Leó Szilárd
Leó Szilárd (1898–1964)
Born	(1898-02-11)February 11, 1898 Budapest, Austria-Hungary
Died	May 30, 1964(1964-05-30) (aged 66) La Jolla, California, U.S.
Residence	Hungary Germany United States United Kingdom
Nationality	Austro-Hungarian Hungarian German American
Fields	[Nuclear physics, Molecular physicist]
Institutions	Budapest Technical University Technical University of Berlin Humboldt University of Berlin Columbia University University of Chicago Brandeis University Salk Institute
Alma mater	Technische Universität Berlin Humboldt Universität zu Berlin
Doctoral advisor	Max von Laue
Other academic advisors	Albert Einstein
Notable students	Bernard T. Feld
Known for	Nuclear chain reaction Szilárd petition Einstein–Szilárd letter Cobalt bomb Absorption refrigerator Szilárd Engine Einstein-Szilard refrigerator
Influenced	James L. Tuck
Notable awards	Atoms for Peace Award (1959)

Leó Szilárd (Hungarian: Szilárd Leó, February 11, 1898 – May 30, 1964 German: Spitz, Leo until age 2) was an Austro-Hungarian physicist and inventor who conceived the nuclear chain reaction in 1933, patented the idea of a nuclear reactor with Enrico Fermi, and in late 1939 wrote the letter for Albert Einstein's signature that resulted in the Manhattan Project that built the atomic bomb. He also conceived the electron microscope, the linear accelerator (1928, not knowing Gustav Ising's 1924 journal article and Rolf Widerøe's operational device) and the cyclotron.^[1] Szilárd himself did not build all of these devices, or publish these ideas in scientific journals, and so their credit often went to others. As a result, Szilárd never received the Nobel Prize, but two of his inventions did.^[2]

He was born in Budapest in the Austro-Hungarian Empire, and died in La Jolla, California.

Early life[link]

Leo Szilárd at age 18

Szilárd was born in 1898 to middle-class parents in Budapest, Hungary as the son of a civil engineer. His parents, both Jewish, Louis Spitz and Thekla Vidor, raised Leó in the Városligeti fasor of Pest, Hungary. From 1908–1916 Leó attended Reáliskola high school in his home town. Showing an early interest in physics and a proficiency in mathematics, in 1916 took the Eötvös Prize, a national prize for mathematics.^[3][4]

He enrolled as an engineering student at Budapest Technical University during 1916. The following year the Austro-Hungarian Army drafted him as an officer-candidate. Prior to his regiment being sent to the front lines, Szilárd fell ill with Spanish Influenza and he was returned home for hospitalization. Later he was informed that his regiment had been nearly annihilated in battle, so the sickness probably saved his life.^[5] He was discharged honorably at the end of the war.

During 1919 he resumed engineering studies at Budapest Technical University but soon decided to leave Hungary because of the chaotic political situation and the rising antisemitism under the Horthy regime. Szilárd 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 Über die thermodynamischen Schwankungserscheinungen (On The Manifestation of Thermodynamic Fluctuations), praised by Einstein, won top honors in 1922. In 1923 he was awarded a doctorate in physics from Humboldt University of Berlin.

He was appointed as assistant to von Laue at the University of Berlin's Institute for Theoretical Physics during 1924. During 1927 he finished his habilitation and became a Privatdozent (private lecturer) in physics at University of Berlin. During his time in Berlin he worked on numerous technical inventions. For example, in 1928 he submitted a patent application for the linear accelerator and, in 1929, he applied for a patent for the cyclotron. During the 1926-1930 period, he worked with Einstein to develop a refrigerator, notable because it had no moving parts.^[6] Szilárd's 1929 paper, Über die Entropieverminderung in einem thermodynamischen System bei Eingriffen intelligenter Wesen" (On the reduction of entropy in a thermodynamic system by the interference of intelligent beings) Z. Physik 53, 840-856, introduced the thought experiment now called Szilárd's engine and became important in the history of attempts to understand Maxwell's demon.

Developing the idea of the nuclear chain reaction[link]

An image from the Fermi–Szilárd "neutronic reactor" patent

Szilárd went to London in 1933 where he read an article in The Times summarizing a speech given by Ernest Rutherford in which he rejected the possibility of using atomic energy for practical purposes. Rutherford's speech remarked specifically on the recent 1932 work of his students John Cockcroft and Ernest Walton in "splitting" lithium into alpha particles, by bombardment with protons from a particle accelerator they had constructed:

We might in these processes obtain very much more energy than the proton supplied, but on the average we could not expect to obtain energy in this way. It was a very poor and inefficient way of producing energy, and anyone who looked for a source of power in the transformation of the atoms was talking moonshine. But the subject was scientifically interesting because it gave insight into the atoms.^[7]

Although the atom had been split and energy released, nuclear fission had not yet been discovered. However Szilárd was reportedly so annoyed at Rutherford's dismissal that on the same day the article about the Rutherford speech was printed in the morning paper, Szilárd conceived of the idea of nuclear chain reaction (analogous to a chemical chain reaction), using recently-discovered neutrons. The idea did not use the mechanism of nuclear fission, which was not then known, but Szilárd realized that if neutrons could initiate any sort of energy-producting nuclear reaction, such as the one that had occurred in lithium, and could be produced themselves by the same reaction, energy might be obtained with little input, since the reaction would be self-sustaining. The following year he filed for a patent on the concept of the neutron-induced nuclear chain reaction. Richard Rhodes described Szilárd's moment of inspiration:

In London, where Southampton Row passes Russell Square, across from the British Museum in Bloomsbury, Leo Szilárd waited irritably one gray Depression morning for the stoplight to change. A trace of rain had fallen during the night; Tuesday, September 12, 1933, dawned cool, humid and dull. Drizzling rain would begin again in early afternoon. When Szilárd told the story later he never mentioned his destination that morning. He may have had none; he often walked to think. In any case another destination intervened. The stoplight changed to green. Szilárd stepped off the curb. As he crossed the street time cracked open before him and he saw a way to the future, death into the world and all our woes, the shape of things to come.^[8]

Szilárd first attempted to create a nuclear chain reaction using beryllium and indium, but these elements did not produce a chain reaction. During 1936, he assigned the chain-reaction patent to the British Admiralty to ensure its secrecy (GB 630726 ). Szilárd also was the co-holder, with Nobel Laureate Enrico Fermi, of the patent on the nuclear reactor (U.S. Patent 2,708,656).

During 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 the successful nuclear fission experiment conducted during 1939 in Germany by Otto Hahn, Fritz Strassmann, Lise Meitner, and Otto Robert Frisch, Szilárd and Fermi 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 enabling nuclear weapons. Szilárd later described the event: "We turned the switch and saw the flashes. We watched them for a little while and then we switched everything off and went home." He understood the implications and consequences of this discovery, though. "That night, there was very little doubt in my mind that the world was headed for grief."^[8]

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 German 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 December 2, 1942.^[9]

The Manhattan Project[link]

The Metallurgical Laboratory scientists, with Szilárd third from right.

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 result in their creation. During August 1939 he approached his old friend and collaborator Albert Einstein and convinced him to sign the letter, lending his fame to the proposal.^[10] The Einstein–Szilárd letter resulted in the establishment of research into nuclear fission by the U.S. government and ultimately to the creation of the Manhattan Project; FDR gave the letter to an aide, General Edwin M. "Pa" Watson with the instruction: "Pa, this requires action!"^[11] Later, Szilárd relocated 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, during 1942.

As the war continued, Szilárd became increasingly dismayed that scientists were losing control over their research to the military, and argued many times with General Leslie Groves, military director of the project. His resentment towards the U.S. government was exacerbated by his failure to prevent the destructive use of the atomic bomb through having a test explosion that could be witnessed by Japanese observers who would then have the opportunity to surrender and spare lives.^[12]

Szilárd became a naturalized citizen of the United States during 1943.

Views on the use of nuclear weapons[link]

In 1932, Szilárd read the science fiction novel The World Set Free by H. G. Wells, a book which he said made a great impression on him.^[13]

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 the political and economic devastation in Hungary following World War I, which had been eviscerated by the Treaty of Trianon, 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 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. suffering many casualties in the Pacific Ocean region, the new U.S. President Harry Truman agreed with advisers and chose to use atomic bombs against Hiroshima and Nagasaki over the protestations of Szilárd and other scientists.

After the war[link]

Szilárd and Norman Hilberry at the site of CP-1, at the University of Chicago, some years after the war

During 1947, Szilárd switched topics of study because of his horror of atomic weapons, changing from physics to molecular biology, working extensively with Aaron Novick. In February 1950 Szilárd proposed a cobalt bomb, a new kind of nuclear weapon using cobalt as a tamper, which he said might destroy 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." He argued that "violence would not have been necessary if we had been willing to negotiate." During 1961 Szilárd published a book of short stories, The Voice of the Dolphins, in which he dealt with the moral and ethical issues raised by the Cold War and his own role in the development of atomic weapons. The title story described an international biology research laboratory in Central Europe. This became reality after a meeting in 1962 with Victor F. Weisskopf, James Watson and John Kendrew.^[14] When the European Molecular Biology Laboratory was established, the library was named The Szilárd Library and the library stamp features dolphins.^[15] Szilárd married Gertrud Weiss in 1951.^[16] During 1960, Szilárd was diagnosed with bladder cancer. He underwent cobalt therapy at New York's Memorial Sloan-Kettering Hospital using a cobalt 60 treatment regimen that he designed himself. He was familiar with the properties of this isotope from his work on the cobalt bomb. A second round of treatment with an increased dose followed during 1962. The doctors tried to tell him that the increased radiation dose would kill him, but he said it wouldn't, and that anyway he would die without it. The higher dose did its job and his cancer never returned. This treatment became standard for many cancers and is still used. During 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 encourage rational arms control and nuclear disarmament. He spent his last years as a fellow of the Salk Institute in San Diego alongside his old friend Jacob Bronowski. During May 1964, Szilárd died in his sleep of a heart attack at the age of sixty-six.

Honors[link]

• American Academy of Arts and Sciences 1954
• American Physical Society
• Atoms for Peace Award 1959
• National Inventors Hall of Fame
• Humanist of the Year 1960

• The crater Szilárd (34.0°N, 105.7°E, 122 km dia.) on the far side of the Moon is named after him.

See also[link]

• Timeline of low-temperature technology

Notes[link]

References[link]

• Bess, Michael (1993). Realism, Utopia, and the Mushroom Cloud: Four Activist Intellectuals and their Strategies for Peace, 1945-1989. University of Chicago Press. ISBN 0-226-04421-1. 
• Blumesberger, Susanne; et al. (2002). Handbuch österreichischer Autorinnen und Autoren jüdischer Herkunft. 1. K. G. Saur. ISBN 3-598-11545-8. 
• Esterer, Arnulf K.; Esterer, Luise A. (1972). Prophet of the Atomic Age: Leo Szilárd. New York: Julian Messner. ISBN 0-671-32523-X. 
• Frank, Tibor (2008). Double exile: migrations of Jewish-Hungarian professionals through Germany to the United States, 1919-1945. Exile Studies. 7. Germany: Peter Lang. ISBN 3-03911-331-3. 
• Lanouette, William; Silard, Bela (1992). Genius in the Shadows: A Biography of Leo Szilárd: The Man Behind The Bomb. New York: Charles Scribner's Sons. ISBN 0-684-19011-7. 
• Rhodes, Richard (1986). The Making of the Atomic Bomb. New York: Simon and Schuster. ISBN 0671441337.  edit
• Szilárd, Leo; Weiss-Szilárd, Gertrud (1978). Leo Szilárd: His Version of the Facts : Selected Recollections and Correspondence. Spencer R. Weart (ed.). Cambridge, MA.: The MIT Press. ISBN 0-262-69070-5. 
• Szilárd, Leo (1992). The Voice of the Dolphins: And Other Stories (Expanded edition from 1961 original ed.). Stanford, CA.: Stanford University Press. ISBN 0-8047-1754-0. 

External links[link]

Wikiquote has a collection of quotations related to: Leó Szilárd

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
• The Szilárd Library at the European Molecular Biology Laboratory
• Szilárd lecture on war
• Szilárd's math genealogy

Patents

• U.S. Patent 2,708,656—Neutronic reactor—E. Fermi, L. Szilárd, filed December 19, 1944, issued May 17, 1955
• U.S. Patent 1,781,541—Einstein Refrigerator—co-developed with Albert Einstein filed in 1926, issued November 11, 1930

Jacob Bronowski (18 January 1908 – 22 August 1974) was a Polish-Jewish British mathematician, biologist, historian of science, theatre author, poet and inventor. He is best remembered as the presenter and writer of the 1973 BBC television documentary series, The Ascent of Man, and the accompanying book.

Life and work[link]

Jacob Bronowski was born in Łódź, Congress Poland, Russian Empire, in 1908. His family moved to Germany during the First World War, and then to England in 1920. Although, according to Bronowski, he knew only two English words on arriving in Great Britain,^[1] he gained admission to the Central Foundation Boys' School in London and went on to study at the University of Cambridge and graduated as the senior wrangler.

As a mathematics student at Jesus College, Cambridge, Bronowski co-edited—with William Empson—the literary periodical Experiment, which first appeared in 1928. Bronowski would pursue this sort of dual activity, in both the mathematical and literary worlds, throughout his professional life. He was also a strong chess player, earning a half-blue while at Cambridge and composing numerous chess problems for the British Chess Magazine between 1926 and 1970.^[2] He received a Ph.D. in mathematics in 1935, writing a dissertation in algebraic geometry. For a time in the 1930s he lived near Laura Riding and Robert Graves in Majorca. From 1934 to 1942 he taught mathematics at the University College of Hull. Beginning in this period, the British secret service MI5 kept Bronowski under surveillance believing he was a security risk, which is thought to have restricted his access to senior posts in the UK.^[3]

During the Second World War Bronowski worked in operations research for the UK's Department of Home Security, where he developed mathematical approaches to bombing strategy for RAF Bomber Command. At the end of the war, Bronowski was part of a British team which visited Japan to document the effects of the atomic bombings of Hiroshima and Nagasaki. Subsequently, he became Director of Research for the National Coal Board in the UK, but following his experiences of the after-effects of the Nagasaki and Hiroshima bombings, he turned to biology, as did his friend Leó Szilárd and many other physicists of that time, to better understand the nature of violence. Bronowski was an associate director of the Salk Institute from 1964.

In 1950, Bronowski was given the Taung child's fossilized skull and asked to try, using his statistical skills, to combine a measure of the size of the skull's teeth with their shape in order to discriminate them from the teeth of apes. Work on this turned his interests towards the human biology of humanity's intellectual products.

In 1967 Bronowski delivered the six Silliman Memorial Lectures at Yale University and chose as his subject the role of imagination and symbolic language in the progress of scientific knowledge. Transcripts of the lectures were published posthumously in 1978 as The Origins of Knowledge and Imagination and remain in print.

He first became familiar to the British public through appearances on the BBC television version of The Brains Trust in the late 1950s. His ability to answer questions on many varied subjects led to an offhand reference in an episode of Monty Python's Flying Circus where one character states that "He knows everything." However Bronowski is best remembered for his thirteen part series The Ascent of Man (1973), a documentary about the history of human beings through scientific endeavour. This project was intended to parallel art historian Kenneth Clark's earlier "personal view" series Civilisation (1969) which had covered cultural history.

During the making of The Ascent of Man, Bronowski was interviewed by the popular British chat show host Michael Parkinson. Parkinson later recounted that Bronowski's description of a visit to Auschwitz—Bronowski had lost many family members during the Nazi era—was one of Parkinson's most memorable interviews.^{[citation needed]}

Jacob Bronowski married Rita Coblentz in 1941.^[4] The couple had four children, all daughters, the eldest being the British academic Lisa Jardine and another being the filmmaker Judith Bronowski. He died in 1974 of a heart attack in East Hampton, New York^[5] a year after The Ascent of Man was completed, and was buried in the western side of London's Highgate Cemetery, near the entrance.

Books[link]

Jacob Bronowski's grave in Highgate Cemetery, London.

• The Poet's Defence (1939)
• William Blake: A Man Without a Mask (1943)
• The Common Sense of Science (1951)
• The Face of Violence (1954)
• Science and Human Values. New York: Julian Messner, Inc.. 1956, 1965. 
• William Blake: The Penguin Poets Series (1958)
• The Western Intellectual Tradition, From Leonardo to Hegel (1960) - with Bruce Mazlish
• Biography of an Atom (1963) - with Millicent Selsam
• Insight (1964)
• The Identity of Man. Garden City: The Natural History Press. 1965. 
• Nature and Knowledge: The Philosophy of Contemporary Science (1969)
• William Blake and the Age of Revolution (1972)
• The Ascent of Man (1974)
• A Sense of the Future (1977)
• Magic, Science & Civilization (1978)
• The Origins of Knowledge and Imagination (1978)
• The Visionary Eye: Essays in the Arts, Literature and Science (1979) - edited by Piero Ariotti and Rita Bronowski.

References[link]

External links[link]

Wikiquote has a collection of quotations related to: Jacob Bronowski

• Jacob Bronowski at the Internet Movie Database
• O'Connor, John J.; Robertson, Edmund F., "Jacob Bronowski", MacTutor History of Mathematics archive, University of St Andrews, http://www-history.mcs.st-andrews.ac.uk/Biographies/Bronowski.html . Has biography, pictures, and obituary.
• The Jacob Bronowski Archive
• Video related to The Ascent of Man - selections vary
• The Bronowski Trophy (chess)