Leó Szilárd

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Leó Szilárd (1960)

Leó Szilárd (born February 11, 1898 in Budapest , Austria-Hungary ; † May 30, 1964 in La Jolla , California ) was a Hungarian - German - American physicist and molecular biologist . Szilárd is best known for his involvement in the construction of the first US atomic bomb ( Manhattan Project ). However, after the successful technical construction of the bomb, he strongly advised against its use in war and tried to prevent it in cooperation with other physicists. He considered the first assignment at Hiroshima to be a mistake, the second at Nagasaki as a cruelty. Szilárd was a highly gifted theorist , a restless inventor and visionary full of ideas, and was considered an original, sometimes bizarre personality.

Life

In Hungary

Leó Szilárd in 1916 at the age of 18

Szilárd came from an upper-class Jewish family in Budapest , whose ancestors had immigrated to Hungary from Galicia . The family originally carried the surname Spitz on the paternal side , but had it changed in 1902 to the Hungarian-sounding Szilárd ( Hungarian for "solid"). The father Lajos (1860–1955) was an engineer and owner of a company for bridge and railway construction. The mother Thekla, b. Vidor (1860-1939) came from a family of doctors. Leó was the oldest of three children and lived his childhood in the old Austro-Hungarian monarchy of the pre-war period. From 1908 to 1916, he attended the Realoberschule in his hometown

In 1916 Szilárd enrolled as a student for an electrical engineering degree at the Budapest Technical University (today: Budapest University of Technology and Economics ). In 1917, however, he was drafted into the Austro-Hungarian Army as an officer candidate , so that he could not resume studies until 1919. Because of the unfavorable economic conditions and the unstable political situation in Hungary in the post-war period and also because of the increasing anti-Semitism under the Horthy regime, which led to restrictions for Jewish students at Hungarian universities, he left his home country for Germany .

In Germany

Szilárd enrolled at the Technical University Berlin-Charlottenburg as an engineering student . After a short time, however, he switched to physics at the Friedrich Wilhelms University , where greats like Albert Einstein , Max Planck and Max von Laue researched and taught. The latter gave him a dissertation topic from the theory of relativity in the first semester , but he never finished it. Instead, he solved a difficult problem in statistical thermodynamics . This work entitled On the thermodynamic fluctuation phenomena prompted Einstein to the highest praise, was promptly recognized as a full doctoral thesis and published in 1925 in the renowned Annalen der Physik .

In 1927 Szilárd received the license to teach as a private lecturer . His post- doctoral thesis published in 1929 on the reduction of entropy in a thermodynamic system during interventions by intelligent beings linked the concepts of intelligence , memory , entropy and information for the first time and became one of the foundations of mathematical information theory after the Second World War . During his time in Berlin he devoted himself to numerous technical inventions (1928 German patent application for a linear accelerator , 1929 German patent application for a cyclotron , since 1926 working together with Einstein on the construction of a refrigerator without a compressor or other moving parts).

In 1932, after the discovery of the neutron , he switched entirely to nuclear physics . However, when the National Socialists seized power, he no longer carried out the experiments he had planned in Lise Meitner's laboratory in Germany. After the Reichstag fire in 1933, he first had to go to Vienna and then to England .

In England

Leo Szilard in London in 1934

The idea of ​​the nuclear chain reaction

According to Szilard's own account, the idea of ​​a nuclear chain reaction by released neutrons came to him after reading an article in the Times on September 12, 1933 , in which Ernest Rutherford was quoted as saying: “ anyone who looked for a source of power in the transformation of the atoms was talking moonshine ”. While he pondered this article as he walked the streets of London , while waiting for the traffic lights on the corner of Southampton Row in Bloomsbury, the crucial idea came to him.

He then began to look for isotopes with which such a chain reaction could be set in motion. The first candidates were isotopes of beryllium , later of indium . While working in the radiation department at St Bartholomew's Hospital in London , he discovered the so-called Szilárd-Chalmers effect for the separation of chemically identical isotopes.

However, significant were two patents on the possible effects of neutron bombardment of atomic nuclei , which he submitted in March 1934, and on June 28 the same year as two parts under one title: Improvements chemical in the conversion elements ( Improvements in or relating to the transmutation of chemical elements ). In the first part he described, among other things, the possibility of radionuclide batteries , as they are used in satellites today , and outlined the mechanisms of nuclear fusion without already coining the term. In the second part, he was the first researcher to describe the nuclear chain reaction when a critical mass is exceeded - that is, the basics of nuclear energy and nuclear weapons .

The secrecy of the patent

Szilárd, who had a keen sense for political processes (he is said to have clearly predicted both world wars and their outcome), made sure that the patent was assigned to the British Admiralty and therefore not published because it was about the possible military usability recognized. Later he said:

“This was probably the first time that the concept of critical mass was developed and a chain reaction was seriously discussed. I knew what that meant (I had read HG Wells ), so I wanted to avoid having this patent published. The only way to do that was to turn it over to the government. And so I ceded the patent rights to the British Admiralty. "

However, his hypotheses have not yet been tested experimentally . On the one hand there was a lack of money for the chemical elements that could be used as neutron multipliers , on the other hand it was due to Szilard's unrest, which persisted even after he was employed at the Clarendon Laboratory in Oxford . In 1938, after the Munich Agreement , he left Europe for the USA because of premonitions of war.

In America

First nuclear reactor and Manhattan project

Einstein's letter to Roosevelt formulated by Szilárd ( original English text here )
The team that built the first nuclear reactor in Chicago in 1942 . Third from the right in a light coat: Szilárd. First row on the far left Enrico Fermi , next to Walter Zinn .

Otto Hahn and Fritz Straßmann succeeded in 1938 in Berlin in converting uranium into barium by means of neutron bombardment , which Lise Meitner and her nephew Otto Frisch correctly interpreted as nuclear fission . Szilárd found out about it through his friend Eugene Wigner in Princeton , and his own experiment took place on March 3, 1939 in the Met Labs of Columbia University . Together with Walter Zinn , Szilárd observed the flashes of light on a television tube caused by nuclear fission by released neutrons . A radium source, borrowed from borrowed money, served as the source for the stimulating neutrons.

Concerned about the lack of further publications by Hahn's researchers on the topic of nuclear fission (which he interpreted as an indication that the German government had recognized the topic as important and would now develop something threatening in military, secret research) and the strengthening of National Socialism and fascism in Europe, he and other researchers persuaded Einstein in 1939 to sign a pre-formulated letter to President Roosevelt , in which he was asked to have an atom bomb developed in order to forestall a possible development of nuclear weapons by Nazi Germany. This letter is seen as a crucial document for the start of the Manhattan Project for the construction of the first nuclear weapons.

The National Socialist police authorities classified Szilárd as an enemy of the state: In the spring of 1940 the Reich Main Security Office in Berlin - which mistakenly suspected him to be in Great Britain - placed him on the special wanted list GB , a list of people who would be killed in the event of a successful invasion and occupation of the British Isles by the Wehrmacht, special SS commandos following the occupation forces were to be identified and arrested with special priority.

Three other people directly or indirectly involved in the Manhattan Project had almost parallel lives to that of Szilárd: Edward Teller , John von Neumann and Eugene Wigner . All came from Budapest Jewish families with a German cultural background. All of them had emigrated from Hungary to Germany, where they had studied and worked intensively in academic research, and all of them had to emigrate again in 1933 because of National Socialism. Because of these parallels, Szilárd occasionally spoke ironically of a "Hungarian conspiracy". The four Hungarians were also respectfully called Martians (Martians) by their American colleagues because of their apparently “extraterrestrial” intellectual abilities .

Together with Enrico Fermi , Szilárd created the first chain reaction in a reactor on December 2, 1942, and thus the first functioning nuclear reactor. Despite Szilard's insistence on secrecy, the most important results were first published by Joliot and finally by all scientists. Szilárd had to sell his patent rights to atomic energy in 1943 under pressure from the US government.

In 1945 Szilárd tried in vain to prevent the use of the constructed bombs in talks with physicists involved in the Manhattan project. He was also one of the co-signers of the Franck Report . He asked in vain to meet with Presidents Roosevelt and Truman . He organized a petition to the president, which 70 scientists signed in Oak Ridge and Chicago, but which never reached Truman and did not become public knowledge until 1961. He strongly condemned the later use of the atomic bomb on Hiroshima and Nagasaki .

Turning to molecular biology

Under the impression of this “fall from grace” of modern physics, but also impressed by the progress in molecular biology, Szilárd turned to molecular biology from 1946 onwards. Here he researched mainly on bacteriophages and bacteria and devoted himself to questions of theoretical biology. His characteristic eccentricity reappeared when he developed bladder cancer in 1959 . He then underwent self-designed radiation therapy at Memorial Hospital in New York City and was actually cured. In the later years of his life he was active in the movement for international disarmament and participated in several Pugwash conferences . He exercised sometimes violent public criticism of the policies of the US government.

Szilárd was also a brilliant writer, who also put his thoughts on paper in a few science fiction short stories (see below: Writings), which are regarded by connoisseurs as absolute classics of the genre.

On May 18, 1960, he and Wigner received the Atoms for Peace Award .

Others

Fonts

  • Leo Szilárd: About the decrease in entropy in a thermodynamic system when intelligent beings intervene . In: Journal of Physics. 53, 1929, pp. 840-856 doi: 10.1007 / BF01341281 . (Habilitation thesis, reproduced by Harvey S. Leff (Eds.) And Andrew F. Rex (Eds.) In: Maxwell's Demon - Entropy, Information, Computing. 1991, ISBN 0-691-08727-X ).
  • Collected Works of Leó Szilárd: Scientific Papers . MIT Press, Boston 1973, ISBN 0-262-06039-6 .
  • Leó Szilárd: The voice of the dolphins. Science fiction stories. Suhrkamp, ​​Frankfurt 1981, ISBN 3-518-37203-3 .

literature

Movies

Web links

Commons : Leó Szilárd  - collection of images, videos and audio files
Wikisource: Einstein-Szilárd-Brief  - Sources and full texts (English)

Individual evidence

  1. ↑ István Hargittai: The Martians of Science. Oxford University Press, 2006, ISBN 0-19-517845-9 , pp. 7 ff.
  2. ↑ Leo Szilard . Mathematics Genealogy Project. Retrieved May 4, 2010.
  3. ↑ About the thermodynamic fluctuation phenomena. Phil. Diss., Berlin 1922.
  4. ↑ Leo Szilard: About the extension of phenomenological thermodynamics to the fluctuation phenomena . In: Journal of Physics . tape 32 , December 1925, p. 753-788 , doi : 10.1007 / BF01331713 .
  5. ↑ Leó Szilárd: About the decrease in entropy in a thermodynamic system during interventions by intelligent beings . In: Journal of Physics . tape 53 , no. November 11-12 , 1929, pp. 840-856 , doi : 10.1007 / BF01341281 .
  6. ↑ Patent US1781541 : Refrigeration. Published November 11, 1930 . ‌
  7. ↑ patent GB630726 : Improvements in or relating to the transmutation of chemical elements. Registered March 30, 1936 , published September 28, 1949 . ‌
  8. ↑ “ This was the first time, I think, that the concept of critical mass was developed and that a chain reaction was seriously discussed. Knowing what this would mean - and I knew it, because I had read HG Wells - I did not want this patent to become public. The only way to keep it from becoming public was to assign it to the government. So I assigned this patent to the British Admiralty. ”Quoted from: Spencer R. Weart and Gertrud Weiss-Szilard (eds.): Leo Szilard, His Version of the Facts. Selected Recollections and Correspondence. MIT, Boston 1978, p. 18.
  9. ^ Entry on Szilárd on the special wanted list GB (reproduced on the website of the Imperial War Museum in London) .
  10. ^ Member Directory: Leo Szilard. National Academy of Sciences, accessed December 10, 2015 (Biographical Memoir by Eugene P. Wigner ).
  11. ↑ 38442 Szilard (1999 SU6) . JPL Small-Body Database Browser. Retrieved May 5, 2010.
  12. ^ The Register of Leo Szilard Papers 1898–1998 ( Memento of February 22, 2014 in the Internet Archive ). Mandeville Special Collections Library, University of California, San Diego. Retrieved February 9, 2014.
  13. ^ Carl Sagan: The Dragons of Eden pp. 354-355 ISBN 978-963-07-8448-1 [1977]
personal data
SURNAME Szilárd, Leó
BRIEF DESCRIPTION Hungarian-German-American physicist and molecular biologist
DATE OF BIRTH February 11, 1898
PLACE OF BIRTH Budapest
DATE OF DEATH May 30, 1964
Place of death La Jolla , California