Sub absolute zero?

Discussion in 'Science and Nature' started by Dryice, Jan 4, 2013.

  1. #1 Dryice, Jan 4, 2013
    Last edited by a moderator: Jan 4, 2013
    Someone I know who frequents this forum sent me this, and immediately my skeptic alarm is going off. How does something like this not violate the uncertainty principle? In that a particle with a fixed position has infinite velocity, or vice versa. I'm a rather fresh physics student (haven't studied quantum mechanics in a class yet) but from books I've read this seems to absolutely contradict quantum mechanics' uncertainty principle, unless the uncertainty principle is a done deal? I was definitely under the impression absolute zero was a theoretical thing, and not something physically possible. I mean time stops at absolute zero, because there's zero motion, no?

    Quantum gas goes below absolute zero : Nature News & Comment
  2. #2 Modality, Jan 4, 2013
    Last edited by a moderator: Jan 4, 2013
    It would be impossible if you applied the Uncertainty Principle to a classical system since all kinetic interactions would cease. However, a quantum-mechanical system can still have a nonzero energy while the temperature of the system is absolute zero. If you introduce absurdities such as particles with negative mass, you can even have systems with temperatures less than absolute 0, in theory at least. HUP becomes increasingly irrelevant as a system reaches temperatures of absolute zero because it becomes meaningless to talk about the position of individual particles due to the Bose-Einstein condesate phenomena. Temperature itself is a statistical, macroscopic quantity and it is nonsensical to talk about the temperature of an individual particle or an atom, for example. It is an emergent phenomena.

    Interesting paper, by the way.

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