Analysis: Albert Einstein's Letter to Franklin D. Roosevelt

Date: August 2, 1939

Authors: Albert Einstein; Leó Szilárd

Genre: letter

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.

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.

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.