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The 3rd law and absolute zero temperature

We cannot reach absolute zero temperature.

  • By the 3rd law, entropy is zero, at zero K.
  • If we think about what the temperature is, it is a measure of internal, randomized energy in a material. Absolute zero is a point at which thermal motions stop entirely.
  • In classic thermos, everything stops at absolute zero. But in reality, quantum mechanics rules. We cannot ever measure the exact position or momentum of a particle with perfect certainty. (Heisenberg uncertainty principle). Thus in quantum world, every motion is governed by uncertainty. We cannot ever measure the particles as not having motion.
  • Thus absolute zero is never attainable!

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This article is from the free online course:

Thermodynamics in Energy Engineering

Hanyang University