Albert Einstein’s Letter to Franklin D. Roosevelt Summary

  • Last updated on November 10, 2022

The discovery of the process of nuclear fission in 1938 very quickly led theoretical physicists such as Niels Bohr, Enrico Fermi, and Leó Szilárd to speculate that the massive amount of energy released by the process would at some point be harnessed by one of the world powers and turned into a bomb. As Europe slid toward another world war, Szilárd, a Hungarian physicist working in New York, became concerned that Nazi Germany might be the first to construct such a weapon. By 1939, when he convinced noted physicist Albert Einstein to sign a letter to US president Franklin D. Roosevelt, Nazi Germany had already occupied the Rhineland (1936), annexed Austria (1938), and occupied Czechoslovakia (1939). The prospect of such an aggressive regime, seemingly bent on dominating Europe, constructing a weapon of such unknown power motivated Szilárd to act in order to convince the United States to do everything it could to construct an atomic fission bomb before the Nazis did.

Summary Overview

The discovery of the process of nuclear fission in 1938 very quickly led theoretical physicists such as Niels Bohr, Enrico Fermi, and Leó Szilárd to speculate that the massive amount of energy released by the process would at some point be harnessed by one of the world powers and turned into a bomb. As Europe slid toward another world war, Szilárd, a Hungarian physicist working in New York, became concerned that Nazi Germany might be the first to construct such a weapon. By 1939, when he convinced noted physicist Albert Einstein to sign a letter to US president Franklin D. Roosevelt, Nazi Germany had already occupied the Rhineland (1936), annexed Austria (1938), and occupied Czechoslovakia (1939). The prospect of such an aggressive regime, seemingly bent on dominating Europe, constructing a weapon of such unknown power motivated Szilárd to act in order to convince the United States to do everything it could to construct an atomic fission bomb before the Nazis did.

Defining Moment

In December 1938, two German scientists, Otto Hahn and Fritz Strassmann, caused a fission reaction for the first time, using an isotope of uranium called uranium 235. The process involved bombarding uranium 235 atoms with neutrons, causing the unstable core of uranium 235 to split into krypton and barium, releasing three neutrons. The process was found to generate an immense amount of heat and energy that, a number of prominent physicists realized, could be used either to generate electricity for a power plant or to unleash destruction in the form of a bomb.

Hungarian Jewish physicist Szilárd was working in the German capital of Berlin during the 1920s and early 1930s, and was among the significant number of scientists who fled Europe in reaction to the rise of Nazi Germany and its growing anti-Semitism. During the mid-1930s, Szilárd had worked with Italian physicist Enrico Fermi on experiments that were based on the theory that nuclear fission was possible. After moving to Columbia University in New York in 1938, Szliárd had been in contact with colleagues in Europe who had successfully initiated the fission process. Working with Fermi, Szilárd was able to prove that a controlled chain reaction was possible—a necessary step to use the nuclear fission process to create both nuclear reactors and atomic bombs.

Szilárd was worried that the US government did not see the tremendous importance of the development of nuclear fission, especially in light of German expansion throughout Europe and the possibility of a second world war. Were scientists in Nazi Germany—which had some of the best theoretical physicists—to develop a sustained chain reaction before scientists in the United States, Szilárd reasoned that the results could be catastrophic for the entire world.

Convinced that he did not have adequate political connections to get noticed, Szilárd enlisted the assistance of Nobel laureate Albert Einstein, whom Szilárd had known and worked with when both were in Germany. Szilárd traveled to Long Island, New York, where Einstein was vacationing, to persuade him both of the feasibility of a nuclear chain reaction and the urgency of contacting someone who could make inroads with the American government to spur its leaders to action. Einstein first sent a letter to the Belgian ambassador to the United States, whom he knew. When that generated no action, Szilárd was put in touch with economist Alexander Sachs, who knew President Franklin D. Roosevelt personally and agreed to deliver a letter directly to him. On August 2, 1939, Szilárd and fellow Hungarian physicist Edward Teller again visited Einstein, Szilárd dictated the letter to the American president, and Einstein signed it.

Author Biography

Although Albert Einstein, a Nobel laureate, was more famous, he and the accomplished nuclear physicist Leó Szilárd had much in common. They were both of Jewish heritage and had both worked in Berlin during the 1920s and early 1930s. They knew one another, and had even worked together to develop a refrigerator pump that worked without moving parts. Both came to be among the leaders in their respective branches of physics. They both fled Nazi Germany in 1933, with Einstein coming to the United States and Szilárd initially based in London. Though the paths of their studies were different, Szilárd knew that Einstein could comprehend the theoretical possibility of an atomic weapon, and therefore would be the perfect person to communicate the threat to those in power in the United States. Though Szilárd was largely responsible for the content of the letter to Roosevelt, it was Einstein's personal prestige that was able to get it delivered to the president.

Historical Document

Old Grove Rd.

Nassau Point

Peconic, Long Island

August 2nd, 1939

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 [illegible] 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 this situation you may think it desirable to have some 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 unofficial capacity. His task might comprise the following:

a) To approach Government Departments, keep them informed of the further development, and out forward recommendations for Government action, giving particular attention to the problem 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 a contribution 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 Weishlicker [sic], is attached to the Kaiser Wilheim Institute in Berlin where some of the American work on uranium is now being repeated.

Yours very truly,

(Albert Einstein)

Document Analysis

The letter written to Roosevelt by Szilárd and signed by Einstein was not very long, comprising only two very brief typewritten pages, and did not go into much scientific detail regarding the development of nuclear fission. However, what it lacked in length and detail it made up for in clarity, logical presentation, and a distinct call to action. It did not take a knowledge of nuclear physics to see what might come to pass should an aggressive nation such as Nazi Germany acquire a weapon of untold destructive force.

The letter begins with a statement of the discoveries that Szilárd and Fermi had made earlier that year. Using simple language, the letter states that uranium might be the key to “a new and important source of energy in the immediate future,” but that “certain aspects of the situation” call for a quick response by the United States. The letter gives a brief overview of the experiments regarding nuclear chain reactions that Szilárd, Fermi, and others had concluded. With the theoretical bases covered, the letter turns to the practical matter at hand: “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.” The theoretical possibility of the creation of such bombs—capable, as the letter surmises, of destroying entire ports—meant that the first possessor of this new technology would have a weapon that could easily turn the tide of a war, were it to take place.

Finally, the letter concludes with some suggestions as to appropriate actions to be taken: that the government become deeply involved in further atomic research, both in terms of keeping tabs on the work of theoretical physicists such as Szilárd and in funding research. The letter asserts that sufficient uranium ore for the construction of nuclear devices exists only in a few places around the world, and that one of them, the former Czechoslovakia, is under the control of the Nazis; furthermore, the Nazis have ceased selling uranium to other countries—the clear implication being that they have already embarked upon a program to develop a weapon. The logical progression of the flow from theory, to practical reality, to the need for urgent action complete, Einstein and Szilárd had to wait to hear if the government was going to respond appropriately.

Essential Themes

Within less than a month of the letter from Einstein and Szilárd, Germany invaded Poland and World War II had officially begun. Though the United States would not become involved in the war for another two years, the developing situation in Europe caused a delay in Roosevelt's receiving the letter. Not until October 11, 1939, did Alexander Sachs, who had suggested that Szilárd and Einstein write Roosevelt, present the letter to the president personally.

Roosevelt replied to Einstein by stating that he was appointing a committee to study the possibility of weaponizing uranium, but the immediate response did not go much further. Szilárd and others continued their experiments in much the same way that they had to that point. Roosevelt, as well as some atomic scientists, doubted the ability to control a chain reaction to the extent necessary to create an atomic bomb. It took until late 1941—around the time of the Japanese attack on Pearl Harbor, which finally drew the United States into World War II—for the American government to begin to work seriously to develop an atomic bomb. Though the letter did not have the immediate effect that Szilárd and Einstein had hoped, it did put the potential of atomic weaponry into the minds of those in charge of wartime policy, and did lead—eventually—to the start of what became known as the Manhattan Project.

However important the Manhattan Project was to ending World War II—by creating the atomic bombs that devastated and led to the surrender of Japan—the implications of Einstein's and Szilárd's letter went much further. Though Germany was not able to develop an atomic bomb before the United States, the United States would not remain the sole nuclear power for very long after the end of the war. Germany would be replaced by the Soviet Union as the main atomic rival of the United States, and the Cold War that followed World War II would shape the majority of the rest of the twentieth century. It also set a precedent that saw the heavy involvement of the US government in scientific weapons research—what future president Dwight D. Eisenhower called the “military-industrial complex.”

Bibliography and Additional Reading
  • Groves, Leslie R. Now It Can Be Told: The Story of the Manhattan Project. New York: Harper, 1962. Print.
  • Hargittai, István. The Martians of Science: Five Physicists Who Changed the Twentieth Century. New York: Oxford UP, 2006. Print.
  • Kelly, Cynthia C., ed. The Manhattan Project: The Birth of the Atomic Bomb in the Words of Its Creators, Eyewitnesses, and Historians. New York: Black Dog & Leventhal, 2007. Print.
  • Lanouette, William, and Bela Silard. Genius in the Shadows: A Biography of Leó Szilárd: The Man Behind the Bomb. New York: Scribner's, 1992. Print.
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