# Cosmic background radiation vs superfluids

I've been reading a lot about superfluids lately (fluids that are cooled to such a degree that they no longer obey the standard laws of physics) in various physics journals and realized that the temperature of a superfluid is not that much lower than the average blackbody temperature of the universe, i.e. I think the fluids are about 2.1 K and the average temp. of the universe is about 2.735 K. Is it possible, given randomized regions of temperature throughout the universe, to have patches of superfluids in outer space, sitting there, taunting us like a gold mine of science just outside the reach of a planet full of monkeys?

Edited for accuracy based on Andrew's comment below.

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LOVE the "planet full of monkeys" bit. :) +1 –  Skava Jul 5 '11 at 16:26
Heh, thanks. :) –  WolfgangSenff Jul 5 '11 at 16:41

No. Densities are far too low for liquids to form and survive for more than a tiny fraction of a second. Furthermore, in the interstellar medium, temperatures are too high - in most of the diffuse interstellar medium, the temperature is around 80 K. Even the densest, coldest spots, molecular cores, are not even close to the densities and temperatures needed; they are around $10^6$ molecules per $cm^3$ and have temperatures around 10 to 20 K.

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Cool, good answer. Thanks. –  WolfgangSenff Jul 5 '11 at 14:28
Not in the ISM, certainly, but in addition to having a better vacuum than labs can produce, space also contains higher density objects than we can manufacture here on Earth. –  Chris White Jan 24 '13 at 10:08

There are two concepts to which your question might actually be referring, since "no longer obey the standard laws of physics" is vague, and I wanted to clarify.

Supercooled fluids- These are fluids that are slowly and gently cooled to below the temperature at which they normally turn to solids. These are perfectly well known and reproducible in the lab. In fact, if you live in a cold climate, you might stumble upon a supercooled pond. Throw in a rock, and the whole thing would freeze in seconds.

Superfluids happen to be very cold, and the temperature you cite is around the superfluid transition of helium-3 or helium-4, but the reason they're interesting is their bizarre fluidity. These, too, can be created in the lab. See the Wikipedia article for a picture.

Finally, the variation in the blackbody temperature of the CMB is more like 2*$10^-5$ degrees, not 0.6 degrees.

So, it's a great idea, but super-whatevers don't actually exist in space, and we don't actually need to go to space to study them. This planet full of monkeys can manufacture our own scientific treasure chests.

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Ahh, good point - was meaning superfluids, the quantum mechanical media darling at present. At the same time, my point was that if there were superfluids in outerspace, it could cause some very strange effects (I would expect). I can't think of anything offhand that it might cause or do, but doesn't it stand to reason that it would be strange? –  WolfgangSenff Jul 6 '11 at 13:28
Superfluids do have surface tension, so if we ignore the evaporation problem, we would most likely see a hypothetical space superfluid as a rotating spheroid. That would indeed be strange (although generic rotating spheroids are not), but what specific strangeness it would manifest is outside my expertise. Probably some weird instability behavior relating to its rotation. –  Andrew Jul 6 '11 at 14:52
But they do exist in space - just not in nice free-floating blobs free from other phenomena. See my answer. –  Chris White Jan 24 '13 at 10:06

The other answers seem to be focused on the interstellar medium, which is perhaps what inspired this question. However, there is another astrophysical source in which superfluidity does occur: neutron stars, whose densities are large enough such that ${}^1S_0$ and maybe ${}^3P_2$ neutron and/or proton superfluids are expected.

There is a vast literature on the subject, mostly due to the fact that the presence of superfluidity can dramatically change the timescale for cooling, both by lowering the specific heat and by suppressing neutrino production. One of many good articles out there is this one by Lattimer et al. Figure 6 from that paper, shown below for convenience, is rather characteristic of the diagrams employed in this field. It shows the critical temperature below which superfluidity sets in as a function of density. The typical neutron star is expected to have thermal energies of (possibly significantly) less than $1~\mathrm{MeV}$.

What's more, we are entering an exiting era of observations on this front. Recently there has been work exploring the cooling of the Cassiopeia A supernova remnant in real time, as announced in this paper and followed up for instance here and here.

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