "intermediate step" might look like, I've always been fascinated by the Portuguese Man o' War, which looks superficially like a single organism but is really a colony of specialized microscopic organisms. I think you'd get effects more like that before you'd get something that looked like a centralized nervous system. But of course, as HiEv points out, when you start asking about how "plants" could become "animals" you have to really closely examine what you mean by the terms, as they are mutually exclusive as generally defined. --98.217.18.109 (talk) 00:24, 28 February 2008 (UTC)[reply]

Thanks for your answers guys, they've lead to a lot of interesting reading. Having had a look at the articles, what I mean seems to be "could an embryophyte evolve so far beyond what it is now that it shares more of the characteristics of an animal (eats food, has a respiratory system and cardiovascular system and can move freely) than of a traditional plant (despite the fact it would still be a plant)?" Is that stil a no? 81.96.160.6 (talk) 01:19, 28 February 2008 (UTC)[reply]

It's something that would be incredibly difficult. As was hinted at above, modern plants and animals diverged from one another while they were still single celled. Plants create their own organic material from their environments, and also capture energy directly from their environment. They are almost completely motionless, and as such have relatively tiny energy requirements per cell. Animals, on the other hand, consume the organic material of other organisms, using this to both make their own and to derive energy. Thanks to the effect most easily explained by pointing you to ecological pyramid, plants can just sit where they are and live a happy life, while an animal's food requirements necessitate moving around and this brings in all those fancy things like complex internal organs, circulatory systems, respiratory systems, and whatnot. And this is why evolving a plant into something like an animal would take so long and be so complex and absurdly unlikely, as you would need to introduce pressures to develop all of these systems and activities plants have never needed. Someguy1221 (talk) 01:38, 28 February 2008 (UTC)[reply]

Rafflesia is a genus of parasitic plants who have lost the ability to use light as an energy source. Icek (talk) 01:58, 28 February 2008 (UTC)[reply]

And let's also look at it this way: modern plants have evolved their particular way of life for billions of years. Even the simplest ones are highly specialized. Modern animals have evolved for hundreds of millions of years. It would take an immense amount of time for one highly specialized group to start to resemble another highly specialized group. There's no a priori reason why it is impossible, but it's pretty unlikely. --98.217.18.109 (talk) 22:32, 28 February 2008 (UTC)[reply]

Yes plants could evolve into something resembling and acting like an animal, but having a different linage they would never be "True" animals, and instead be relegated their own grouping (see convergent evolution). Some of the difficulties they would have to overcome (suggesting intermediate stages) are moving around, eating and digesting other plants (or animals), developing a brain, changing to a squishier/meatier cell structure, developing bilateral symmetry, and various animalesque organs, and whatever else would make the plant seem like an animal to you. The exact definition of a plant-animal is arbitrary, as (again) it is not possible for a plant to become a true animal. —Pengo 06:58, 29 February 2008 (UTC)[reply]

Reducing power consumption by ice machine and misc.

At my place of internship there is an ice machine that produces crushed ice for people to keep reagents on ice while they work with them. It uses about 540 watts and is on all day and all night, and contains at any one time, about enough ice for a week's usage. Would power be saved if it switched off at say, 1600 in the afternoon and switched on again at 0400 in the morning? Probably. What if the window was less? In what ways is energy expended by an ice machine? Does it spend energy keeping the ice cool or only making it (and then lets it melt)?

And why use Kleenex tissues? Surely there is a cheaper alternative without compromise on quality? I bet your lab uses Kleenex, probably because that's what happens to be in a catalogue, and whoever is responsible is too lazy to seek out an alternative.

Legend has it that the plate that covers the UV tubes of the machine that images electrophoresis gels was damaged by someone leaving the UV lights switched on with the door closed; it looks as though it was scratched badly. Could UV do that? I think it should be replaced because the same artifacts show up on every image but I'm told there's no money (while they throw it out the window every day) and the company doesn't seem to make that model of machine any more. I'll contact them to see what they say, but if anyone knows of the sort of UV-induced scratching I may be talking about, perhaps they can suggest how the plate might be recoated or something? —Preceding unsigned comment added by Seans Potato Business (talk • contribs) 19:52, 27 February 2008 (UTC)[reply]

It sounds like you're working at a research lab. One of the unfortunate truths about science labs is that the machinery stays on, all the time, for convenience. Unlike larger-scale industrial deployments, there's not as much effort to squeeze out the efficiency from the machinery. I guess the ultimate question will be, is it really worth cutting the ice-machine power usage? How much energy does that save? Probably not much electricity; and if you're paying commercial rates, probably not much money, either. 500 Watts is pretty small (around here it would cost about 4 cents per hour to operate). Nimur (talk) 23:49, 27 February 2008 (UTC)[reply]

I work with UV systems and I've never seen any sort of wear that would be easily mistaken for scratching. However, I don't know anything about electrophoresis systems, so I don't know what the plate is meant to accomplish or what it is made of. Dragons flight (talk) 03:46, 28 February 2008 (UTC)[reply]

You get cracking in perspex from UV, but just on the exposed side. The setup where I used to work just had a UV light pretty much like a flouro tube desktop lamp over the gel; nothing complicated. The lab only used toilet paper on rolls (amusing all visitors) for wiping things up. The ice machine didn't refrigerate the ice, just drained the water. The machine was shared by several labs and left on all the time. Insulated the big hopper where the ice is stored would have been good.Polypipe Wrangler (talk) 08:02, 28 February 2008 (UTC)[reply]

high frequency photons

what would a photon of ~3.5×10²⁷Hz do to a nucleus if it was absorbed? what other uses are their for high frequency photons? —Preceding unsigned comment added by 172.142.196.236 (talk) 21:57, 27 February 2008 (UTC)[reply]

Convert from frequency to energy( E = h*f ) and compare that to the binding energy of the nucleus in question. Nimur (talk) 23:50, 27 February 2008 (UTC)[reply]

Article on speech/thought disorder

I realize now that I posted this on the wrong RD...

I remember reading an article about a symptom (or something) of schizophrenics (or some other antisocial personality disorder) where the person would give very short answers to questions which "normal" people would usually expound upon, such as one's children, which was an example in the article. Someone would ask "do you have any children" and the other person would only answer "yes" rather than say "yes, i have one boy and one daughter, they're 6 and 8 years old". Something like that. Does anyone know the name of this symptom, I'd like to read the article again. Thanks. Jack Daw (talk) 23:08, 27 February 2008 (UTC)[reply]

Try googling Monosyllabic response. It gives lots of refereces to mental illness of various sorts. —Preceding unsigned comment added by 79.76.173.143 (talk) 01:11, 28 February 2008 (UTC)[reply]

Sounds kinda vague and attributes a pathology to something which might be arbitrary when considered across various cultures (or generations). It's sometimes considered "assertive" to refrain from giving too much information; in some fields it's behaviour that's normal based on "need to know". People with issues about disclosing family information, for example, might only give the short answer. Others might be impatient making chit chat with strangers they don't expect to meet again and use a short answer to discourage further conversation. Are you asking if the "antisocial" aspect is that someone only ever gives a yes or no answer? Julia Rossi (talk) 01:17, 28 February 2008 (UTC)[reply]

(moved from humanities desk)

It's paucity of speech but I don't know where it is in Wikipedia. - Nunh-huh 23:32, 27 February 2008 (UTC)[reply]

Loose associations and disordered speech patterns in chronic schizophrenia. fits the bill. --Tagishsimon (talk) 23:59, 27 February 2008 (UTC)[reply]

So what's all this with the "antisocial personality disorder" Methinks we are not doing a service or showing sufficient compassion with the arbitrary use of such negative (and medically incorrect) terminology. I have cared for hundreds of people suffering from so-called schizophrenia and the sign (it's not a symptom) is very rare and has more to do with the premorbid personality than the pathological condition. It may also be related to people who have a subclinical level of suspicion in their attitude and may be disinclined to impart more information than is necessary. I have also met many people who one might regard as normal who tend to conduct conversations with an economy of words. Richard Avery (talk) 08:52, 28 February 2008 (UTC)[reply]

That's nice. The fact remains that the answer the questioner was looking for is "paucity of speech". - Nunh-huh 13:19, 28 February 2008 (UTC)[reply]

One of the most famous and successful practitioners of which was the US President Calvin Coolidge, who, although his duties required him to make speeches etc, in his private life became known as "Silent Cal". -- JackofOz (talk) 22:32, 28 February 2008 (UTC)[reply]

I found it now, it was alogia. I found it by way of schizophrenia. Thanks for your efforts though. Jack Daw (talk) 04:12, 3 March 2008 (UTC)[reply]