I am NOT referring to laser cooling, the technique for supercooling atoms. The 1980 science fiction novel Sundiver by David Brin describes a kind of spaceship that could fly into the sun. One way described to keep the inside of the ship cool was to concentrate the heat inside the ship with some kind of heat pump, and then use the heat energy to power a laser which effectively dumps the excess heat energy out into space. Thermodynamically, for a refrigerator to work, you need two things, right? One is some place to put the heat energy; and two is some place to put the entropy. Or, since pumping heat against the normal flow takes work, you have to increase the net entropy of the system um, somewhere? The technique seems to explain the former, but not the latter, which brings me to the question, is a refrigeration laser (as described) thermodynamically possible? And if so where does the entropy of the system increase? Could you use part of the laser beam to power the concentrator pump in the first place?