Wikipedia:Reference desk/Archives/Science/2008 April 8

= April 8 =

Origin of Universe - nothing has to be somewhere- doesnt it?
If the universe suddenly came into being from nothing (a zero dimension, zero time nothingness), (as some theories say), where and how did this nothingness exist? I mean even nothing has to be somewhere dosent it? —Preceding unsigned comment added by 79.76.170.42 (talk) 00:18, 8 April 2008 (UTC)


 * It didn't exist. By virtue of being nothing it was not a thing and therefore never had a spatio-temporal location, as it preceded spacetime. Hope someone tells me I'm wrong though 81.96.161.104 (talk) 00:24, 8 April 2008 (UTC)


 * The accepted theories of physics simply don't cover what happened before the Big Bang; they generally posit that time literally began existing in that event, and so there is no meaning to "before the Big Bang." This may not be literally true however, and it is merely part of the model; indeed, the model (based on the standard model and general relativity) actually breaks down at the moment of the Big Bang, since it can't handle the singularity. Once again, the singularity, the infinite density of energy, at the moment of the Big Bang is also part of the model, and may not be literally true. Big_Bang contains links to some popular alternative models. Someguy1221 (talk) 00:28, 8 April 2008 (UTC)

Does what Stephen Hawking once said--Whatever happened before the Big Bang could not affect the Universe after--still stand? If so, it may be a partial answer to the OP--there's simply no connection between what may have happened beforehand, even if that can be defined, and what happened in the Big Bang, so to talk of "nothing into something" is misleading. Imagine Reason (talk) 02:55, 8 April 2008 (UTC)


 * If the universe came into being from a zero dimensional point, then it makes as much sense to say it happened everywhere as nowhere, seems to me. Or to play on the thread title here, nothing is everywhere? Pfly (talk) 02:22, 9 April 2008 (UTC)


 * It must also be pointed out that it is not a "failure" of the big bang theory that it can't explain what happened before the big bang.. It is only intended to explain what happened after. For a really dumb analogy, birthdays are only recognized/celebrated after you're born :-> Saintrain (talk) 17:38, 14 April 2008 (UTC)

Super powers
Assuming medicine continues to develop at the same rate it is now, as do robotics and science in general, what's the closest we could come to super-powered human beings in the next 20-50 years? The powers can be temporary but robo-suits don't count. What sort of super-powers is it feasibly even vaguely plausible that we could develop? 81.96.161.104 (talk) 00:24, 8 April 2008 (UTC)


 * Work is underway artificial retinas. Right now they're extremely primitive, so I don't know if they'll qualify as "super powers" in your 20-50year time frame, but you could imagine them being made to work on ultraviolet or infrared. That'd be a neat super power. APL (talk) 00:39, 8 April 2008 (UTC)


 * Most "super powers" in comic strips involved violating conservation of energy one way or another (e.g. the beams just come out of nowhere). So if we're discounting everything like that, we're probably talking just about enhancement of existing abilities. It wouldn't be too hard to imagine better hearing, for example—we've already got hearing aides that are pretty small. But I don't know why you're discounting robo-suits—humans have always done better when they've learned to use technology along with their own natural abilities, rather than trying to just improve their natural abilities. It also makes more economic sense to have one set of tools that anybody can use than to try and modify each individual themselves. But anyway, these are practical considerations, and not much fodder for fun speculation... --Captain Ref Desk (talk) 00:50, 8 April 2008 (UTC)


 * I'm fine with robotic enhancement, but the suits could not be small enough to be manouvereable in that little time. Robotic legs that can jump 50feet counts as a super-power, to me, but a huge clunking suit that can run at 10mph and has guns for arms doesn't. And what about genetic modification? Could we have ant-strength? Or poisonous saliva? The ability to change your hair length/colour? Maybe skin colour? There must be some great traits out there to steal.
 * The artificial retinas sound great. Zoom would be a bitch to master, though. 81.96.161.104 (talk) 01:24, 8 April 2008 (UTC)
 * I'd go for a direct brain-internet type link, lets you research anything by thinking hard about it somehow. Any other brain enhancement, extra memory, some type of processing demultiplication? 200.127.59.151 (talk) 02:21, 8 April 2008 (UTC)

From a biological perspective:
 * Healing factor - if we could figure out how to incorporate the regenerative qualities of other animals like starfishes (using gene theraphy) then we are all set.
 * Immortality - if we could stop aging (probably using stem cells) then we already beaten death herself-- Lenticel ( talk ) 02:35, 8 April 2008 (UTC)

red wine, larger and ale.
hi, I like a drink occasionally and have noticed (as i approach 40) that ale really settles the stomach. I had for the past few years had a rather mild IBS type thing going on.

Is there a chemical present in ale that is perhaps sorting this all out nicely?

thx guys —Preceding unsigned comment added by 89.242.133.70 (talk) 00:34, 8 April 2008 (UTC)

that is to say that red wine and larger have not had a such good effect on the stomach.. —Preceding unsigned comment added by 89.242.133.70 (talk) 00:36, 8 April 2008 (UTC)


 * Maybe it's the fizz? I've found fizzy drinks can help with queasy stomachs. But beer foamy, beer good, hotclaws 07:16, 14 April 2008 (UTC)


 * The questioner said ale settles the stomach, but not lager -- and both are fizzy. I think there may be a different feature of ale vs lager and wine being referred to here.
 * That said, the only major difference between ale, lager, and wine, is that ale uses top-fermenting yeast while lager and (I believe) wine use bottom-fermenting yeast. That might make a difference.
 * I also notice a difference in taste between wine made the "usual" way by inoculating it with yeast to begin fermentation, versus letting the same grapes ferment using the wild yeast already present on the grape skin; the latter tastes better to me, and also gives me a subjective "more settled" feeling in my stomach.
 * So the effect may be due to the yeast. That's my guess. ~Amatulić (talk) 23:47, 14 April 2008 (UTC)

Clouds, aerial photos and a dead bird
I have a series of pictures I took where I'm looking for help in identifying stuff, or confirming my identifications. Would anyone be able to help? Comments below the gallery please. Thanks. Carcharoth (talk) 01:44, 8 April 2008 (UTC)
 * (1) Can anyone identify the type of clouds in this picture I took from an aeroplane?
 * (2) Can anyone confirm my identification of what is seen in this aerial picture?
 * (3) Again, can anyone confirm my identification of what is seen in this aerial picture?
 * (4) Finally, a dead bird on a beach. Head can be seen better in this picture. Is it a seagull? Maybe it is a gannet?

?? For your number 2 and number 3, I assume you're talking about clouds? Or what we see in general? This seems pretty.. either point lacking, or it's a quiz. *shrug* Neal (talk) 02:09, 8 April 2008 (UTC).
 * Click on the pictures to see descriptions on the image page of what is in the pictures. For 2 and 3, I'm looking for confirmation that my Google Mapping of what I saw out of the aeroplane window isn't totally off-beam. I initially thought 3 was the main part of the Thames Estuary, but then I realised nothing on the map was matching what I saw on the picture, so I looked around a bit on the map, and spotted the distinctive shape of Mersea Island. But ideally I'd like someone else to say "yes, that looks like you've identified it correctly". One day, of course, all cameras will automatically have GPS geocoding built into their picture metadata. But until that day arrives, we have to scribble notes on bits of paper, or, in my case, rely on memory and detective work afterwards. Unfortunately I have a nice picture of hills in Eastern Europe that is pretty much unusable as I don't remember where in the country the picture was taken... Picture 2 is also a case where my Google Mapping needs double-checking. As for the clouds in picture 1, see Cloud - an amazing resource for different cloud types. But I need an expert to identify the clouds here. I would also like an expert to confirm my identification of what I now think is a gannet in picture 4. So yes, a quiz of sorts, but also me looking for some corroboration and confirmation. Carcharoth (talk) 02:18, 8 April 2008 (UTC)
 * For #1, those are altocumulus clouds. I can't figure out which variety, though. For #3, I see a turbofan. :) Tito xd (?!? - cool stuff) 02:21, 8 April 2008 (UTC)
 * Yes, I must remember not to sit near the engines and the wings if I want to engage in amateur aerial photography! :-) But seriously, does no-one else here use Google Maps to check things like this. It is great fun! Carcharoth (talk) 02:25, 8 April 2008 (UTC)
 * On topic spur, to get that blue tinge off the iamges you can use a photo editor like Microsoft Photo Editor, to reduce the blue brightness and increase its contrast by the same amount, perhaps to 75%, it gives a more natural looking colour for things viewed a long way through air. Graeme Bartlett (talk) 05:33, 8 April 2008 (UTC)

The dead bird in image 4 is certainly a northern gannet, given that it was taken in England. The markings on the bill are distinctive and you can see the pointed, black-tipped wings. It certainly is not a gull. I'm not an expert, but I been a birder for many years.--Eriastrum (talk) 20:00, 8 April 2008 (UTC)
 * Thanks. I've asked at WikiProject Birds just to be sure (I'm sure you will see the question there as well). I've asked about a picture of some swans over there as well. Carcharoth (talk) 21:18, 8 April 2008 (UTC)

Herbivores with horns
Do herbivores like antelopes and buffalos ever defend against predators consistently? As a child my father would tell me that certain animals would form circles around their young and defend against lions and such, but I've never been able to confirm any instance of the behavior. Thanks in advance. Imagine Reason (talk) 02:57, 8 April 2008 (UTC)


 * Herbivores don't need horns to defend the young. I believe elephants will do so, for example.  Surprisingly, though, many large species which travel in herds and would seem to be capable of defending the young opt not to.  I chalk it up to predation actually being good for the species in the long run, by only allowing those with the strongest genes to pass them on. StuRat (talk) 03:14, 8 April 2008 (UTC)


 * Yeah, um, I was actually looking for an example also partly to refute group selection, including species selection. The best explanation I've come across to explain this odd behavior is Richard Dawkins's gene selection, which is sometimes reflected in apparent individual selection--an antelope that goes against the lion might win, but the benefit is shared by everyone else in the herd, including everyone who's disappeared from the battle, while the cost is very real and probably fatal to the brave individual. Thus any individual that carries such a "brave" gene will mostly likely die out from any species. I suspect that species that can communicate effectively, including dolphins, will exhibit more cooperation. Imagine Reason (talk) 03:32, 8 April 2008 (UTC)


 * Musk oxen do in fact form a tight outward-facing circle to defend their young. Great tactic against wolves. Very bad tactic against rifle-equipped humans. -208.226.76.43 (talk) 12:48, 8 April 2008 (UTC)


 * Wow, that actually looks like the animal my father told me about. Thanks! Imagine Reason (talk) 16:11, 8 April 2008 (UTC)
 * Musk oxen are the exception that proves the rule. Any species using this tactic that was co-extensive with primitive humans is now extinct. Musk oxen were the only species that used this tactic and whose range had at least a few spots with no humans up until the time (about 1880) that humans became squeemish about driving (mammal) apecies to extinction. I seem to recall written descriptions from the midd-1800's of hunting parties finding a herd of musk oxen and calmly shooting them all one by one, as they stood in a circle. There are earlier accounts of Inuit hunters doing the same thing, more slowly and more carefully, with spears. -Arch dude (talk) 01:10, 9 April 2008 (UTC)
 * Interesting. What other species, if any, have you come across for which written accounts exist that suggest similar behavior? Thanks. Imagine Reason (talk) 03:35, 9 April 2008 (UTC)

Will hoofs instead of horns and no circle do it for you? Some farmers mix burros with livestock to protect their herd. Burros fight where others run. Feisty enough? Lisa4edit


 * That makes sense, since donkeys are domesticated animals and are thus probably artificially selected partly for their fighting spirit. Imagine Reason (talk) 18:31, 13 April 2008 (UTC)

Butanoic acid
how exactly do u make it from fermenting sugar? —Preceding unsigned comment added by 76.14.124.175 (talk) 04:41, 8 April 2008 (UTC)
 * You need the right kind of bacteria. Are you sure you want to make it? It does not smell good. Graeme Bartlett (talk) 05:28, 8 April 2008 (UTC)
 * The A.B.E. process (Acetone Butanol Ethanol process) developed by Chaim Weizmann 1916 described at the Clostridium acetobutylicum article might be the right point to start, also the Butyric acid article is a strting point.--Stone (talk) 11:36, 8 April 2008 (UTC)

General Relativity
If a force of gravity is an effect of space-time distortion by gravitational field, how can it be explained, that the force is much, much stronger, than one might expect from such a tiny distortion? E.g. on Earth's surface, acceleration due to gravity is 9.81 m/s2, but Earth's gravitational field curves space-time very miserably and cannot cause such huge acceleration. Maybe, I'm missing some important points. Abdullais4u (talk) 10:54, 8 April 2008 (UTC)


 * There's no reason to think that the earth has a small effect on space-time, because it's all relative. You said that "Earth's gravitational field curves space-time very miserably", but compared to a 1 kg mass, the earth has a huge effect on space-time. - Akamad (talk) 11:11, 8 April 2008 (UTC)
 * Well, Earth's effect on space-time still not big enough, even when you're comparing Earth's mass to a kilogram. Light beam, flying-by Earth, bends only to some millionth parts of a degree. Abdullais4u (talk) 11:53, 8 April 2008 (UTC)
 * Keep in mind that gravity follows the Inverse-square law, so the distortion you describe drops off very quickly. Also, light is only barely affected by gravity, having zero rest mass, so it takes an immensely massive object to produce observable gravitational lensing.  --  JSBillings  12:30, 8 April 2008 (UTC)


 * If light bends only a millionth of a degree, then so would a rock traveling along the same path at highly relativistic speed. That's the essence of the equivalence principle. We think of light as being only slightly effected by gravity, but that's only because it usually moves so fast. In an optical cavity in which light can reflect back and forth between two mirrors for one second before dissipating (and such things are not unheard of), the light would fall 4.9 meters if the mirrors were exactly vertical, the same distance a rock would fall. So light falls in a gravitational field, just like anything else. (In fact, the mirrors of an optical cavity are almost always curved and tilted at some tiny angle to prevent the light from falling, but that doesn't invalidate my argument. Light will fall like a rock if you give it a chance.) —Keenan Pepper 12:44, 8 April 2008 (UTC)
 * KP, I knew your general point about light falling like a stone was true, but doubted your assertion that it was a practical concern with current technology (I thought it would dissipate too soon to be an issue), so did the math for letting light fall for a second at one of the LIGO facilities that uses a 10 watt laser across a 4 kilometer long range and assuming 99.99% reflective mirrors: $$1s * 10W * .9999 ^ \frac{3 * 10^8m/s}{4km} \approx 5.6 mW$$, which is certainly detectable, at about the strength of a CD drive's laser. Thanks for disabusing me of some false knowledge!  --Sean 15:22, 8 April 2008 (UTC)
 * Perhaps you mean $$(10\mathrm W).9999 ^ \frac{3\times10^8\mathrm{m/s}(1\mathrm s)}{4\mathrm{km}} \approx 5.53 \mathrm{mW}$$? The units and rounding don't work out otherwise... --Tardis (talk) 03:31, 9 April 2008 (UTC)
 * Oh right, I see what you mean about the units. --Sean 12:20, 9 April 2008 (UTC)


 * Be careful with that equivalence! As described at general relativity, light suffers twice the deflection that one would naïvely expect from analogy with a fast rock.  --Tardis (talk) 15:21, 8 April 2008 (UTC)
 * Kewl :-) Thank you all for answers. Abdullais4u (talk) 16:09, 8 April 2008 (UTC)

burning match
Why does a match (or any fire) smoke the most the moment the flame goes out? And while we're here, what exactly are we seeing when we look at a flame. The best I could think of was ionizing O2, which doesn't really explain it.

Cheers —Preceding unsigned comment added by 59.100.248.6 (talk) 13:15, 8 April 2008 (UTC)


 * Our candle article provides a fair description of what's happening within a flame, but most of the light comes from incandescent carbon particles. Fire and Flame have more information.


 * Atlant (talk) 13:47, 8 April 2008 (UTC)


 * Visible smoke is usually the result of incomplete combustion. You get the formation of small carbon particulates which are of a large enough size to substantially perturb light. If you have more complete combustion, these carbon particles oxidize fully to carbon dioxide - a clear, colorless gas. So you get the most visible smoke when combustion is weak/failing - like when the material is wet, or the fire is smoldering, or when it is just extinguished. -- 128.104.112.85 (talk) 20:06, 8 April 2008 (UTC)


 * Here's a very thorough treatment - The Chemical History of a Candle, by Michael Faraday. Full text available from Project Gutenberg. Nimur (talk) 14:47, 9 April 2008 (UTC)

Is it known whether prion is present in milk from BSE-infected cows?
Is it known whether prion is present in dairy products made with milk from BSE-infected cows? --71.162.249.117 (talk) 14:03, 8 April 2008 (UTC)


 * According to this paper, it's not. Someguy1221 (talk) 17:46, 8 April 2008 (UTC)


 * By "not", do you mean the question remains unresolved, or do you mean prion is known not to be present in dairy products? --71.162.249.117 (talk) 18:27, 8 April 2008 (UTC)


 * Sorry. I mean the milk of infected cows does not contain prions, or at the very least that researches have tested for the presence of prions in infected cows' milk and found none. Someguy1221 (talk) 23:10, 8 April 2008 (UTC)


 * This demonstrates why it's always a good idea to ask questions that can be answered, unambigously, with yes or no. In this case "Is the prion present in dairy products made with milk from BSE-infected cows ?".  People could still answer "We don't know", if this is the case. StuRat (talk) 16:58, 9 April 2008 (UTC)

Related to this question is that of whether prions can be transmitted via milk. The latest research says the answer is "Yes." Scrapie is a disease in sheep spread by prions, and it was transmitted via sheep milk to the ewe. The report denied any evidence of transmission of prions to humans via milk. Seems strange only lambs would be infected. Edison (talk) 17:33, 9 April 2008 (UTC)

Timing of Chinese mantis ootheca hatching
I have found three four ootheca of the Chinese mantis (Tenodera aridifolia sinensis) in my neighborhood. How can I tell when they are going to hatch, so that I can hope to take pictures of the hatching process for Commons? I know precision is impossible, but the general seasonality, necessary precedent weather conditions, or other natural processes that preceed the hatching would be helpful. GRBerry 14:14, 8 April 2008 (UTC)
 * Hatching usually takes between 3 and 6 months. The young may hatch all at once or in batches over a period of several weeks. Another suggests hatching occurs spring/summer of the following year.  Julia Rossi (talk) 07:30, 10 April 2008 (UTC)
 * Precision flash – what would it be like to use a stethoscope to track the nymphs becoming active? The hardened ooth is just packaging for them. Borrow or make one and bobsyerunkl... Julia Rossi (talk) 10:25, 10 April 2008 (UTC)
 * The stethoscope is a good idea, and we already have one. I'll try it; hopefully the highway a couple roads away won't render it useless.  Hopefully with four now found I can also be alerted by the hatching of one to photograph the others.  GRBerry 13:52, 10 April 2008 (UTC)
 * It's a cool project. Maybe adapting industrial ear muffs, a biker helmet or wooly hat with turnup would give you a noise break. Awaiting the pics, Julia Rossi (talk) 23:17, 10 April 2008 (UTC)

Food intended as whose primary function is food
Just for the sake of my own personal edification (and morbid curiosity), I'm trying to come up with a list of foods humans eat whose primary biological function is to be food. The two obvious ones I can think of are milk and honey. Excluded from the list would be meat (whose primary biological purpose is to be the muscles and organs of the animal it comes from) and leafy vegetables (whose primary biological function is to enable photosynthesis). But I'm having trouble deciding on things like fruits, nuts, seeds, and eggs. On the one hand, you could say their primary biological function is reproduction, but all of them (I think) also contain material intended to supply energy (i.e. be food) for the growing seedling/embryo. So would these go on the list or not? And a lot of plants rely on birds to eat their fruit so that the seeds will be dispersed in the birds' excrement; so maybe one could say the primary function of (at least some) fruits is to be food for the birds that will be dispersing the seeds. And what about root vegetables like potatoes and carrots? Isn't the function of roots to store energy for the plant to use? And if so, doesn't that mean their function is basically to provide food for the plant? What do the rest of you think? —Angr If you've written a quality article... 14:22, 8 April 2008 (UTC)


 * Hmm, the minute you start saying that nature has an intent, it's murky. One could say that deer muscle is meant as food.. for lions.  The whole ecosystem evolved together, by necessity.  There are connections and dependencies everywhere.  Friday (talk) 14:25, 8 April 2008 (UTC)


 * I think most fruit, with some exceptions, have evolved to be eaten. That's why they're sweet and delicious. -- MacAddct &#xF8FF; 1984 (talk &#149; contribs) 14:28, 8 April 2008 (UTC)


 * They are not intended to be eaten. They are intended to provide a good growing environment for the seeds inside the fruit.  If we eat all of the fruit and never allow any to turn into new trees, then the old trees would eventually die and the fruit would no longer be available. --  k a i n a w &trade; 14:37, 8 April 2008 (UTC)


 * Oh really? My whole mindset of the purpose of fruit has been wrong all along! I was once told that it's so animals eat the fruit and spread the seeds around. -- MacAddct &#xF8FF; 1984 (talk &#149; contribs) 14:40, 8 April 2008 (UTC)
 * Hmm, the fruit article states: "The sweet flesh of many fruits is "deliberately" appealing to animals, so that the seeds held within are eaten and "unwittingly" carried away and deposited at a distance from the parent." -- MacAddct &#xF8FF; 1984 (talk &#149; contribs) 14:42, 8 April 2008 (UTC)


 * Most fruit has indeed evolved in such a way as to facilitate the dispersion of seeds. Take for example, the strawberry (technically an false berry, not a berry) - the red part is in fact not a seed, the seeds are the white/yellow little hard bits on the outside.  The part that we like to eat turns sweet and red when the seeds are ripe, causing the whole to be eaten, and the seeds defecated away from the parent plant.  Thus, to the extent that purpose is meaningful, all accessory fruits clearly have a sole function of being eaten by something, and most fruits humans eat have a, but not sole, function of enticing something to eat the fruit and disperse the seeds contained within, while the seeds contain their own energy stores.  Nuts, seeds, and eggs, on the other hand are generally intended to be the energy store for the embryo within - but oaks, for example, depend on acorn dispersal agents to move their seeds away from the parent, and thus must make acorns that are palatable to such animals as food in return for a few getting lost and becoming plants.  (Yes, acorns are also a human food.)  Modern corn has clearly evolved under human selection for edible seeds (compare Teosinte) ... as have most other human eaten crops.  So in that sense, most seed foods are also evolved to be eaten.  I'm not as sure of the balance among nuts, but suspect acorns may be representative here.  I'm not aware of any eggs that need dispersion by dispersion agents.  GRBerry 14:50, 8 April 2008 (UTC)


 * I can see that argument. It assumes that the seeds will still be viable when pooped out.  It also assumes the plants purposely evolved into a relationship where they cannot multiply on their own.  They require animals to eat the fruit.  Both are rather big assumptions.  In my opinion, the simpler explanation is better.  The plants provide a rich growing environment for their seeds - which animals have evolved to enjoy eating. --  k a i n a w &trade; 14:53, 8 April 2008 (UTC)


 * When you look at ecosystems from a low-level biological perspective, the amount of cross-dependency is really quite astounding.  So these may be big assumptions, but you find examples of this everywhere.  Forget reproduction- you and I could not even digest the food we eat, without the help of our gut fauna.  Friday (talk) 15:01, 8 April 2008 (UTC)


 * That's not necessarily true - there are studies with rats and mice which are kept free of microorganisms and are about as healthy as normal rats and mice. If you are isolated from microorganisms you would probably do well as long as you get all vitamins in sufficient quantity (I think vitamin K and biotin are synthesized by some common human gut bacteria). Note that cellulose is not degraded in normal human intestines - so it would probably not be a problem if a few additional polysaccharides are also not degraded (the degradation by bacteria happens primarily in the colon, so the human can hardly use any resulting monosaccharides; starch, on the other hand, is degraded by human enzymes). Icek (talk) 17:57, 8 April 2008 (UTC)


 * Seed predation, biological dispersal and seed survival rates are topics of scientific study. Here are a couple of papers with a decent online presence (to someone not subscribed to any journal or JSTOR or ....) that include all the terms "rainforest seed survival rate insect".  What happens to only partially eaten seeds Effect on mangroves A particular species.  I've seen elsewhere estimates that for rainforest seeds that end up under the parent, 0% of seed s survive insect predation, but that was probably a species specific study.  Similarly, insects living under an oak can kill more than 95% of those seeds that hit the ground under the tree and escape mammalian and avian predation.  On the other hand, an adult oak can live for centuries and produce hundreds of thousands of acorns, only a few of which need to live to become trees in order to keep the species going - in fact, on average, one tree needs to produce one child tree... so the needed surival rate is barely more than 0%, and might be hard to measure in a scientific study.  All plants are essentially high r, low K strategists, though some are higher r than others like the nut bearing trees.   GRBerry 15:18, 8 April 2008 (UTC)


 * Friday, I tried (not entirely successfully, I see) to avoid the words intend and intent and speak of the "primary function" instead. I think it's safe to speak of things in nature as having functions. Now it really does seem that many plants have evolved in such a way that their fruits are palatable to animals, in order that the seeds may be dispersed more efficiently and effectively. But that doesn't necessarily make it the case that the primary biological function of fruit is to be food for animals. On the other hand, it may well be the case that the primary biological function of fruit is to supply energy to the growing seed, which is the same thing as being "food" for the growing seed. —Angr If you've written a quality article... 16:27, 8 April 2008 (UTC)


 * According to GRBerry's comment, my understanding that the fruit provides a fertile growing area for the seed is incorrect. It actually causes insects to quickly devour the fruit (and seed).  If that is accepted, then the fruit is only viable as a method of getting seeds mixed into another fertilizer (animal feces) and dropped onto the ground.  But, claiming that this benefit is "indented" is what bothered me.  I do not see any form of evolution as the result of intent by a plant.  Also, if we accept that the function of the fruit being nice to eat is an intended function from the plant, then it is easy to argue that the reason animals taste nice is because they are intended to be eaten to kill off the weak animals, leaving the strong ones to reproduce. --  k a i n a w &trade; 16:34, 8 April 2008 (UTC)
 * With evolution, a particular function can't be considered to have evolved intentionally for to fill that role -- it was a process of selection that produced that phenotype. For example, many of the aforementioned fruits evolved from ancient plants that might have dispersed their seeds in another way, or a different animal.  As for tasty animals -- I doubt that a prey animal would have much selective pressure to be more tasty, since being preyed upon effectively ends the gene's ability to propagate.  The 'tastiness' is most likely the result of the evolution of the predator's sense of taste and preferences.  Taste is a way to determine the content and quality of food, so something tasty would provide the predator with much-needed nutrition. --  JSBillings  16:59, 8 April 2008 (UTC)
 * I agree that my use of the word "intended" in the title and question is something of a pathetic fallacy, so let's stick to "function". Now even that can be hard to define; things can have more than one function, and deciding which of them is the primary function is probably highly subjective. Maybe my question is unanswerable. I only asked because it recently occurred to me that milk is unique in being the only food "intended" (whatever that means) to be food. But then it immediately occurred to me that honey is also "intended" as food, so milk isn't unique after all. And then the more I thought about, the more I realized that an argument could be made for many other foods being "intended" as foods, and that's when it occurred to me that speaking of "intent" was complicating things and so maybe I should reformulate the question in terms of primary biological function. So I did, and I still think it's an interesting question, but I don't think there's ever going to be a definitive list of foods whose primary biological function is to be food such that everyone can agree that for any given foodstuff, that foodstuff unambiguously either does or does not belong on the list. —Angr If you've written a quality article... 17:01, 8 April 2008 (UTC)
 * Honey is a manufactured product (albeit by bees), so I think it could be cataloged as a food right along side of twinkies. Also, a lot of organisms that either are, or produce substances that are food have evolved, and their ecological niche is not static.  For example, mammary glands in mammals are believed to be adapted sweat glands.  You're going to have to specify your definition of 'food'.  --  JSBillings  17:34, 8 April 2008 (UTC)
 * Selective pressures should favor undelicious meat but this would lead to problems in overpopulation and the restoration of energy into the system. I would venture to hypothesize that there might be a sort of meta-darwinian selection that disfavors unbalanced ecosystems.  For instance, the fundamental niche of a species is limited in an ecosystem to its realized niche.  Our articles on niches attribute this to competition but that doesn't explain why species are, to my knowledge, not found outside their realized niche at all when competition would only restrict their appearance in niche overlap.  I might be espousing an aspect of the Gaia hypothesis. — Æµ§œš¹  [aɪm ˈfɻɛ̃ⁿdˡi]  19:02, 8 April 2008 (UTC)

Since our own bones and muscles store nutrients which may be used during famine, rather like tubers, and many animals recycle their skin, let's stick to foods whose function is to be eaten by another creature, excluding internal or attached symbionts: Definitely most fruits; some plants can hardly reproduce unless their seeds pass through an animals gut. Milk. Nectar (function is to attract pollinators). Aphid & scale honeydew. Hemolymph (many mother spiders let their young suck them dry—there are also other non-mammals that feed their young from their bodies after birth, though none come to mind at the moment). Beltian bodies. I'm sure there are lots more. kwami (talk) 21:52, 8 April 2008 (UTC)

Oops! Forgot that you were looking for human food. Nectar still counts, though it's extremely minor. I wouldn't count honey, since its function is to be food for bees, not us. Nuts neither—in most cases, at least, the primary function of a nut is as a seed, which is why so many are toxic (including almonds, before we domesticated them). kwami (talk) 22:24, 8 April 2008 (UTC)


 * Given that the function of genes is to make more copies of themselves, and given the wide prevalence of cattle on the planet, one could argue that the function of all parts of the cow, especially the tasty bits, is to further the species by being human food. The cow has responded to selection pressure and become docile and nutritious, thereby expanding its numbers far beyond what could be achieved by being nasty and stringy. So tenderloin counts as "primary biological function is to be eaten by humans" and the cows have done rather well at it, their burps are threatening the planetary envionment. Franamax (talk) 23:23, 8 April 2008 (UTC)
 * I'm starting to regret asking the question. Kwami, yes, honey definitely counts since (1) humans eat it and (2) its primary function is to be food for an organism different from the one producing it. And as far as I'm concerned cows don't count regardless of how much they've been genetically engineered to be tasty and nutritious. Nuts and seeds are out, since their primary function is to grow into new plants. Fruits are sort of a borderline case - their primary function from the plant's point of view is to serve as seed distribution mechanisms. To return to the convenient pathetic fallacy, the plant doesn't care about nourishing the animals eating the fruit, the plant cares about getting its seeds distributed, and takes advantage of animals' appetites to accomplish that goal. Eggs are also a borderline case - eggs can be considered the animal equivalent of a nut or seed, so their primary function is to grow into baby chicks (or whatever), but of course the contents of an egg are "intended" as food for the embryo. An unfertilized egg, while being tasty and nutritious for humans and weasels, is of no use whatever to the chicken, so from the chicken's POV it has no function at all. —Angr 05:51, 9 April 2008 (UTC)


 * I think you're right about potatoes and carrots and the like, they store energy (food) for the plant to use. But they are only part of the plant, so by the same logic one could consider animal fat to be perform the same function (it does keep the animal warm too though).--Shniken1 (talk) 07:03, 9 April 2008 (UTC)

Mirror
Maybe a silly question but... is the light reflected in a mirror the same light that fell on the mirror? To clarify, if a photon strikes a reflective surface, does it bounce off, or is it absorbed and a "new" photon emitted in it's place? Astronaut (talk) 14:41, 8 April 2008 (UTC)


 * Please see this archived question. -- Coneslayer (talk) 15:54, 8 April 2008 (UTC)

Black holes
I saw part of a documentary the other day about Stephen Hawking (maybe it was the same one as mentioned previously). In the part I saw, the documentary explained that throughout the universe particle/anti-particle pairs are spontaneously created and then anihilate a small fraction of a second later - presumably they are created from the conversion of dark energy - but near a black hole one particle can fall into the black hole and the other particle escapes. The thing that bothered me was the assumption that it is always the anti-particle that gets dragged into the black hole, giving the appearance of particles escaping from the black hole. Surely particles and anti-particles would be equally likely to escape the black hole, and then encounter each other and anihilate. So, do particles appear to escape from black holes (and I just missed the bit of the documantary which explained it fully), or do black holes absorb dark energy with no outward effect on the rest of the universe? Astronaut (talk) 15:19, 8 April 2008 (UTC)


 * There is no assumption that only particles (not anti-particles) survive. If the produced particles are photons, there is no issue, because the photon is its own antiparticle.  If other particles are produced, as you say, it could be the particle or its antiparticle, leading to annihilations.  These annihilations produce... photons.  Either way, the Hawking radiation is in the form of photons.  -- Coneslayer (talk) 15:51, 8 April 2008 (UTC)


 * It is worthy to note that there is by no measure consensus that Hawking radiation is the result of the quantum pair-creation process described above. In fact, there is a (mounting) evidence that Hawking radiation is a purely kinematic effect, which occurs in the absence of any quantum, or gravitational effects, as a direct result of horizon-formation in any medium in which signals propagate under a Lorentzian metric. This is the result of (groundbreaking) work on acoustic black-hole analogues. For further reference, please see various papers of Visser, et al, and references/co-citations therefrom. 153.1.253.5 (talk) 13:31, 14 April 2008 (UTC)

Pre Genus Species
Before science discovered flies were not the spawn of rotting meat, before they'd even classified the creatures with proper names, what did people identify flies as? Did they just call them "flies"? Beekone (talk) 17:38, 8 April 2008 (UTC)
 * Well, not "flies" per se -- that experiment in spontaneous generation was conducted in Italy, not in an English-speaking area. However, people did call flies by their common name in whatever the relevant language was, and have for thousands of years -- probably since language originated.  I'm not sure what other alternative there could be.  To take the housefly specifically, though, the scientific name -- musca domestica -- is the Latin for house (domestica) fly (musca). &mdash; Lomn 17:47, 8 April 2008 (UTC)
 * Cool, that's exactly what I was wondering about. Between all the differences in modern and old English maybe there was a term that had gotten lost, but if they just called them house flies or we can logically assume that they did that's exactly what I need.  Thank you! Beekone (talk) 20:29, 8 April 2008 (UTC)

DNA
please tell me what is the best proffesional text book about DNA
 * I don't know about the best, but here is a list of books about DNA D0762 (talk) 18:30, 8 April 2008 (UTC)
 * I doubt there is a 'best' If you are studying as part of a course, doesn't the course list a recommended text book or books? If it really doesn't try asking your course coordinator/professor for advice Nil Einne (talk) 07:43, 9 April 2008 (UTC)

gold from rock
What are the steps to get the gold out of the rocks. my friend gave me a rock from a mine and i want to learn to brake it up and get the gold --added by Cameron from WP:HD on behalf of 24.121.165.249.


 * We have an article on Gold extraction, but it should be noted that several of the listed methods are EXTREMELY dangerous and should not be tried at home. Just to stress that a little more -- enjoy the piece of ore you were given, don't try to extract the gold, it is way too risky.  -- LarryMac  | Talk  18:14, 8 April 2008 (UTC)


 * The traditional method used by the ancient Egyptians is to grind up the rock into fine powder (good luck!) and then wash or pan it in the traditional way. The gold particles sink while the rock dust washes away. No chemicals needed and should be 100% safe (just don't breathe the dust); have fun with this project! Jeff Dahl (Talk • contribs) 23:12, 8 April 2008 (UTC)


 * Also note that you may very well spend more money to extract the gold than the tiny amount of gold is actually worth. StuRat (talk) 16:14, 9 April 2008 (UTC)

unable to stop
Are there any animals that will eat until they pop? —Preceding unsigned comment added by Backscracher (talk • contribs) 18:26, 8 April 2008 (UTC)
 * Maybe, though it would seem unwise from a evolutionary point of view. D0762 (talk) 18:31, 8 April 2008 (UTC)


 * Surely your mother warned you not to overfeed the goldfish! -- Coneslayer (talk) 19:11, 8 April 2008 (UTC)


 * Mr Creosote?


 * Atlant (talk) 19:21, 8 April 2008 (UTC)


 * Domesticated animals often overeat, while wild animals rarely do because they have to work for each meal. They burn energy hunting or foraging for food, and do not have the luxury of an unlimited supply. Have a look at the obesity article, which covers humans as well as other mammals. As for if they would "pop", I don't know, but this picture seems to indicate they wouldn't. D0762 (talk) 19:32, 8 April 2008 (UTC)


 * Not "pop", but Argentine horned frogs will choke, it seems. --Elliskev 20:08, 8 April 2008 (UTC)

This doesn't exactly answer the question, but it's the only example that comes to my mind: If you see a mosquito biting you, you can restrain yourself from slapping it, and instead pinch your flesh around the mosquito. If you do this just right, you can force your blood into the insect so fast that it pops. A friend told me that he managed to get just enough into the mosquito that it popped as it attempted to fly away. ~Amatulić (talk) 23:55, 14 April 2008 (UTC)

noise only teens can hear?
There are some old people where I live and they are always complaining about the local yobs congregating around the library car park and being generally anti-social. Eventually our local council told them that a new system had been fitted called "mosquito" which wards off teenagers by emitting a high pitched sound, like a cat scarer does. I find it hard to believe that you can target teenagers specifically with such as device. Is the council lying to them?


 * The technology has been reported in the news before and is not supposed to be a hoax. See . --71.162.249.117 (talk) 18:32, 8 April 2008 (UTC)


 * ...and we have an article on The Mosquito. Obviously we can't tell whether your council really has fitted this device. Gandalf61 (talk) 18:34, 8 April 2008 (UTC)


 * Of course, you can't precisely target teenagers this way. Not all teenagers will hear the sound, and some non-teenagers will hear it.  As for whether there's a Mosquito installed at your library, I'd ask a teenager.  --Allen (talk) 20:33, 8 April 2008 (UTC)


 * And most children with their parents will hear it too. From what I recall, the device doesn't really achieve the desired result as well as, for example, playing loud classical music seems to. Entertainingly, you can get 'the Mosquito' as a ringtone, the theory being that the students can hear their phone ring without the teacher being alerted. In practice, many teachers and teaching assistants can hear it, as can many other students who get annoyed by this whining sound. 130.88.140.121 (talk) 11:47, 9 April 2008 (UTC)
 * Yes, while not a teen, I can still hear reasonably high frequency noises. When I first tested one of the ring tones, I thought people must be nuts to use that as their ringtone Nil Einne (talk) 13:21, 11 April 2008 (UTC)


 * They don't target teen's in particular. Its just an annoying sound that is played. If you are walking past you hadly notice, its only if you want to hang around and stand there that it gets on your nerves, this is the point, just like playing classical music. Teens don't hear any frequencies that adults and children don't.--155.144.40.31 (talk) 03:43, 10 April 2008 (UTC)
 * Barry Manilow's early hits seem to do the trick in some parts of Australia. He could be classed as a psychological biological weapon. Julia Rossi (talk) 07:13, 10 April 2008 (UTC)


 * Not true. The mosquito is specifically a higher frequency. As people age, they are less able to hear higher frequencies. On average, a teenager can hear higher frequencies than an adult. This is the point. Of course, younger children can also hear those frequencies, often more clearly than teenagers, but younger children don't get a say in stopping 'youths' hanging out. 130.88.140.121 (talk) 09:12, 10 April 2008 (UTC)


 * Indeed high frequencies are also used by some teens as a ringtone which their teachers and/or parents hopefully can't hear (of course some can). The Mosquito has some details Nil Einne (talk) 13:19, 11 April 2008 (UTC)

Something higher than 15 kHz will be irritating to teens and generally silent to adults. In fact, many students set their ringtones on their cellphone to this sound so they can text message in class without the teacher hearing their phone. Very sneaky. Ilikefood (talk) 23:18, 13 April 2008 (UTC)

Terminology question
As a humanities student poorly versed in anything resembling science, I'm having some difficulty interpreting the following sentence: "They express identical epizootiological patterns characterised by devastating dieback epizootics and panzootics when they infect susceptible unchallenged host populations."

In this context, what is meant by 'dieback' and 'unchallenged'? Many thanks in advance. Random Nonsense (talk) 20:11, 8 April 2008 (UTC)


 * I did some Googling and found the book you're reading. It looks like it this section may have been written in a hurry.  I can't even parse the grammar of the next sentence after the one you quote.  "Dieback" usually refers to plants or sessile animals, not mammals.  I guess it's being used here to mean "fatal".  "Unchallenged" does seem to have some meaning in the context of populations, based on Googling, but I don't know exactly what it means.  I would guess it means populations that haven't been exposed to a given disease before.  --Allen (talk) 20:48, 8 April 2008 (UTC)


 * True, the book could have done with some very serious copy-editing, but people writing about dead cows are few and far between, so I guess I'm stuck with it. :) Thanks for your help, that seems to make sense... Random Nonsense (talk) 21:17, 8 April 2008 (UTC)


 * Yes, the syntax is hopeless, but we can at least pick those two words from the mire. "Dieback" is a term from ecology: it referes to a population, not an individual. a plague can cause a dieback, meaning a population reduction. "Unchallenged host population" is a term from epidemiology. A population that has never been exposed to a pathogen is "unchallenged." Classic examples are The black plague in europe, syphilis in Europe, and measles among native Americans. In the sentence you quote, "suceptible" is redundant. A related term is "greenfield epidemic." -Arch dude (talk) 00:38, 9 April 2008 (UTC)


 * I don't agree that "unchallenged" and "susceptible" mean the same thing. Human populations which have never been exposed to smallpox but have been exposed to cowpox, and thus developed a smallpox immunity, would be one example.  They are "unchallenged" but not "susceptible", to smallpox.  For the reverse case, look at mad cow disease.  A population exposed to this may not develop an immunity, in which case they are not "unchallenged" but are "susceptible". StuRat (talk) 16:09, 9 April 2008 (UTC)

Gull behaviour
Today, whilst having a bite to eat in the town square, I observed a new (for me) piece of gull behaviour. As I sat on a bench eating my burger, I watched the local urban avifauna going about their business - the pigeons and starlings pecking around on the cobbles for scraps, a few gulls bathing, swimming and sleepily hanging around in the fountain. A pretty normal afternoon scene, as it goes - until one of the pigeons walked a little too close to the edge of the fountain pool and then turned its back, as though to walk back in the direction it came.

Quick as a flash, one particular Herring Gull snapped wide awake - and pounced. I've never seen a gull move like that before - it lowered its head, flattened its body to the water and elongated itself, then skimmed across the surface incredibly quickly (and presumably silently), covering the distance between itself and the pigeon in a couple of seconds. I don't think that the pigeon expected it either - the gull's beak closed around its neck from behind before it even had the chance to look around. The gull rolled a full 360, flipping the pigeon into the water without letting go of it and somehow ending up on top. Then it pushed its (the pigeon's) head underwater and held it there, driving with its wings as though to apply more force. The pigeon was struggling wildly but the gull's strength was far superior.

If some kids hadn't intervened at that moment and scared the gull away, I fully expect that it would've waited for the pigeon to drown before chowing down on the carcass. The sodden pigeon had a nasty-looking throat wound and struggled to fly after they'd pulled it from the water - so maybe the gull tracked it down later to finish the job?

So, has anyone ever seen a gull hunt like this before? The actions of this bird today reminded me of those crocodile vs. antelope encounters from wildlife documentaries on the Discovery Channel. There was definitely something crocadillian there about the way the gull submerged its head to eye level. --Kurt Shaped Box (talk) 21:10, 8 April 2008 (UTC)


 * These are dinosaurs with feathers, mind. If I am to speculate wildly (to entertain us both)) what you saw might have been a strange trace of ultra-carnivorous behaviour (and I kid you not, avian dinosaur has been made redirect to bird, I laughed like mad). 81.93.102.185 (talk) 21:35, 8 April 2008 (UTC)


 * I find it quite interesting that a gull understands the concept of 'death by drowning' - bearing in mind that gulls float like corks and that drowning a gull would be only slightly less difficult than drowning a fish. I definitely see the reptile in there when I watch magpies interacting with each other on the ground. They remind me of those quick little lizards that live in the desert (I think the long tail helps). --Kurt Shaped Box (talk) 21:48, 8 April 2008 (UTC)


 * Reminds me of the youtube video of the pelican snapping up a pigeon in the park. Gulls are carnivores, not just piscivores, but I thought the mostly raided nests for fledglings and pups. Maybe hunting is a bigger part of their life than we give them credit for. kwami (talk) 22:00, 8 April 2008 (UTC)


 * I just found this on YouTube (searched for 'gull hunting'). The bird in the video (towards the end) displays similar behaviour to the one I saw today, though 'my' gull was much lower in the water. I've seen large gulls killing rats and mice on occasion - by shaking them and bashing their heads against the ground. --Kurt Shaped Box (talk) 22:12, 8 April 2008 (UTC)


 * Perhaps the gull prey on smaller birds and drown them when they're above the sea? Imagine Reason (talk) 22:26, 8 April 2008 (UTC)


 * Aye - perhaps they deliberately try to knock them out of the air and into the drink? You ever see a gull's 'air crash' attack against a corvid or a bird of prey? --Kurt Shaped Box (talk) 00:40, 9 April 2008 (UTC)


 * I wish, not being a birder myself. Imagine Reason (talk) 03:36, 9 April 2008 (UTC)
 * Blimey! Killer gulls! An' all this time I thought gulls were only interested in my potato chips/french fries. aark! Julia Rossi (talk) 10:15, 9 April 2008 (UTC)


 * Aye, they'll happily scrounge off humans and scavenge our organic refuse - but one look at the shape of the beak should tell you what they were built to be capable of. This (right) is a wonderful image. For a first-hand demonstration of the ferocity of these birds, try approaching a female gull of the largest species you can find in your area when she's sitting on her eggs, maintaining unblinking eye contact at all time. If you're lucky, the rest of the gulls in the area might take a keen interest in you showing you what they've got too... :) --Kurt Shaped Box (talk) 23:15, 10 April 2008 (UTC)


 * Well, now you know. Don't say Kurt didn't warn you. Imagine Reason (talk) 17:53, 9 April 2008 (UTC)


 * Hitchcock warned us too. 206.252.74.48 (talk) 19:36, 9 April 2008 (UTC)


 * Anyone know if there's any truth to the legend that they fed vodka-soaked bread to the gulls in the final scene of The Birds in order to make them docile? There's quite a few semi-humourous stories about the making of that film - my favourite probably being the one about Hitchcock neglecting to tell Tippi Hedren that she was about to get a real, angry gull to the face as soon as the cameras started rolling - so that her reaction would appear 'authentic' on film... ;) --Kurt Shaped Box (talk) 23:24, 10 April 2008 (UTC)


 * That innocent cruisy impression they give needs rounding out in the article, maybe with a section on the dark side of gulls. That coot pic would do it, Julia Rossi (talk) 23:30, 10 April 2008 (UTC)


 * The problem here is (once again) finding references from reliable sources. The subject is covered in the Great Black-backed Gull article (where that image is used), however... --Kurt Shaped Box (talk) 20:20, 12 April 2008 (UTC)

I just saw a wildlife program on PBS that mentioned that gulls can kill tiny seal pops. Imagine Reason (talk) 01:44, 17 April 2008 (UTC)

Monogamy and health
Does monogamy have any known health drawbacks? Neon Merlin  22:04, 8 April 2008 (UTC)
 * Is there any reason why you think it might? Ignore for the moment that it is often not the best reproductive strategy. Imagine Reason (talk) 22:07, 8 April 2008 (UTC)


 * Sex is healthy, but sex with multiple partners carries a high risk of disease, so I'd think monogamy or near monogamy would be healthy. kwami (talk) 22:19, 8 April 2008 (UTC)


 * Enforced monogamy with a poor match can have psychological drawbacks, to say the least. --Captain Ref Desk (talk) 00:37, 9 April 2008 (UTC)


 * Well, if you're going to go there, then in a society which does not allow divorce, but does allow remarriage after the death of a spouse, you could get some very unhealthy results. kwami (talk) 07:32, 9 April 2008 (UTC)


 * "I've been searching all my life for the perfect wife whose execution would finally bring me happiness." - Homer Simpson as Henry VIII. StuRat (talk) 15:57, 9 April 2008 (UTC)


 * Do you know which episode that was from, i don't remember hearing it!--155.144.40.31 (talk) 03:37, 10 April 2008 (UTC)


 * Not specifically, but I think it was a Halloween episode. StuRat (talk) 04:08, 10 April 2008 (UTC)


 * It was Margical History Tour. But that doesn't answer my question. Neon  Merlin  18:36, 10 April 2008 (UTC)


 * As per CRDesk, the downside psychologically could result in chronic stress and its symptoms as well as magnesium deficiency. Julia Rossi (talk) 23:38, 10 April 2008 (UTC)

Distances in the Universe
How exactly do cosmologists determine how far away a star/galaxy etc is? It seems that if they're infering based on chemical composition, energy levels and brightness then they coulkd easily be wrong as stars could actually much brighter but further away or something similar. How accurate are the distances given between the Earth and stars? Are they debated within the field? 81.96.161.104 (talk) 22:44, 8 April 2008 (UTC)


 * See the article cosmic distance ladder for an explanation of methods used to measure stellar distances.


 * You might also want to look at the main sequence article. Stars fall into families with known compositions and luminosities.  If you know the spectral properties of a star, you know where it falls on the main sequence, so you know how much light it's putting out, and you can compare that with how bright it appears in our sky and from that get an idea of the distance.


 * Certain stars such as cepheid variable stars oscillate in brightness, and these have fairly well tight correlation between luminosity and periodicity. Thesehese stars, when found in other galaxies, can be used as a "brightness standard" to judge the distance to galaxies.


 * Further out, one can gauge distances to galaxies by looking at their red shift. ~Amatulić (talk) 22:58, 8 April 2008 (UTC)


 * But it should be noted that redshift tells us nothing about distance, only our relative speeds. Its up to other methods to determine expansion of the universe which combine to figure out the distance.--155.144.40.31 (talk) 03:36, 10 April 2008 (UTC)


 * Good question. There are fifteen to twenty interlocking methods, each applicable to a particular range of distances, and all underpinned by some heavy duty models of stellar evolution, cosmology and statistics. Here is a specific example showing how 8 different methods are used to estimate the distance to the Virgo cluster. There are uncertainties in these measurements, but notice that some of those uncertainty ranges are less than 10%, which is quite remarkable. Gandalf61 (talk) 15:00, 9 April 2008 (UTC)

Intelligence as something attractive
Disclaimer: This is not a personal question but personal advice will be appreciated.

Okay here it goes. There's a girl which I am attracted to. She's not that pretty but she extremely intelligent (she graduated suma cum laude) and is a very impressive public speaker. My question is, do males get attracted to intelligence as well or should we "ahem" get interested in the female anatomy only. Note that I'm a biologist first and a hopeless romantic later.

By the way how do we know if it is love or simply a stirring in the lower part of the male anatomy-- Lenticel ( talk ) 23:18, 8 April 2008 (UTC)


 * It's all about what fertility, procreation, and the survival of children into adulthood. Imagine Reason (talk) 23:20, 8 April 2008 (UTC)


 * It's also about picking the best mate for the continuation of the species, so if you see intelligence as positive thing to pass on to your children then maybe that could make you attracted to her. 81.96.161.104 (talk) 00:30, 9 April 2008 (UTC)


 * I subscribe to the view that no one reproduces for the good of the species. Insofar as their behavior improves the survival of the species, they are only demonstrating an evolutionarily stable strategy. The result here, of course, is the same--intelligence improves the chances a child will survive--but we must remember that others' children may be affected adversely as a result. At the very least, they are deprived for at least a while of the availability of the mother's good genes. Imagine Reason (talk) 01:10, 9 April 2008 (UTC)


 * Trying to use a reductionist approach to make sense of individual preferences is pretty hopeless. There's no good evolutionary explanation for, say, furries. It's easier to use psychological explanations. There are more things involved than simple natural selection when we are talking about human societies. On some level, James Joyce was, like all males in a species, just trying to procreate. But that fact doesn't illuminate his work at all, and doesn't distinguish between him and any other male in the species. --Captain Ref Desk (talk) 00:34, 9 April 2008 (UTC)


 * I disagree. I think it's the Stickleback fish that will mistake a red bottomed toy for a receptive female. Human fetishes may be a misfiring of our arousal mechanisms in the face of modern creations that remind us of something in prehistoric past. As for artistic ventures, the brain is obviously using some of its communications abilities. Imagine Reason (talk) 01:10, 9 April 2008 (UTC)


 * "Do males get attracted to intelligence"? Of course, some do. Some don't. It's hard to generalize human mating preferences. In practice I've found that most males cannot fathom a long term relationship with a female mate smarter than themselves, at least in the US.
 * As for love versus lust; it's an age old question. There's no easy answer. Except when it fails. Then you know. --Captain Ref Desk (talk) 00:34, 9 April 2008 (UTC)
 * I concur. Imagine Reason (talk) 01:15, 9 April 2008 (UTC)
 * Two things, on the one hand, maybe it's about selection and evolution: you're attracted to mental proficiency = success potential to enhance and promote the survival of your own genetic material. On the other, you value a powerful, confident mind. Lucky for you it's a girl as well. My observation is males like to be the smarter/stonger in a pairing – that could be an ego thing and/or an instinct to protect the family group. Julia Rossi (talk) 01:58, 9 April 2008 (UTC)
 * I think the problem is a two way street. It's probably true that the majority of males indeed have problems accepting a partner who is smarter then them but I would say it's equally true many females have problems accepting a (long term) partner who is not as smart as them. While I'm sure there's at least some biological component to this, I wouldn't over-emphasise it. Even in the modern world, there is still a strong culturally ingrained view that the male partner should be the smarter (and stronger) one. Nil Einne (talk) 07:57, 9 April 2008 (UTC)
 * Agreed. There's a big component of environment and cultural conditioning. The nice thing is when someone finds they're attracted, and it's mutual esteem, everything else (including judging) just fa-ades away. Julia Rossi (talk) 10:12, 9 April 2008 (UTC)
 * The problem I see here is trying to explain being attracted to intelligence from a evolutionary point of view. The main stumbling block is that the visual markers for intelligence aren't as pronounced as say a formidable bosom or a symmetrical face. I would tend to think that intelligence isn't something that one would be able to specifically select for in pre-historic times. Intelligence by itself though would enhance the ability for an individual of a species to thrive whereas others of the same species with a lesser intellect would not (as much). The result of this of course is an individual who is bigger/stronger and all around more healthy looking than other members of the species. However I would tend to believe that being attracted to an intelligent girl is more a result of the culture you grow up in and not so much any inborn genetic preference. PvT (talk) 10:52, 9 April 2008 (UTC)
 * Don't forget things don't have to have a direct effect to be selected for. For example, if the more intelligent human is able to find a better cave, build a better tool, find better food, decorate themselves better, win a fight against a stronger competitor or even simply be smarter in working out to to convince a potential mate to choose them, these may very well have a significant effect on mate choice Nil Einne (talk) 11:30, 9 April 2008 (UTC)
 * Or if intelligence is correlated with an ability to tell jokes, use wit, make music, etc so that the male can get the woman to have sex with him. Further reading on this approach can be found in Geoffrey Miller's The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature.--droptone (talk) 11:53, 9 April 2008 (UTC)
 * Curious how, despite the actual situation in the question, you manage to fall straight back into evolution being about man evolving to get women to to have sex with him. Oh that mighty hunter! Cultural programming is strong. 130.88.140.107 (talk) 18:26, 9 April 2008 (UTC)
 * My post was meant mainly as a response to the idea proposed by previous posters that questioned whether intelligence could be selected for in the realm of sexual attraction. Another issue is that I am not really interested in answering the original question which asked if males are attracted to intelligence in females (which has to be the case some of the time given the OP claimed that he was) and the next question about whether men should be attracted to intelligent females or merely to females' anatomy (which mixes normative questions with biological ones to which I (a) do not feel comfortable answering giving the complexity of those sorts of questions and (b) was unsure exactly what the OP meant in his normative use of "should").--droptone (talk) 11:59, 10 April 2008 (UTC)
 * That intelligence brings pleasure in this case is obviously a physiological event, which in turn was programmed for at least partially by genes alone. If beauty (aka symmetry) represents health while intelligence improves survivability, then there may be a stable trade-off between the two, and in a section of the population intelligence may be selected over physical attributes so long as the gain from a good brain overcomes the decline in health. Imagine Reason (talk) 18:05, 9 April 2008 (UTC)

Thanks to all for their explanations. At least I know now that there's a biological side in my preference for intelligence. Now I'm planning on how could I impress her with my intelligence. Well, I think that's beyond the scope of the reference desk.-- Lenticel ( talk ) 21:55, 9 April 2008 (UTC)


 * NLP. ; )  Julia Rossi (talk) 23:00, 9 April 2008 (UTC)
 * Breaking away to all the evolutionary psychology here, I believe I am attracted to intelligence simply because I couldn't bear to be with somebody I couldn't relate to. Mac Davis (talk) 23:11, 9 April 2008 (UTC)
 * Don't we all? Imagine Reason (talk) 02:05, 10 April 2008 (UTC)

If boosting your intelligence to make yourself attractive to her won't work, try chemistry. I don't think there is a link between body chemistry and intelligence, but there is a very real link between smell and attraction. This is on a level past Chanel no. X because smell (olfaction) here refers to the part your brain has somewhen in evolution given up communicating to the higher regions that recognize, identify and name the chemical info your nose provides. This goes straight to the "like that", "this is good" parts. Industry has tried to come up with the recipe for human pheromones in a bottle, but what's nice and compatible to one human is incompatible and repulsive to the next. All sorts of things get analyzed in this internal human lab for chemical analysis, like complimentary immune system, sexual availability and a host of other factors that the next generations of scientists will spend figuring out. The catch: there's very little apart from the usual advice of "diet and exercise" that you can do to change anything and no way of knowing what you've changed and what effect it's having. If she starts liking you and won't be able to say why, it might just be chemistry. Literally! --Lisa4edit (talk) 14:18, 13 April 2008 (UTC)