How did Pavlov's hungry dogs uncover truths about our behavior? Who was the "lunatic" who came up with radio? What vaccine saved the children of a nation and how did it come about? A companion to Flashpoints: History, this heavily illustrated timeline for readers 10 to adult identifies key moments in science and technology in the 20th century. Such flashpoints include Max Planck's idea that energy comes in chunks, or "quanta," followed by Einstein's theories of relativity, the invention of radio and radar, the discovery of antibiotics, the development of nylon and other plastics, the advent of rocketry, the creation of computers, and the mapping of DNA.