Prevost Theory of Heat Exchange and Emissivity

Prevost's theory of heat exchange states that every object at a temperature above absolute zero continuously emits thermal radiation into its surroundings, while simultaneously absorbing radiation arriving from those surroundings -- both directions happen at once, always. A hotter body radiates away more heat than it absorbs, which is why it feels hot to the touch; a cooler body absorbs more than it radiates away, which is why it feels cold. Once both bodies reach the same temperature, their two rates of radiative exchange become exactly equal, and they are said to be in thermal equilibrium, even with no physical contact between them at all -- this is exactly how the Sun (at about 5700 K) and the Earth (re-emitting at around 300 K) continuously exchange radiation across empty space. Only at absolute zero would emission stop entirely. If a body is not a perfect absorber/emitter (not a perfect black body), its emitted power is reduced …