To detect objects, people use radar (radio detection and ranging), which sends radio waves outwards. The waves collide with something and immediately send back and echo, which helps the computer figure out how far away the object is. In 1935, the British Government assigned Robert Watson-Watt to make a death ray, because they desired help in defending their borders. They feared a bombardment from the Luftwaffe (a new German air-force). Since he thought the death ray wasn’t a suitable plan, Watson-Watt perfected something else called Chain Home Network, which successfully warned Britain of attacks. World War II motivated the acceleration in radar technology.