Bose-Einstein and Fermionic condensates in space?

[Suekdccia]

TL;DR Summary

Can Bose-Einstein condensates and Fermionic condensates survive for long periods of time in space?

Imagine we have a cold region of the universe, almost devoid of matter and radiation. Or perhaps in a future universe where the CMB has "cooled" down to sufficiently low "temperatures"

Could there be long lived macroscopic Bose-Einstein and Fermionic states of matter there? Could matter composing these states clump together by itself (by its own gravitarional attraction)? Or perhaps if we had at first some matter that would attract the gas gravitationally so that the gas is already clumped (even if the matter that caused it to clump eventually disappeared or decayed)?

 

[Hornbein]

TL;DR Summary: Can Bose-Einstein condensates and Fermionic condensates survive for long periods of time in space?

Imagine we have a cold region of the universe, almost devoid of matter and radiation. Or perhaps in a future universe where the CMB has "cooled" down to sufficiently low "temperatures"

Could there be long lived macroscopic Bose-Einstein and Fermionic states of matter there? Could matter composing these states clump together by itself (by its own gravitarional attraction)? Or perhaps if we had at first some matter that would attract the gas gravitationally so that the gas is already clumped (even if the matter that caused it to clump eventually disappeared or decayed)?

There is a theory that the dark matter is superfluid of a very low mass particle.

 

[DrClaude]

At the temperatures where BEC can be obtained, normal matter would be solid. It takes special conditions to get condensation, and BEC can be lost very easily due to external perturbations. It would very surprising that the right conditions for BEC be found in nature.

As for "fermionic states of matter," I don't understand what you mean.

 

[Suekdccia]

As for "fermionic states of matter," I don't understand what you mean

I meant Fermionic condensates (https://en.wikipedia.org/wiki/Fermionic_condensate)

 

[Ken G]

It should also be mentioned that the cosmos are currently dotted with countless examples of Fermionic condensates still in the process of condensing, they are the endpoints of low mass stars called white dwarfs.

 

[PeterDonis]

white dwarfs

And neutron stars, correct?

 

[Ken G]

Yes, very true, though with all those quarks in there it's kind of a mixture of degenerate condensates.

 

[Vanadium 50]

The question is so vague as to be unanswerable. Does a chunk of metal "count"? Probably not. So the whole question boils down to guessing what "counts" and does not to the OP.

 

[Hornbein]

Yes, very true, though with all those quarks in there it's kind of a mixture of degenerate condensates.

I haven't kept up these past few years but in 2020 or so it was controversial. It depends on the size ie. density ie. equation of state of the neutron star, which is hard to measure. I don't know how this could be done at all. I suppose some clever PhD will come up with something someday.

Most of the core of a neutron star is superconducting and superfluid.* They can tell because the transition to this state releases scads of neutrinos, which cool the star rapidly. This can be measured. The data isn't great but is OK and everyone pretty much believed this already so it was accepted. The question is what goes on in the central core. In the most massive neutron stars there might be a quark plasma there. Or maybe not. It depends on the equation of state, which depends on the size of the star, which I don't know how to measure. There also might be exotic particles like kaons, which would make things more viscous. It also depends on one's faith in the models of neutron star physics, but there's no getting away from that until they figure out how to replicate those pressures in the laboratory and then measure what is going on there. No easy task and too esoteric to attract major funding.

My silly view is that Man has made a quark plasma in the lab so it must be out there in nature somewhere.
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*The protons form Cooper pairs and are superconducting. The electrons are ordinary. No one knows precisely what percentage of the core matter is protons and electrons, but the star is so dense it could be the highest concentration of each in our Universe. The electrons in the crust are so dense they form a powerful insulator. Such is the topsy-turvy nature of neutron stars.

 

[Hornbein]

To return to the original question, it made me think. Would gravity cause a very low mass BEC aka. superfluid (I think there is some subtle difference but I don't know what it is) to condense further? One would have to do the math but I'd say the the basic nature of a BEC is against it. The idea is that the BEC is in the same state everywhere. That means it is more or less the same density everywhere. In a neutron star the density at the very center is about twice what it is at the outer edges of the superfluid, much less than you would expect. In a very low mass BEC I'd expect the difference to be even less. What's more, in a free space BEC one presumes a halo of dark matter around it. So I would expect very little in the way of a density gradient that one needs for condensation. Furthermore if said matter doesn't interact with anything then there isn't a way for said matter to get rid of it's momentum ie. relative velocity to the BEC, so I don't see how it clumps.

A BEC has to have a certain density before it will form. So that wouldn't happen in a excessively rarified region.

Last I looked at it no theory of cosmic dark matter was working. My guess is the problems are that the theories are too simple, but since there is so little data to go on any more complex theories are too speculative, something not worth spending time on for the time being. There is no reason to think that the physics of dark matter is any simpler than the physics of bright matter. Who knows?

 

[Vanadium 50]

They can tell because the transition to this state releases scads of neutrinos, which cool the star rapidly. This can be measured.

I find this very hard to believe.
Very, very hard.

The number of neutrinos that have been observed from SNe throughout all of human history is....zero. Sure, we have seen antineutrinos from SN1987a, but besides being a different particle altogether, they don't even come from the core.

Maybe there is some model somewhere, but a model is not a measurement.

 

[Hornbein]

I find this very hard to believe.
Very, very hard.

The number of neutrinos that have been observed from SNe throughout all of human history is....zero. Sure, we have seen antineutrinos from SN1987a, but besides being a different particle altogether, they don't even come from the core.

Maybe there is some model somewhere, but a model is not a measurement.

The neutrinos were not observed. The more rapid cooling owing to the neutrino emissions was observed.

 

[Vanadium 50]

That says "rapid cooling is observed". It does not say what the cause is.

 

[Ken G]

Still, it's not unusual for dense cores to cool by neutrino losses, that's more or less the cause of core collapse supernova explosions. They might be antineutrinos, but it's still considered neutrino losses (especially since we don't really know that an antineutrino is a different particle). Electron capture plays a role in neutrino creation, but there is also the celebrated "Urca process", whereby neutrinos and antineutrinos are emitted in a never ending nuclear cycle that reminded Gamow of people gambling at a casino.