According to IFLScience, above the Planck Temperature (absolute hot) conventional physics breaks down.
My question is what happens as you approach this temperature, and, if it is possible, what happens when you cross it?
[Physics] What happens as you approach/cross the Planck temperature
absolute-unitsphysical constantsquantum-gravitytemperaturethermodynamics
Best Answer
I expect it's impossible to cross the Planck temperature, just like it's impossible to cross absolute zero or the speed of light.
At the Planck temperature, you start producing miniature Planck-mass black holes, which are the hottest black holes that can exist. If you try to put more energy in the system, you would get larger black holes, which are cooler, and they would start absorbing stuff and cooling things down.