• Question: Why is it impossible to get colder than absolute zero - is it because of Heisenberg's uncertainty principle stating we can't know a particle's position and velocity at the same time (hence if we knew the velocity was zero, we would be completely uncertain as to where the particle was?)

    Asked by doppler to Adam, Geoff, Rob, Sheila, Suzie on 22 Mar 2011 in Categories: .
    • Photo: Suzie Sheehy

      Suzie Sheehy answered on 21 Mar 2011:

      Every atom has a “ground state” beyond which you can’t remove any more energy from a system. While the energy is very small it isn’t zero – and that’s when you get to absolute zero… when you can’t take any more energy from the system. And yes, you can think about it in terms of Heisenberg’s uncertainty principle – good one!

    • Photo: Robert Simpson

      Robert Simpson answered on 21 Mar 2011:

      Temperature is a measure of how much energy exchange is going on in a material due to the movement of atoms and molecules. Materials whose molecule are not moving at all are not exchanging any energy this way and so have no temperature – this is why the Kelvin scale was developed and why absolute zero is as low as you can get.

    • Photo: Adam Tuff

      Adam Tuff answered on 22 Mar 2011:

      You couldn’t get to absolute zero using thermodynamical means – I’m not entirely sure why this is. Interesting point on the Heisenberg uncertainty, although I don’t think this is entirely true as even at zero thermal energy it would still maintain a residual energy from it’s ground state (the Fermi energy).

    • Photo: Sheila Kanani

      Sheila Kanani answered on 22 Mar 2011:

      I think it is to do with Heisenberg yes, and also because of things like E=MC^2. At absolute zero you would have no energy, which means you would have no mass, which isnt possible in ‘real’ terms….

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