If you live in the United States, odds are a machine much like those stacked on the right rests on a kitchen countertop in your home. If so, your microwave is a descendant of the device on the right. This is the first microwave oven, built by Massachusetts-based Raytheon in 1947; it operated for three decades in the kitchen of one of Raytheon's founders. Raytheon named the original microwave the "Radarange" because it cooked food using the same radio-wave-producing magnetron tubes that the company manufactured for use in military radar.

Raytheon credits the discovery of microwave cooking to a grade-school-educated engineer named Percy L. Spencer. One day in 1945, Spencer was walking through a radar test room with a chocolate bar in his pocket; he came too close to a running magnetron tube and the candy began to melt.