ELi5: How does a laser have “negative temperature” if it’s not cold?
In: Physics
Lasers having a “negative temperature” isn’t a measurable thing. It’s conceptual. The Boltzmann factor does a good job of explaining how there is a probability of temperature increasing when energy increases. It describes a thermal equilibrium where at 0 K, the excited state has a factor of 0 and the gain state has a factor of 1. Lasers aren’t in thermal equilibrium and would theoretically be found to be negative if they did follow this scale. The exited/gain state of lasers is called a “population inversion” referring to how lasers emit exponentially more excited particles than ground state.
Excited particles from certain lasers will transfer energy to objects and produce heat, though. The laser itself is not something that has temperature. The whole “negative temp” thing is just physics mumbo jumbo
Latest Answers