Microwaves come in all sizes, but one thing is for sure, radio waves penetrate the food and excite water and fat molecules pretty much evenly throughout the food. In other words, food tends to dry out, like pizza. No heat has to migrate toward the interior by conduction. There’s heat everywhere all at once because the molecules are all excited together. There are limits, of course. Microwaves penetrate unevenly in thick pieces of food, and there are also “hot spots” caused by wave interference – the whole heating process is different because you are “exciting atoms” rather than “conducting heat.” Place a small glass of water inside while re-heating old pizza, and it will make all the difference, or at least for the crust. Continue reading for more.