Otto Robert Frisch

Otto Robert Frisch FRS[1] (1 October 1904 – 22 September 1979) was an Austrian physicist who worked on nuclear physics. With Lise Meitner he advanced the first theoretical explanation of nuclear fission (coining the term) and first experimentally detected the fission by-products. Later, with his collaborator Rudolf Peierls[1] he designed the first theoretical mechanism for the detonation of an atomic bomb in 1940.[2]

Otto Robert Frisch
Otto Frisch ID badge
Otto Robert Frisch's wartime Los Alamos ID badge photo.
Born1 October 1904
Died22 September 1979 (aged 74)
Cambridge, United Kingdom
United Kingdom
Known forAtomic bomb
AwardsFellow of the Royal Society[1]
Scientific career
InfluencesRudolf Peierls
Otto Robert Frisch signature

Early life

Frisch was born in Vienna in 1904, the son of Justinian Frisch, a painter, and Auguste Meitner Frisch, a concert pianist. He himself was talented at both but also shared his aunt Lise Meitner's love of physics and commenced a period of study at the University of Vienna, graduating in 1926 with some work on the effect of the newly discovered electron on salts.

Nuclear physics

After some years working in relatively obscure laboratories in Germany, Frisch obtained a position in Hamburg under the Nobel Prize-winning scientist Otto Stern. Here he produced work on the diffraction of atoms (using crystal surfaces) and also proved that the magnetic moment of the proton was much larger than had been previously supposed.[3]

The accession of Adolf Hitler to the chancellorship of Germany in 1933 caused Otto Robert Frisch to make the decision to move to London, where he joined the staff at Birkbeck College and worked with the physicist Patrick Maynard Stuart Blackett on cloud chamber technology and artificial radioactivity. He followed this with a five-year stint in Copenhagen with Niels Bohr where he increasingly specialised in nuclear physics, particularly in neutron physics.

Nuclear fission

Lise Meitner
Otto Frisch, Lise Meitner, and Glenn Seaborg

During the Christmas holiday in 1938 he visited his aunt Lise Meitner in Kungälv. While there she received the news that Otto Hahn and Fritz Strassmann in Berlin had discovered that the collision of a neutron with a uranium nucleus produced the element barium as one of its byproducts. Hahn, in a letter to Meitner, called this new reaction a "bursting" of the uranium nucleus. Frisch and Meitner hypothesized that the uranium nucleus had split in two, explained the process, estimated the energy released, and Frisch coined the term fission to describe it.

Political restraints of the Nazi era forced the team of Hahn and that of Frisch and Meitner (both of whom were Jewish) to publish separately. Hahn's paper described the experiment and the finding of the barium byproduct.[4] Meitner's and Frisch's paper explained the physics behind the phenomenon.[5]

Frisch went back to Copenhagen, where he was quickly able to isolate the pieces produced by fission reactions.[6] As Frisch himself later recalls, a fundamental idea of the direct experimental proof of the nuclear fission was suggested to him by George Placzek.[7][8] Many feel that Meitner and Frisch deserved Nobel Prize recognition for their contributions to understanding fission.[9]

In mid-1939 Frisch left Denmark for what he anticipated would be a short trip to Birmingham, but the outbreak of World War II precluded his return. With war on his mind, he and the physicist Rudolf Peierls produced the Frisch–Peierls memorandum at the University of Birmingham, which was the first document to set out a process by which an atomic explosion could be generated. Their process would use separated uranium-235, which would require a fairly small critical mass and could be made to achieve criticality using conventional explosives to create an immensely powerful detonation. The memorandum went on to predict the effects of such an explosion—from the initial blast to the resulting fallout. This memorandum was the basis of British work on building an atomic device (the Tube Alloys project) and also that of the Manhattan Project on which Frisch worked as part of the British delegation. Frisch and Rudolf Peierls worked together in the Physics Department at the University of Birmingham 1939–40.[10] He went to America in 1943 having been hurriedly made a British citizen.

Manhattan Project

The Godiva device at Los Alamos

In 1944 at Los Alamos, one of Frisch's tasks as the leader of the Critical Assemblies group was to accurately determine the exact amount of enriched uranium which would be required to create the critical mass, the mass of uranium which would sustain a nuclear chain reaction.[11] He did this by stacking several dozen 3 cm bars of enriched uranium hydride at a time and measuring rising neutron activity as the critical mass was approached. The hydrogen in the metal bars increased the time that the reaction required to accelerate. One day Frisch almost caused a runaway reaction by leaning over the stack, which he termed the "Lady Godiva assembly".[12] His body reflected neutrons back into the stack. Out of the corner of his eye he saw that the red lamps that flickered intermittently when neutrons were being emitted, were 'glowing continuously'.[12] Realizing what was happening, Frisch quickly scattered the bars with his hand. Later he calculated that the radiation dose was "quite harmless" but that if he "had hesitated for another two seconds before removing the material ... the dose would have been fatal".[12] "In two seconds he received, by the generous standards of the time, a full day's permissible dose of neutron radiation."[13] In this way his experiments determined the exact masses of uranium required to fire the Little Boy bomb over Hiroshima.

He also designed the "dragon's tail" or "guillotine" experiment in which a uranium slug was dropped through a hole in larger fixed mass of uranium, reaching just above critical mass (0.1%) for a fraction of a second.[14] At the meeting to approve the experiment, Richard Feynman, commenting on the transient danger involved, said it was "just like tickling the tail of a sleeping dragon." In the period of about 3 milliseconds, the temperature rose at a rate of 2000 °C per sec and over 1015 excess neutrons were emitted.[15]

Return to England

William Penney, Otto Frisch, Rudolf Peierls and John Cockroft
Left to right: William Penney, Otto Frisch, Rudolf Peierls and John Cockcroft in 1946

In 1946 he returned to England to take up the post of head of the nuclear physics division of the Atomic Energy Research Establishment at Harwell, though he also spent much of the next thirty years teaching at Cambridge where he was Jacksonian Professor of Natural Philosophy and a fellow of Trinity College.

Before he retired he designed[16] a device, SWEEPNIK, that used a laser and computer to measure tracks in bubble chambers. Seeing that this had wider applications, he helped found a company, Laser-Scan Limited, now known as 1Spatial, to exploit the idea.


University of Birmingham - Poynting Physics Building - blue plaques group - Frisch Peierls
University of Birmingham - Poynting Physics Building - blue plaque

He retired from the chair in 1972 as required by University regulations.[16] He died on 22 September 1979 and was cremated on 5 October at Cambridge City Crematorium. His son, Tony Frisch, is also a physicist.


  1. ^ a b c Peierls, R. (1981). "Otto Robert Frisch. 1 October 1904 – 22 September 1979". Biographical Memoirs of Fellows of the Royal Society. 27: 283–306. doi:10.1098/rsbm.1981.0012. JSTOR 769874.
  2. ^ Bethe, H. A.; Winter, George (January 1980). "Obituary: Otto Robert Frisch". Physics Today. 33 (1): 99–100. Bibcode:1980PhT....33a..99B. doi:10.1063/1.2913924. Archived from the original on 2013-09-28.
  3. ^ Frisch, Otto R.; Stern, Otto (1933). "Über die magnetische Ablenkung von Wasserstoffmolekülen und das magnetische Moment des Protons". Zeitschrift für Physik (in German). 85 (1–2): 4–16. Bibcode:1933ZPhy...85....4F. doi:10.1007/BF01330773.
  4. ^ Hahn, O.; Strassmann, F. (1939). "Über den Nachweis und das Verhalten der bei der Bestrahlung des Urans mittels Neutronen entstehenden Erdalkalimetalle [On the detection and characteristics of the alkaline earth metals formed by irradiation of uranium without neutrons]". Naturwissenschaften (in German). 27 (1): 11–15. Bibcode:1939NW.....27...11H. doi:10.1007/BF01488241. The authors were identified as being at the Kaiser-Wilhelm-Institut für Chemie, Berlin-Dahlem. Received 22 December 1938.
  5. ^ Meitner, Lise; Frisch, O. R. (1939). "Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction". Nature. 143 (3615): 239–240. Bibcode:1939Natur.143..239M. doi:10.1038/143239a0. The paper is dated 16 January 1939. Meitner is identified as being at the Physical Institute, Academy of Sciences, Stockholm. Frisch is identified as being at the Institute of Theoretical Physics, University of Copenhagen.
  6. ^ Frisch, O. R. (1939). "Physical Evidence for the Division of Heavy Nuclei under Neutron Bombardment". Nature. 143 (3616): 276. Bibcode:1939Natur.143..276F. doi:10.1038/143276a0. Archived from the original on 3 August 2004. The paper is dated 17 January 1939. [The experiment for this letter to the editor was conducted on 13 January 1939; see Rhodes, Richard (1986). The Making of the Atomic Bomb. Simon and Schuster. pp. 263 and 268.
  7. ^ Otto R. Frisch, "The Discovery of Fission – How It All Began", Physics Today, V20, N11, pp. 43-48 (1967).
  8. ^ J. A. Wheeler, "Mechanism of Fission", Physics Today V20, N11, pp. 49-52 (1967).
  9. ^ "Fame without a Nobel Prize".
  10. ^
  11. ^ Rhodes, Richard (1986). The Making of the Atomic Bomb. Simon and Schuster. pp. 612–613.
  12. ^ a b c Frisch, Otto Robert (1980). What Little I Remember. Cambridge University Press. pp. 161–162. ISBN 0-52-128010-9. We were building an unusual assembly, with no reflecting material around it; just the reacting compound of uranium-235 ... For obvious reasons we called it the Lady Godiva assembly.
  13. ^ Rhodes, Richard (1986). The Making of the Atomic Bomb. Simon and Schuster. pp. 610–11. ISBN 9780671441333.
  14. ^ "Here Be Dragons".
  15. ^ "Experiments with the Dragon Machine".
  16. ^ a b Otto Frisch, "What Little I Remember", Cambridge University Press (1979), ISBN 0-521-40583-1


  • Atomic Physics Today (1961)
  • What Little I Remember (1979)

External links

1938 in science

The year 1938 in science and technology involved some significant events, listed below.

Contemporary Physics

Contemporary Physics is a peer-reviewed scientific journal publishing introductory articles on important recent developments in physics.

Editorial screening and peer review is carried out by members of the editorial board.

Eugene T. Booth

Eugene Theodore Booth, Jr. (28 September 1912 – 6 March 2004) was an American nuclear physicist. He was a member of the historic Columbia University team which made the first demonstration of nuclear fission in the United States. During the Manhattan Project, he worked on gaseous diffusion for isotope separation. He was the director of the design, construction, and operation project for the 385-Mev synchrocyclotron at the Nevis Laboratories, the scientific director of the SCALANT Research Center, and dean of graduate studies at Stevens Institute of Technology.Booth was the scientific director of the SCALANT Research Center, in Italy.

Francis G. Slack

Francis Goddard Slack (November 1, 1897 in – February 2, 1985) was an American physicist. He was a physics teacher, researcher, and administrator in academia who was renowned for placing equal emphasis on teaching and on research.


Frisch is a surname. Notable people with the surname include:

Aileen Frisch, South Korean luger

Arno Frisch, Austrian actor

Cyrus Frisch, Dutch film director

David Frisch (American football), American football player

David H. Frisch (1918–1991), American physicist

Deborah Frisch, American psychologist

Frankie Frisch, American baseball player

Irene Frisch (born 1931), Holocaust survivor and author

Johan Dalgas Frisch (born 1930), Brazilian engineer and ornithologist

Karl von Frisch (1886–1982), Austrian ethologist

Martin Frisch (1899–1959), Hungarian/American mechanical engineer

Max Frisch, Swiss architect, playwright, and novelist

Morten Frisch, Danish epidemiologist

Otto Robert Frisch (1904–1979), Austrian-British physicist

Ragnar Anton Kittil Frisch (1895–1979), Norwegian economist

Thierry Frisch, Luxembourgish photographer

Uriel Frisch (born 1940), French mathematical physicist

Georg Joos

Georg Jakob Christof Joos (25 May 1894 in Bad Urach, German Empire – 20 May 1959 in Munich, West Germany) was a German experimental physicist. He wrote Lehrbuch der theoretischen Physik, first published in 1932 and one of the most influential theoretical physics textbooks of the 20th Century.

Gerhard Hoffmann

Gerhard Hoffmann (4 August 1880 – 18 June 1945) was a German nuclear physicist. During World War II, he contributed to the German nuclear energy project, also known as the Uranium Club.

Ida Noddack

Ida Noddack (25 February 1896 – 24 September 1978), née Tacke, was a German chemist and physicist. In 1934 she was the first to mention the idea later named nuclear fission. With her husband Walter Noddack she discovered element 75, rhenium. She was nominated three times for the Nobel Prize in Chemistry.

Index of physics articles (O)

The index of physics articles is split into multiple pages due to its size.

To navigate by individual letter use the table of contents below.

Lise Meitner

Lise Meitner (; German: [ˈmaɪtnɐ]; 7 November 1878 – 27 October 1968) was an Austrian-Swedish physicist who worked on radioactivity and nuclear physics. Meitner, Otto Hahn and Otto Robert Frisch led the small group of scientists who first discovered nuclear fission of uranium when it absorbed an extra neutron; the results were published in early 1939. Meitner, Hahn and Frisch understood that the fission process, which splits the atomic nucleus of uranium into two smaller nuclei, must be accompanied by an enormous release of energy. Nuclear fission is the process exploited by nuclear reactors to generate heat and, subsequently, electricity. This process is also one of the basics of nuclear weapons that were developed in the U.S. during World War II and used against Japan in 1945.

Meitner spent most of her scientific career in Berlin, Germany, where she was a physics professor and a department head at the Kaiser Wilhelm Institute; she was the first woman to become a full professor of physics in Germany. She lost these positions in the 1930s because of the anti-Jewish Nuremberg Laws of Nazi Germany, and in 1938 she fled to Sweden, where she lived for many years, ultimately becoming a Swedish citizen.

Meitner received many awards and honors late in her life, but she and Otto Frisch, did not share in the 1944 Nobel Prize in Chemistry for nuclear fission that was awarded exclusively to her long-time collaborator Otto Hahn. In the 1990s, the records of the committee that decided on that prize were opened. Based on this information, several scientists and journalists have called her exclusion "unjust", and Meitner has received many posthumous honors, including naming chemical element 109 meitnerium in 1992. Despite not having been awarded the Nobel Prize, Lise Meitner was invited to attend the Lindau Nobel Laureate Meeting in 1962.

List of British Jewish scientists

List of British Jewish scientists is a list that includes scientists from the United Kingdom and its predecessor states who are or were Jewish or of Jewish descent.

MAUD Committee

The MAUD Committee was a British scientific working group formed during the Second World War. It was established to perform the research required to determine if an atomic bomb was feasible. The name MAUD came from a strange line in a telegram from Danish physicist Niels Bohr referring to his housekeeper, Maud Ray.

The MAUD Committee was founded in response to the Frisch-Peierls memorandum, which was written in March 1940 by Rudolf Peierls and Otto Robert Frisch, two physicists who were refugees from Nazi Germany working at the University of Birmingham under the direction of Mark Oliphant. The memorandum argued that a small sphere of pure uranium-235 could have the explosive power of thousands of tons of TNT.

The chairman of the MAUD Committee was George Thomson. Research was split among four different universities: the University of Birmingham, University of Liverpool, University of Cambridge and the University of Oxford. Each university where its research was carried out had a director as well. Various means of uranium enrichment were examined, as was nuclear reactor design, the properties of uranium-235, the use of the then-hypothetical element plutonium, and theoretical aspects of nuclear weapon design.

After fifteen months of work, the research culminated in two reports, "Use of Uranium for a Bomb" and "Use of Uranium as a Source of Power", known collectively as the MAUD Report. These reports discussed the feasibility and necessity of an atomic bomb for the war effort. In response, the British created a nuclear weapons project officially named Tube Alloys. The MAUD Report was made available to the United States, where it energised the American effort, which eventually became the Manhattan Project. The report was handed over to the Soviet Union by its atomic spies, and helped start the Soviet atomic bomb project.

Nuclear fission

In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller, lighter nuclei. The fission process often produces free neutrons and gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay.

Nuclear fission of heavy elements was discovered on December 17, 1938 by German Otto Hahn and his assistant Fritz Strassmann, and explained theoretically in January 1939 by Lise Meitner and her nephew Otto Robert Frisch. Frisch named the process by analogy with biological fission of living cells. For heavy nuclides, it is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments (heating the bulk material where fission takes place). In order for fission to produce energy, the total binding energy of the resulting elements must be more negative (greater binding energy) than that of the starting element.

Fission is a form of nuclear transmutation because the resulting fragments are not the same element as the original atom. The two nuclei produced are most often of comparable but slightly different sizes, typically with a mass ratio of products of about 3 to 2, for common fissile isotopes. Most fissions are binary fissions (producing two charged fragments), but occasionally (2 to 4 times per 1000 events), three positively charged fragments are produced, in a ternary fission. The smallest of these fragments in ternary processes ranges in size from a proton to an argon nucleus.

Apart from fission induced by a neutron, harnessed and exploited by humans, a natural form of spontaneous radioactive decay (not requiring a neutron) is also referred to as fission, and occurs especially in very high-mass-number isotopes. Spontaneous fission was discovered in 1940 by Flyorov, Petrzhak and Kurchatov in Moscow, when they decided to confirm that, without bombardment by neutrons, the fission rate of uranium was indeed negligible, as predicted by Niels Bohr; it was not.The unpredictable composition of the products (which vary in a broad probabilistic and somewhat chaotic manner) distinguishes fission from purely quantum-tunneling processes such as proton emission, alpha decay, and cluster decay, which give the same products each time. Nuclear fission produces energy for nuclear power and drives the explosion of nuclear weapons. Both uses are possible because certain substances called nuclear fuels undergo fission when struck by fission neutrons, and in turn emit neutrons when they break apart. This makes a self-sustaining nuclear chain reaction possible, releasing energy at a controlled rate in a nuclear reactor or at a very rapid, uncontrolled rate in a nuclear weapon.

The amount of free energy contained in nuclear fuel is millions of times the amount of free energy contained in a similar mass of chemical fuel such as gasoline, making nuclear fission a very dense source of energy. The products of nuclear fission, however, are on average far more radioactive than the heavy elements which are normally fissioned as fuel, and remain so for significant amounts of time, giving rise to a nuclear waste problem. Concerns over nuclear waste accumulation and over the destructive potential of nuclear weapons are a counterbalance to the peaceful desire to use fission as an energy source.

October 1

October 1 is the 274th day of the year (275th in leap years) in the Gregorian calendar. There are 91 days remaining until the end of the year.

It is the first day of the fourth quarter of the year.

Otto Hahn

Otto Hahn (8 March 1879 – 28 July 1968) was a German chemist and pioneer in the fields of radioactivity and radiochemistry. Otto Hahn discovered nuclear fission in 1938. He is referred to as the father of nuclear chemistry. He was awarded the Nobel Prize in Chemistry in 1944 for the discovery and the radiochemical proof of nuclear fission. This process is exploited by nuclear reactors and is one of the basics of nuclear weapons that were developed in the U.S. during World War II.

He served as the last President of the Kaiser Wilhelm Society (KWG) in 1946 and as the founding President of the Max Planck Society (MPG) from 1948 to 1960. Considered by many to be a model for scholarly excellence and personal integrity, he became one of the most influential and respected citizens of the new postwar country West Germany.

Hahn was an opponent of national socialism and Jewish persecution by the Nazi Party. Albert Einstein wrote that Hahn was "one of the very few who stood upright and did the best he could in these years of evil". After World War II, Hahn became a passionate campaigner against the use of nuclear energy as a weapon.

Rudolf Peierls

Sir Rudolf Ernst Peierls, (; German: [ˈpaɪɐls]; 5 June 1907 – 19 September 1995) was a German-born British physicist who played a major role in the Manhattan Project and Tube Alloys, Britain's nuclear programme. His obituary in Physics Today described him as "a major player in the drama of the eruption of nuclear physics into world affairs".Peierls studied physics at the University of Berlin, at the University of Munich under Arnold Sommerfeld, the University of Leipzig under Werner Heisenberg, and ETH Zurich under Wolfgang Pauli. After receiving his DPhil from Leipzig in 1929, he became an assistant to Pauli in Zurich.

In 1932, he was awarded a Rockefeller Fellowship, which he used to study in Rome under Enrico Fermi, and then at the Cavendish Laboratory at the University of Cambridge under Ralph H. Fowler. Due to Adolf Hitler's rise to power in Germany, he elected to not return home in 1933, but to remain in Britain, where he worked with Hans Bethe at the University of Manchester, then at the Mond Laboratory at Cambridge. In 1937, Mark Oliphant, the newly-appointed Australian professor of physics at the University of Birmingham recruited him for a new chair there in applied mathematics.

In March 1940, Peierls co-authored the Frisch–Peierls memorandum with Otto Robert Frisch. This short paper was the first to set out that one could construct an atomic bomb from a small amount of fissile uranium-235. Until then it had been assumed that such a bomb would require many tons of uranium, and consequently was impractical to build and use. The paper was pivotal in igniting the interest of first the British and later the American authorities in nuclear weapons. He was also responsible for the recruitment of his compatriot Klaus Fuchs to work on Tube Alloys, as the British nuclear weapons project was called, which resulted in Peierls falling under suspicion when Fuchs was exposed as a spy for the Soviet Union in 1950.

After the war, Peierls returned to the University of Birmingham, where he worked until 1963, and then was the Wykeham Professor of Physics at the University of Oxford until he retired in 1974. At Birmingham he worked on nuclear forces, scattering, quantum field theories, collective motion in nuclei, transport theory and statistical mechanics, and was a consultant to the Atomic Energy Research Establishment at Harwell. He received many awards, including a knighthood in 1968, and wrote several books including Quantum Theory of Solids, The Laws of Nature (1955), Surprises in Theoretical Physics (1979), More Surprises in Theoretical Physics (1991) and an autobiography, Bird of Passage (1985). Concerned with the nuclear weapons he had helped to unleash, he worked on the Bulletin of the Atomic Scientists, was President of the Atomic Scientists' Association in the UK, and was involved in the Pugwash movement.

Timeline of nuclear weapons development

This timeline of nuclear weapons development is a chronological catalog of the evolution of nuclear weapons rooting from the development of the science surrounding nuclear fission and nuclear fusion. In addition to the scientific advancements, this timeline also includes several political events relating to the development of nuclear weapons. The availability of intelligence on recent advancements in nuclear weapons of several major countries (such as United States and the Soviet Union) is limited because of the classification of technical knowledge of nuclear weapons development.

Trinity College Chapel, Cambridge

Trinity College Chapel is the chapel of Trinity College, Cambridge, a constituent college of the University of Cambridge. Part of a complex of Grade I listed buildings at Trinity, it dates from the mid 16th Century. It is an Anglican church in the Anglo-Catholic tradition.

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