Question: Why did Einstein write a letter to Franklin Roosevelt?
Answer: When the Nazis came to power in Germany, Einstein emigrated to U.S. The American physicists were in an uproar because of the discovery of nuclear fission in Berlin. They feared the Nazis could now build and use an atomic bomb. Einstein’s associates feared that the Americans too might try to make a similar invention. Einstein wrote to the American President, Franklin D. Roosevelt to warm him of the dire consequences of an atomic explosion.