Felix Bloch

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Felix Bloch (1961)

Felix Bloch (born October 23, 1905 in Zurich ; † September 10, 1983 in Zollikon ) was an Austrian-Swiss-American physicist and avowed pacifist of Jewish origin. In 1952 he received the Nobel Prize in Physics for the development of new methods for nuclear magnetic precision measurement and the discoveries made with them ( nuclear magnetic resonance spectroscopy ).

life and work

His father, Gustav Bloch (1868-1947) was a Moravian grain merchant, his mother Agnes nee Mauer (1878-1970) came from Vienna. After attending the city school in Zurich from 1912 and graduating from the Rämibühl canton school , Felix Bloch began studying mechanical engineering; between 1924 and 1927 he studied mathematics and physics at the Swiss Federal Institute of Technology in Zurich (ETH). When one of his Zurich teachers, the chemist Peter Debye , moved to the University of Leipzig , he followed him to the Free State of Saxony in 1927 . Felix Bloch continued his studies in Leipzig a. a. continued with Werner Heisenberg . The subject of his thesis was the Schrödinger equation . The doctoral thesis dealt with the behavior of electrons in crystal lattices and was the starting point for his life's work: the quantum mechanical treatment of solid-state physics , to the foundations of which he contributed a great deal, such as the ribbon model of electrons in solids and the Bloch function . He was Werner Heisenberg's first doctoral student in 1928 and returned to ETH Zurich for a year, where he was assistant to Wolfgang Pauli until 1929 .

After stops in Utrecht and Haarlem in the Netherlands , Felix Bloch became an assistant to Werner Heisenberg in Leipzig in 1931. He completed his habilitation in 1932 with a thesis “On the theory of the exchange problem and the remanence phenomenon of ferromagnetics” in which, among other things, he deals with the transition areas between different magnetized domains known today as Bloch walls. After the seizure of power of the Nazis , he fled back to Switzerland and went in 1934 to Stanford University , where he remained until the 1,971th He was the first to take over the chair for theoretical physics. In 1937 he became a Fellow of the American Physical Society . In 1939 he became an American citizen.

From the summer of 1942 Bloch worked on the Manhattan project in Los Alamos , to which he had been invited by Robert Oppenheimer , whom he still knew from Berkeley. He worked in Seth Neddermeyer's group on the implosion version of the atomic bomb . According to his own statements, however, at the end of 1943 he saw his work as done and left. He didn't like the military atmosphere of secrecy and he also had doubts that the real reason - a possible lead the Germans had in developing the atomic bomb - was still relevant. After the memories of Edward Teller , there were also differences with Oppenheimer. November 1943 he left Los Alamos as one of the few physicists who was allowed to do so. He switched to radar research at Harvard.

He then did important work on ferromagnetism and the measurement of the magnetic moments of atomic nuclei . In 1946 he discovered independently by Edward Mills Purcell and together with William Webster Hansen and Martin Packard , the nuclear magnetic resonance ( english Nuclear Magnetic Resonance , NMR), which is used to illustrate the composition and structure of solids and liquids and chemical compounds and basis of magnetic resonance imaging is.

Bloch was General Director of CERN in Geneva from 1954 to 1955 .

family

In 1940 Felix Bloch married the physicist Lore Misch in Las Vegas , daughter of the philosopher Georg Misch , professor of philosophy at the University of Göttingen . The three sons Georg Jacob (* 1941), Daniel Arthur (* 1941) and Frank Samuel (* 1945) as well as Ruth Hedy, née Bloch (* 1949) emerged from this marriage. The latter became a historian.

Honors

The following physical objects bear his name:

Bloch and Arnold Nordsieck also wrote the Bloch-Nordsieck theorem , named after them , which represents the solution to the infrared problem in quantum electrodynamics .

Fonts (selection)

  • About the quantum mechanics of electrons in crystal lattices , Berlin 1928 (also dissertation at the University of Leipzig ).
  • Comment on the electron theory of ferromagnetism and electrical conductivity . In: Zeitschrift für Physik 57 (1929), pp. 545-555.
  • with G. Gentile: On the anisotropy of the magnetization of ferromagnetic single crystals . In: Zeitschrift für Physik 70 (1931), pp. 395-408.
  • On the theory of the exchange problem and the remanence of ferromagnetics . In: Zeitschrift für Physik 74 (1932), H. 5/6, P. 295-335 (also habilitation at the University of Leipzig from January 30, 1932).
  • For braking rapidly moving particles when passing through matter . In: Annals of Physics 16 (1932), pp. 285-320.
  • The electron theory of metals . In: E. Marx (Ed.): Handbuch der Radiologie , Vol. 6, Leipzig 1934, pp. 226-278.
  • Molecular Theory of Magnetism . In: E. Marx (Ed.): Handbuch der Radiologie , Vol. 6, Leipzig 1934, pp. 375-484.
  • On the magnetic scattering of neutrons . In: Physical Review 50 (1936), pp. 259f. and 51 (1937), p. 994.
  • with LW Alvarez: A quantitative determination of the neutron moment in absolute nuclear magnetons . In: Physical Review 57 (1940), pp. 111-122.
  • with A. Siegert: Magnetic resonance for nonrotating fields . In: Physical Review 57 (1940), pp. 522-527.
  • with WW Hansen: Nuclear induction . In: Physical Review 70 (1946), pp. 460-474.
  • with M. Packard: Nuclear induction experiment . In: Physical Review 70 (1946), pp. 474-485.
  • with JH Van Vleck and M. Hamermesh: Theory of radar reflections from wires or thin metallic strips . In: Journal of Applied Physics 18 (1947), pp. 274-294.
  • Nuclear induction . In: Physica 17 (1951), issue 3/4, pp. 272-281.
  • The Dynamical Theory of Nuclear Induction . In: Physical Review 89 (1953), pp. 728-739.
  • The Dynamical Theory of Nuclear Induction . In: Physical Reviwe 102 (1956), pp. 104-135.
  • Fundamentals of Statistical Mechanics. Manuscript and Notes of Felix Bloch (edited by John Dirk Walecka ). Stanford University Press 1989, World Scientific 2000.

literature

Fiction

Quote

"Free imagination is the priceless prerogative of youth, and it must be cherished and guarded like a treasure."

Web links

Commons : Felix Bloch  - Collection of images, videos and audio files

Individual evidence

  1. ↑ Harenberg Knowledge Calendar Einstein for Quantum Dilettantes 2017, 4./5. March
  2. ↑ Isabella Seemann: The pacifist who built the uranium bomb . Tagblatt der Stadt Zürich , November 25, 2015
  3. ↑ Felix Bloch: About the quantum mechanics of electrons in crystal lattices . Berlin 1928, OCLC 43394732 (Inaug.-Diss., Leipzig).
  4. ↑ Felix Bloch: About the quantum mechanics of electrons in crystal lattices . In: Journal of Physics . tape 52 , no. 7–8 , July 1929, pp. 555-600 , doi : 10.1007 / BF01339455 .
  5. ^ Oral History Interview with Charles Weiner
  6. ↑ Edward Teller, Memoirs, Perseus Publ. 2001, p. 180. According to Teller, the differences were irreconcilable from Bloch's point of view, who said the way the laboratory was organized would waste his time. As a farewell, he gave his friend Teller a plaque with a car that crashed into a tree as a symbol of his view of Los Alamos.
  7. ↑ A few months earlier, Edward Condon had left Los Alamos due to differences with Oppenheimer
  8. ↑ http://www.watson.ch/Wissen/Schweiz/937819437-Gestatten--Felix-Bloch--ein-Z%C3%BCrcher-Nobelpreistr%C3%A4ger--der-die-Alpen-liebte-%E2 % 80% 93-and-helped-build-the-atom-bomb
  9. ↑ Member History: Felix Bloch. American Philosophical Society, accessed May 6, 2018 .
  10. ^ Biographical Index: Former RSE Fellows 1783–2002. Royal Society of Edinburgh, accessed October 9, 2019 .
  11. ↑ Felix Bloch in: Orden pour le Mérite for Sciences and Arts, 1842-2002 , Bleicher Verlag, Gerlingen, 2002, ISBN 3-88350-175-1
  12. ↑ Bloch, Nordsieck Note on the radiation field of the electron , Physical Review, Volume 52, 1937, p. 54.
  13. ↑ Harenberg Knowledge Calendar Einstein for Quantum Dilettantes 2017, 4./5. March
personal data
SURNAME Bloch, Felix
BRIEF DESCRIPTION Swiss-American physicist
DATE OF BIRTH October 23, 1905
PLACE OF BIRTH Zurich
DATE OF DEATH September 10, 1983
Place of death Zurich