Wikipedia:Reference desk/Archives/Science/2012 November 18

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November 18

Where is the Heisenberg cut article?

I searched for Heisenberg cut but didn't find it. So does it exist as a subsection somewhere or is it just a dead cat? Hcobb (talk) 01:10, 18 November 2012 (UTC)

There is certainly enough information out there to create an article: see [1]. Wikipedia only exists because people no different than you created and expanded all of the articles. That is, if you find something is missing from Wikipedia, you are literally the best person in the world to add it; or you're no worse than anyone else. So, feel free to create that article! --Jayron3201:44, 18 November 2012 (UTC)

Excellent, by the way Hcobb, on creating the article. This looks like an excellent candidate for WP:DYK if you can expand it a bit! --Jayron32 12:38, 18 November 2012 (UTC)

At the moment the article is (intentionally) isolated with no inbound links, but I hope it can either serve as the main article for the subsections in other articles that it notes, or be merged into a slightly more broad article that covers the concept. If so it might well be split between Heisenberg's own writings and other contributions to the subject, and the more general concept that has been taken up by quantum computing. Hcobb (talk) 17:49, 18 November 2012 (UTC)

BTW, suppose that you did have a Heisenberg cut device, that I suppose would measure all possible quantum numbers inside a box. Say you subjected an average sized household cat to this, how big would the resulting explosion be? A chemical explosive because you've just messed up all the electron orbitals? A nuclear explosion because you've swatted all the nucleons? Or an anti-matter level explosion because you've sampled all the quark states? Hcobb (talk) 17:59, 18 November 2012 (UTC)

Based on this question and what you wrote in the new article, I think you don't understand what the cut is. The cut is the correspondence you define between quantities in a theory that you want to test and quantities that you know how to measure in the real world. To put it another way, it's the boundary at which you splice a speculative theory to a commonsense engineer's physics that everyone already accepts as true. This is a necessary part of any theory that claims to describe the real world. To a large extent it doesn't matter where you place the cut, but it needs to be at a high enough level that all the controversial physics is handled by your theory.

A nice non-quantum example is Einstein's 1905 paper on special relativity. The math of special relativity had already been worked out at that time. Einstein's only contribution was giving it an interpretation that made sense. He did that by moving the cut. Instead of assuming that distances and time intervals are things that can in principle be measured to arbitrary accuracy by sufficiently good instruments, as everyone had assumed in the past, he treated those instruments as part of the system to be modeled by the new theory. As his measurable quantities, instead of position and time, he used the time shown on a clock face when some event happens at the clock's location. The assumption that a human experimenter (his "observer", though the meaning of that term has changed since then) can read a clock face is much weaker than the assumption that an experimenter can measure true distances and times. And it turned out that the latter assumption was actually wrong.

In quantum mechanics, if you make the usual division between quantum system and measurement apparatus, the disappearance of the interference pattern in the double-slit experiment seems bizarre. If you instead do as Einstein did and make the apparatus part of the quantum system, using readings on dials as your measurable quantities, you get a much more comprehensible result: the wave function gives a classical probability for each possible readout, the collapse is just a Bayesian update, and the disappearance of the interference pattern is caused by a quantum interaction between the photon/electron and the apparatus (quantum decoherence) which couldn't be modeled when you assumed the apparatus wasn't quantum.

By the way, I've never heard the term "Heisenberg cut" before. I've seen occasional mentions of the cut between theory and experiment, but not with Heisenberg's name attached. It does get a fair number of Google hits, but I think it's an unfamiliar term to most physicists and is probably used mostly by people like Stapp (who I consider a crank). -- BenRG (talk) 21:05, 18 November 2012 (UTC)

I agree with BenRG. I've read more than a few books on atomic physics, and I've never encountered this phrase in the context of quantum physics. From a cursory glance at the references in our new article, it appears to be a sort of popular science neologism used by "physics-philosophers." Nimur (talk) 12:34, 19 November 2012 (UTC)

To be entirely fair, being quackery doesn't mean it isn't proper article fodder. It may be quackery, and if so, the article should use reliable sources to report it as such. But quackery alone is not enough of a reason to not have an article. We have articles on homeopathy and astrology; the articles both report the "internal logic" of the beliefs and also explain clearly and unambiguously that the scientific community thinks they are bullshit. I have absolutely no familiarity with the term either, but I also don't have the physics background that you two do to find sources that refute it. If the rather stubby article needs expansion, one needed route of expansion may be some explanation (properly cited) of this as a not-accepted thing. --Jayron32 13:54, 19 November 2012 (UTC)

The final reference in the article doesn't look like quackery [2] - it describes specific writings by Heisenberg in the 1930s about contextual hidden variable theory, which he considered by postulating various placements of a cut "Schnitt" between observer and observed. I'm not likely to answer this question, but at least it is a valid concept from the development of quantum mechanics. Wnt (talk) 19:12, 19 November 2012 (UTC)

Just to clarify. I'm not saying one way or the other if the concept is quackery or not. The concept could be sound science, or it could be bullshit. Being bullshit is not, of itself, however, grounds for not having an article on something. Homeopathy is unmitigated bullshit, but that doesn't mean Wikipedia doesn't have an article describing it. Which is not to say that this concept is bullshit. It may not be; just that Ben and Nimur's objections to it are not grounds for not having an article about the concept. --Jayron32 20:19, 19 November 2012 (UTC)

I am also somewhat concerned that the article currently states "there are no actual Heisenberg cuts anywhere...". That last reference describes the Heisenberg cut as an integral part of the Copenhagen interpretation, so that statement appears to assert that Copenhagen is wrong. Copenhagen is certainly not as popular as it used to be, but I do not think it has been so soundly rejected as to allow an NPOV article to assert that. --Trovatore (talk) 19:32, 19 November 2012 (UTC)

Whoops, sorry, not the same ref -- I'm talking about this one. --Trovatore (talk) 19:35, 19 November 2012 (UTC)

I agree - we cannot be certain that Heisenberg cuts do not exist. They are required in some interpretations of quantum mechanics, but not in others. I have tried to make the article more NPOV. Gandalf61 (talk) 09:46, 20 November 2012 (UTC)

Voltage across an inductor

I read about the self inductance phenomenon and about the equation V=L(di/dt). But I am confused about the direction of V. My confusion is that current flowing through an inductor causes a 'back-emf', and the back emf is equal to V(or so I think). If so, shouldn't the direction of V be in the opposite of that of I? Also, in the Voltage and Current graph sketch across the inductor, I saw that the phase difference is 90 degree, but the voltage and the current are infact, in the same direction. I just don't get the fact that how V is in the same direction of the current that causes it. According to Lenz's law, it should be in the opposite direction. — Preceding unsigned comment added by 210.4.65.52 (talk) 04:17, 18 November 2012 (UTC)

Voltage doesn't have a direction; I guess you're talking about the direction of the voltage drop, which is what's meant by V. I don't know if this helps, but in the hydraulic analogy, an ideal inductor is like a heavy but frictionless paddlewheel. Its inertia opposes any attempt to either increase or decrease the current, which leads to a downstream pressure drop (positive V) or gain (negative V) in the case of a forced current increase or decrease respectively. -- BenRG (talk) 07:23, 18 November 2012 (UTC)

Another point to consider is that the induced voltage depends on the _change_ in current, not the static (DC) current. If you have a perfect inductor carrying a DC current, it won't have any voltage across it (because its DC resistance is zero). If you increase the current, the induced voltage will be in the "opposite direction" to the DC current - if you reduce it, the induced voltage will be in the "same direction". Tevildo (talk) 21:14, 18 November 2012 (UTC)

URGENT INFO NEEDED

Dear all, I need to know how thymoquinone actually acts! I mean does it pass through the cell membrane? Does it have a receptor? How does it expert its effect? attaches to a protein to change its activity? ... Any info regarding that will be appreciated. Best kukubah 04:51, 18 November 2012 (UTC) — Preceding unsigned comment added by Kukubah (talk • contribs)

PubChem is a good place to start for stuff like this (see here). Also, note the warning at the top of this page about timeliness - this really isn't the best place to ask urgent questions. Zoonoses (talk) 05:46, 18 November 2012 (UTC)

Hmmm, oddly enough I'm finding a source that the antinociception and anticonvulsant effects work via the kappa opioid receptor. [3][4] Wnt (talk) 06:04, 18 November 2012 (UTC)

When did dark energy start to dominate?

There's a graph currently on the Hubble's law article that shows universal expansion. It's hard to read the inflection point, and I don't find it mentioned in the article or any related articles.

That is to say: after inflation ended, the universal expansion was decelerating. Now it is accelerating. When was the critical time when deceleration became acceleration?

(Let's say, treating the dark energy as a cosmological constant... do other proposals imply a different critical time?) — Preceding unsigned comment added by 174.118.1.24 (talk) 08:07, 18 November 2012 (UTC)

Ignoring radiation (which only matters at early times) and assuming the universe is flat (no global curvature), the evolution of the cosmological scale factor is:

$\left({{\dot {a}} \over a}\right)^{2}=H_{0}^{2}\left(\Omega _{M}a^{-3}+\Omega _{\Lambda }\right)$

Where $a$ is the scale factor, $H_{0}$ is the current Hubble constant, $\Omega _{M}$ is the fraction of the closure density in mass (including dark mass) and $\Omega _{\Lambda }$ is the fraction of the closure density in dark energy. (See also: Lambda-CDM model)

The inflection point occurs at ${\ddot {a}}=0$.

Rewriting the above we get:

${\dot {a}}^{2}=H_{0}^{2}\left(\Omega _{M}a^{-1}+\Omega _{\Lambda }a^{2}\right)$

$2{\dot {a}}{\ddot {a}}=H_{0}^{2}\left(-\Omega _{M}a^{-2}{\dot {a}}+2\Omega _{\Lambda }a{\dot {a}}\right)$

$0=\left({{\dot {a}} \over a}\right)\left(-\Omega _{M}a^{-1}+2\Omega _{\Lambda }a^{2}\right)$

Given that ${\dot {a}}>0$ for all times since the creation of the universe, it follows that inflection occurs at:

$\Omega _{M}=2\Omega _{\Lambda }a^{3}$

$a=\left({\Omega _{M} \over 2\Omega _{\Lambda }}\right)^{1/3}$

Using current values for $\Omega _{M}$ and $\Omega _{\Lambda }$, gives $a\approx 0.57$. Which implies that the inflection occurred when the universe was about 57% of its current size. Getting the corresponding time will require integrating the equations above with respect to time, but since the expansion was roughly linear, the 57% of size is approximately 57% of time, implying that the inflection point occurred roughly 7.8 billion years after the Big Bang, or roughly 5.9 billion years ago. Dragons flight (talk) 09:36, 18 November 2012 (UTC)

Brilliant, thanks --174.118.1.24 (talk) 17:36, 18 November 2012 (UTC)

When Ω_M + Ω_Λ = 1 there's an exact solution, $a(t)=\left({\tfrac {\Omega _{M}}{\Omega _{\Lambda }}}\sinh ^{2}\left({\tfrac {3}{2}}{\sqrt {\Omega _{\Lambda }}}H_{0}t\right)\right)^{1/3}$ (copied from here). That gives $t={\frac {2\sinh ^{-1}{\sqrt {1/2}}}{3{\sqrt {\Omega _{\Lambda }}}H_{0}}}$ at the inflection point, which is about 7.1 billion years a.b.b. or 6.6 billion years ago (using parameters from here, which also give me a ≈ 0.57). -- BenRG (talk) 18:28, 18 November 2012 (UTC)

What happens if someone were to be struck by something like the Oh-My-God particle?

I mean, being hit by a 60 mph baseball is pretty painful. I mean, it was pretty unlikely for any one particular particle to have struck that particular sensor at Dugway Proving Ground, so there is likely some finite flux/second for that kind of particle. Yet there really isn't a recorded instance in history where someone suddenly suffered a severe injury (on the magnitude of a gunshot wound) suddenly and catastrophically for no reason at all. 71.207.151.227 (talk) 10:07, 18 November 2012 (UTC)

I don't think you'd notice, if as this site says, normal cosmic rays " pass through us, through our houses, through our bodies" every day, why do you think this particular form of cosmic ray would be any different? --TammyMoet (talk) 14:17, 18 November 2012 (UTC)

I think the OP was shocked by the exceptionally high energy (as I was, and the observers were). If all of that energy were absorbed by a human body, it would certainly have a significant effect on a par with a gunshot, but, fortunately for us, most of the energy is carried away by other particles without interacting significantly with the human body. Usually, damage at atomic level is not significant at cellular level, though it would be interesting to know if genetic change is caused by such particles. Perhaps they are the main driver of evolution? Dbfirs 15:35, 18 November 2012 (UTC)

Also note that 50 J is the amount of energy delivered to a typical household incandescent light bulb lit for about 1 second. That's really not that much energy from a macroscopic point of view. Dauto (talk) 16:20, 18 November 2012 (UTC)

Lesser rays are noticeable. [5] See also Cosmic ray visual phenomena. The "Oh-My-God particle" was a very rare event in the upper atmosphere and so has not been experienced yet by anyone, and until such time as it happens we can't really know what the effect would be like. Wnt (talk) 17:14, 18 November 2012 (UTC)

It could lead to a dose of a few Sievert and that can be deadly. UHECRs won't penetrate the atmosphere, hit your body and cause the equivalence of an air shower inside your body. But you can think of other ways this can theoretically happen. E.g. a cosmic ray particle can hit a dark matter particle, and that dark matter particle can then get a a similar energy. Most likely such a high energy dark matter would move through your body and the Earth, but there is then a small chance that it would interact with a nucleus in your body, giving you a potentially fatal dose of radiation. Count Iblis (talk) 17:28, 18 November 2012 (UTC)

(ec) As an aside, the detection system used (the 'Fly's Eye', a predecessor to the High Resolution Fly's Eye Cosmic Ray Detector which worked on similar principles) wasn't solely dependent on detectors on the Earth's surface, and didn't just sit and wait for a single 50-joule particle to smack into a single ground-based sensor. What the Fly's Eye picked up were showers of particles generated when a high-energy cosmic ray started to interact with the upper atmosphere; using an array of telescopes it could (literally) see these interactions by the light they produced, as collision after collision ionized atmospheric gases and generated sprays of new, fast particles that in turn triggered further ionization events. Those interactions would have occurred across several kilometers of atmosphere. To be clear, it wasn't a single *pop* and *flash* as the entire 50 joules was deposited at a single point of collision; instead, energy would be deposited along a long, branched track as the particle kicked off other fast particles produced by collisions and gradually came to rest.

In the unlikely event that such a particle did reach the Earth's surface (and a human being there) without interacting with anything else, it still wouldn't do much to a person. I don't know what the linear energy transfer rate would be for a proton in this energy regime, but I strongly suspect that the proton would emerge from the other side of your body with nearly all of its energy still intact, having deposited only a tiny, tiny faction of its 50 joules inside you. TenOfAllTrades(talk) 17:36, 18 November 2012 (UTC)

But how far does an air shower (physics) spread within a human body? Wnt (talk) 19:12, 18 November 2012 (UTC)

The density of the human body is a few thousand that of the atmosphere (at the relevant height), so you'll get a significant part of the air shower in your body (70 cm times 3000 is 2.1 km ). Count Iblis (talk) 19:48, 18 November 2012 (UTC)

The interaction length for daughter particle creation from ultrahigh energy protons is about 400 meters of air or 40 cm of water. The energy loss scale per particle is about 2-3 MeV / cm in water. If the Oh-My-God particle hit you directly, traveling vertically through you, it would have about 1.8 m to work with. So, roughly, say 3 MeV / cm * 40 cm for the initial particle + 2 * 3 MeV / cm * 40 cm for the first daughter pair + 4 * 3 MeV / cm * 40 cm for the second daughters + 8 * 3 MeV / cm * 40 cm for the third daughters + 16 * 3 MeV / cm * 20 cm for the last generation before exiting. In total, it would have deposited about 0.4 nanojoules of energy while passing through you, or roughly 0.000000001% of its energy in the 6 nanoseconds it took for the particle to enter and exit your body. You would not even notice a direct hit by such a particle. Such a particle could keep producing daughters out to the hundreds of billions. Though, even if you got him with 100 billion high energy particles, odds are you still wouldn't notice much effect. Even absorbing the full 50 J, is only an amount of heat equal to what humans produce every 0.5 seconds. 50 J is an enormous amount of energy for a single particle to have, but the energy and momentum of that particle would seem trivial to macroscopic objects like us since we are composed of roughly 7×10²⁷ atoms. Dragons flight (talk) 22:28, 18 November 2012 (UTC)

And yet the astronauts do notice being hit with ordinary cosmic rays, even to the extent that the flickering disturbs their sleep according to the source I listed, so there must be something off there? Wnt (talk) 23:10, 18 November 2012 (UTC)

In a completely dark room, after adjusting, the eyes are sensitive to light flashes with as few as about 10 photons entering the eye. That amounts to a detection limit of about 5×10⁻¹⁹ J. Hence, it's not surprising that cosmic rays crossing the eyeball can be seen, but that's because the eyes are exquisitely sensitive and not because the energy is in any bulk way significant. Dragons flight (talk) 23:59, 18 November 2012 (UTC)

I remembered as a child reading about a "scorch mark" left by the passage of a cosmic ray through an astronaut's helmet, which had much impressed me, but looking into it now, and seeing your estimate of the power released, I think that this must have been a sensationalization of something like the use of parthicle track-etch technique in "the Apollo helmet dosimetry experiment". Wnt (talk) 14:58, 19 November 2012 (UTC)

If you absorb 50 J from such a process, that would roughly be equivalent to 1 Sievert which is potentially deadly. Count Iblis (talk) 01:52, 19 November 2012 (UTC)

As I pointed out, what would actually absorbed be from a direct hit by the Oh-My-God particle is negligible. You can't capture 50 J unless it has already cascaded to roughly 100 billion lower energy particles before it reaches you and yet somehow remained confined enough to hit a single person. Dragons flight (talk) 04:46, 19 November 2012 (UTC)

Yes, although the 2 daugher particles per collisions in the beginning seems a bit low i.m.o. The COM energy here is huge... Count Iblis (talk) 19:21, 19 November 2012 (UTC)

If someone did drop dead from a cosmic ray, how would the coroner be able to tell afterwards? μηδείς (talk) 04:37, 19 November 2012 (UTC)

50 J is the energy of a 60 mph baseball. That's gotta hurt! 199.111.203.215 (talk) 04:39, 19 November 2012 (UTC)

It's the momentum of grain of salt in very light breeze. You'd never notice. Dragons flight (talk) 04:46, 19 November 2012 (UTC)

That's not what the linked article says. Is there a factor of 1000 error in a calculation? Dbfirs 07:28, 19 November 2012 (UTC)

The article is talking about kinetic energy, not momentum. --Trovatore (talk) 07:47, 19 November 2012 (UTC)

Sorry Dragons flight, and thanks for the explanation, Trovatore. I must learn to read carefully before commenting! I ought to know the difference, though anyone who has been hit with a hollow-point rifle bullet will know that energy can cause a lot of damage without carrying much momentum. Dbfirs 07:39, 20 November 2012 (UTC)

• Again, I ask, how would one know someone had been hit by one of these particles? μηδείς (talk) 18:04, 19 November 2012 (UTC)

• There will be a trail of minute trace amounts of radioactive isotopes in your body. The first part of the equivalent of the air shower in your body will be due to collisions that have so much center of mass energy that they completely shatter a nucleus to pieces. The COM energy of an incoming proton of energy E = 10^20 eV and an Iron nucleus of mass m = 52 GeV at rest is sqrt[2*10^20 eV*52 GeV + (52 GeV)^2] =3.2*10^15 eV which is hundreds of times larger than the COM energy at which the LHC can carry out collisions of nuclei to create a quark gluon plasma. Count Iblis (talk) 19:18, 19 November 2012 (UTC)

So this is apparently not something that is ever likely to be observed, but may happen all the time for all we know? μηδείς (talk) 17:31, 20 November 2012 (UTC)

You would not be aware of it if it were to happen, so you would have to describe the state of the universe where you are as a superposition containing a component with a very small amplitude where such things have happened to your body. Count Iblis (talk) 17:38, 20 November 2012 (UTC)

The Philippines and total plastic bag bans (again)

I've taken the liberty of moving this to the Humanities Refdesk. That's where you should ask questions about laws. Wnt (talk) 19:10, 18 November 2012 (UTC)

Electroshocking people

If someone is holding you and you electroshock him (with a regular electroshock weapon), can the shock pass to you? And if you apply it to his arm, does it affect his legs? Comploose (talk) 16:25, 18 November 2012 (UTC)

Not sure, but you may find some of the answers (and/or sadistic pleasure) in this Brainiac clip. - Cucumber Mike (talk) 17:47, 18 November 2012 (UTC)

Of course, unless you were insulated from them by clothing, etc. Here's a pertinent demonstration with a whole bunch of people in a row and an electric fence: [[6]]. And yess, it affects the whole body, and not just the part it's applied to. There wouldn't be much point to using one if it didn't. There designed to incapacitate the target, not just make them go "Ouch!'. Dominus Vobisdu (talk) 19:20, 18 November 2012 (UTC)

No, most regular electroshock weapons have two contacts and the current flows between the two, so others in physical contact are unlikely to feel a significant shock. If there is a voltage relative to earth (as in electric fences), then the shock can be passed through many participants. Dbfirs 07:18, 19 November 2012 (UTC)

How many people are dying in Gaza?

In response to complaints, I've taken the liberty of moving this to the Humanities Refdesk. (It's not that complicated to do this if a thread bothers people) Wnt (talk) 05:14, 19 November 2012 (UTC)

Asbestos in the WTC

Was asbestos in the WTC, and was it blown in the air, or not? Comploose (talk) 18:38, 18 November 2012 (UTC)

Typing "asbestos in world trade center" into Google got me this: [7]. It looks as though it shouldn't be too hard to find the answer among those search results. --Jayron32 19:15, 18 November 2012 (UTC)

"no asbestos" in world trade center also generates many results. Comploose (talk) 20:27, 18 November 2012 (UTC)

Many of those results aren't reliable sources (conspiracytheorists etc.). Trio The Punch (talk) 22:34, 18 November 2012 (UTC)

Yep. Read this. The NYT wrote: "Anticipating a ban, the builders stopped using the materials by the time they reached the 40th floor of the north tower, the first one to go up. ". Trio The Punch (talk) 20:12, 18 November 2012 (UTC)

Lump of fat close to the heart — in roe deer in the winter season — What is it called?

I have heard that roe deer, and other wild animals living in places with cold and snowy winters, every autumn developes a big lump of fat close to the heart.
(I presume that this somehow helps them survive through the winter season).
I want to read more about this phenomenon but: what is it called? or where might be a good place to start searching for for this?
Could you please help me?89.9.197.219 (talk) 19:33, 18 November 2012 (UTC)

Quote from Bone Marrow Fat as an Indicator of Condition in Roe Deer: "Fat reserves are generally utilised sequentially starting with the subcutaneous deposits, followed by the mesenteric, kidney and finally bone marrow fat". So I think roe deer store fat in those 4 places. Trio The Punch (talk) 20:01, 18 November 2012 (UTC)

The lump of fat by the heart would be mesenteric, but there may be a specific name for it as well. μηδείς (talk) 23:10, 18 November 2012 (UTC)

The OP is possibly referring to a dewlap (accumulation of fat under the neck or at the front of and external to the ribcage), common on hooved animals - though I didn't think deer grow noticable dewlaps. The mesentery is on the other side of the diaphram and not near the heart - Medeis is wrong again. Floda 124.182.38.51 (talk) 14:49, 19 November 2012 (UTC)

It's quite possible the OP may have meant a dewlap, although the wording of the question seemed to imply something internal. And while the mesentery holding the guts in place is often referred to as "the mesentery", mesentery tissue and its derivatives occur wherever there are organs, such as the heart, situated within the coelom. For example, cardiac messentery. The OP may be referring to epicardial adipose tissue or brown adipose tissue. Without a better explanation we can't be sure. μηδείς (talk) 17:45, 19 November 2012 (UTC)

The link provided by Medeis does not provide access to the book text. I just love posters who provide links that for this and other reasons do not support their claims. Entering "cardiac mesentery" in AltaVista does not return anything that supports the idea of live mammals having a cardiac mesentery. Possibly Medeis was thinking about the mesothelium, which has a different function and is not likely to be related to the OP's question. Floda 60.228.244.240 (talk) 01:07, 20 November 2012 (UTC)

The link works for me, perhaps it's a region issue for google books? Anyway, right or wrong, Medeis seems to be linking in good faith, to an anatomy monograph from 1906. The text does list "cardiac mesentary" in a caption for a plate, saying the diagram shows "Transverse section of a tadpole, showing ... ventral cardiac mesentary." If this is not standard usage today, then perhaps the terminology has changed in the past ~100 years... SemanticMantis (talk) 02:40, 20 November 2012 (UTC)

Ahah! Tadpoles! Organisms evolutionary less developed than mammals, and embryos, are described as having a cardiac mesentery. The ventral mesentary in mammals is not cardiac as it is after the diaphram. The book access could be a regional issue or perhps is enabled if you access from within a library?? Floda 121.215.68.108 (talk) 02:50, 20 November 2012 (UTC)

Do you even know what ventral means? It's just a direction. The heart has a ventral surface as does the brain, etc. What's referred to as the ventral mesentery in humans is the mesentery closest to the belly. (Aha!) Cardiac mesentery in adult mammals doesn't disappear, it just doesn't hold the heart in place because the heart grows to fill the pericardium. It could potentially become fatty in deer, but we still don't even know what the OP is specifically talking about. Besides your bizarre need to attack me, what for I don't know, do you have anything to add to this discussion? μηδείς (talk) 03:11, 20 November 2012 (UTC)

The ventral mesentery is mesentery closest to what is the front in humans, but this is below (in humans) the diaphram as I said. What is above/in front of the diapham as a lining is the mesothelium. Any cardiac mesentery could be described as ventral, dorsal or whatever according to standard terminology, but flexibility in terminology does not mean it actually is there. Fat occurs in the vicinity of the heart but big lumps of it (to use the OP's term) would compromise breathing. So, yes, we don't know what the OP had in mind (he was quite possibly missinformed anyway - he doesn't cite a source), but fat external to the ribcage is more likely. Do you have anything usefull to add, apart from trying to defend an unsupported opinion by personal attack? Your link doesn't count as according to SemanticMantis it is about tadpoles. You might as well claim that deer do not have diaphrams and breath via gills. Floda 121.215.68.108 (talk) 04:01, 20 November 2012 (UTC)

@ Semantic Mantis, I simply provided a copy to the first link at google that mentioned cardiac mesentery; it wasn't really meant to be relevant to the deer question as such, just to show that mesentery is a type of tissue found in relation to organs that float in the coelom, not some sort of organ that resides only in the abdomen. This article is interesting, it mentions studies of fatty female elk hearts themselves, as well as fat surrounding them on the pericardium, as well as the kidneys. They study this muscular and mesenteric fat because it is a sign of fertility. I presume they don't study bone marrow fat since it would only be lost in starving deer and subcutaneous fat since it would be a sign of obesity. Searches for "roe deer dewlap" don't seem to get any relevant hits and image searches aren't encouraging. American elk don't seem to have dewlaps either. Moose do, but they hardly seem to be fat storage organs. μηδείς (talk) 03:52, 20 November 2012 (UTC)

Again, Medeis, you have provided a link that does not support your claim. Yes, fat occurs around the heart, but the link does not even use the term mesentery, and does not in any way indicate "big lumps". Floda 121.215.68.108 (talk) 04:01, 20 November 2012 (UTC)

• From Trio The Punch we know that mesenteric fat is important in the roe deer, and Medeis referenced epicardial adipose tissue. In better-studied organisms (humans) we know that there are indeed epicardial fat deposits which share a common embryological origin with those of the mesentery.[8][9] While researchers show more interest in the pathology, this fat serves as a source of triglycerides and perhaps regulatory signals affecting the heart and arteries in subtle ways (the object of their present research). "Epicardial fat can be abundant especially in ruminants" and is absent in starving animals, and the pointed shape of the apex of the heart "can be pronounced in starving animals due to lack of epicardial fat." [10] At this point we're probably nearing the edge of what is known; roe deer are not model organisms and the amount of effort people have put in to figure out the role of epicardial fat is probably limited. I doubt that anyone has really liposuctioned it from the animals and seen what happens to their cardiovascular fitness or whatever. But you can do a lot of reading about epicardial fat in other organisms.[11] Wnt (talk) 18:06, 20 November 2012 (UTC)

Floda and Medeis, would you please both be so kind to refrain from interacting with/talking about the other person? This message is carefully worded to be as neutral as possible, but that does not mean I don't have an opinion. According to the rules of the internet you both lost the debate. Jimbo won, because he did not participate. This is not an invitation to say something like: "I'll stop talking to x because x is an idiot". There is no need to respond to this message. Thanks in advance, Trio The Punch (talk) 20:40, 20 November 2012 (UTC)

There is a need to respond. Wnt has usefully added to the discussion by a well considered post that includes links to relevent references. Where I or Medeis have or have not won any debate is perhaps of no relavence - the OP has been presented with some information, albeit some contradictory but the OP can weigh it up, and Wnt has usefully added information that should assist the OP (should he/she be interested) and anyone else in understanding just what fat occurs around the heart. Floda 120.145.137.177 (talk) 00:30, 21 November 2012 (UTC)