If Helium, when cooled to a few degrees above absolute zero, becomes a superfluid with all sorts of gnarly properties, would it be possible to cool it even more so that is freezes solid?

 

What would that be like, d'you think?

cold and hard and pretty useless. At least super cooled helium can be used for super conducting magnets - eg fusion reactor - but a 'solid' lump of helium?

 

You would have to keep it contained in whatever device you used to cool it which would negate it's low density.

Supersolidity in He-4 is actually quite an exciting new discovery. See Moses Chan's paper from last year.

 

Solid He is nothing new though. It is well known that He will freeze at high pressures. That He-4 will continue to be a BEC in the "solid" phase is what's interesting !

If Helium' date=' when cooled to a few degrees above absolute zero, becomes a superfluid with all sorts of gnarly properties, would it be possible to cool it even more so that is freezes solid?

 

What would [i']that[/i] be like, d'you think?

Helium-4 superfluid is really cool.

It is a bose-condensate, a property of boson particles. As a superfluid, every particle is in the exact same quantum state (in direct violation of the Pauli exclusion principle, which only applies to fermions).

It is a bose-condensate, a property of boson particles. As a superfluid, every particle is in the exact same quantum state (in direct violation of the Pauli exclusion principle, which only applies to fermions).

Bose-condensate aka Bose-Einstein condensate.

 

It's not really violating the Pauli Exclusion principle since that only applies to fermions and He4 is a boson.

 

(I think you knew that, just making it clearer for others )