Wikipedia:Reference desk/Archives/Science/2009 March 23

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March 23

zero point energy questions

Hello

Apologies, I know you guys must get stupid questions like this alot, but I cant get a straight answer anywhere else. From this quote "A potentially promising area for research is the fact that if particles become more energetic as they are heated or accelerated their gravitational field increases. Changes in gravity can perhaps be attributed to a change in a spherical zpf energy density gradient surrounding an accelerated or decelerated massive particle." It seems to suggust that the zero point field can effect gravity, and the casimir effect moves objects, would it be possible , If we had better tech than we do now, to make a device that can manipulate zero point energy to move objects like the gravity gun if halflife 2 for example. I know this is stupid question but i cant get a strait answer from anyone about this, if not thats fine , if so thats fine too, if opinions are devided who current has the strongest case scientifically.

Thank you so much —Preceding unsigned comment added by 80.6.41.111 (talk) 00:37, 23 March 2009 (UTC)

The Casimir effect is a fairly weak force equivalent to van der Waals bond. It's potential energy must be very low and contribute very little to a measured mass. Its effect will be the greatest on the smallest scales, such as between nucleons. However this mass would already be measured when the mass of nuclei is determined, so there should not be lots of spare energy there for the taking. This force is what gives grease its strength. Graeme Bartlett (talk) 04:24, 23 March 2009 (UTC)

protonation of the alcohol group in 2-methylcyclohexanol

In order to protonate the OH group with phosphoric acid to weaken the C-(H)OH bond so a dehydration elimination reaction can occur to yield 1-methylcyclohexene, does this mixture need to be subjected to heat? At what stage of the mechanism for the elimination reaction is heat needed? John Riemann Soong (talk) 01:42, 23 March 2009 (UTC)

Heat probably doesn't affect the extent of protonation much. However, heat probably does promote loss of water because that is a fragmentation reaction, and increasing temperature makes this change in entropy an increasingly important part of the overall energy of the reaction. Heat also makes all reactions faster, so you'll be able to get out of lab in time for the next class:) DMacks (talk) 01:49, 23 March 2009 (UTC)

Well, I'm a bit confused by my lab manual. It seems to imply that the thermodynamic stability difference between 1-methylcyclohexene and 3-methycyclohexene is greater than the stability difference between 1-methylcyclohexene and 1-methylcyclohexanol. If I look at it a certain way, it almost seems that the 1-methylcyclohexene product is lower in energy than the alkane product! I'm wondering at what point the heat input is critical for what must be an endothermic reaction (reversal of saturation/addition of an alkane). And the protonation of the OH group appears to require the greatest activation energy in the reaction. I know heat aids in reactivity, but surely it can't be just that (as well as yes, the steam distillation of my product?) According to the energy diagram, the loss of the water molecule after the alcohol has been protonated is exothermic so heat would only appear to aid in speed of the fragmentation step. John Riemann Soong (talk) 02:15, 23 March 2009 (UTC)

If you have the actual energy diagram, then you know exactly where energy needs to be added to make the reaction go:) I assume that it is ΔG, so steps where ΔS changes are generally the ones that are the most affectable by T. You always need energy to get over the activation barrier, but once you have "at least that much", the equilibrium will always be establishable. And no matter what the role of heat may be in the chemistry or where each equilibrium lies, "removing the product as soon as it's formed" is going to drive an even fairly unfavorable (by product stability) reaction, thanks to Le Chatelier. Once you're steam-distilling the product out, that's all that really matters for accomplishing this reaction in practice. DMacks (talk) 02:29, 23 March 2009 (UTC)

I'm not sure if the diagram is being held at constant temperature though. Fragmentation generally would be exergonic yes? It wouldn't be that elevated temperature between the protonation and fragmentation steps allows fragmentation to proceed, e.g. s*dT exceeds a positive dH? I'm confused about energy flow -- e.g. whether the diagram includes the phosphoric acid in the system or not. The lab manual says the phosphoric acid "catalyses" the reaction so would it be that the H+ is what injects free energy into the system before the mixture is heated? Removing the product sounds really promising as a "drive" for the reaction, except I think the methylcyclohexanol is being distilled too (along with the aqueous components). Is this where volatility and vapor pressure would start to be important as well? I'm trying to finalise my understanding of this process. Thanks for all the help anyway! John Riemann Soong (talk) 05:19, 23 March 2009 (UTC)

Also, I note interestingly that methylcyclohexanol has a boiling point of 165-168 degrees Celsius. It's miscible with water, so it would probably form some kind of azeotrope and I'm correct to assume it wouldn't boil at significant amounts at 96 degrees Celsius compared with the methylcyclohexenes (bp 104-110)? John Riemann Soong (talk) 05:19, 23 March 2009 (UTC)

Folic acid

I'm currently working on a spoken version of folic acid. However, as I was going through it for a quick copyedit, I ran into a problem; the equation at the end of the section Biochemistry of DNA base and amino acid production seems, to me, to be nonsensical. I'm having difficulty determining what it's actually supposed to be. Is it wrong, or is it just my sight beginning to blur from too much editing? If someone could take a look at it, I would be much obliged. Thanks! Sophus Bie ^(talk) 10:00, 23 March 2009 (UTC)

I simplified the equation and added an image from Commons. Axl ¤ [Talk] 12:21, 23 March 2009 (UTC)

Thanks very much! Sophus Bie ^(talk) 01:23, 24 March 2009 (UTC)

Scaled Drawing

For my science class on a project, we have to draw a scaled drawing showing improvements we made to a windmill. How would I show that I made the turbines out of carbon fiber? <(^_^)> Pokegeek42 (talk) 13:13, 23 March 2009 (UTC)

By writing "carbon fibre" next to them. Technical drawings are often annotated to include information on construction materials and lots of other stuff. --Tango (talk) 13:23, 23 March 2009 (UTC)

Maybe you could copy (as in make a similar drawing not photocopy) a micrograph or show how the fiber reinforces the material [1]. Then compare to other materials and say why carbon fiber is better. or do s.th. like Crystal structure. You could also do a drawing of the windmill shaded with areas showing high strain and how your carbon fiber would be an improvement there. S.th. like this would be over the top. [2]. Just get some colored pencils and shade in a turbine image.76.97.245.5 (talk) 13:51, 23 March 2009 (UTC)

Tango's absolutely right. Use any method that makes your intention clear. I've recently been involved in a rather large construction project and, besides the sheer volume of drawings required, which is staggering, I've also noticed that formality tends to go out the window if there's a more clear way of expressing what you need to. Matt Deres (talk) 19:56, 23 March 2009 (UTC)

Given that this is a school project the prime target is to impress the teacher, not necessarily communicate with the reader. So something that shows a little effort will help. 76.97.245.5 (talk) 12:42, 24 March 2009 (UTC)

mirlodermabration

can microdermabration application cause purging ?70.216.81.127 (talk) 13:20, 23 March 2009 (UTC)

Did you mean Microdermabrasion? What do you think is being purged? 76.97.245.5 (talk) 14:01, 23 March 2009 (UTC)

Probably "purging of toxins". In this case, no, not to any significant degree. Also, it's a mistake to believe that we are all suffering from mysterious unnamed "toxins" in the first place. This is just a marketing scam. StuRat (talk) 15:53, 23 March 2009 (UTC)

Another possible interpretation is that they are asking if microdermabrasion can cause vomiting. I sure hope not. If so, I'd never do that again. StuRat (talk) 15:55, 23 March 2009 (UTC)

There is certainly a lot of crap out there about these 'toxins' and things you need to get rid of or deal with. Our bodies pretty much maintain themselves - there are very few things we need to do to it to allow it to keep functioning efficiently. The skin sheds cells very effectively without dermabrasion. Our kidneys filter out most kinds of routine toxins and flush them out when we pee. None of these silly treatments are needed for a normally functioning person. We'd never have survived all of those hundreds of thousands of years without these things if our bodies were really that pathetic. So eat sensibly - exercise moderately - bathe periodically - and you're doing about the best you can. SteveBaker (talk) 11:27, 24 March 2009 (UTC)

Part of this toxins scam is the claim that they are all a recent occurrence; chemicals created as part of our modern industrial world. In some parts of the world with dismal environment practices, this may actually be true. However, in the West, most of us don't absorb this level of toxins (except for smokers, perhaps). And, in any case, all of these "cures" that promise to remove the toxins are unable to remove a significant portion. StuRat (talk) 14:44, 24 March 2009 (UTC)

Monophyly of amphibians

Nowadays, the consensus is that amphibians form a monophiletic group. Nonetheless, in the past there was much debate over whether they were paraphyletic (i.e., amniotes descend from them). I have looked in Amphibian articles on Wikipedia and I have done google searches, but I haven't found much; does anybody know some place where I might find an in-depth discussion of the taxonomy of amphibans over the last few decades? Thank you. –Leptictidium (mt) 19:43, 23 March 2009 (UTC)

I doubt this is part of your problem but monophyletic is the correct spelling. Some of the references in this article may help. The American Museum of Natural History seemed to have overhauled its taxonomy system and googling this may lead to relevant information. This paper, THE AMPHIBIAN TREE OF LIFE, by the American Museum of Natural History seems to go over the various DNA tests, the reasoning for classification, and what changes they suggest in taxonomy. I would raid the sources and check out other works by the authors to look for more material on the topic. I found that paper by googling "Amphibian taxonomic philosophy" without the quotes. Sifaka ^talk 17:18, 24 March 2009 (UTC)

Expansion of Space

I have a hard time understanding what we mean when we say our universe is expanding. What exactly is expanding? Is it the distances between all cosmological objects? (Are these objects themselves expanding?) If it is, where is it expanding to? Where does this extra space come from? If I get it right, it is the space itself which is expanding. If it is so, is it expanding into its own dimension? I mean in 3 dimensions or something else is going on here. If we assume a hypothetical picture of seeing the universe from 4th dimension, we will see its edge. is this edge moving outside? If yes, what is this outside and what is this outside composed of? Please clarify. - DSachan (talk) 20:11, 23 March 2009 (UTC)

We have an article Metric expansion of space. Algebraist 20:13, 23 March 2009 (UTC)

Does that mean I have to go and learn the Metric system, now ? :-) StuRat (talk) 20:40, 23 March 2009 (UTC)

"What exactly is expanding?" pace itself is stretching

"Are these objects themselves expanding?" Objects that are gravitationally bound like galaxies and solar systems are not expanding. Larger objects like galaxy super clusters may still have some residual expansion but could possibly complete their gravitational 'colapse' in the future and become bound, after which the space within them would have stopped expanding (Only at a very large scale the universe can be considered to have a uniforme rate of expansion).

"If we assume a hypothetical picture of seeing the universe from 4th dimension, we will see its edge. is this edge moving outside?" There is no evidence that the universe has an 'edge'. Dauto (talk) 21:07, 23 March 2009 (UTC)

If you were to embed the universe in some 4D space, then there would be an edge - well, the whole thing would be edge, but it would still make sense to talk about it expanding into something that is outside it. General Relativity does not involve any higher dimensional space that the universe is contained in, but there are version of String Theory that do (see Brane cosmology). --Tango (talk) 22:15, 23 March 2009 (UTC)

Tango, it's not clear to me how would someone embed the universe in a 4D space when the universe itself is already 4D. Still, even if you embed the universe in a higher dimensional space it is istill improper to talk about the edge of the universe. Dauto (talk) 22:25, 23 March 2009 (UTC)

Ok, a 3+1 universe embedded in a 4+1 space. The OP was talking about just space, not spacetime, so I followed the same convention. --Tango (talk) 23:47, 23 March 2009 (UTC)

Those who claim to understand this concept often claim that the distance between objects in space expands, such as interstellar or interplanetary distance, but smaller distances, such as my meter stick, or some other measuring device, do not expand at all. This leads to the absurdity that two objects in space linked by a gossamer thread of great length would remain unaffected in their separation by the cosmic expansion, while two similar objects not linked by a gossamer thread would move apart, the hypothetical gossamer thread having a specified length but negligible tensile strength. This makes cosmic expansion a form of magic. Edison (talk) 03:07, 24 March 2009 (UTC)

It is important to understand that the cosmic expansion is governed through the Einstein GR equations that relate the behaviour of the space-time metric to the density and flux of energy and momentum. The universe has a uniforme distribution of matter on a very large scale and on that scale the expansion of the universe is uniform. But if you look closer, you will see that the universe has clumps of matter (Superclusters, Clusters, Galaxies, etc...). On those smaller scales, the space expansion is not uniforme. In fact, locally you might even have some shrinking. Inside a clump of matter that has virialised (achived an equilibrium) like galaxies, for instance, there is no space expansion (or shrinking) at all. So, the interplanetary and interstellar distances are not expanding, but the intergalactic distances are. A yardstick wouldn't expand even if it were on intergalactic space because it is an object bound by interatomic forces which govern it's size. The gossamer seems to be simple nonsense. Dauto (talk) 04:26, 24 March 2009 (UTC)

If I am in free fall orbiting the Earth, and I place two grains of sand 1 meter apart, will the space between those grains expand? I gather no because locally space does not expand? If I take more grains of sand, and place each one meter from the previous one, forming a line all the way to a distant galaxy with measurable redshift, will some of those grains move away from their previous neighbor? Such as those far away from significant concentrations of mass. Is it specifically the mass of galaxies which prevents expansion? 88.112.62.225 (talk) 06:12, 24 March 2009 (UTC)

Yes, that's correct. Within galaxy clusters the expansion has been halted by the gravitational effect of the mass within the cluster.The placement of the grains should be at rest with respect to the comoving coordinates. Dauto (talk) 01:05, 25 March 2009 (UTC)

So is there a "local space" where space does not expand, and when I go outwards, one meter a time (or even one nanometer at a time), suddenly one of those meters is outside the "local space" and that meter does expand? A sudden jump from zero expansion to non-zero expansion? I'm a bit startled by such non-linearities... 88.112.62.225 (talk) 20:51, 25 March 2009 (UTC)

Wren diet

Hi. I've got another bird question, this one about Thryothorus ludovicianus.

So, there's a mated pair of Carlina Wrens that frequent my backyard, foraging together. They're quite cute. Now, I read in our article that: "They eat insects, found in leaf litter or on tree trunks; they may also eat small lizards or tree frogs. In winter, they occasionally eat seeds, berries, and other small fruits." This doesn't quite agree with my observation.

Both of them come to my feeder, in which I've got a variety of seeds and nuts, and also a container of delicious mealworms on top. The smaller member of the pair eats only mealworms, never nuts, and the larger eats only seeds and nuts, never mealworms. Sometimes the larger one will bring the smaller one a bite of peanut, and pass it between their beaks, but it just ends up getting passed back, and the smaller wren goes back for more yummy beetle larvae.

Does anyone know what's going on there? I wonder if the smaller one is the female, loading up on bugs to feed to some chicks back at home? Why is the other one (male?) an apparent vegetarian? -GTBacchus^(talk) 20:51, 23 March 2009 (UTC) They are not nearly as "nice as 1 might think. Besides monopoloizing as many nest cavities as possible (let's not even go into monogamy and cuckoldry in small birds)They also have been known to pierce the eggs of thier nieghbouring insect eaters just before thier own hatch! As an aside, just look at the bill of any bird and it will tell a great deal about how it makes a living. The Ojib word for wren translates as "little bignose", just right for probing to find protein rich insects, not so good for seeds tho? As to what your pair are upto with thier diet choice, I suspect the below to be correct but I can't know for sure. I'm not a wren, i'm a FROG. 67.193.179.241 (talk) 12:38, 24 March 2009 (UTC) Rana sylvatica.

Could the female be preggers ? And does that alter their diets like in human women (to provide nutrients needed to grow the offspring) ? StuRat (talk) 21:19, 23 March 2009 (UTC)

Given the season, that makes a bit of sense. I'm not actually sure which one is female, or whether peanuts or bugs make better food for pregnant wrens. -GTBacchus^(talk) 21:26, 23 March 2009 (UTC)

It could just be that your feeder is the easiest food source and the wrens are taking advantage of it. If your feeder contained lizards and insects, it would be spot on! Livewireo (talk) 15:38, 24 March 2009 (UTC)

Wolves, dogs and foxes

Wolves, dogs and foxes are all of the same family (canine) and give birth to cubs, pups and kits (respectively). Lions and bears also have cubs (but are not of the same family as the aforementioned canines nor of each other - not to mention that the latter adults are boars and sows but not related to pigs). Seals have pups (but are not related to canines). Where is the logic in how offspring are named? —Preceding unsigned comment added by 69.77.185.91 (talk) 21:51, 23 March 2009 (UTC)

As far as I am aware, there is no logic to it whatsoever. Even less logical are the names for groups of a certain animal. --Tango (talk) 22:07, 23 March 2009 (UTC)

Actually, seals (and bears) are more closely related to canines than any of them is to felines. See Caniformia. -GTBacchus^(talk) 22:38, 23 March 2009 (UTC)

May be the people at the Language desk will be able to explain that? Dauto (talk) 22:51, 23 March 2009 (UTC)

Bears are in the canine family too, (im pretty sure). —Preceding unsigned comment added by 84.66.48.29 (talk) 10:49, 25 March 2009 (UTC)

Windmill Turbines

For a 300 foot high windmill, how big would the turbines be? I need to know how much carbon fiber material would be needed to make them. <(^_^)> Pokegeek42 (talk) 22:18, 23 March 2009 (UTC)

I think you need to try other research methods for this project than asking us everything... I'm sure the rough technical specs for some wind turbines are available online - try Google. --Tango (talk) 22:21, 23 March 2009 (UTC)

My search engines suck-all they give me is porn. My group members don't help either, they just claim their computers had a "virus" and nothing worked. I have no life anyway-this is the only human interaction I get. Mostly I ask you because I'm lonely. Seriously, do you think a total nerd has many friends? I read manga in japanese, for crying out loud. Cut me a break. I need some social time. When I'm not playing video games or reading manga or watching anime...actually, I don't do anything besides that. God, I need a life. <(^_^)> Pokegeek42 (talk) 22:29, 23 March 2009 (UTC)

I need to get your search engine, mine just keeps giving me pics of cats. :-) StuRat (talk) 22:39, 23 March 2009 (UTC)

Try googling for "wind turbine specs", I don't you'll just much porn from that (give or take Rule 34!). I'm sorry to hear that you are lonely - there are plenty of people that share your manga and anime obsession, why don't you see if you can find a local anime society where you can meet up with people and watch anime together? (Such societies certainly exist at most universities, I expect you can find them in the real world as well - although I warn you, the kind of people that are members are often pretty... um... intense.) --Tango (talk) 23:44, 23 March 2009 (UTC)

Intense... er, as opposed to the kind of people one is likely to meet here? - Eron^Talk 23:48, 23 March 2009 (UTC)

I'm always surprised at Wikipedia meetups by how normal everyone is. I've never heard anyone describe an AnimeSoc member as "normal"! --Tango (talk) 00:37, 24 March 2009 (UTC)

I wish I could join something like that, but I'm too "young" in my mom's opinion. I haven't finished sixth grade yet. If I joined something like that, my parents would think I'm like, totally emo and trying to commit suicide. Can you say "paranoid"? Thanks for the help, anyway. <(^_^)> Pokegeek42 (talk) 19:16, 24 March 2009 (UTC)

Perhaps you could find an anime fan, a little older than you, that is (or, at least, does a good impression of being!) pretty normal. Your parents may then be more inclined to allow you to go to anime meetings with that person. (There are normal anime fans out there if you look for them!) --Tango (talk) 20:21, 25 March 2009 (UTC)

The good news is that considering your age, you will probably not be expected to provide an in depth stress analysis using finite-element methods. 65.121.141.34 (talk) 20:39, 24 March 2009 (UTC)

What?? <(^_^)> Pokegeek42 (talk) 19:54, 25 March 2009 (UTC)

The anon is saying you won't be expected to do advanced engineering with your 6th grade project. (Too advanced for me, anyway - I have no idea what a finite-element method is!) --Tango (talk) 20:21, 25 March 2009 (UTC)

ammonium nitrate

If you were to heat up ammonium nitrate(safely) and send the resulting gasses through water...would it make nitric acid?? —Preceding unsigned comment added by 76.14.124.175 (talk) 23:22, 23 March 2009 (UTC)

Once you dissolved the resultant gases in water, you would regenerate the ammonium and nitrate ions, which would just give you a solution of ammonium nitrate back again. What you would need to do is to have some way to seperate the nitrogen oxides from the ammonia gas in the gas phase before dissolving them into water individually. --Jayron32.talk.contribs 00:36, 24 March 2009 (UTC)

Are you sure about that, I expected that water and nitrous oxide (N₂O) are produced, do they react with each other? Graeme Bartlett (talk) 20:30, 24 March 2009 (UTC)

Actually, I expect three products from heating ammonium nitrate: ammonia gas, water vapor, and Dinitrogen pentoxide (which is NOT nitrous oxide). Ammonia + water = ammonium hydroxide. Dinitrogen pentoxide + water = nitric acid. Unless you seperate these gases, the ammonium hydroxide and nitric acid, both dissolved in the same water, will just give you ammonium nitrate back again... --Jayron32.talk.contribs 02:23, 25 March 2009 (UTC)