World War II neatly divides the twentieth century in almost every historical way imaginable. Few people on Earth were unaffected by that titanic struggle. Old empires ended, ideologies gained fresh power, and science and technology gained a sharp boost. World War II has also been called the physicists’ war because scientists and engineers developed many important weapons that fundamentally changed the course of the war, including rockets, radar, proximity fuses, the electronic computer, and the mightiest weapon of all, the atomic bomb.(See Nuclear Physics; Physics.) The American economy boomed during World War II for many reasons, including a sense of shared purpose, the expansion of military forces that solved unemployment problems, and massive armaments spending that kept factories running at full capacity. Significant scientific and technological innovation occurred during the war, and that innovation, combined with prudent government economic policies, helped fuel the postwar economic boom. Multiple economic studies have found that scientific and technological research lead to greater productivity and economic growth. At the end of the war, the United States dominated the world, its gross national product making up half of the world economy. This enabled Americans to expand their extensive higher education system and to pour money into scientific and technological research.(See National Institutes of Health; Universities.)

The United States became scientifically assertive during the postwar years. Many scientists, especially Jewish scientists from Germany, had fled to the United States and continued their work in their …