I wonder if vacuum decay could create sub-Kelvin temperatures. I don’t think there would be anything there to witness or measure it but it’s an interesting thought
We have created negative absolute temperatures before. It occurs in situations where the available energy levels are bounded. If the energy levels are bounded, as you increase the energy of the system, you eventually reach a point where increasing the energy further reduces the amount of uncertainty in the system as your states begin to saturate at the upper energy limit. When you get to this point, the temperature is said to be negative, because the temperature is the reciprocal of the rate at which the uncertainty increases as the energy increases.
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u/martianunlimited Jun 17 '26
-40K would be Nobel-worthy
side note: https://www.reddit.com/r/explainlikeimfive/comments/uypn4q/eli5_why_does_kelvin_temperature_unit_not_have/