Negative absolute temperature

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A search on negative temperature shows that quantum thermodynamics actually operate with negative temperature. This is temperatures above infinite positive temperatures and thus the hottest temperatures of anything: https://wiki2.org/en/Negative_temperature https://wiki2.org/en/Negative_temperature

Negative absolute temperature can be achieved from population inversion in LASERs where more of the atoms are in higher excited states than in lower unexcited states: https://wiki2.org/En/Population_inversion https://wiki2.org/En/Population_inversion.
 
Here is a video showing what happens:
What Happens if You Focus a 5W Laser With a Giant Magnifying Glass? Negative Kelvin Temperature! (8:25): https://www.youtube.com/watch?v=jdjTYlReE-I https://www.youtube.com/watch?v=jdjTYlReE-I 

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Ole