The first microwave was invented by accident in a Raytheon laboratory testing magnetrons. Perry Spencer, the accidental inventor, was a Raytheon employee and self-taught engineer. One day while working near the magnetrons, which are high-powered vacuum tubes inside radars, Spencer noticed a peanut butter chocolate candy bar in his pocket had begun to melt. With this newfound knowledge of how to cook food within seconds, Spencer, together with Raytheon, patented the invention. Two years later, the first commercial microwave oven was launched by Raytheon, cost $5,000 at the time, and approximated 750 pounds in weight and nearly 6 feet in height.