Wikipedia:Reference desk/Archives/Science/2013 June 19

Science desk
< June 18	<< May | June | Jul >>	June 20 >

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

June 19

The psychology of flirting between men and women

Can anyone help me learn the basic instinct behind the actions men and women reflexively take when trying to attract each other? Out of all the junk Google spews at me whenever I try to research the subject I got one good link from one site that took me to another website that said, for example, that women try to make themselves appear smaller when flirting with a man and men try to make themselves appear bigger when flirting with a woman. This sounds interesting, like animal behavior. I'd like to learn the "Why" behind these primal? instincts within us ("Women try to make themselves appear smaller BECAUSE thousands of years ago...") as well as see a list of actions that men and women take when flirting with each other. I don't care about trivial modern stuff like "Women should wear red!" and "Men, don't wear too much cologne!" I'm trying to explore the basic or primal instincts in our brains that's left over from ancient times. — Preceding unsigned comment added by 174.65.51.113 (talk) 00:39, 19 June 2013 (UTC)

Have you tried Google Scholar instead of regular Google? It does a good job of seperating the wheat from the chaff. Select the "More" option at the top, then select "Even more" from that menu, and page down, there's a "Scholar" option on the next page. That's usually a good way to seek actual research and scholarly papers on topics. --Jayron32 01:11, 19 June 2013 (UTC)

The "Women should wear red!" thing is not trivial modern stuff. Dauto (talk) 03:25, 19 June 2013 (UTC)

Flirting is like foreplay. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:39, 19 June 2013 (UTC)

if a neutrino goes on a bullseye towards a nucleus will it usually pass right thru?

Or will the weak force interaction that I've read about probably occur? 2. Same questions for a neutrino on bullseye toward and into a lone proton. Will it usually just go past those 3 little quarks inside the proton like Road Runner or will it more likely interact? Thanks76.218.104.120 (talk) 05:16, 19 June 2013 (UTC)

Straight through most of the time. Some relevant detail in neutrino and neutrino detector. Dragons flight (talk) 05:33, 19 June 2013 (UTC)

One issue is the uncertainty principle meas that you don't know where that neutrino is or what path it follows. Graeme Bartlett (talk) 21:54, 19 June 2013 (UTC)

Searching for Jimmy Hoffa...

(For those of you not familiar with the case, Jimmy Hoffa was the head of the Teamsters Union who apparently was murdered by the Mafia in Detroit and buried in an unknown location, and they try to find him by digging up some new place every few years.)

My question is, in the latest excavation, they brought in a cadaver dog to sniff him out. Now, the remains of somebody dead for decades can't stink of decomp any more, right (at least in normal circumstances) ? So would the dogs do any good ? StuRat (talk) 06:29, 19 June 2013 (UTC)

According to [1] some dogs can still detect dry bones 30 years after death. Dragons flight (talk) 06:54, 19 June 2013 (UTC)

Just as importantly, they're a "possible benefit, no downside" option. Dogs have extremely sensitive noses, so even an insignificantly small amount of "fresh" material might still register with them. And if it doesn't, you're no worse off than otherwise. Matt Deres (talk) 16:37, 19 June 2013 (UTC)

% [Where is Jimmy Hoffa?

Missing ]. Tevildo (talk) 21:33, 19 June 2013 (UTC)

Perhaps Amelia Earhart flew him to a secret rendezvous in Shangri La with Judge Crater and D. B. Cooper. Edison (talk) 22:55, 19 June 2013 (UTC)

Someone once postulated a town called Craterville, named for the judge, to which every missing person since then would turn up. And probably all those missing socks from your dryer. Shangri-La works even better. ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:17, 20 June 2013 (UTC)

Trace element changing the properties of a whole substance

How can it be that, if you mix less than 100 parts per million of some trace element into a substance, it changes the properties (melting point, for example) of a whole substance? Why isn't this trace element insignificant? OsmanRF34 (talk) 13:34, 19 June 2013 (UTC)

That's because the property of a substance is not a democracy where every atom votes and whoever wins, caries the day. Look for instance at Doping (semiconductor). The trace elements provides electrons (and holes) that work as charge carriers. That drastically change the properties of the substance. Dauto (talk) 14:26, 19 June 2013 (UTC)

100 ppm is one part in 10000. Note the potential effect of a 10 g bullet or 10 g of Botulinum toxin (talk of overkill!) on a 100 kg human. --Stephan Schulz (talk) 15:55, 19 June 2013 (UTC)

That's a bad analogy - a human is a complex machine, not an homogenous substance. AlexTiefling (talk) 16:55, 19 June 2013 (UTC)

Indeed, and it's not the bullet that kills, but the energy of it, applied to the wrong place. You could also say that a little bit of sand changes completely the properties of a gear. OsmanRF34 (talk) 17:55, 19 June 2013 (UTC)

Ok, maybe Stephan's analogies are not the best, but your sand/gear one is pretty good! As Dauto says, bulk properties of a substance are not a democracy. In this case, a little bit of sand can make a gearbox freeze, even though there isn't much sand by weight. It's how the trace constituent interacts with the bulk that's important. That being said, you might get better, more physical/chemical answers if you tell us what specific systems or materials you're thinking of. We can't give a one-size-fits-all explanation for the effects of trace elements in bulk substances -- some trace elements have negligible effects, while others can have large effects. Here's another analogy that you might like better: reinforced concrete. The rebar is a small part of the total mass, but radically changes the tensile strength and ductility. In that case, humans need to organize the geometry of the rebar, but in materials, chemistry can conspire to set the patterning on its own. SemanticMantis (talk) 18:22, 19 June 2013 (UTC)

OK, imagine you have some wood and you mixture a trace of iron. It's hardness won't change much. But in other contexts, it's the trace that determines a higher hardness. Provided that no atom can bind to thousand of atoms, and that the relation of trace/substance is 1/several thousands, then, how can it happen? OsmanRF34 (talk) 19:09, 19 June 2013 (UTC)

You may be thinking about alloys. In this case, the mechanical properties of the material depend very much on the crystal structure of the material. Even a small amount of different material may either disrupt crystal formation or serve as a nucleus for the same, and hence lead to a different structure of the material. Imagine a square densely packed full of marbles in a regular structure. If only one of them is bigger, very many other marbles will have to move somewhat out of alignment to accomodate it. --Stephan Schulz (talk) 19:30, 19 June 2013 (UTC)

(EC, saying similar to Stephan above) I'm no materials scientist, but have a look at steel. Small amounts of carbon prevent flaws in the iron crystal lattice from forming, and thereby make steel harder than iron. I can't explain why from a chemistry perspective, but maybe somebody here can. What I understand more generally is that the crystal lattice is a higher-order structure, and a few atoms here and there can cause the lattice to have a very different structure. You might like the pictures at dislocation. From a more geometrical perspective, you may enjoy reading Tiling_by_regular_polygons#Archimedean.2C_uniform_or_semiregular_tilings. Consider that there is only one way to tile with squares, and only one way to tile with hexagons. BUT-- if you mix in a few small triangles, there are many tilings available, and each will have different structural properties. Atoms in materials aren't exactly like geometrical tilings, but the the lattice structures of compounds do strongly affect bulk material properties. Hope that helps, SemanticMantis (talk) 19:36, 19 June 2013 (UTC)

One of the weirder instances is Technetium - according to our article 55 ppm of one of its compounds will protect steel from corrosion. Pity that no non-radioactive nuclear isomer has yet been discovered ... Wnt (talk) 22:34, 19 June 2013 (UTC)

And never will... Dauto (talk) 15:41, 20 June 2013 (UTC)

Do you actually know that all the nuclear isomers are known, or that the undiscovered ones are less stable? Wnt (talk) 17:53, 20 June 2013 (UTC)

No to the first question and yes to the second. Note that the halflife of the most stable isotope is over a million years. Dauto (talk) 22:00, 20 June 2013 (UTC)

The thing is, sometimes the "m" isotopes are more stable than the lighter ones. So how do you know there isn't a super-m isotope? (True, it would have to something not made in supernovas, but surely there must be some things they don't make...) Wnt (talk) 15:47, 21 June 2013 (UTC)

Actin Protein

Hello, I have read in the article http://en.wikipedia.org/wiki/Actin that Actin is not found in nematode's sperm,can u please give refference to thi. I shall be very thankful, — Preceding unsigned comment added by 182.185.192.49 (talk) 14:03, 19 June 2013 (UTC)

Unfortunately the editor who added that fact did not provide a reference, but a search of Google Scholar for "actin nematode sperm" finds plenty of them. The paper that apparently first established this fact is PMID 7199049. Looie496 (talk) 15:17, 19 June 2013 (UTC)

Two related questions about lightning

It's a commonly believed factoid that either one lightning bolt, or one lightning storm delivers enough energy to power a major city for some impressive length of time.

Is this factoid anywhere near true? The article on lightning estimates a single bolt at half a gigajoule, which is a good amount of energy, but a major city would burn through that in moments.

The second half of the commonly believed factoid is that (Even though lightning will supposedly power a major city) there's no way to capture this energy, because it's delivered too fast.

To me, this doesn't ring true either. Project Gnome would have captured massive amounts of instantaneous energy for later use, and recreating it on the smaller scale of a lightning bolt doesn't seem impossible at all. In fact, it seems like it would be quite easy if the energy involved made it worth doing. (The Lightning rod of a tall building could be directed through a tall cylinder of material that could melt and store the heat energy long enough for it to be exploited.)

So my questions is, are either of these common factoids true? 75.69.10.209 (talk) 18:54, 19 June 2013 (UTC)

A quick googling suggests a five megajoule lightning strike could power a household for a month.

If we have a city of 2.5 million households, we would need 2.5 million lightning strikes a month. Which happens to be one strike per second, 24 hours a day, seven days a week, every day of the month, all year around. BOOM ...one second... BOOM ...one second... BOOM - all the time, from the moment you are born, to the day you die (probably due to being hit by lightning.)

This seems a rather implausible climate. If you have this kind of weather every day forever and ever, rather than worrying about your electric bill, move the hell out!

(Also see harvesting lightning energy.) 88.112.41.6 (talk) 19:35, 19 June 2013 (UTC)

Generally speaking, energy is more useful when it is released quickly, because we can always slow it down to the level we want. Speeding up its release on the other hand is more difficult. A good example is a pile driver. You put energy into it by raising it, but that slow release of energy into raising it wouldn't be enough to drive anything into the ground. The quick release of dropping the thing does the job though. 39.214.158.84 (talk) 22:28, 19 June 2013 (UTC)

5 MJ converts to about 1400 W hours; that would run my house for about an hour, not a month. Atlant (talk) 23:30, 20 June 2013 (UTC)

If you built a machine with a lightning rod to carry energy from a lightning strike down to an insulated chamber where the current melted metal or heated some phase-change substance, and then a heat exchanger used the stored heat energy to boil some working fluid and run a turbine or other engine coupled to a generator, you could produce energy until the heat reservoir cooled off. It sounds like an expensive machine, since the conductor would have to be strong enough to withstand huge mechanical forces, and insulated to a high level, not to mention the heat storage, turbine, generator, and utility interface. How would you arrange for the lightning to strike it frequently enough to operate it efficiently? I cannot imagine it would be cost effective to install such a machine on every hill, mountain top and tall building in a region, and then wait for the monthly lightning bolt. It would be like a wind generator waiting for the monthly gust of wind, or a solar panel waiting for the monthly hour of full sun. Ben Franklin built a machine which had a lightning rod (his invention) which charged a metal ball, which was then attracted to a grounded bell, with the cycle repeating. It probably generated milliwatts of energy several times a year for a few minutes, but it sounds more cost effective than the proposal, though at the risk of burning down the house. Edison (talk) 22:48, 19 June 2013 (UTC)

Though, if you were in one of the gas giant's atmospheres, it would work perfectly. The lightning strike density is so high in the lower levels, that you can read by the perpetual glow. Plasmic Physics (talk) 07:03, 20 June 2013 (UTC)

Evolutionary advantage of food allergies

Are there any evolutionary advantages of being allergic to specific foodstuffs? Horatio Snickers (talk) 21:26, 19 June 2013 (UTC)

Allergies are an over-reaction of the immune system, so I guess you could say one advantage is having an immune system. 39.214.158.84 (talk) 22:22, 19 June 2013 (UTC)

That a trait exists is not evidence of evolutionary advantage. It is merely evidence that it is not enough of a disadvantage to prevent the trait from being passed on. For example, if we go back hundreds of thousands of years in human history; and come upon a population of humans that develops a genetic predisposition to a peanut allergy, but also that population is never exposed to peanuts, it will never affect them, and the gene will get distributed until modern times, when modern food distribution systems allow peanuts to reach people with that genetic predisposition to the allergy. There's nothing advantageous about the gene, it's just that there was nothing disadvantageous to stop the spread of the gene, at least until modern times, and today there is still not much of a disadvantage, given modern medicine's ability to treat it, and people's ability to consciously choose to avoid the allergan. But the ultimate point is that not every single trait in the world represents an evolutionary advantage, and that a trait exists is not evidence that it is good for anything. See Mutation#By effect on fitness which briefly notes several types of mutations, such as "neutral mutations", which do not have deleterious effects on a population. --Jayron32 00:55, 20 June 2013 (UTC)

There are two other possibilities worth mentioned. 1) It's possible that everyone has the genes for a certain trait, but that the phenotype has incomplete penetrance. That is, everyone can get peanut allergies, but not everyone does. There is probably a genetic component to peanut allergies (see this twin study), though, so maybe that's not the case. 2) It's possible that a certain trait did not exist until recently, even though the genes that give rise to the trait are ancient. Following the hygiene hypothesis, we would say that throughout human evolutionary history, almost no one had peanut allergy, or any allergies for that matter. Rather, such a trait only arose in recently due to the change in our environment, which is why it was not selected out of the species. Someguy1221 (talk) 01:05, 20 June 2013 (UTC)

I don't think they have any advantage, it's just a defect. In the US at least, the cashews would say on the package something like "Packaged at a facility which also processes peanuts and other tree nuts" or simple "May contain peanuts". This is the clue that there may be cross-contamination. In some cases, it's just certain components of the food to which the person is allergic, like lactose in milk. Such people can have lactose-free milk or some other substitute, like almond milk. In extreme cases, such people would be advised to avoid all pre-packaged foods, restaurant meals, and meals prepared by others. Instead, they should buy all the raw ingredients and prepare meals from scratch. While this is a lot of effort, it's also what we should probably all be doing, to avoid all the unhealthy additives in everything we eat. StuRat (talk) 20:07, 18 June 2013 (UTC)

Milk allergy has nothing to do with lactose. The IgE antibodies are directed against milk proteins. See Lactose intolerance and the IUIS web page on milk allergens [2]. --NorwegianBlue ^talk 20:00, 20 June 2013 (UTC)

Our article on Food allergy doesn't seem to have anything about it that I can see. There may be advantages even for just eating food never mind the immune system for all I know, after all putting petrol into a diesel car can destroy the engine, Is a diesel car that can happily use petrol really a better diesel car? Peanuts grow underground rather than in the trees so there would not be a reason even for our distant ape ancestors to gain immunity from anything in them. Dmcq (talk) 11:16, 20 June 2013 (UTC)

• Here's the closest I can find, in the discussion section of this Science article, titled "Immunity, Inflammation, and Allergy in the Gut" [3], DOI: 10.1126/science.1106442

“ In the evolutionary battle against infectious disease, the immune system cannot afford to err on the side of caution, because failure to mount effective and vigorous immune responses will be exploited by pathogens. This is best exemplified by celiac disease, in which the high prevalence of HLA-DQ2 in the general population suggests an evolutionary advantage of this allele against infection, even in the face of the negative effects of the coincidental affinity of gluten peptides for HLA-DQ2 to cause celiac disease. ”

(emphasis mine )It is unclear to me whether scientists consider celiac disease to be a food allergy, but our article wheat allergy says there are similar proteins involved. The article is honestly a bit over my head, but it also discusses the role of that allele in food allergies. Anyway, I know it's a stretch, there it is. SemanticMantis (talk) 16:29, 20 June 2013 (UTC)

Whether celiac disease is an allergy or not, depends on which definition of "allergy" you use. It is an allergy in the sense of "a reaction of your immune system to something that does not bother most other people" [4]. It is not an allergy in the more restricted sense of our allergy article, which only discusses type I hypersensitivity reactions according to the Coombs and Gell classification. --NorwegianBlue ^talk 20:00, 20 June 2013 (UTC)

It is difficult to imagine an evolutionary advantage of being intolerant to otherwise nutritional food. There is, however, an evolutionary advantage in having the Immunoglobulin E mediated responses that cause allergies. Our article mentions defense against intestinal parasites, possibly also protozoa. Food allergy is increasing rapidly (PMID 23578298), and is probably a recent disease. The hygiene hypothesis that others have mentioned, is a plausible explanation of the increase. We know that hay fever, also IgE-mediated, is a recent disease. It was first described by John Bostock in 1819, and at the time it appeared to affect only the middle and upper classes of society, consistent with the hygiene hypothesis. --NorwegianBlue ^talk 20:51, 20 June 2013 (UTC)

There is one classic example of the situation that you find difficult to imagine.

Lactose intolerance is the norm for adult mammals - because you want babies to wean themselves off of mother's milk before the next litter is born. For most mammals, lactose intolerance is "being intolerant to otherwise nutritional food" - and it's a clear evolutionary advantage for them.

Humans evolved to have tolerance for lactose into adulthood soon after starting to farm dairy animals because the benefits of being able to consume milk products gave better survival rates than the benefits of lactose intolerance could provide. But that was thousands of years ago. In the meantime, we've kinda progressed past the point where either tolerance or intolerance of lactose makes any difference to reproductive success - so we've gotten "stuck" with some part of the population having the lactose-tolerance mutation - and others not. SteveBaker (talk) 02:11, 21 June 2013 (UTC)

Strictly speaking, lactose intolerance is nothing like an allergy. It does not lead to a histamine response or any other immune response at all. It's a digestive issue with no immune issues at all. It's the same sort of digestive intolerance that leads to the "bean reaction" whereby undigested sugars pass into the colon and feed the gut flora there. Many foods lead to such reactions, but milk products (in the absence of lactase) are particularly severe. --Jayron32 02:20, 21 June 2013 (UTC)

Although food allergies have doubled in the last twenty years, it is not a recent disease according to this source http://www.allergyclinic.co.nz/guides/39.html. --Modocc (talk) 03:59, 21 June 2013 (UTC)

There is an article published in Nature http://www.nature.com/nature/journal/v484/n7395/full/nature11047.html that hypothesizes that "allergic hypersensitivity evolved to elicit anticipatory responses and to promote avoidance of suboptimal environments." --Modocc (talk) 03:18, 21 June 2013 (UTC)

Neutron stars and black holes inside

Could a neutron star have many tiny black holes being constantly created and rapidly evaporating especially deeper inside? Or from impacts of incoming stuff at the surface? For neutron stars that are near the upper mass limit especially. Thanks.Rich (talk) 22:54, 19 June 2013 (UTC)

The weird thing about black holes is that the bigger they are the less dense they need to be. A very large supermassive black hole can actually be less dense than ordinary air. [5] So just because a neutron star is on the verge of becoming a hole doesn't mean that little pieces of it are at the verge also. Wnt (talk) 02:17, 20 June 2013 (UTC)

Your final sentence might be right, but this use of the word "density" is kind of bogus. Theoretically, once a mass becomes into a black hole, there is no force that can prevent all its mass from collapsing into an infinitely dense spacetime singularity at the center. This "density" calculation is apparently based on dividing the mass of the black hole by the volume within the event horizon (note that "volume" is also a bit problematic here, because there's no canonical coordinate system to measure it in). But nothing special happens at the event horizon; it's just empty space, but a marker from which you can't return. --Trovatore (talk) 02:45, 20 June 2013 (UTC)

"the bigger they are the less dense [the structures that gave rise to them] need to have been." Someguy1221 (talk) 03:14, 20 June 2013 (UTC)

That I'll buy. But I think it's confusing to say that the black holes themselves are less dense. --Trovatore (talk) 04:01, 20 June 2013 (UTC)

I feel ignoredRich (talk) 04:53, 20 June 2013 (UTC)

Why? Wnt answered your question. --Trovatore (talk) 05:16, 20 June 2013 (UTC)

yes, but I didn't realize that until later.Rich (talk) 09:31, 23 June 2013 (UTC)

I don't know enough for my opinion to matter, but subjectively I find Fuzzball (string theory) appealing. The notion of "singularity" doesn't smell real to me. I am content to measure the black hole's density in terms of the mass I can measure and the volume I can measure, and ignore what I can't which varies between models. Wnt (talk) 05:34, 20 June 2013 (UTC)

Hmm — my equally subjective view is that the black hole information paradox is no paradox at all, because the supposed reversibility principle that it violates should be false. That principle is based, albeit in a somewhat indirect way, on determinism, and determinism is wrong, because we have free will (in the strong sense incompatible with determinism). But I also don't know enough for my opinion to matter; I just find the queasiness that leads to these elaborate workarounds to be misplaced. --Trovatore (talk) 05:51, 20 June 2013 (UTC)

But how do you know that we have free will? I see no proof of that - and I believe that the hypothesis of the existence of free will is unfalsifiable. Using that to overturn what seems like an otherwise perfectly reasonable hypothesis makes no sense. But we're getting *way* off-topic here! SteveBaker (talk) 13:52, 20 June 2013 (UTC)

The problem, Trovatore, is that the reversibility principle we're talking about here (Which really is just the fact the the evolution operator must be unitary) cannot be false without messing up the conservation of probability. In other words, you will find yourself with a theory that predicts that some events will happen with a probability larger than 100%. That makes no sense which makes this kind of non-unitary theories complete rubbish. Dauto (talk) 14:11, 20 June 2013 (UTC)

Whether that can happen or not, depends on the local density within the star, and lifetime, and size of the microblackholes. They need to evaporate faster than what they can grow to ensure a stable existence of the neutron star. Plasmic Physics (talk) 05:02, 20 June 2013 (UTC)

These black holes would then convert the neutrons and other particles into photons which leads to heat production in the core. You'll reach dynamical equilibrium where this heat is radiated away and the core is at constant temperature. This means that the conversion of neutrons to photons leads to mass loss of the neutron star, eventually the lower mass limit where neutron stars are just stable will be reached, the neutron star will then explode. Count Iblis (talk) 12:47, 20 June 2013 (UTC)

Wouldn't microblackholes only form above a critical mass/volume density, or is the interior of neutron star sufficiently dynamic, that density fluctuations will lead to momentary sufficient densities for microblackhole formation? According to the first scenario, the neutron star will scintillate with microblackholes losing mass at a linear rate, until it reaches the critical density limit, whereupon the scintillation ceases completely. According to the second scenario, the star will scintillate indefinitely, but at an exponentially decaying rate, and lose mass correspondingly at, until it reaches bellow the minimum neutron star mass. Plasmic Physics (talk) 13:12, 20 June 2013 (UTC)

The point of what I said above is that the interior of the neutron star is not at the verge of forming black holes, when the entire neutron star is. That's the screwed up thing about it - it is a macroscopic property, not microscopic! According to Schwarzschild radius a region the size of the Earth would have to be 10¹¹ denser than a region the size of the sun to become a black hole, for example. It is very weird to picture there could be so much change (in the case of "fuzzball"s, even a change in the essence of the contents; in the case of the black hole, their loss of all ability to orbit one another) based on just adding some more matter. Wnt (talk) 21:32, 20 June 2013 (UTC)

Now I'm getting what i think your original point above was was-macroscopic property vs microscopic. But isn't it possible that the increase in density near the core could catch up to the increased densities required for tiny black holes? Also, if a neutron star had the upper range of possible masses, wouldn't we exxpect by "continuity" the beginning of "warning signs" that the star was getting close to a black hole size mass? On another point that Count Iblis raised, about micro black holes inside the star causing mass to be lost, i agree that could be important though as all of this, outside my expertise, but it talking about the case where the star is isolated, not picking up mass from stuff nearby, such as an accretion disk. Thanks.Rich (talk) 09:40, 23 June 2013 (UTC)

Well, do the math at Schwartzschild radius (which is easier than spelling it, after all): the critical density p = 3m/(4 pi r_s³) with r_s = 2 Gm/c², i.e. p = (3m / 4pi) (c⁶/8 G³ m³) = (3/32 pi) c⁶ / G³ m²) There's a fair chance I just fouled that up somewhere, but at least the inverse square relationship with mass seems to match the pattern of the examples from the article: if you want to consider the deeper half of the neutron star's mass, it has to be four times denser to make a black hole than the whole star - fitting not in 1/2 the space of the whole star, but 1/8 the space. Now our article on neutron stars makes it clear that they are much less homogeneous than I thought, with some considerable uncertainties in inner structure, but I don't think there's that much difference in density at least from our cute little diagram. Wnt (talk) 13:14, 23 June 2013 (UTC)