Einstein reflects on his role in the birth of the Atomic Bomb

August 6, 1945. Over Hiroshima, a blinding flash, then a rising mushroom cloud: the atomic bomb had entered history. In an instant, over 70,000 lives were erased, with tens of thousands more lost to radiation in the months that followed. Yet the bombing, followed days later by Nagasaki, also brought about Japan’s surrender and the end of the Second World War—a moment of relief for millions. This dual legacy of devastation and peace defined the nuclear age. And behind it stood a single gesture from a physicist in Princeton: Albert Einstein’s decision in 1939 to co-sign a letter to President Roosevelt urging the development of such a weapon before Nazi Germany could do the same.

In early 1953, as the Japanese public was finally allowed to see images of the destruction wrought by the bomb, the editor of Kaizō wrote to Einstein with a pointed question: “Why did you co-operate with the production of the atomic bomb although you were aware of its tremendous destructive power?” Einstein, who had long avoided extended public comment on the subject, responded with what became his most direct and personal statement:

My participation in the production of the atom bomb consisted in a single act: I signed a letter to President Roosevelt.

However, what I find most revealing in this signed typescript - translated and annotated by Einstein himself - is how deeply personal his regret was. Although he had remained a committed pacifist, the fear of a Nazi bomb had overridden his principles in 1939.

I was well aware of the dreadful danger for all mankind, if these experiments would succeed. But the probability that the Germans might work on this very problem with good chance of success prompted me to take that step. I did not see any other way out, although I always was a convinced pacifist. To kill in war time, it seems to me, is in no ways better than common murder.

Einstein warns of the inevitability of war if nations continue to arm themselves and, at the end of this powerful manuscript - never republished in this form - the German scientist invokes Gandhi, whom he greatly admired.

Gandhi, the greatest political genius of our time has shown the way, and has demonstrated the sacrifices man is willing to bring if only he has found the right way. His work for the liberation of India is a living example that man’s will, sustained by an indomitable conviction is stronger than apparently invincible material power.

One last important detail: Einstein’s handwritten signature, “einverstanden, Einstein” (“agreed, Einstein”), is no trivial gesture, it signals his full, conscious endorsement of the text’s content, a rare and weighty affirmation given the moral gravity of the subject.