Discover

(Redirected from Leo Szilard)

'Leó Szilárd' (Hungarian: ''Szilárd Leó'', February 11, 1898 – May 30, 1964) was a Hungarian-American physicist who conceived the nuclear chain reaction and worked on the Manhattan Project. He was born in Budapest under the Austro-Hungarian Empire, and died in La Jolla, California.

Contents

Early life

Developing the idea of the nuclear chain reaction

The Manhattan Project

Views on the use of nuclear weapons

After the war

Personality

Honors

Bibliography

References

External links

Early life

Szilárd was born in Budapest to a Jewish family at the time of the Austro-Hungarian monarchy before World War I as the son of a civil engineer. From 1908-1916 he attended ''Reáliskola'' in his home town. He was enrolled as an engineering student at Budapest Technical University in 1916 but had to join the Austro-Hungarian Army in 1917 as officer-candidate where he was honorably discharged at the end of the war. In 1919 he resumed engineering studies at Budapest Technical University but soon decided to leave Hungary because of the rising antisemitism under the Horthy regime which led to the introduction of a numerus clausus for Jewish students at Hungary's universities. He continued engineering studies at Technische Hochschule (Institute of Technology) in Berlin-Charlottenburg. He soon changed to physics there and took physics classes from Einstein, Planck, and Max von Laue. His dissertation on thermodynamics in 1922 was praised by Einstein and awarded the highest honor. In 1923 he received the doctorate in physics from the Humboldt University of Berlin. He was appointed as assistant to von Laue at the University of Berlin's Institute for Theoretical Physics in 1924. In 1927 he finished his habilitation and became a ''Privatdozent'' (instructor) in Physics at University of Berlin. During his time in Berlin he was working on numerous technical inventions (1928 German patent application on the linear accelerator, 1929 German patent application on the cyclotron, since 1926 work with Einstein on the construction of a refrigerator without moving parts (US patent number 1,781,541 on November 11, 1930).

Developing the idea of the nuclear chain reaction

In 1933 Szilárd fled to London to escape Nazi persecution, where he read an article written by Ernest Rutherford in ''The Times'' which rejected the possibility of using atomic energy for practical purposes. Although nuclear fission had not yet been discovered, Szilárd was reportedly so annoyed at this dismissal that he conceived of the idea of the nuclear chain reaction while waiting for traffic lights to change on Southampton Row in Bloomsbury. The following year he filed for a patent on the concept.
Szilárd first attempted to create a chain reaction using beryllium and indium, but these elements did not produce a chain reaction. In 1936, he assigned the chain-reaction patent to the British Admiralty to ensure its secrecy (). Szilárd also was the co-holder, with Nobel Laureate Enrico Fermi, of the patent on the nuclear reactor ().
In 1938 Szilárd accepted an offer to conduct research at Columbia University in Manhattan, and moved to New York, and was soon joined by Fermi. After learning about nuclear fission in 1939, they concluded that uranium would be the element capable of sustaining a chain reaction. Szilárd and Fermi conducted a simple experiment at Columbia and discovered significant neutron multiplication in Uranium, proving that the chain reaction was possible and opening the way to nuclear weapons. Szilárd later described the event: "We turned the switch, saw the flashes, watched for ten minutes, then switched everything off and went home. That night I knew the world was headed for sorrow".^[1]
At around that time the Germans and others were in a race to produce a nuclear chain reaction. German attempts to control the chain reaction sought to do so using graphite, but these attempts proved unsuccessful. Szilárd realized graphite was indeed perfect for controlling chain reactions, just as the Germans had determined, but that the method of producing graphite used boron carbide rods, and the minute amount of boron impurities in the manufactured graphite was enough to stop the chain reaction. Szilárd had graphite manufacturers produce boron-free graphite. As a result, the first human-controlled chain reaction occurred on 2 December 1942.^[2]

The Manhattan Project

Szilárd was directly responsible for the creation of the Manhattan Project. He drafted a confidential letter to Franklin D. Roosevelt explaining the possibility of nuclear weapons, warning of Nazi work on such weapons and encouraging the development of a program which could lead to their creation. In August 1939 he approached his old friend and collaborator Albert Einstein and convinced him to sign the letter, lending the weight of his fame to the proposal.^[3] The Einstein-Szilárd letter led directly to the establishment of research into nuclear fission by the U.S. government and ultimately to the creation of the Manhattan Project; FDR handed the letter off to an aide, General Edwin M. "Pa" Watson with the instruction: "Pa, this requires action!"^[4] Later, Szilárd moved to the University of Chicago to continue work on the project. There, along with Fermi, he helped to construct the first "neutronic reactor", a uranium and graphite "atomic pile" in which the first self-sustaining nuclear chain reaction was achieved, in 1942.
As the war continued, Szilárd became increasingly dismayed that scientists were losing control over their research to the military, and clashed many times with General Leslie Groves, military head of the project. His resentment towards the U.S. government was exacerbated by his failed attempt to avoid the use of the atomic bomb in war.
Szilárd became a naturalized citizen of the United States in 1943.

Views on the use of nuclear weapons

In 1932, Szilárd had read about the fictional "atomic bombs" described in H. G. Wells's science fiction novel ''The World Set Free''. This inspired him to be the first scientist to seriously examine the science behind the creation of nuclear weapons.
As a scientist, he was the first person to conceive of a device that, using a nuclear chain reaction as fuel, could be used as a bomb.
As a survivor of a devastated Hungary after World War I, and having witnessed the subsequent terror of the Reds and the Whites, Szilárd developed an enduring passion for the preservation of human life and freedom, especially freedom to communicate ideas.
He hoped that the U.S. government, which prior to World War II had staunchly opposed the bombing of civilians, would not use nuclear weapons because of their potential for use against civilian populations. Szilárd hoped that the mere threat of such weapons would force Germany and/or Japan to surrender. He drafted the Szilárd petition advocating demonstration of the atomic bomb. However with the European war concluded and the U.S. taking heavy casualties in the Pacific, the new U.S. President Harry Truman sided with advisors and chose to use atomic bombs against Hiroshima and Nagasaki over the protestations of Szilárd and other scientists.
Before the war Szilárd had considered the U.S. to be the one truly humane government in the world. That was the reason why he chose to assist the U.S. in developing the atomic bomb. He abandoned this view after the weapons' use.

After the war

In 1947, Szilárd switched fields of study because of his horror of atomic weapons, moving from physics to molecular biology, working extensively with Aaron Novick. He proposed, in February of 1950, a new kind of nuclear weapon using cobalt as a tamper, a cobalt bomb, which he said might wipe out all life on the planet. ''U.S. News & World Report'' featured an interview with Szilárd in its August 15, 1960 issue, "President Truman Didn't Understand." His penchant to use language provocatively and say things which most readers would dismiss as absurd is well evidenced in this quote from that interview, "But again, I don't believe this staging a demonstration was the real issue, and in a sense it is just as immoral to force a sudden ending of a war by threatening violence as by using violence. My point is that violence would not have been necessary if we had been willing to negotiate."
Szilárd married Gertrud Weiss in 1951. He spent his last years as a fellow at the Salk Institute in San Diego.
In 1960, Szilárd was diagnosed with bladder cancer. He underwent radiation therapy at New York's Memorial Hospital using a treatment regimen that he designed himself. A second round of treatment followed in 1962; Szilárd's cancer remained in remission thereafter.
In 1962, Szilárd was part of a group of scientists who founded the Council for a Livable World. The Council's goal was to warn the public and Congress of the threat of nuclear war and lead the way to rational arms control and nuclear disarmament.
In May of 1964, Szilárd died in his sleep of a heart attack at the age of sixty-six. At his memorial it was said that Death was required to come to him while asleep, or otherwise he would have outwitted it.

Personality

Szilárd was well known to his colleagues as an eccentric, lightning-quick thinker who "seemed fond of startling people" with strange, seemingly incongruous, yet extremely perceptive statements and questions. He was also extremely good at predicting political events. He is said to have predicted World War I as a boy, and when the Nazi party first appeared, he predicted that it would one day control Europe. In 1934, he foresaw the details of World War II. He then made a habit of residing in hotel rooms, with a packed suitcase always on hand. He often did a lot of his best thinking while taking a bath.

Honors

★ American Academy of Arts and Sciences 1954

★ American Physical Society

★ National Inventors Hall of Fame

★ The impact crater Szilárd (34.0°N, 105.7°E, 122km dia.) on the lunar farside is named after him.

Bibliography

★ William Lanouette with Bela Silard, "Genius in the Shadows: A Biography of Leo Szilard: The Man Behind The Bomb" (Charles Scribner's Sons, 1992) ISBN 0684190117

References

1. Rhodes, "The Making Of The Atomic Bomb", Simon & Schuster, 1986
2. The German Uranium Project, , Hans A., Bethe, Physics Today Online,
3. Einstein's Letter to Franklin D. Roosevelt
4. "Pa, this requires action!"

External links

'Information'

★ Leo Szilárd Online - an "Internet Historic Site" (first created March 30, 1995) maintained by Gene Dannen

★ Leo Szilárd's page at atomicarchive.com

★ Einstein's Letter to President Roosevelt - 1939

★ Annotated bibliography for Leo Szilárd from the Alsos Digital Library

★ Szilárd biography at Hungary.hu

★ Council for a Livable World
'Patents'

★ -- ''Neutronic reactor'' -- E. Fermi, L. Szilárd, filed December 19, 1944, issued May 17, 1955

★ -- Einstein Refrigerator -- co-developed with Albert Einstein filed in 1926, issued November 11, 1930