# The 3rd law and absolute zero temperature

Absolute zero temperature unattainable

### 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!