Hungarian-American physicist, Leo Szilard was the proponent of the nuclear chain reaction in 1933. He was one of the first scientists who recognized the significance of nuclear fission which was the key element behind The Manhattan Project and the development of atomic weapons.
With Enrico Fermi, he built the first nuclear reactor.
He also developed of a means to separate radioactive elements and isotopes, known as the Szilard-Chalmers effect, which was extensively used in the preparation of medical isotopes.
Early Life and Educational Background
Born in 1898, on the eleventh day of February, Leo Szilard was the son of an engineer, Louis Spitz, and a member of one of the more affluent Jewish families. His name was originally Leo Spitz, but it was changed to the Hungarian version, Szilard, in 1900.
As a child, his interest in physics came at an early age of just 13 years old and he won a mathematics prize in 1916. He attended the public school of Budapest before he was drafted into the 1917 Austro-Hungarian army.
While he was in the army, Szilard was sent to the officer’s training school but was spared having to engage in active duty because he caught influenza. When the war ended, Szilard initially stayed in Budapest but, because of political unrest in the area and due to a lack of better educational opportunities, he moved to Berlin in 1919.
During his time in Berlin, Szilard took engineering courses at the Technische Hochschule or the Institute of Technology. His main interest was still physics and he was drawn to the works of the great minds such as Albert Einstein, Erwin Schroedinger, Max Von Laue, Fritz Haber, Walter Nernst, and Max Planck. Most of these physicists were teaching in Berlin at that time.
Szilard gave up his courses in engineering in 1921, and instead studied physics in the University of Berlin, being taught by the renowned physicist Max von Laue. A year later, Szilard earned his cum laude doctorate with his dissertation “Uber die thermodynamischen Schwankungserscheinungen” (About the thermodynamic fluctuation phenomena) where he discussed the Second Law of Thermodynamics and how it affected not just mean values but the fluctuating values. The ideas from his dissertation are now the bases of modern theories.
After completing his doctorate, Szilard worked at the Kaiser Wilhelm Institute in Berlin along with Hermann Mark, a chemist who is well known for his contributions for the progress of polymer science. During this time, the studies conducted by Szilard focused on how X-rays scattered in crystals and the polarization of x-rays when reflected by crystals.
During the years 1925-1933, Szilard worked with Albert Einstein and together they applied for numerous patents for their collaborative work. One of their more famous patents was the refrigeration system which they based on pumping metals through a moving magnetic field. Their interest during that time caught the attention of A.E.G.—a company which was also known as the German General Electric company. They hoped that the company would produce a refrigerator based on the patent they held. While this refrigerator never materialized, the same refrigeration system they created was used in 1942 to develop an atomic reactor.
Szilard relocated to England in 1933—the same time when Adolf Hitler rose to power. There, he had collaborations with Thomas A. Chalmers where they devised the Szilard-Chalmers process. This is a technique for isotopes separation and was extensively used in the preparation of medical isotopes. Most of Szilard’s activities during his stay in London involved patents for his inventions, as these patents helped improve his income. During this time, he helped persuade Sir William Beveridge to establish the Academic Assistance Council, which aimed to help prosecuted scientists to leave then Nazi Germany.
From 1935 to 1937, Szilard was one of the research physicists of the Clarendon Laboratory at Oxford University and researched nuclear physics, investigating nuclear chain reactions.
The Nuclear Chain Reaction
During his time in London, Szilard first attempted to create a nuclear chain reaction by using indium and beryllium, but he did not achieve the desired effects.
Szilard emigrated to the United States in 1938 and joined the Manhattan Project for research into creating an atomic bomb. He worked at Columbia University, New York and shortly after, physicist Enrico Fermi joined him. With Enrico Fermi, Szilard deduced how uranium could sustain a chain reaction so that it can be used for nuclear weapons. When the scientists realized this, Szilard also understood what their discovery implied—that it could cause much grief for the world if in the wrong way.
He carried out further nuclear research at the University of Chicago from 1942 to 1945 and with Enrico Fermi, they built the first nuclear reactor.
Szilard’s Ideas and Views Concerning Nuclear Weapons
Szilard read H.G. Wells’ “The World Set Free”; a novel which had a great impact on his thoughts. Since he was a survivor of economic and political strife in Hungary, he developed an unending passion for preserving the human life as well as maintaining freedoms.
He had advocated against using atomic bombs, knowing how it would also affect not just those considered as “enemies” but civilians and innocents. Szilard had hoped that the mere thought of such a weapon could make Japan and Germany surrender and end The Second World War. However, the atomic bombs used in Nagasaki and Hiroshima were used despite the protests from Szilard and other scientists.
Szilard joined the Emergency Committee of Atomic Scientists in 1946 and concentrated his efforts on nuclear safety and promoting the peaceful use of nuclear energy. He spent his final years as a fellow of the Salk Institute for Biological Studies in California.
Leo Szilard died on May 30, 1964, aged 66 in La Jolla, California.