Hans Bethe

Name	Hans Bethe
Birth date	July 2, 1906
Birth place	Strasbourg, Germany
Residence	United States
Nationality	GermanAmerican
Death date	March 06, 2005
Death place	Ithaca, New York, US
Field	Nuclear Physics
Alma mater	University of FrankfurtUniversity of Munich
Work institution	University of TübingenCornell UniversityUniversity of Manchester
Doctoral advisor	Arnold Sommerfeld
Doctoral students	M K SundaresanJeffrey GoldstoneRoman JackiwFreeman DysonRobert Eugene MarshakJohn IrwinDavid J. ThoulessP. S. Epstein Gordon L. Shaw
Known for	Nuclear PhysicsStellar nucleosynthesisQuantum electrodynamics
Prizes

Hans Albrecht Bethe (; July 2, 1906 – March 6, 2005) was a German-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. 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 Straßburg, Germany. Although his mother was Jewish, he was raised a Christian in the religion of his father. Bethe studied physics at JWG University, 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.

Bethe became a naturalized citizen of the United States in 1941. He was an honorary member of the International Academy of Science.

Manhattan Project

ID badge.]] When the war began, Bethe wanted to contribute to the war effort. Following the advice of the Caltech aerodynamicist Theodore von Karman, 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, an English 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:

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As for his own role in the project, and its relation to the famous Teller-Ulam priority dispute, Bethe later said that:

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

, 1978]] 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 was a definite starting point. This work provided the impetus for the pioneering 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. In his 80s, he wrote an important article about the solar neutrino problem in which he dealt with the conversion of electron neutrinos into muon neutrinos that was proposed to explain the 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 Henry Draper Medal of the National Academy of Sciences (1947)

Max Planck medal (1955)

Benjamin 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) 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

See also

Bethe-Salpeter equation

Bethe formula

List of Jewish Nobel laureates

The Day After Trinity (1980)

Notes

References

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.

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.

Publications

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).

External links

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

Hans Bethe at Britannica Nobel Prizes

Text of the Eddington Medal award speech

Bruce Medal page

Three Lectures by Hans Bethe videos on Quantum Mechanics given at Cornell University in 1999.

Obituaries

* from (Wikinews)

*Hans Bethe obituary from Scientific journal Nature

*Hans Bethe obituary from The Economist magazine

*Hans Bethe obituary from The Guardian Newspaper

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

Obituary by R. (Dougy) Rajaraman

Oral History interview transcript with Hans Bethe 17 January 1967, American Institute of Physics, Niels Bohr Library and Archives

Oral History interview transcript with Hans Bethe 27 October 1966, 17 November 1967, & 8 May 1972, American Institute of Physics, Niels Bohr Library and Archives

Oral History interview transcript with Hans Bethe 29 April 1981, American Institute of Physics, Niels Bohr Library and Archives

S.S. Schweber ">Video of a talk titled "Writing the Biography of a Living Scientist: Hans Bethe," delivered by S.S. Schweber

Hans Bethe tells his life story at Web of Stories

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