A laser or maser shows amplification of incident electromagnetic field due to stimulated emission, which can be treated as positive feedback.

There exist numerous phenomena in macroscopic physics which are similar in nature and need quantum explanation.

Thermodynamics of these phenomena is also similar. The following examples are briefly discussed: a) Rotating black hole , Hawking radiation and amplification of incident fields (e.g. gravity waves) b) ``Quantum `` approach to ocean wave generation by wind and electromagnetic radiation emitted by rotating dielectric. c) Sonic booms and Cherenkov radiation. d) Heating of stellar atmosphere by ``surerradiance" of Alfven waves.