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Thermal energy is the energy an object due to the motion of it's molecules. This means as long as an objects molecules have kinetic energy, it will not reach absolute zero. Does that mean if there was a complete vacuum (no molecules or waves inside the vacuum at all), it would be at absolute zero inside the vacuum because there is no molecules, meaning they can't have kinetic energy, and theirs no radiation to heat the space. So I was thinking it would be absolute zero in a complete vacuum.

Qmechanic
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Daniel Turczynskyj
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This means as long as an objects molecules have kinetic energy, it will not reach absolute zero.

Classically, you would be correct. Quantum physics says that this isn't quite correct. Even at absolute zero, objects would still have a non-zero amount of kinetic energy. This would be the system's zero-point energy.

Does that mean if there was a complete vacuum, it would be at absolute zero inside the vacuum.

No. It would be more difficult to define a temperature at all. That wouldn't make it a temperature of "zero".

Even without any atoms inside the space, there would still be radiation. Only if all the radiation were eliminated could you describe the temperature in that region as consistent with a temperature of absolute zero.

BowlOfRed
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Is Absolute Zero Possible?

Yes. In a black hole.

Thermal energy is the energy an object due to the motion of its molecules. This means as long as an objects molecules have kinetic energy, it will not reach absolute zero.

That's true.

Does that mean if there was a complete vacuum, it would be at absolute zero inside the vacuum because there is no molecules, meaning they can't have kinetic energy.

No, because "the vacuum" isn't something that's totally empty, it has vacuum fluctuations. Think of them as something like the little ripples on the surface of the ocean.

Or is it even possible at all for any object to reach absolute zero?

Yes, a black hole is a place where time dilation goes infinite, so there is no motion, so there is no heat or temperature. I know people talk about Hawking radiation, but that is said to emanate from near the black hole, not within it.

John Duffield
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