Einstein–Szilard letter
Otto Hahn and Fritz Strassmann reported the discovery of nuclear fission in uranium on the 6th of January 1939. Lise Meitner identified this process as nuclear fission just five days later in a February 11 issue of Nature. This scientific breakthrough generated intense interest among physicists across Europe and America. Danish physicist Niels Bohr brought the news to the United States shortly after. The U.S. opened the Fifth Washington Conference on Theoretical Physics with Enrico Fermi on the 26th of January 1939. Experimental physicists quickly corroborated these results. John R. Dunning at Columbia University was one such notable figure. Hungarian physicist Leo Szilard realized that neutron-driven fission could create a chain reaction. He had first formulated this idea while living in London in 1933. Szilard read Ernest Rutherford's disparaging remarks about generating power from protons splitting lithium. That experiment occurred in 1932. Szilard believed if secondary neutrons exceeded one per reaction, they would trigger multiple additional reactions. This exponential increase could yield vast amounts of energy for electric power or atomic bombs.
On the 12th of July 1939, Szilard and Wigner drove to Cutchogue on New York's Long Island. Einstein stayed there when they arrived. They explained the possibility of atomic bombs to him. Einstein replied in German: "Daran habe ich gar nicht gedacht." This phrase translates to "I did not even think about that." Wigner wrote down the letter as Einstein dictated it in German. Einstein agreed and signed the document. Wigner suggested preparing a second letter for the State Department. This gave officials two weeks to respond with any objections. Another friend named Gustav Stolper suggested approaching Alexander Sachs. Sachs had access to President Franklin D. Roosevelt. Sachs told Szilard that Fermi and Pegram reported prospects for building an atomic bomb were remote. Sachs said he would deliver the letter but wanted someone more prestigious. Einstein was again the obvious choice. On August 2, Szilard co-opted Edward Teller to drive. Szilard dictated the English version to Janet Coatesworth. She later recalled thinking she worked for a nut when he mentioned extremely powerful bombs. Both letters were posted to Einstein for his signature.
Szilard received the signed letter back from Einstein on August 9. He gave both letters to Sachs on August 15. Sachs asked the White House staff for an appointment to see President Roosevelt. The administration became embroiled in a crisis due to Germany's invasion of Poland. World War II started shortly after. Sachs delayed his appointment until October so the president would give the letter due attention. He secured an appointment on October 11. That date he met with the president, Brigadier General Edwin "Pa" Watson, and two ordnance experts. Army Lieutenant Colonel Keith F. Adamson and Navy Commander Gilbert C. Hoover attended. Sachs presented the Einstein, Szilard letter and accompanying materials. He read the materials aloud to Roosevelt. The president was not persuaded that the U.S. government should get involved. Sachs managed to get an invitation to breakfast the next morning. He spent a sleepless night trying to conceive how he might persuade the president. On October 12, Sachs told the president a story about Alexander Hamilton. FDR called for a bottle of brandy from Napoleon's time. He poured it into two glasses for himself and Sachs. The president remarked, "Alex, what you are after is to see that the Nazis don't blow us up?" Sachs replied, "Precisely." Roosevelt turned to General Watson and declared, "Pa, this requires action!"
Roosevelt decided that the letter required action. He authorized the creation of the Advisory Committee on Uranium. Lyman James Briggs chaired the committee as Director of the Bureau of Standards. Adamson and Hoover served as its other members. It convened for the first time on October 21. Fred L. Mohler from the Bureau of Standards attended. Richard B. Roberts of the Carnegie Institution of Washington also joined. Szilard, Teller, and Wigner were present at the meeting. Adamson was skeptical about building an atomic bomb. He was willing to authorize $6,000 for purchasing uranium and graphite. This amount equals roughly $100,000 in current USD. The Advisory Committee on Uranium began the U.S. government's effort to develop an atomic bomb. It did not vigorously pursue weapon development initially. Instead, it focused on theoretical physics concerning practical nuclear fission. The ACU was superseded by the National Defense Research Committee in 1940. Then came the Office of Scientific Research and Development in 1941. The Frisch, Peierls memorandum and British Maud Reports prompted Roosevelt to authorize full-scale development. This occurred in January 1942.
Work coordinating funding, material, personnel, security, and civilian research fell to the S-1 Executive Committee. The United States Army Corps of Engineers' Manhattan District took charge in June 1942. They directed the all-out bomb development program known as the Manhattan Project. Seven months after the initial letter, a breakthrough in Britain estimated critical mass to be less than 10 kilograms. This made delivery of a bomb by air possible. Earlier estimates required several tons of material for a chain reaction. Einstein did not work on the Manhattan Project. The Army and Vannevar Bush denied him clearance needed in July 1940. Officials said his pacifist leanings and celebrity status made him a security risk. At least one source states that Einstein did clandestinely contribute some equations to the project. He was allowed to work as a consultant to the Navy's Bureau of Ordnance instead. He had no knowledge of atomic bomb development. He held no influence over decisions regarding its use.
Einstein later regretted signing the letter because it led to the development and use of the atomic bomb. Linus Pauling noted this sentiment. Einstein justified his decision based on the greater danger Nazi Germany would develop the bomb first. In 1947 Einstein told Newsweek magazine about his feelings. He stated, "had I known that the Germans would not succeed in developing an atomic bomb, I would have done nothing." Einstein sent two more letters to Roosevelt on the 7th of March 1940, and the 25th of April 1940. These called for action on nuclear research. Szilard drafted a fourth letter for Einstein's signature urging a meeting with the President. Dated the 25th of March 1945, it did not reach Roosevelt before his death on the 12th of April 1945. The bombs were eventually used on Hiroshima and Nagasaki. This outcome haunted Einstein until his own death.
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Common questions
What was the Einstein, Szilard letter to U.S. president Franklin D. Roosevelt?
The Einstein, Szilard letter was a document signed by Albert Einstein on the 2nd of August 1939, warning President Franklin D. Roosevelt about the possibility of Nazi Germany developing atomic bombs. Leo Szilard dictated the English version and enlisted Edward Teller to drive while they arranged for the letter to be delivered via Alexander Sachs.
When did Otto Hahn and Fritz Strassmann report nuclear fission in uranium?
Otto Hahn and Fritz Strassmann reported the discovery of nuclear fission in uranium on the 6th of January 1939. Lise Meitner identified this process as nuclear fission five days later in a February 11 issue of Nature.
Why did officials deny Albert Einstein clearance for the Manhattan Project?
Officials denied Albert Einstein clearance needed in July 1940 because his pacifist leanings and celebrity status made him a security risk. He had no knowledge of atomic bomb development and held no influence over decisions regarding its use.
How much money did Adamson authorize for purchasing uranium and graphite initially?
Adamson authorized $6,000 for purchasing uranium and graphite, which equals roughly $100,000 in current USD. This amount was approved by the Advisory Committee on Uranium when it convened for the first time on October 21.
What happened after Alexander Sachs met with President Roosevelt on October 11?
After meeting with President Roosevelt on October 11, Alexander Sachs secured an invitation to breakfast the next morning where he persuaded the president to take action. Roosevelt declared that the letter required action and authorized the creation of the Advisory Committee on Uranium.