Felix Bloch

Template:Short description Template:About Template:Use dmy dates Template:Infobox scientist

Felix Bloch (Template:IPAc-en;<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> {{#invoke:IPA|main}}; 23 October 1905 – 10 September 1983) was a Swiss-American physicist<ref>Template:Cite journal</ref> who shared the 1952 Nobel Prize in Physics with Edward Mills Purcell "for their development of new methods for nuclear magnetic precision measurements and discoveries in connection therewith".<ref name="fn_1">Sohlman, M (Ed.) Nobel Foundation directory 2003. Vastervik, Sweden: AB CO Ekblad; 2003.</ref> Bloch made fundamental theoretical contributions to the understanding of ferromagnetism and electron behavior in crystal lattices. He is also considered one of the developers of nuclear magnetic resonance.

BiographyEdit

File:Felix Bloch 1950s.jpg

Felix Bloch in the lab, 1950s

Early life, education, and familyEdit

Bloch was born in Zürich, Switzerland to Jewish<ref>Template:Cite book</ref> parents Gustav and Agnes Bloch. Gustav Bloch, his father, was financially unable to attend university and worked as a wholesale grain dealer in Zürich.<ref name=HofstadterBioMemoir>Template:Cite book</ref> Gustav moved to Zürich from Moravia in 1890 to become a Swiss citizen. Their first child was a girl born in 1902 while Felix was born three years later.<ref name=HofstadterBioMemoir />

Bloch entered public elementary school at the age of six and is said to have been teased, in part because he "spoke Swiss German with a somewhat different accent than most members of the class".<ref name=HofstadterBioMemoir /> He received support from his older sister during much of this time, but she died at the age of twelve, devastating Felix, who is said to have lived a "depressed and isolated life" in the following years.<ref name=HofstadterBioMemoir /> Bloch learned to play the piano by the age of eight and was drawn to arithmetic for its "clarity and beauty".<ref name=HofstadterBioMemoir /> Bloch graduated from elementary school at twelve and enrolled in the Cantonal Gymnasium in Zürich for secondary school in 1918. He was placed on a six-year curriculum here to prepare him for university. He continued his curriculum through 1924, even through his study of engineering and physics in other schools, though it was limited to mathematics and languages after the first three years. After these first three years at the Gymnasium, at age fifteen Bloch began to study at the Eidgenössische Technische Hochschule (ETHZ), also in Zürich. Although he initially studied 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.<ref name="Stanford-physics-memorial">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Bloch became Heisenberg's first graduate student, and gained his doctorate in 1928.<ref name="Stanford-physics-memorial"/> His doctoral thesis established the quantum theory of solids, using waves to describe electrons in periodic lattices.

On 14 March 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.<ref name="royalsoced1">Former Fellows of The Royal Society of Edinburgh 1783 – 2002 Template:Webarchive. royalsoced.org.uk</ref> They had four children, twins George Jacob Bloch and Daniel Arthur Bloch (born 15 January 1941), son Frank Samuel Bloch (born 16 January 1945), and daughter Ruth Hedy Bloch (born 15 September 1949).<ref name="Stanford-physics-memorial"/><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

CareerEdit

Bloch 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", and theoretically proposed a concept of spin waves, excitations of magnetic structure; 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.<ref name="Stanford-physics-memorial"/> In 1932, Bloch returned to Leipzig to assume a position as "Privatdozent" (lecturer).<ref name="Stanford-physics-memorial"/> 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.<ref>"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."</ref>

In 1934, the chairman of Stanford Physics invited Bloch to join the faculty.<ref name="Stanford-physics-memorial"/> 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, 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.

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.<ref name="AIP-oral-history">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

After the war, he concentrated on investigations into nuclear induction and nuclear magnetic resonance, which are the underlying principles of MRI.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> In 1946 he proposed the Bloch equations which determine the time evolution of nuclear magnetization. He was elected to the United States National Academy of Sciences in 1948.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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 stature and international prestige to head the fledgling international laboratory, and in 1954 Professor Bloch became CERN's first director-general,<ref>Template:Cite journal</ref> 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.

In 1964, he was elected a foreign member of the Royal Netherlands Academy of Arts and Sciences.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> He was also a member of the American Academy of Arts and Sciences and the American Philosophical Society.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Bloch died in Zürich in 1983.<ref name="royalsoced1"/>