I recently talked to a friend of mine about microwaves. Specifically that (to my knowlege) the microwave radiation is primarily absorbed by a rotational degree of freedom of water molecules. Which got me thinking. 1.First of all what would happen if you put a extremely cold ice cube ( with no liquid water on surface)into the microwave ? Wouldn't the water in the ice be unable to absorb the radiation because it is bound in the crystal lattice ? 2.Second what happens when you don't put anything into the microwave ? Resonance catastrophe ??? Is the radiation just absorbed by the walls as the Intensity in the box builds up more and more? Maybe gas discarge ... that would be cool, but i doubt it would happen. Is doing it actually dangerous, since a observer might get hit by high levels of microwave radiation "leakage"? The third question is the one from the title: Why can't i kill the ice cubes ? When you freeze(glass) water bottles they will get destroyed by the expansion of water to ice. But when i put a half frozen ice cube into the microwave and the ice melts form the inside out, the ice cube doesn't collapse in on itself(implode) because of the contraction. That was a huge disappointment. I heard some quiet crackling but no big structural difference can be observed. 3.How are these stresses released ? Does air somehow enter through cracks ? BTW If you replicate this make sure you let the ice cubes lay around for a while before putting them in the microwave, since a surface layer of water might warm the initially cold surface wich would make it crack due to thermal shock. PS I realized something similar must also happen when freezing ice cubes from the inside out... When the outer shell freezes it takes a shape that would accomodate some volume of water. However this water expands when freezing and pushes on the outside shell. I have actually observed the surface bulging out on some ice cubes. I am confused how it can change shape so much without completely breaking apart. Could someone explain it ?