Einstein–Szilárd letter

Copy of the letter

The Einstein–Szilárd letter was a letter sent to the United States President Franklin D. Roosevelt on August 2, 1939, that was signed by Albert Einstein but largely written by Leó Szilárd in consultation with fellow Hungarian physicists Edward Teller and Eugene Wigner. The letter suggested that the U.S. should begin its own research because of the potentially vast destructive power of atomic bombs. Einstein, Szilárd, Teller and Wigner were among a number concerned scientists who initially feared Nazi Germany would develop the weapon first.

Contents

The letter warned that:

In the course of the last four months it has been made probable — through the work of Joliot in France as well as Fermi and Szilard in America — that it may become possible to set up a nuclear chain reaction in a large mass of uranium, by which vast amounts of power and large quantities of new radium-like elements would be generated. Now it appears almost certain that this could be achieved in the immediate future. This new phenomenon would also lead to the construction of bombs, and it is conceivable — though much less certain — that extremely powerful bombs of a new type may thus be constructed. A single bomb of this type, carried by boat and exploded in a port, might very well destroy the whole port together with some of the surrounding territory. However, such bombs might very well prove to be too heavy for transportation by air.

It also specifically warned about Germany:

I understand that Germany has actually stopped the sale of uranium from the Czechoslovakian mines which she has taken over. That she should have taken such early action might perhaps be understood on the ground that the son of the German Under-Secretary of State, von Weizsäcker, is attached to the Kaiser-Wilhelm-Institut in Berlin where some of the American work on uranium is now being repeated.

Roosevelt's answer

The letter was signed by Einstein on August 2 and delivered to Roosevelt by economist Alexander Sachs. But Sachs was delayed until October 11 because of the president's preoccupation with Adolf Hitler's invasion of Poland, which started World War II. After hearing Sachs' summary of the letter, Roosevelt authorized the creation of the Advisory Committee on Uranium. The Committee first met on October 21 and was headed by Lyman James Briggs, Director of the National Bureau of Standards. Six thousand dollars were budgeted for neutron experiments performed by Fermi at the University of Chicago.

The Advisory Committee on Uranium did not vigorously pursue development of a weapon, and two other organizations superseded it (the National Defense Research Committee and the Office of Scientific Research and Development) before the work of fission research was taken over by the Manhattan Engineering District (MED) in 1942. It directed a full-scale bomb development program.

Einstein did not work on the atomic bomb project because General Leslie Groves considered him to be a security risk because of his pacifist leanings, so he was assigned to work on improving conventional artillery for the U.S. Navy. According to Linus Pauling, Einstein later regretted having signed the letter because it led to development and use of the atomic bomb against civilian populations. Einstein justified his decision because of the greater danger that Nazi Germany would develop the bomb first.

Complete Text of Letter

From: Albert Einstein, Old Grove Rd., Nassau Point, Peconic, Long Island, August 2nd 1939

To: F.D. Roosevelt, President of the United States, White House, Washington, D.C.

Sir:

Some recent work by E.Fermi and L. Szilard, which has been communicated to me in manuscript, leads me to expect that the element uranium may be turned into a new and important source of energy in the immediate future. Certain aspects of the situation which has arisen seem to call for watchfulness and, if necessary, quick action on the part of the Administration. I believe therefore that it is my duty to bring to your attention the following facts and recommendations:

In the course of the last four months it has been made probable - through the work of Joliot in France as well as Fermi and Szilard in America - that it may become possible to set up a nuclear chain reaction in a large mass of uranium,by which vast amounts of power and large quantities of new radium-like elements would be generated. Now it appears almost certain that this could be achieved in the immediate future.

This new phenomenon would also lead to the construction of bombs, and it is conceivable - though much less certain - that extremely powerful bombs of a new type may thus be constructed. A single bomb of this type, carried by boat and exploded in a port, might very well destroy the whole port together with some of the surrounding territory. However, such bombs might very well prove to be too heavy for transportation by air.

The United States has only very poor ores of uranium in moderate quantities. There is some good ore in Canada and the former Czechoslovakia. while the most important source of uranium is Belgian Congo.

In view of the situation you may think it desirable to have more permanent contact maintained between the Administration and the group of physicists working on chain reactions in America. One possible way of achieving this might be for you to entrust with this task a person who has your confidence and who could perhaps serve in an inofficial capacity. His task might comprise the following:

a) to approach Government Departments, keep them informed of the further development, and put forward recommendations for Government action, giving particular attention to the problem of securing a supply of uranium ore for the United States;

b) to speed up the experimental work,which is at present being carried on within the limits of the budgets of University laboratories, by providing funds, if such funds be required, through his contacts with private persons who are willing to make contributions for this cause, and perhaps also by obtaining the co-operation of industrial laboratories which have the necessary equipment.

I understand that Germany has actually stopped the sale of uranium from the Czechoslovakian mines which she has taken over. That she should have taken such early action might perhaps be understood on the ground that the son of the German Under-Secretary of State, von Weizsäcker, is attached to the Kaiser-Wilhelm-Institut in Berlin where some of the American work on uranium is now being repeated.

Yours very truly, signature (Albert Einstein)

See also

• Timeline of the Manhattan Project
• Frisch–Peierls memorandum

External links

• "Albert Einstein's Letters to President Franklin Delano Roosevelt". E-World. 1997. http://hypertextbook.com/eworld/einstein.shtml. 
• Reproduction of 1939 Einstein-Szilard letter
• President Roosevelt's response to Dr. Einstein Letter, Atomic Archive
• Roosevelt correspondence with Einstein and Szilard, FDR library, Marist University