Felix Bloch

Last updated

Felix Bloch
Felix Bloch, Stanford University.jpg
Born(1905-10-23)23 October 1905
Died10 September 1983(1983-09-10) (aged 77)
CitizenshipSwiss, American
Alma mater ETH Zürich and University of Leipzig
Known for NMR
Bloch wall
Bloch's Theorem
Bloch Function (Wave)
Bloch sphere
Awards Nobel Prize for Physics (1952)
Scientific career
Fields Physics
Institutions Stanford University
University of California, Berkeley
Doctoral advisor Werner Heisenberg
Doctoral students Carson D. Jeffries

Felix Bloch (23 October 1905 – 10 September 1983) was a Swiss-American physicist and Nobel physics laureate who worked mainly in the U.S. [1] He and Edward Mills Purcell were awarded the 1952 Nobel Prize for Physics for "their development of new ways and methods for nuclear magnetic precision measurements." [2] In 1954–1955, he served for one year as the first Director-General of CERN. Felix Bloch made fundamental theoretical contributions to the understanding of electron behavior in crystal lattices, ferromagnetism, and nuclear magnetic resonance.

United States Federal republic in North America

The United States of America (USA), commonly known as the United States or America, is a country comprising 50 states, a federal district, five major self-governing territories, and various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is slightly smaller than the entire continent of Europe. With a population of over 327 million people, the U.S. is the third most populous country. The capital is Washington, D.C., and the most populous city is New York City. Most of the country is located contiguously in North America between Canada and Mexico.

Physicist scientist who does research in physics

A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate causes of phenomena, and usually frame their understanding in mathematical terms. Physicists work across a wide range of research fields, spanning all length scales: from sub-atomic and particle physics, through biological physics, to cosmological length scales encompassing the universe as a whole. The field generally includes two types of physicists: experimental physicists who specialize in the observation of physical phenomena and the analysis of experiments, and theoretical physicists who specialize in mathematical modeling of physical systems to rationalize, explain and predict natural phenomena. Physicists can apply their knowledge towards solving practical problems or to developing new technologies.

Edward Mills Purcell American physicist

Edward Mills Purcell was an American physicist who shared the 1952 Nobel Prize for Physics for his independent discovery of nuclear magnetic resonance in liquids and in solids. Nuclear magnetic resonance (NMR) has become widely used to study the molecular structure of pure materials and the composition of mixtures.


Life and work

Felix Bloch in the lab, 1950s Felix Bloch 1950s.jpg
Felix Bloch in the lab, 1950s

Bloch was born in Zürich, Switzerland to Jewish [3] parents Gustav and Agnes Bloch.

Zürich Place in Switzerland

Zürich or Zurich is the largest city in Switzerland and the capital of the canton of Zürich. It is located in north-central Switzerland at the northwestern tip of Lake Zürich. The municipality has approximately 409,000 inhabitants, the urban agglomeration 1.315 million and the Zürich metropolitan area 1.83 million. Zürich is a hub for railways, roads, and air traffic. Both Zurich Airport and railway station are the largest and busiest in the country.

He was educated at the Cantonal Gymnasium in Zürich and at the Eidgenössische Technische Hochschule (ETHZ), also in Zürich. Initially studying engineering he soon changed to physics. During this time he attended lectures and seminars given by Peter Debye and Hermann Weyl at ETH Zürich and Erwin Schrödinger at the neighboring University of Zürich. A fellow student in these seminars was John von Neumann. Bloch graduated in 1927, and was encouraged by Debye to go to Leipzig to study with Werner Heisenberg. [4] Bloch became Heisenberg's first graduate student, and gained his doctorate in 1928. [4] His doctoral thesis established the quantum theory of solids, using Bloch waves to describe electrons in periodic lattices.

Physics Study of the fundamental properties of matter and energy

Physics is the natural science that studies matter, its motion and behavior through space and time, and that studies the related entities of energy and force. Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves.

Peter Debye Dutch-American physicist and physical chemist

Peter Joseph William Debye was a Dutch-American physicist and physical chemist, and Nobel laureate in Chemistry.

Hermann Weyl German mathematician

Hermann Klaus Hugo Weyl, was a German mathematician, theoretical physicist and philosopher. Although much of his working life was spent in Zürich, Switzerland and then Princeton, New Jersey, he is associated with the University of Göttingen tradition of mathematics, represented by David Hilbert and Hermann Minkowski.

He remained in European academia, working on superconductivity with Wolfgang Pauli in Zürich; with Hans Kramers and Adriaan Fokker in Holland; with Heisenberg on ferromagnetism, where he developed a description of boundaries between magnetic domains, now known as "Bloch walls"; with Niels Bohr in Copenhagen, where he worked on a theoretical description of the stopping of charged particles traveling through matter; and with Enrico Fermi in Rome. [4] In 1932, Bloch returned to Leipzig to assume a position as "Privatdozent" (lecturer). [4] In 1933, immediately after Hitler came to power, he left Germany because he was Jewish, returning to Zürich, before traveling to Paris to lecture at the Institut Henri Poincaré. [5]

Wolfgang Pauli Austrian physicist, Nobel prize winner

Wolfgang Ernst Pauli was an Austrian-born Swiss and American theoretical physicist and one of the pioneers of quantum physics. In 1945, after having been nominated by Albert Einstein, Pauli received the Nobel Prize in Physics for his "decisive contribution through his discovery of a new law of Nature, the exclusion principle or Pauli principle". The discovery involved spin theory, which is the basis of a theory of the structure of matter.

Hans Kramers Dutch physicist

Hendrik Anthony "Hans" Kramers was a Dutch physicist who worked with Niels Bohr to understand how electromagnetic waves interact with matter.

Adriaan Fokker Dutch physicist

Adriaan Daniël Fokker was a Dutch physicist and musician. He was the inventor of the Fokker organ, a 31-tone equal-tempered organ.

In 1934, the chairman of Stanford Physics invited Bloch to join the faculty. [4] Bloch accepted the offer and emigrated to the United States. In the fall of 1938, Bloch began working with the 37 inch cyclotron at the University of California at Berkeley to determine the magnetic moment of the neutron. Bloch went on to become the first professor for theoretical physics at Stanford. In 1939, he became a naturalized citizen of the United States.

Stanford University Private research university in Stanford, California

Leland Stanford Junior University is a private research university in Stanford, California. Stanford is known for its academic strength, wealth, selectivity, proximity to Silicon Valley, and ranking as one of the world's top universities.

On March 14, 1940, Bloch married Lore Clara Misch (1911–1996), a fellow physicist working on X-ray crystallography, whom he had met at an American Physical Society meeting. [6] They had four children, twins George Jacob Bloch and Daniel Arthur Bloch (born January 15, 1941), son Frank Samuel Bloch (born January 16, 1945), and daughter Ruth Hedy Bloch Alexander (born September 15, 1949). [4] [7]

X-ray crystallography Technique used in studying crystal structure

X-ray crystallography (XRC) is a technique used to determine the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information.

The American Physical Society (APS) is the world's second largest organization of physicists. The Society publishes more than a dozen scientific journals, including the prestigious Physical Review and Physical Review Letters, and organizes more than twenty science meetings each year. APS is a member society of the American Institute of Physics. Kate Kirby is APS's current chief executive officer. She took on the role on in February 2015.

During WWII, Bloch briefly worked on the atomic bomb project at Los Alamos. Disliking the military atmosphere of the laboratory and uninterested in the theoretical work there, Bloch left to join the radar project at Harvard University. [8]

After the war, he concentrated on investigations into nuclear induction and nuclear magnetic resonance, which are the underlying principles of MRI. [9] [10] [11] In 1946 he proposed the Bloch equations which determine the time evolution of nuclear magnetization. Along with Edward Purcell, Bloch was awarded the 1952 Nobel Prize in Physics for his work on nuclear magnetic induction.

When CERN was being set up in the early 1950s, its founders were searching for someone of the stature and international prestige to head the fledgling international laboratory, and in 1954 Professor Bloch became CERN's first Director-General, [12] at the time when construction was getting under way on the present Meyrin site and plans for the first machines were being drawn up. After leaving CERN, he returned to Stanford University, where he in 1961 was made Max Stein Professor of Physics.

At Stanford, he was the advisor of Carson D. Jeffries, who became a professor of Physics at the University of California, Berkeley.

In 1964, he was elected a foreign member of the Royal Netherlands Academy of Arts and Sciences. [13]

Bloch died in Zürich in 1983. [6]

See also


  1. Hofstadter, Robert (March 1984). "Obituary: Felix Bloch". Physics Today. 37 (3): 115–116. Bibcode:1984PhT....37c.115H. doi:10.1063/1.2916128. Archived from the original on 30 September 2013.
  2. Sohlman, M (Ed.) Nobel Foundation directory 2003. Vastervik, Sweden: AB CO Ekblad; 2003.
  3. Fraser, Gordon (2012). "Chapter 7". The Quantum Exodus. Oxford University Press. p. 182. ISBN   978-0-19-959215-9.
  4. 1 2 3 4 5 6 Hofstadter, Robert; Chodorow, Marvin; Schawlow, Arthur; Walecka, Dirk. ""Memorial Resolution: Felix Bloch (1905 - 1983)"" (PDF). Archived from the original (PDF) on 11 March 2017. Retrieved 11 November 2017.
  5. "Bloch, Felix", Current Biography , H. W. Wilson Company, 1954. Accessed 24 February 2013. "Because of his Jewish faith, his position soon became uncomfortable and he went to Paris, where he lectured at the Institut Henri Poincaré."
  6. 1 2 Former Fellows of The Royal Society of Edinburgh 1783 – 2002. royalsoced.org.uk
  7. https://oac.cdlib.org/findaid/ark:/13030/kt3580367x/admin/
  8. Charles, Weiner (15 August 1968). ""Oral Histories: Felix Bloch"". American Institute of Physics. Retrieved 11 November 2017.
  9. Alvarez, Luis W.; Bloch, F. (1940). "A Quantitative Determination of the Neutron Moment in Absolute Nuclear Magnetons". Physical Review . 57 (2): 111–122. Bibcode:1940PhRv...57..111A. doi:10.1103/PhysRev.57.111.
  10. Bloch, F.; Hansen, W. W.; Packard, Martin (1 February 1946). "Nuclear Induction". Physical Review . 69: 127. Bibcode:1946PhRv...69..127B. doi:10.1103/PhysRev.69.127.
  11. Shampo, M A; Kyle R A (September 1995). "Felix Bloch—developer of magnetic resonance imaging". Mayo Clin. Proc. 70 (9): 889. doi:10.4065/70.9.889. PMID   7643644.
  12. "People and things : Felix Bloch". CERN Courier. CERN. Retrieved 1 September 2015.
  13. "F. Bloch (1905 - 1983)". Royal Netherlands Academy of Arts and Sciences. Retrieved 22 May 2016.

Related Research Articles

Aage Bohr Danish physicist

Aage Niels Bohr was a Danish nuclear physicist who shared the Nobel Prize in Physics in 1975 with Ben Mottelson and James Rainwater "for the discovery of the connection between collective motion and particle motion in atomic nuclei and the development of the theory of the structure of the atomic nucleus based on this connection". Starting from Rainwater's concept of an irregular-shaped liquid drop model of the nucleus, Bohr and Mottelson developed a detailed theory that was in close agreement with experiments. Since his father, Niels Bohr, had won the prize in 1922, he and his father were one of the six pairs of fathers and sons who have both won the Nobel Prize and one of the four pairs who have both won the Nobel Prize in Physics.

Niels Bohr Danish physicist

Niels Henrik David Bohr was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922. Bohr was also a philosopher and a promoter of scientific research.

Werner Heisenberg German theoretical physicist

Werner Karl Heisenberg was a German theoretical physicist and one of the key pioneers of quantum mechanics. He published his work in 1925 in a breakthrough paper. In the subsequent series of papers with Max Born and Pascual Jordan, during the same year, this matrix formulation of quantum mechanics was substantially elaborated. He is known for the Heisenberg uncertainty principle, which he published in 1927. Heisenberg was awarded the 1932 Nobel Prize in Physics "for the creation of quantum mechanics".

Erich Hückel German physical chemist known for the Debye-Hückel Theory and the Hückel method

Erich Armand Arthur Joseph Hückel was a German physicist and physical chemist. He is known for two major contributions:

Max Born physicist

Max Born was a German-Jewish physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a number of notable physicists in the 1920s and 1930s. Born won the 1954 Nobel Prize in Physics for his "fundamental research in quantum mechanics, especially in the statistical interpretation of the wave function".

Isidor Isaac Rabi American physicist

Isidor Isaac Rabi was an American physicist who won the Nobel Prize in Physics in 1944 for his discovery of nuclear magnetic resonance, which is used in magnetic resonance imaging. He was also one of the first scientists in the United States to work on the cavity magnetron, which is used in microwave radar and microwave ovens.

James Rainwater American physicist

Leo James Rainwater was an American physicist who shared the Nobel Prize in Physics in 1975 for his part in determining the asymmetrical shapes of certain atomic nuclei.

John Hasbrouck Van Vleck American physicist

John Hasbrouck Van Vleck was an American physicist and mathematician. He was co-awarded the Nobel Prize in Physics in 1977, for his contributions to the understanding of the behavior of electrons in magnetic solids.

Otto Robert Frisch Austrian physicist

Otto Robert Frisch FRS was an Austrian-born British physicist who worked on nuclear physics. With Lise Meitner he advanced the first theoretical explanation of nuclear fission and first experimentally detected the fission by-products. Later, with his collaborator Rudolf Peierls he designed the first theoretical mechanism for the detonation of an atomic bomb in 1940.

Victor Weisskopf Austrian-born American theoretical physicist

Victor Frederick "Viki" Weisskopf was an Austrian-born American theoretical physicist. He did postdoctoral work with Werner Heisenberg, Erwin Schrödinger, Wolfgang Pauli and Niels Bohr. During World War II he was Group Leader of the Theoretical Division of the Manhattan Project at Los Alamos, and later campaigned against the proliferation of nuclear weapons.

Rudolf Peierls physicist

Sir Rudolf Ernst Peierls, was a Jewish 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".

George Placzek physicist

George Placzek was a Czech physicist.

Erwin Louis Hahn was an American physicist, best known for his work on nuclear magnetic resonance (NMR). In 1950 he discovered the spin echo.

The neutron magnetic moment is the intrinsic magnetic dipole moment of the neutron, symbol μn. Protons and neutrons, both nucleons, comprise the nucleus of atoms, and both nucleons behave as small magnets whose strengths are measured by their magnetic moments. The neutron interacts with normal matter through either the nuclear force or its magnetic moment. The neutron's magnetic moment is exploited to probe the atomic structure of materials using scattering methods and to manipulate the properties of neutron beams in particle accelerators. The neutron was determined to have a magnetic moment by indirect methods in the mid 1930s. Luis Alvarez and Felix Bloch made the first accurate, direct measurement of the neutron's magnetic moment in 1940. The existence of the neutron's magnetic moment indicates the neutron is not an elementary particle. For an elementary particle to have an intrinsic magnetic moment, it must have both spin and electric charge. The neutron has spin 1/2 ħ, but it has no net charge. The existence of the neutron's magnetic moment was puzzling and defied a correct explanation until the quark model for particles was developed in the 1960s. The neutron is composed of three quarks, and the magnetic moments of these elementary particles combine to give the neutron its magnetic moment.

Egon Bretscher (1901–1973) was a Swiss-born British chemist and nuclear physicist and Head of the Nuclear Physics Division from 1948 to 1966 at the Atomic Energy Research Establishment, also known as Harwell Laboratory, in Harwell, United Kingdom. He was one of the pioneers in nuclear fission research and one of the first to foresee that plutonium could be used as an energy source. His work on nuclear physics led to his involvement in the British atomic bomb research project Tube Alloys and his membership of the British Mission to the Manhattan Project at Los Alamos, where he worked in Enrico Fermi's Advanced Development Division in the F-3 Super Experimentation group. His contributions up to 1945 are discussed by Margaret Gowing in her "Britain and Atomic Energy, 1935-1945."

Jochen Heisenberg German physicist

Jochen Heisenberg is a German physicist specializing in nuclear physics, and Professor Emeritus of Physics at the University of New Hampshire. He is the son of Nobel Prize-winning physicist Werner Heisenberg, who is best known for the uncertainty principle. He is the brother of German neurobiologist and geneticist Martin Heisenberg and the uncle of film director Benjamin Heisenberg.

Cornelis Jacobus (Cor) Gorter was a Dutch experimental and theoretical physicist. Among other work, he discovered paramagnetic relaxation and was a pioneer in low temperature physics.

Discovery of the neutron

The discovery of the neutron and its properties was central to the extraordinary developments in atomic physics in the first half of the 20th century. Early in the century, Ernest Rutherford developed a crude model of the atom, based on the gold foil experiment of Hans Geiger and Ernest Marsden. In this model, atoms had their mass and positive electric charge concentrated in a very small nucleus. By 1920 chemical isotopes had been discovered, the atomic masses had been determined to be (approximately) integer multiples of the mass of the hydrogen atom, and the atomic number had been identified as the charge on the nucleus. Throughout the 1920s, the nucleus was viewed as composed of combinations of protons and electrons, the two elementary particles known at the time, but that model presented several experimental and theoretical contradictions.

Jan Korringa Dutch-American physicist

Jan Korringa was a Dutch-American physicist, specializing in theoretical condensed matter physics. He was writing notes to his students in his famous illegible script, correcting their explanations of his scientific discoveries, within weeks of his death.


Further reading

Business positions
Preceded by
Position created
First Director-General of CERN
Succeeded by
Cornelis Bakker