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Temperature in different frames

  1. Dec 17, 2011 #1
    Does the temperature a body depend on its frame of reference?
    Does the internal kinetic energy depend on frame of reference?
    In short does it depend on velocity of body at relativistic velocities?

    the body doesn't know it is moving at that velocity,so i think temperature must not depend on velocity
  2. jcsd
  3. Dec 17, 2011 #2
    In reasonably flat regions, the temperature of a fluid or a solid is defined for the frame in which the centre of mass is at rest. Any energy added by moving to another frame is kinetic energy but not heat, because it is associated with directional momentum. There are probably considerable difficulties extending this definition to regions of space time with a large amount of curvature, as one frame will not do but, in such regions, a temperature may be loosely defined for each point in space time, by using a smaller region around that point. This temperature will be frame independent for the same reason.
  4. Dec 17, 2011 #3


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    Usually temperature is only defined in one frame, the rest frame of the thermodynamic fluid.

    There are some formulations where inverse temperature is part of a 4-vector, rather than a scalar - much as energy is part of the energy momentum 4-vector. See http://arxiv.org/abs/physics/0505004 ,and not that there is some controversy over the best way to handle relativistic thermodynamics.
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