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Leó Szilárd (right) and Albert Einstein re-enact the signing of the famous letter to Franklin Delano Roosevelt.

Leó Szilárd (February 11, 1898May 30, 1964) was a Jewish Hungarian-American physicist who worked on the Manhattan Project. He was born in Budapest and died in La Jolla, California.

He was probably the first scientist to think seriously of building real atomic bombs. (He knew of the fictional "atomic bombs" described in H. G. Wells's science-fiction novel The World Set Free). The possibility of a nuclear chain reaction came to him on September 12, 1933 while he was waiting for a red light on Southampton Row in Bloomsbury. Reportedly, the thought had occurred to Szilárd as a result of his having been annoyed by Ernest Rutherford's dismissal of any talk of atomic energy as "moonshine." Szilárd also was the co-holder, with Enrico Fermi, of the patent on the nuclear reactor (Template:US patent).

He was well known to his colleagues as an eccentric, lightning-quick thinker who "seems fond of startling people" with strange, seemingly incongruous, yet extremely perceptive statements and questions.

He was extremely good at predicting political events. He predicted World War I as a boy, several years before the fact. When the Nazi party first appeared, he predicted that it would one day control Europe. In 1934, he foresaw the details of World War II. He then later made it a habit to reside exclusively in hotel rooms, with a packed suitcase always on hand.

Szilard fled to London in 1933 to escape Nazi persecution. While in London, he read an article written by Ernest Rutherford in The Times, after which he conceived the idea of a nuclear chain reaction. In the following year, he filed for a patent on the nuclear chain reaction. He first attempted to create a chain reaction using beryllium and indium, but neither yielded the reaction he expected. In 1936, he assigned the chain-reaction patent to the British Admiralty to ensure secrecy of the patent (Template:UK patent).

In 1938, he accepted an offer to conduct research at Columbia University in Manhattan, and moved to New York. Nobel Laureate Enrico Fermi soon joined him there. After learning about fission in 1939, he concluded that uranium would be the element capable of the chain reaction.

Szilárd was instrumental in the development of the Manhattan Project. He conceived of the idea of sending a confidential letter to Franklin D. Roosevelt, explaining the possibility, and encouraging the development of such a program, and obtained Albert Einstein's endorsement in August 1939. Later, he moved to the University of Chicago to continue to work on developing the bomb. There, along with Fermi, he helped to construct the first "neutronic reactor", a uranium and graphite "pile" in which the first self-sustaining nuclear chain reaction was achieved in 1942.

As the war continued, Szilárd became increasingly annoyed at the fact that he was losing power over his scientific developments to the military, and clashed many times with General Leslie Groves, military head of the Manhattan Project. His resentment towards the U.S. government was further exacerbated by his failed attempt to avoid the use of the atomic bomb in war.

As a survivor of the 'shipwreck' of Hungary after World War I, having experienced both red terror and white terror, Szilárd developed an enduring passion for preservation of human life and freedom, especially freedom to communicate ideas. He hoped that the U.S. Government, which before the war was much opposed to the bombing of civilians, would not use the bomb, as the only possible purpose of a weapon of that magnitude could be to slaughter civilians. He hoped that the mere threat of the bomb would force Germany and/or Japan to surrender. Rather than threatening the Axis with the bomb, Harry Truman chose simply to use it, despite the protestations of Szilárd and many of the other top scientists in the project, resulting in the deaths of roughly 300,000 Japanese civilians, the total destruction of Hiroshima, and the partial destruction of Nagasaki. Before the war, Szilárd had considered the U.S. the one truly humane government in the world; that is why he chose to give them, over everyone else, the atomic bomb. He no longer felt that way afterwards.

In 1943, he became a naturalized citizen of the United States.

In 1947, he changed fields from physics to molecular biology, working extensively with Aaron Novick. He spent his last years as a fellow at the Salk Institute in San Diego.

External links




  • US2708656 ( -- Neutronic reactor -- E. Fermi et.ó Szilárd

hu:Szilárd Leó fr:Leó Szilárd


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