What's Bose-Einstein condensates?

[gib65]

I just wanted to know if I have the right understanding of what Bose-Einstein condensates are. Are they a state of matter that you get at extremely low temperatures where the atoms that compose it become "smeared out" in a quantum mechanical sense (excuse my crude terminology )? What exactly is happening to the atoms at this low temperature?

[Kyrisch]

I think absolute zero has something to do with this... You know, 0º Kelvin which translates to something like -375º C or something like that. I also vaguely remember superfluidity or superconductivity, something that I believe arises from how close all the atoms are and their state that allows the substance to be superconductive.

[DV8 2XL]

At very low temps all the indivdual atoms condence into a "super atom" and yes I guess you could say they were "smeared out" in a quantum mechanical sense

[swansont]

The momentum is small, meaning that the deBroglie wavelength is large; you can't discern individual atoms. Because of the low temperature they have condensed into the ground state (being Bosons, they can all be in one state) of the trapping potential, so you have coherent behavior — the atoms will behave in ways similar to laser light.

[gib65]

That's very interesting.

 

I've got a follow-up question now, so I'm going to change the topic just slightly.

 

What kind of implications do Bose-Einstein condensates have for the "heat death" scenario of the universe's long-term fate? That is, from what I understand, the universe is eventually going to cool down and all matter is going become cold rocks floating apart into distant space forever. If this is the fate of the universe, and if it cools down to the critical point where Bose-Einstein condensates start forming, what kind of picture does this paint of the universe? Could the entire universe merge, in principle, into one "super atom" as DV8 puts it?

[swansont]

BEC has a density requirement as well as temperature. AFAIK it's a non-issue with regards to the heat-death scenario.

[Locrian]

Gib65, keep in mind that only condensations that have integer spin can be bose-einstein condensates, which doesn't include an awful lot of matter. Also, the very idea of everything condensing in a heat death scenario is pretty much the opposite of what is expected to happen.