We know that when you touch a hot cup of tea it can warm your hands. That’s heat conduction: Two surfaces of different temperatures make physical contact and heat is transferred from one to the other. We are also pretty aware of convective heat transfer, though it may not be quite as simple. In convection, the heat transfer occurs when a fluid—this can be air, some other gas, or even a liquid—is caused to move away from a source of heat and in the process carries energy with it. For instance, above the hot surface of a stove, the air being warmed expands, becomes less dense than the surrounding cold air, and rises.
The reason for this elementary explanation of heat transfer is to set them apart from another means of thermal energy transfer. Objects can also transfer heat to their surroundings using light, but that method of heat exchange has always been thought to be very weak compared with conduction and convection. Now, in collaborative research among researchers at Columbia, Cornell, and Stanford, they discovered that we just weren’t doing it right. Their conclusion: light could become the most dominant form of heat exchange between objects.