Some inventions have amazing stories behind, so does the microwave - a thing we can't live without today. In the 1940's Percy Spencer noticed his chocolate bar melted in his pocket after standing in front of an active radar set working on magnetrons. Percy, being an expert in radar tube designing, decided to conduct an experiment. He ended up creating a high density electromagnetic field in a metal box. Thus, this metal box now heats up our burritos today thankfully to Percy Spencer.