Well, you can figure out the potential energy in an atomic bomb, which is converted to heat and sound and EM energy during detonation. So there is a number. It’s different for every bomb, but it’s based on mass.
Temperature is a measure of the kinetic energy of molecules, so the idea that there is something driving these temperatures so high isn’t that inconceivable. Yes the writing is poor, but so is all science writing. Par for the course.
“It’s different for every bomb, but it’s based on mass.”
Well, not really.
And there's the rub. If every inch were a different length, we'd probably have to find a different unit of measure.
Cheers!