After Hitler came to power, Einstein was granted asylum in the United States. In 1938, Einstein was also understood by German physicists Otto Han and Fritz Strassman about the importance of fission to uranium. Einstein knew that this weapon was developed to release energy from nuclear fission. He and several of his fellow physicists were worried that the Nazis would develop such a weapon and use it to destroy and/or occupy other parts of the world.

Other physicists tried to warn the American government of this danger, but with little success until Einstein signed his famous letter to American President Roosevelt. Einstein's fame and his letter attracted Roosevelt's attention, and soon the American government began the Manhattan Project. This letter is the only time Einstein actively devoted himself to developing a nuclear bomb.

Einstein wrote this article in 1952 to explain his views on the atomic bomb:

My participation in making the atomic bomb includes only one thing: I wrote a letter to President Roosevelt. This letter emphasizes the necessity of conducting large-scale experiments to determine the possibility of making an atomic bomb.

I am well aware of the terrible danger that these experiments will bring to all mankind if they are successful. But the Germans are likely to solve this problem, and they are likely to succeed, which prompted me to take this step. Although I have always been a staunch pacifist, I can't see any other way out. In my opinion, murder in wartime is not much better than ordinary murder.

However, as long as countries are willing to take joint actions to eliminate wars and peacefully resolve conflicts on the basis of law. They felt it necessary to prepare for the war. In addition, they feel that they must prepare the most abominable means to avoid falling behind in the general arms race. This procedure inevitably leads to war, and war has caused extensive damage under today's conditions.

In this case, there is no hope to oppose the production of specific weapons or destructive means. Only by completely eliminating war and the danger of war can it help. For this goal, first, we must work hard; In fact, no one should be forced to take actions that run counter to this goal. This is a harsh requirement for anyone who is aware of their social interrelationships; But it can be followed.

Gandhi, the greatest political genius of our time, has pointed out the way and proved the sacrifices that mankind is willing to make as long as it finds the right way. His work for the liberation of India is a living example, which shows that the human will supported by indomitable beliefs is stronger than the obviously invincible material force.