Heat Movements Within Steaks

When you put a piece of steak in an enclosed vessel like a grill, smoker, or an oven, the hot air, which has lots of vibrating molecules, transfers some of its energy to the exterior of the meat. The energy in the air excites the molecules on the surface of the meat and then they transfer heat to the molecules inside it and so on, slowly passing the energy towards the center of the meat like a wave of heat. It takes time because meat is about 75% water, and water is a good insulator, especially when trapped inside muscle. The heat moves inward because physics dictates the the meat seeks equilibrium in an effort to make the temperature the same from edge to edge. So most of the meat is cooked by the meat, not by the air. Bones heat at a different rate than muscle tissue because they are filled with air or fat, so in most cases they warm more slowly than the rest of the meat.