It is, apparently, possible to have temperatures in negative Kelvin.
As old as I am and as long as I’ve been reading about physics, I’ve always shied away from Quantum Physics, just because no matter what I did it confused me. I understand this is true for everybody but still, I felt I grasped Newton almost perfectly, Einstein reasonably well, and Quantum physics not at all.
One thing I always had trouble wrapping my brain around, for some reason, is that heat is not its own form of energy, which my brain wanted it to be. I know this is High School stuff but for whatever reason it bothered me, and accepting that heat is just another form of motion, another form of kinetic energy if you will, bothered me. It’s not that I didn’t, or don’t, accept it, but my brain wanted it to be something else for some reason, its own totally uniquely discrete form of energy. Call it my own failing, as that’s almost certainly what it is and was. In any case, once I fully accepted that heat is just motion, period, then the idea that you could have something less than 0 Kelvin was self-evidently impossible. But now, apparently, it’s not impossible, and I’m going to have to spend time wrapping my head around that.
We think we understand the universe. But we don’t even understand a fraction of what we think we do, do we?