I am studying some quantum mechanics and thermodynamics. I have seen that in QM temperature doesn't appears in the formulas. But it appears in statistical mechanics formulas.
The question is: Temperature appears as a phaenomena of a big number of particles? How big must be that number?
I have seen the link Can a single molecule have a temperature? but there is no agreement on the answers. So, this question might be
Can a single molecule have a temperature? revisited