|Born||Hans Albrecht Bethe
July 2, 1906
|Died||March 6, 2005
Ithaca, New York, United States
|Institutions||University of Tübingen
University of Manchester
|Alma mater||University of Frankfurt
University of Munich
|Doctoral advisor||Arnold Sommerfeld|
|Doctoral students||Ajoy Ghatak
Robert Eugene Marshak
David J. Thouless
P. S. Epstein
Gordon L. Shaw
|Other notable students||Freeman Dyson|
|Known for||Nuclear Physics
|Notable awards||Nobel Prize in Physics (1967)|
|Spouse||Rose Ewald (m. 1939; two children)|
Hans Albrecht Bethe (German: [ˈhans ˈalbʁɛçt ˈbeːtə]; July 2, 1906 – March 6, 2005) was a German and American nuclear physicist, and Nobel laureate in physics for his work on the theory of stellar nucleosynthesis. A versatile theoretical physicist, Bethe also made important contributions to quantum electrodynamics, nuclear physics, solid-state physics and astrophysics. During World War II, he was head of the Theoretical Division at the secret Los Alamos laboratory which developed the first atomic bombs. There he played a key role in calculating the critical mass of the weapons, and did theoretical work on the implosion method used in both the Trinity test and the "Fat Man" weapon dropped on Nagasaki, Japan. For most of his career, Bethe was a professor at Cornell University.
During the early 1950s, Bethe also played an important role in the development of the larger hydrogen bomb, though he had originally joined the project with the hope of proving it could not be made. Bethe later campaigned together with Albert Einstein in the Emergency Committee of Atomic Scientists against nuclear testing and the nuclear arms race. He influenced the White House to sign the ban of atmospheric nuclear tests in 1963 and the 1972 Anti-Ballistic Missile Treaty, SALT I. His scientific research never ceased even into the later years of his life and he was publishing papers well into his nineties. He is one of the few scientists who can claim a major paper in his field every decade of his career, which spanned nearly 70 years. Freeman Dyson called Bethe the "supreme problem solver of the 20th century."
Early years 
Bethe was born in Strasbourg, Germany, the son of Anna (née Kuhn) and Albrecht Bethe, a professor of physiology. Although his mother was Jewish, he was raised a Christian in the religion of his father. Despite having a religious background, he was not a religious person in later life and called himself an atheist. Bethe studied physics at the Goethe University in Frankfurt, and went on to earn his doctorate from the University of Munich with supervisor Arnold Sommerfeld, after which he did postdoctoral stints in Cambridge and at Enrico Fermi's laboratory in Rome. He was influenced by Fermi's simplicity and Sommerfeld's rigor in approaching problems, and these qualities influenced his own later research.
In 1929, Bethe made an important contribution to solid state physics and chemistry, with his formulation of the basic concepts of crystal field theory. His paper is regarded as the starting point for all serious later discussions of the topic. In 1930, he devised a formula for the energy loss of swift charged particles in matter called the Bethe formula, which is as important now as it was then.
Bethe left Germany in 1933 when the Nazis came to power and he lost his job at the University of Tübingen, moving first to England where he held a provisory position of Lecturer for the year 1933-1934 at the University of Manchester and in the fall of 1934, a fellowship at the University of Bristol. In England, Bethe worked with the theoretician Rudolf Peierls on a comprehensive theory of the deuteron.
In 1935 Bethe moved to the United States, and joined the faculty at Cornell University, a position which he occupied for the rest of his career. During 1948–1949 he was a Visiting Professor at Columbia University. At Cornell, Bethe became known as one of the leading theoretical physicists of his generation, and along with upcoming physicists such as cyclotron pioneer Milton Stanley Livingston, and later, after the war, experimentalist Robert R. Wilson and theoretician Robert Bacher, put Cornell on the world physics map. Together with Robert Bacher and Livingston, Bethe published a series of three articles which summarized most of what was known on the subject of nuclear physics until that time, an account that became informally known as "Bethe's Bible", and remained the standard work on the subject for many years. In this account, he also continued where others left off, filling in gaps from the older literature. From 1935–1938, he studied nuclear reactions and reaction cross sections, carbon-oxygen-nitrogen cycle, leading to his important contribution to stellar nucleosynthesis. This research was later useful to Bethe in more quantitatively developing Niels Bohr's theory of the compound nucleus.
Manhattan Project 
When the war began, Bethe wanted to contribute to the war effort. Following the advice of the Caltech aerodynamicist Theodore von Kármán, Bethe collaborated with his friend Edward Teller, then at George Washington University, on a theory of shock waves which are generated by the passage of a projectile through a gas. This work was later useful to researchers investigating ballistic reentry. Bethe also worked on a theory of armor penetration, which was immediately classified by the Army, making it inaccessible to Bethe, who was not an American citizen at the time.
During the summer of 1942, he served as part of a special session at the University of California, Berkeley at the invitation of Robert Oppenheimer, which outlined the first designs for the atomic bomb. Initially, Bethe was skeptical of the possibility of making a nuclear weapon from uranium. In the late 1930s, he wrote a theoretical paper arguing against fission, but was convinced by Teller to join the Manhattan Project. When Oppenheimer was put in charge of forming a secret weapons design laboratory, Los Alamos, he appointed Bethe Director of the Theoretical Division, a move that irked Teller, who had coveted the job for himself.
Bethe's work at Los Alamos included calculating the critical mass of uranium-235 and the multiplication of nuclear fission in an exploding atomic bomb. Along with Richard Feynman, he developed a formula for calculating the explosive yield of the bomb. After November 1943, when the laboratory had been reoriented to solve the implosion problem of the plutonium bomb, Bethe spent much of his time studying the hydrodynamic aspects of implosion, a job which he continued into 1944. In 1945, he worked on the neutron initiator, and later on radiation propagation from an exploding atomic bomb.
During the project, Klaus Fuchs, a German scientist spying for the Russians, was also in Bethe's division (often doing work which had originally been assigned to Teller). Like everyone else, Bethe had no knowledge that Fuchs was a spy.
When the first atomic bomb (an implosion design) was detonated in the New Mexico desert on July 16, 1945, at the Trinity test, Bethe's immediate concern was for its efficient operation, and not its moral implications. He is reported to have commented: "I am not a philosopher."
Hydrogen bomb 
After the war, Bethe argued that a crash project for the hydrogen bomb should not be attempted, though after President Harry Truman announced the beginning of such a crash project, and the outbreak of the Korean War, Bethe signed up and played a key role in the weapon's development. Though he would see the project through to its end, in Bethe's account he personally hoped that it would be impossible to create the hydrogen bomb. He would later remark in 1968 on the apparent contradiction in his stance, having first opposed the development of the weapon and later helping to create it:
Just a few months before, the Korean war had broken out, and for the first time I saw direct confrontation with the communists. It was too disturbing. The cold war looked as if it were about to get hot. I knew then I had to reverse my earlier position. If I did not work on the bomb, somebody else would — and I had thought if I were around Los Alamos I might still be a force for disarmament. So I agreed to join in developing the H-bomb. It seemed quite logical. But sometimes I wish I were a more consistent idealist.
As for his own role in the project, and its relation to the famous Teller-Ulam priority dispute, Bethe later said that:
After the H-bomb was made, reporters started to call Teller the father of the H-bomb. For the sake of history, I think it is more precise to say that Ulam is the father, because he provided the seed, and Teller is the mother, because he remained with the child. As for me, I guess I am the midwife.
In 1954, Bethe testified on behalf of Oppenheimer during the latter's high-profile security clearance hearing. Specifically, Bethe argued that Oppenheimer's stances against developing the hydrogen bomb in the late 1940s had not hindered its actual development, a topic which was seen as a key motivating factor behind the hearing. Bethe contended that the developments which led to the successful Teller-Ulam design were a matter of serendipity and not a question of manpower or logical development of previously existing ideas. During the hearing, Bethe and his wife also tried hard to convince Edward Teller against testifying. However, Teller did not agree, and his testimony played a major role in the revocation of Oppenheimer's security clearance. While Bethe and Teller had been on very good terms during the pre-war years, the conflict between them during the Manhattan Project, and especially during the Oppenheimer episode, permanently marred their relation.
Political stances 
In 1968, Bethe, along with IBM physicist Richard Garwin, published an article criticising in detail the anti-ICBM defense system proposed by the Department of Defense. The two physicists described in the article that nearly any measure taken by the US would be easily thwarted with the deployment of relatively simple decoys. Bethe was one of the primary voices in the scientific community behind the signing of the 1963 Partial Test Ban Treaty prohibiting further atmospheric testing of nuclear weapons.
During the 1980s and 1990s, Bethe campaigned for the peaceful use of nuclear energy. After the Chernobyl disaster, Bethe put together a committee of experts that analysed the incident, and concluded that a similar episode would not happen in any good US reactor, as the Russian reactor suffered from a fundamentally faulty design and human error also had significantly contributed to the accident. Throughout his life Bethe remained a strong advocate for electricity from nuclear energy.
In the 1980s he and other physicists opposed the Strategic Defense Initiative missile system conceived by the Ronald Reagan administration. In 1995, at the age of 88, Bethe wrote an open letter calling on all scientists to "cease and desist" from working on any aspect of nuclear weapons development and manufacture. In 2004, he signed a letter along with 47 other Nobel laureates endorsing John Kerry for President of the United States.
Later work 
In 1967, Bethe was awarded the Nobel Prize in Physics "for his contributions to the theory of nuclear reactions, especially his discoveries concerning the energy production in stars". His postulate was that the source of this stellar nucleosynthesis was thermonuclear reactions in which hydrogen is converted into helium.
Bethe was also noted for his theories on atomic properties. In the late 1940s, he provided the first way out of the infinities that plagued the explanation of the so-called Lamb shift. Although his calculation was a non-relativistic one, it provided the impetus for later work done by Richard Feynman, Julian Schwinger and others which marked the beginning of modern quantum electrodynamics.
Bethe continued to do research on supernovae, neutron stars, black holes, and other problems in theoretical astrophysics into his late nineties. In doing this, he collaborated with Gerald Brown of the State University of New York at Stony Brook. At age 85, he wrote an important article about the solar neutrino problem, in which he helped establish the conversion mechanism for electron neutrinos into muon neutrinos proposed by Mikheyev and Smirnov to explain a vexing discrepancy between theory and experiment. Physicist Kurt Gottfried says that he does not know anyone in the history of modern physics who has done work of such calibre in his 80s.
Bethe's hobbies included a passion for history and also stamp-collecting. About the latter, he wryly remarked that it was the only instance where all the countries in the world could coexist by each other's side in peace. He loved the outdoors, and was an enthusiastic mountain climber all his life. Bethe was also known for his sense of humor, and once published a parody in 1931, On the Quantum Theory of the Temperature of Absolute Zero where he calculated the fine structure constant from the absolute zero temperature in Celsius units, causing a scandal in the scientific world. This second parody paper was intended to characterize a certain class of papers in theoretical physics of the day, which were purely speculative and based on spurious numerical arguments such as Sir Arthur Eddington's claim to have calculated the fine structure constant from fundamental quantities in an earlier paper. He has also, wrongly, been credited for allowing his name to be used in the Alpher-Bethe-Gamow paper in which he did not participate; in fact, George Gamow added Bethe's name without consulting him, and against Ralph Alpher's wishes.
Bethe died in his home in Ithaca, New York on March 6, 2005  of congestive heart failure. At the time of his death, he was the John Wendell Anderson Professor of Physics Emeritus at Cornell University. He also was, reaching the age of 98, the third-oldest Nobel laureate ever. Since his death, Cornell has announced that the third of five new residential colleges, each of which will be named after a distinguished former member of the Cornell faculty, will be named the Hans Bethe House.
While lecturing at Duke University in 1937, Hans Bethe met Rose Ewald, who was a daughter of his former professor Paul Peter Ewald. They were married in September 1939. The Bethes, who had two children, Henry and Monica, spent most of their lives in Ithaca.
Honors and awards 
- Awards and honors
- Fellow of the American Academy of Arts and Sciences (1947)
- Henry Draper Medal of the National Academy of Sciences (1947)
- Max Planck medal (1955)
- Franklin Medal (1959)
- Eddington Medal of the Royal Astronomical Society (1961)
- Enrico Fermi Award (1961)
- Rumford Prize (1963)
- Nobel Prize in Physics (1967)
- National Medal of Science (1975)
- Lomonosov Gold Medal (1989)
- Oersted Medal (1993)
- Bruce Medal (2001)
- Benjamin Franklin Medal for Distinguished Achievement in the Sciences of the American Philosophical Society (2005)
- Named after him
- Asteroid 30828 Bethe
- Hans Bethe Prize of the American Physical Society
- Hans Bethe House at Cornell University
- Bethe ansatz, a method for finding the exact solutions of certain one-dimensional quantum many-body models
- Hans Bethe Center, 322 4th St. NE, Washington, DC 20002. The Center is home to the Council for a Livable World, where Bethe was a longtime board member.
- Bethe Center for Theoretical Physics, University of Bonn, Germany
- Bethe-Salpeter equation
- Bethe formula
- Bethe, H. A. "Theory of High Frequency Rectification by Silicon Crystals", Massachusetts Institute of Technology (MIT) Radiation Laboratory, United States Department of Energy (through predecessor agency the Atomic Energy Commission), (October 29, 1942).
- Bethe, H. A. "Theoretical Estimate of Maximum Possible Nuclear Explosion", Knolls Atomic Power Laboratory-Schenectady, N.Y., United States Department of Energy (through predecessor agency the Atomic Energy Commission), (January 31, 1950).
- Bethe, H. A.; Rajaraman, R. "Three-body Problem in Nuclear Matter", University of Southern California-Los Angeles, United States Department of Energy (through predecessor agency the Atomic Energy Commission), (1967).
- Bethe, H. A. "Note on Inverse Bremsstrahlung in a Strong Electromagnetic Field", Los Alamos National Laboratory (LANL), United States Department of Energy (through predecessor agency the Atomic Energy Commission), (September 1972).
- Bethe, H. A. "Pauli Principle and Pion Scattering", Los Alamos National Laboratory (LANL), United States Department of Energy (through predecessor agency the Atomic Energy Commission), (October 1972).
- Bethe, H. A. "Fusion Hybrid Reactor", Sandia National Laboratories, United States Department of Energy, (August 1981).
See also 
- List of German inventors and discoverers
- List of Jewish Nobel laureates
- The Day After Trinity (1980)
- Lee, S.; Brown, G. E. (2007). "Hans Albrecht Bethe. 2 July 1906 -- 6 March 2005: Elected ForMemRS 1957". Biographical Memoirs of Fellows of the Royal Society 53: 1–20. doi:10.1098/rsbm.2007.0018.
- Horgan, J. (1992) Profile: Hans A. Bethe – Illuminator of the Stars, Scientific American 267(4), 32–40.
- Available at www.JamesKeckCollectedWorks.org  are the class notes taken by one of his students at Cornell from the graduate courses on Nuclear Physics and on Applications of Quantum Mechanics he taught in the spring of 1947.
- Wark, David (2007-01-11). "The supreme problem solver". Nature 445 (7124): 149. Bibcode:2007Natur.445..149W. doi:10.1038/445149a.
- "Interview with Hans Bethe by Charles Weiner at Cornell University". American Institute of Physics. November 17, 1967. Retrieved 25 April 2012. "When asked by Charles Weiner if there was religion in his home, Bethe replied: "No. My father was, I think, slightly religious. I was taught to pray in the evening before going to bed, and I attended the Protestant religious instruction, which was given in the schools in Germany. I was also confirmed, and the instruction which I got in this connection got religion out of my system completely. It was never very strong before, and the confirmation had the consequence that I Just didn't believe.""
- Denis Brian (2001). The Voice Of Genius: Conversations With Nobel Scientists And Other Luminaries. Basic Books. p. 117. ISBN 9780738204475. "Bethe: "I am an atheist.""
- Bethe, H.; Bacher, R (1936). "Nuclear Physics. A: Stationary States of Nuclei". Reviews of Modern Physics 8 (2): 82. Bibcode:1936RvMP....8...82B. doi:10.1103/RevModPhys.8.82.
- Bethe, H. (1937). "Nuclear Physics. B: Nuclear Dynamics, Theoretical". Reviews of Modern Physics 9 (2): 69. Bibcode:1937RvMP....9...69B. doi:10.1103/RevModPhys.9.69.
- Brand, David E. , Cornell News, March 10, 2005, accessed September 22, 2011.
- Schweber, S. S. (2000). In the Shadow of the Bomb: Bethe, Oppenheimer, and the Moral Responsibility of the Scientist. Princeton: Princeton University Press. p. 166. ISBN 978-0-691-04989-2.
- Garwin, R. L.; Bethe, H.A. (March 1968). "Anti-Ballistic Missile Systems". Scientific American 218 (3): 21–31. doi:10.1038/scientificamerican0368-21.
- Beck, G.; Bethe, H.; Riezler, W. (January 1931). "Remarks on the quantum theory of the absolute zero of temperature". Die Naturwissenschaften 19 (2): 39. Bibcode:1931NW.....19...37C. doi:10.1007/BF01523870. Retrieved 2008-12-02.
- Nobel Laureate Hans Bethe passes away at age of 98, March 7, 2005, Wikinews
- Hans Bethe Biography, Encyclopedia of World Biography
- "Book of Members, 1780–2010: Chapter B". American Academy of Arts and Sciences. Retrieved June 24, 2011.
- "Henry Draper Medal". National Academy of Sciences. Retrieved 24 February 2011.
- "Past Recipients of the Rumford Prize". American Academy of Arts and Sciences. Retrieved 24 February 2011.
- National Science Foundation
- "Past Winners of the Catherine Wolfe Bruce Gold Medal". Astronomical Society of the Pacific. Retrieved 24 February 2011.
- "Benjamin Franklin Medal for Distinguished Achievement in the Sciences Recipients". American Philosophical Society. Retrieved November 26, 2011.
- Council for a Livable World, Our Legacy
- Bernstein, Jeremy. Hans Bethe, Prophet of Energy. New York : Basic Books, 1980. ISBN 978-0-465-02903-7.
- Bethe, Hans A. The Road from Los Alamos. New York: American Institute of Physics, 1991. ISBN 978-0-88318-707-4.
- Schweber, Silvan S. Nuclear Forces: The Making of the Physicist Hans Bethe (Harvard University Press; 2012) 608 pages; scholarly biography
- Streeter, E.C. Solving the Solar Enigma: The Story of the Scientists Behind the Discovery of the Sun's Energy Source Dimension Engineering Press, 2005. ISBN 978-1-888381-12-2.
|Wikiquote has a collection of quotations related to: Hans Bethe|
- Three Lectures by Hans Bethe, from the Cornell University
- Biography and Bibliographic Resources, from the Office of Scientific and Technical Information, United States Department of Energy
- Hans Bethe at Nobel lectures
- Hans Bethe at World of Science
- Text of the Eddington Medal award speech
- Bruce Medal page
- Hans Bethe And His Physics
- his contributions to the theory of nuclear reactions, especially his discoveries concerning the energy production in stars.
- Annotated bibliography for Hans Bethe from the Alsos Digital Library for Nuclear Issues
- Oral History interview transcript with Hans Bethe 17 January 1967, American Institute of Physics, Niels Bohr Library and Archives
- [http://osulibrary.orst.edu/specialcollections/events/1995paulingconference/video-s4-1-schweber.html Video of a talk titled "Writing the Biography of a Living Scientist: Hans Bethe," delivered by S.S. Schweber
- [http://webofstories.com/gl/hans.bethe Hans Bethe tells his life story at Web of Stories
- O'Connor, John J.; Robertson, Edmund F., "Hans Bethe", MacTutor History of Mathematics archive, University of St Andrews.
- Hans Bethe at the Mathematics Genealogy Project
- National Academy of Sciences Biographical Memoir
- Bowley, Roger; Merrifield, Michael; Padilla, Antonio (Tony). "αβγ – The Alpha Beta Gamma Paper". Sixty Symbols. Brady Haran for the University of Nottingham.