View source for Hans Bethe

{{short description|German-American physicist (1906–2005)}}
{{Use mdy dates|date=September 2020}}
{{good article}}
{{Infobox scientist
| honorific_suffix  = {{post-nominals|country=GBR|size=100%|ForMemRS}}
| image             = Hans Bethe.jpg
| birth_name        = Hans Albrecht Eduard Bethe
| birth_date        = {{birth date|1906|7|2}}
| birth_place       = [[Straßburg]], [[Alsace–Lorraine]], [[German Empire]]
| death_date        = {{death date and age|2005|3|6|1906|7|2}}
| death_place       = [[Ithaca, New York]], U.S.
| citizenship       = {{ubl|Germany|United States (1941–2005)}}
| alma_mater        = {{ubl|[[Johann Wolfgang Goethe University Frankfurt am Main|University of Frankfurt]]|[[University of Munich]] ([[PhD]])}}
| known_for         = {{ubl|[[Bethe ansatz]]|[[Bethe formula]]|[[Bethe lattice]]|[[Bethe–Slater curve]]|[[Bethe–Salpeter equation]]|[[Bethe–Feynman formula]]||[[Bethe–Weizsäcker formula]]|[[Bethe–Weizsäcker process]]|[[Non ideal compressible fluid dynamics#Non-classical gas-dynamic regime|BZT fluid]]|[[Mott–Bethe formula]]|[[Cavity perturbation theory]]|[[Crystal field theory]]|[[Double group]]|[[Quantum electrodynamics]]|[[Stellar nucleosynthesis]]}}
| spouse            = {{marriage|Rose Ewald|1939}} (1917-2019)
| awards            = {{ubl|[[Henry Draper Medal]] (1947)|[[List of fellows of the Royal Society elected in 1957|ForMemRS (1957)]]<ref name=frs/>|[[Franklin Medal]] (1959)|[[Eddington Medal]] (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 (American Philosophical Society)|Benjamin Franklin Medal]] (2005)}}
| fields            = {{ubl|[[Nuclear physics]]|[[Theoretical physics]]}}
| work_institution  = {{ubl|[[University of Tübingen]]|[[Cornell University]]|[[University of Bristol]]|[[University of Manchester]]|[[University of Chicago]]}}
| doctoral_advisor  = [[Arnold Sommerfeld]]
| thesis_title      = Theorie der Beugung von Elektronen an Kristallen
| thesis_url        = https://worldcat.org/en/title/793769538
| thesis_year       = 1928
| doctoral_students = {{ubl|[[Michel Baranger]]|[[David Breed Beard]]|[[Hildred Blewett]]|[[Peter A. Carruthers]]|[[Ajoy Ghatak]]|[[Jeffrey Goldstone]]|[[Roman Jackiw]]|[[Francis E. Low]]|[[Robert Eugene Marshak]]|[[Walter McAfee]]|[[Boyce McDaniel]]|[[Asoke Nath Mitra]]|[[Michael Nauenberg]]|[[John W. Negele]]|[[Mark Nelkin]]|[[Ramamurti Rajaraman]]|[[J. J. Sakurai]]| {{ill|Gordon Shaw|it}}|[[David J. Thouless]]}}
| notable_students  = [[Freeman Dyson]]
| signature         = Hans Bethe (signature).png
}}
'''Hans Albrecht Eduard Bethe'''<ref>{{Cite web |title=1 E 336 - Naissances : actes n° 1761 à 2774 (09/05/1906 au 23/07/1906). - 1906 Archives de la Ville et l'Eurométropole de Strasbourg |url=https://archives.strasbourg.eu/ark:/39332/vta4accc99dfdec1b1e/daogrp/0/390#id:1993225906 |access-date=2025-03-19 |website=Archives de la ville et de l'Eurométropole de Strasbourg |archive-url=https://archive.today/20250319203104/https://archives.strasbourg.eu/ark:/39332/vta4accc99dfdec1b1e/daogrp/0/390%23id:1993225906?gallery=true&center=1761.224,-715.252&zoom=11&rotation=0.000&brightness=100.00 |archive-date=2025-03-19 |url-status=live |language=fr-fr}}</ref> ({{IPAc-en|ˈ|b|ɛ|θ|ə}}; {{IPA|de|ˈhans ˈbeːtə|lang|De-Hans Bethe.ogg}}; July 2, 1906 – March 6, 2005) was a German-American [[physicist]] who made major contributions to [[nuclear physics]], [[astrophysics]], [[quantum electrodynamics]] and [[solid-state physics]], and received the [[Nobel Prize in Physics]] in 1967 for his work on the theory of [[stellar nucleosynthesis]].<ref name=frs>{{cite journal |doi=10.1098/rsbm.2007.0018 |title=Hans Albrecht Bethe. 2 July 1906 – 6 March 2005: Elected ForMemRS 1957 |date=2007 |last1=Lee |first1=S. |last2=Brown |first2=G. E. |journal=[[Biographical Memoirs of Fellows of the Royal Society]] |volume=53 |pages=1|doi-access=free }}</ref><ref>{{cite journal |doi=10.1038/scientificamerican1092-32 |title=Illuminator of the Stars |date=1992 |last1=Horgan |first1=John |journal=Scientific American |volume=267 |issue=4 |pages=32–40|bibcode = 1992SciAm.267d..32H }}</ref><ref>{{Citation |last1=Mermin |first1=N. David |title=Hans Bethe's Contributions to Solid-State Physics |date=2006 |work=Hans Bethe and His Physics |pages=189–200 |url=http://www.worldscientific.com/doi/abs/10.1142/9789812774507_0013 |access-date=2025-01-01 |publisher=WORLD SCIENTIFIC |language=en |doi=10.1142/9789812774507_0013 |isbn=978-981-256-609-6 |last2=Ashcroft |first2=Neil W.|bibcode=2006hbhp.book..189M |url-access=subscription }}</ref><ref>{{Cite journal |date=2019-07-02 |title=Hans Bethe |url=https://pubs.aip.org/physicstoday/online/4553 |journal=Physics Today |language=en |volume=2019 |issue=7 |article-number=4553 |doi=10.1063/pt.6.6.20190702a|bibcode=2019PhT..2019g4553. |url-access=subscription }}</ref> For most of his career, Bethe was a professor at [[Cornell University]].<ref name="Keck1947">[http://www.jameskeckcollectedworks.org James C. Keck Collected Works and Biography] ({{Webarchive|url=https://web.archive.org/web/20190509175534/http://www.jameskeckcollectedworks.org/|date=May 9, 2019}}) has the class notes taken by one of Bethe's students at Cornell from the graduate courses on Nuclear Physics and on Applications of Quantum Mechanics he taught in the spring of 1947.</ref>

In 1931, Bethe developed the [[Bethe ansatz]], which is a method for finding the exact solutions for the [[Eigenvalue|eigenvalues]] and [[Eigenvector|eigenvectors]] of certain one-dimensional quantum many-body models.<ref>{{Cite journal |last=Batchelor |first=Murray T. |date=2007-01-01 |title=The Bethe ansatz after 75 years |url=https://pubs.aip.org/physicstoday/article/60/1/36/918724/The-Bethe-ansatz-after-75-yearsA-1931-result-that |journal=Physics Today |language=en |volume=60 |issue=1 |pages=36–40 |doi=10.1063/1.2709557 |bibcode=2007PhT....60a..36B |issn=0031-9228|hdl=1885/95035 |hdl-access=free |url-access=subscription }}</ref> In 1939, Bethe published a paper which established the [[CNO cycle]] as the primary energy source for heavier stars in the [[main sequence]] classification of stars, which earned him a Nobel Prize in 1967.<ref>{{Cite journal |last=Mazumdar |first=Indranil |date=2005 |title=Nucleosynthesis and energy production in stars: Bethe's crowning achievement |url=http://link.springer.com/10.1007/BF02867168 |journal=Resonance |language=en |volume=10 |issue=10 |pages=67–77 |doi=10.1007/BF02867168 |issn=0971-8044|url-access=subscription }}</ref> During [[World War II]], Bethe was head of the Theoretical Division at the secret [[Los Alamos National Laboratory]] that [[Manhattan Project|developed]] the first [[atomic bomb]]s. There he played a key role in calculating the [[Critical mass (nuclear)|critical mass]] of the weapons and developing the theory behind the [[Implosion-type nuclear weapon|implosion method]] used in both the [[Trinity test]] and the "[[Fat Man]]" weapon [[Atomic bombings of Hiroshima and Nagasaki|dropped on Nagasaki in August 1945]].

After the war, Bethe played an important role in the development of the [[hydrogen bomb]], as he also served as the head of the theoretical division for the project, although he had originally joined the project with the hope of proving it could not be made.<ref>{{Cite journal |last1=Garwin |first1=Richard L. |last2=Gottfried |first2=Kurt |date=2005-10-01 |title=Hans in War and Peace |url=https://pubs.aip.org/physicstoday/article/58/10/52/396031/Hans-in-War-and-PeaceHans-Bethe-spent-a-lifetime |journal=Physics Today |language=en |volume=58 |issue=10 |pages=52–57 |doi=10.1063/1.2138421 |bibcode=2005PhT....58j..52G |issn=0031-9228}}</ref> He later campaigned with [[Albert Einstein]] and the [[Emergency Committee of Atomic Scientists]] against [[nuclear testing]] and the [[nuclear arms race]]. He helped persuade the [[Kennedy administration|Kennedy]] and [[Nixon administration]]s to sign, respectively, the 1963 [[Partial Nuclear Test Ban Treaty]] and 1972 [[Anti-Ballistic Missile Treaty]] ([[SALT I]]). In 1947, he wrote an important paper which provided the calculation of the [[Lamb shift]], which is credited with revolutionizing quantum electrodynamics and further "opened the way to the modern era of [[particle physics]]".<ref name="Bethe 1947" />{{sfn|Brown|Lee|2006|pp=118, 161}}<ref name=":0">{{Cite journal |last=Maclay |first=G. Jordan |date=2020-04-13 |title=History and Some Aspects of the Lamb Shift |journal=Physics |language=en |volume=2 |issue=2 |pages=105–149 |doi=10.3390/physics2020008 |doi-access=free |bibcode=2020Physi...2..105M |issn=2624-8174}}</ref> He contributed to the understanding of [[Neutrino|neutrinos]]<ref>{{Cite journal |last1=Bethe |first1=H. |last2=Peierls |first2=R. |date=1934 |title=The "Neutrino" |url=https://www.nature.com/articles/133532a0 |journal=Nature |language=en |volume=133 |issue=3362 |pages=532 |doi=10.1038/133532a0 |bibcode=1934Natur.133..532B |issn=0028-0836}}</ref> and was key in the solving of the [[solar neutrino problem]].<ref>{{Cite journal |last1=Bahcall |first1=John N. |last2=Salpeter |first2=Edwin E. |date=2005-10-01 |title=Stellar Energy Generation and Solar Neutrinos |url=https://pubs.aip.org/physicstoday/article/58/10/44/396081/Stellar-Energy-Generation-and-Solar-NeutrinosHalf |journal=Physics Today |language=en |volume=58 |issue=10 |pages=44–47 |doi=10.1063/1.2138419 |bibcode=2005PhT....58j..44B |issn=0031-9228|url-access=subscription }}</ref> He contributed to the understanding of [[Supernova|supernovas]] and their processes.<ref>{{Cite journal |last1=Woosley |first1=S |last2=Heger |first2=A |date=2007 |title=Nucleosynthesis and remnants in massive stars of solar metallicity |url=https://linkinghub.elsevier.com/retrieve/pii/S037015730700049X |journal=Physics Reports |language=en |volume=442 |issue=1–6 |pages=269–283 |doi=10.1016/j.physrep.2007.02.009|arxiv=astro-ph/0702176 |bibcode=2007PhR...442..269W }}</ref>

His scientific research never ceased, and he was publishing papers well into his nineties, making him one of the few scientists to have published at least one major paper in his field during every decade of his career, which in Bethe's case spanned nearly seventy years. Physicist [[Freeman Dyson]], once his doctoral student, called him "the supreme problem-solver of the 20th century",<ref name="Wark2007">{{cite journal |title=The Supreme Problem Solver |journal=Nature |date=January 11, 2007 |first=David |pages=149–150 |last=Wark |volume=445|doi=10.1038/445149a |bibcode=2007Natur.445..149W |issue=7124|doi-access=free }}</ref> and cosmologist [[Edward Kolb]] called him "the last of the old masters" of physics.<ref>{{Cite news |last1=Maugh II |first1=Thomas H. |last2=Cole |first2=K.C. |date=2005-03-08 |title='The Last of the Old Masters' of Physics |url=https://www.latimes.com/archives/la-xpm-2005-mar-08-sci-bethe8-story.html |access-date=2025-01-01 |work=Los Angeles Times}}</ref>

== Early life ==

Bethe was born in [[Strasbourg]], which at the time was part of the [[Reichsland Elsaß-Lothringen]], [[Germany]], on July 2, 1906, the only child of Anna (née Kuhn) and [[Albrecht Bethe]], a {{lang|de|[[Privatdozent]]}} of physiology at the [[University of Strasbourg]].{{sfn|Bernstein|1980|p=7}} Although his mother, the daughter of [[Abraham Kuhn]], professor at the University of Strasbourg, had a [[Jewish]] background,{{sfn|Bernstein|1980|p=8}} Bethe was raised [[Protestant]], like his father;{{sfn|Schweber|2012|pp=32–34}}<ref>{{cite web|title=Interview with Hans Bethe by Charles Weiner at Cornell University|url=http://www.aip.org/history/ohilist/4504_2.html|publisher=American Institute of Physics|access-date=April 25, 2012|date=November 17, 1967|quote=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."|archive-date=February 21, 2015|archive-url=https://web.archive.org/web/20150221063507/http://www.aip.org/history/ohilist/4504_2.html|url-status=dead}}</ref> and he became an [[atheist]] later in life.{{sfn|Brian|2001|p=117}}

[[File:Hans Bethe, aged 12.jpg|thumb|left|Hans Bethe, aged 12, with his parents]]
His father accepted a position as professor and director of the Institute of Physiology at the [[University of Kiel]] in 1912, and the family moved into the director's apartment at the institute. Initially, he was schooled privately by a professional teacher as part of a group of eight girls and boys.{{sfn|Schweber|2012|pp=30–31}} The family moved again in 1915 when his father became the head of the new Institute of Physiology at the [[Goethe University Frankfurt]].{{sfn|Schweber|2012|pp=32–34}}

Bethe attended the {{lang|de|[[Goethe-Gymnasium, Frankfurt|Goethe-Gymnasium]]|italic=no}} in [[Frankfurt]], Germany. His education was interrupted in 1916, when he contracted [[tuberculosis]], and he was sent to [[Bad Kreuznach]] to recuperate. By 1917, he had recovered sufficiently to attend the local {{lang|de|[[Realschule]]}} and the following year, he was sent to the {{lang|de|[[Odenwaldschule]]}}, a private, coeducational [[boarding school]].{{sfn|Schweber|2012|pp=36–40}} He attended the {{lang|de|Goethe-Gymnasium}} again for his final three years of secondary schooling, from 1922 to 1924.{{sfn|Schweber|2012|p=45}}

Having passed his {{lang|de|[[Abitur]]}}, Bethe entered the University of Frankfurt in 1924. He decided to major in [[chemistry]]. The instruction in physics was poor, and while there were distinguished mathematicians in Frankfurt such as [[Carl Ludwig Siegel]] and [[Otto Szász]], Bethe disliked their approaches, which presented mathematics without reference to the other sciences.{{sfn|Bernstein|1980|pp=11–12}} Bethe found that he was a poor experimentalist who destroyed his lab coat by spilling [[sulfuric acid]] on it, but he found the advanced physics taught by the associate professor, [[Walter Gerlach]], more interesting.{{sfn|Bernstein|1980|pp=11–12}}{{sfn|Schweber|2012|pp=70–73}} Gerlach left in 1925 and was replaced by [[Karl Meissner]], who advised Bethe that he should go to a university with a better school of theoretical physics, specifically the [[Ludwig Maximilian University of Munich|University of Munich]], where he could study under [[Arnold Sommerfeld]].{{sfn|Bernstein|1980|p=13}}{{sfn|Schweber|2012|p=93}}

Bethe entered the University of Munich in April 1926, where Sommerfeld took him on as a student on Meissner's recommendation.{{sfn|Schweber|2012|pp=118–119}} Sommerfeld taught an advanced course on differential equations in physics, which Bethe enjoyed. Because he was such a renowned scholar, Sommerfeld frequently received advance copies of scientific papers, which he put up for discussion at weekly evening seminars. When Bethe arrived, Sommerfeld had just received [[Erwin Schrödinger]]'s papers on [[Schrödinger equation|wave mechanics]].{{sfn|Bernstein|1980|pp=15–16}}

For his [[PhD]] thesis, Sommerfeld suggested that Bethe examine [[electron diffraction]] in [[crystal]]s. As a starting point, Sommerfeld suggested [[Paul Peter Ewald|Paul Ewald]]'s 1914 paper on [[X-ray diffraction]] in crystals. Bethe later recalled that he became too ambitious, and, in pursuit of greater accuracy, his calculations became unnecessarily complicated.{{sfn|Bernstein|1980|pp=20–21}} When he met [[Wolfgang Pauli]] for the first time, Pauli told him: "After Sommerfeld's tales about you, I had expected much better from you than your thesis."{{sfn|Schweber|2012|p=142}} "I guess from Pauli," Bethe later recalled, "that was a compliment."{{sfn|Schweber|2012|p=142}}

== Early work ==
After Bethe received his doctorate, [[Erwin Madelung]] offered him an assistantship in Frankfurt, and in September 1928 Bethe moved in with his father, who had recently divorced his mother. His father had met Vera Congehl earlier that year and married her in 1929. They had two children, Doris, born in 1933, and Klaus, born in 1934.{{sfn|Schweber|2012|pp=156–157}}

Bethe did not find the work in Frankfurt very stimulating, and in 1929 he accepted an offer from Ewald at the ''[[Technische Hochschule]]'' in [[Stuttgart]]. While there, he wrote what he considered to be his greatest paper,{{sfn|Bernstein|1980|pp=25–27}} ''Zur Theorie des Durchgangs schneller Korpuskularstrahlen durch Materie'' ("The Theory of the Passage of Fast Corpuscular Rays Through Matter").<ref>{{cite journal |last=Bethe |first=Hans |journal=Annalen der Physik |title=Zur Theorie des Durchgangs schneller Korpuskularstrahlen durch Materie |language=German |volume=397 |issue=3 |date=1930 |pages=325–400 |doi=10.1002/andp.19303970303 |bibcode = 1930AnP...397..325B }}</ref> Starting from [[Max Born]]'s interpretation of the [[Schrödinger equation]], Bethe produced a simplified formula for collision problems using a [[Fourier transform]], which is known today as the [[Bethe formula]]. He submitted this paper for his ''[[habilitation]]'' in 1930.{{sfn|Bernstein|1980|pp=25–27}}{{sfn|Schweber|2012|p=181}}{{sfn|Brown|Lee|2006|p=7}}

Sommerfeld recommended Bethe for a [[Rockefeller Foundation]] Travelling Scholarship in 1929. This provided $150 a month (about ${{Inflation|US|0.15|1929|r=0}},000 in {{inflation/year|US}} dollars{{Inflation-fn|US|group=upper-alpha}}) to study abroad. In 1930, Bethe chose to do postdoctoral work at the [[Cavendish Laboratory]] at the [[University of Cambridge]] in England, where he worked under the supervision of [[Ralph Fowler]].{{sfn|Schweber|2012|pp=182–183}} At the request of [[Patrick Blackett]], who was working with [[cloud chamber]]s, Bethe created a [[Special relativity|relativistic]] version of the Bethe formula.{{sfn|Schweber|2012|p=187}}

Bethe was known for his sense of humor, and with [[Guido Beck]] and {{ill|Wolfgang Riezler|de|Wolfgang Riezler}}, two other postdoctoral [[research fellow]]s, created a [[List of scholarly publishing stings|hoax paper]] ''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.<ref>{{cite journal | doi= 10.1007/BF01523870 | title= Zuschriften | date= 1931 | last1= Corlin | first1= Axel | last2= Stein | first2= J. S. | last3= Beck | first3= G. | last4= Bethe | first4= H. | last5= Riezler | first5= W. | journal= Die Naturwissenschaften | volume= 19 | issue= 2 | pages= 37|bibcode = 1931NW.....19...37C | s2cid= 260488517 }}</ref> The paper poked fun at a certain class of papers in theoretical physics of the day, which were purely speculative and based on spurious numerical arguments, such as [[Arthur Eddington]]'s attempts to explain the value of the [[fine structure constant]] from fundamental quantities in an earlier paper. They were forced to issue an apology.{{sfn|Schweber|2012|pp=190–192}}

For the second half of his scholarship, Bethe chose to go to [[Enrico Fermi]]'s laboratory in Rome in February 1931. He was greatly impressed by Fermi and regretted that he had not gone to Rome first.{{sfn|Schweber|2012|p=193}} Bethe developed the [[Bethe ansatz]], a method for finding the exact solutions for the [[eigenvalue]]s and [[eigenvector]]s of certain one-dimensional quantum many-body models.{{sfn|Schweber|2012|pp=199–202}} He was influenced by Fermi's simplicity and Sommerfeld's rigor in approaching problems and these qualities influenced his own later research.{{sfn|Schweber|2012|p=195}}

The Rockefeller Foundation offered an extension of Bethe's fellowship, allowing him to return to Italy in 1932.{{sfn|Schweber|2012|pp=202–208}} In the meantime, Bethe worked for Sommerfeld in Munich as a ''privatdozent''. Since Bethe was fluent in English, Sommerfeld had Bethe supervise all his English-speaking postdoctoral fellows, including [[Lloyd P. Smith]] from [[Cornell University]].{{sfn|Bernstein|1980|p=32}} Bethe accepted a request from [[Karl Scheel]] to write an article for the ''Handbuch der Physik'' on the [[quantum mechanics]] of hydrogen and helium. Reviewing the article decades later, [[Robert Bacher]] and [[Victor Weisskopf]] noted that it was unusual in the depth and breadth of its treatment of the subject that required very little updating for the 1959 edition. Bethe was then asked by Sommerfeld to help him with the ''handbuch'' article on electrons in metals. The article covered the basis of what is now called [[solid state physics]]. Bethe took a very new field and provided a clear, coherent, and complete coverage of it.{{sfn|Schweber|2012|pp=202–208}} His work on the ''handbuch'' articles occupied most of his time in Rome, but he also co-wrote a paper with Fermi on another new field, [[quantum electrodynamics]], describing the relativistic interactions of charged particles.{{sfn|Schweber|2012|pp=211, 220–221}}

In 1932, Bethe accepted an appointment as an assistant professor at the [[University of Tübingen]], where [[Hans Geiger]] was the professor of experimental physics.{{sfn|Bernstein|1980|p=33}}{{sfn|Schweber|2012|pp=223–224}} One of the first laws passed by the new [[Nazi]] government was the [[Law for the Restoration of the Professional Civil Service]]. Due to his Jewish background, Bethe was dismissed from his job at the university, which was a government post. Geiger refused to help, but Sommerfeld immediately gave Bethe back his fellowship at Munich. Sommerfeld spent much of the summer term of 1933 finding places for Jewish students and colleagues.{{sfn|Bernstein|1980|p=35}}

Bethe left Germany in 1933, moving to England after receiving an offer for a position as lecturer at the [[University of Manchester]] for a year through Sommerfeld's connection to [[William Lawrence Bragg]].{{sfn|Bernstein|1980|p=35}} He moved in with his friend [[Rudolf Peierls]] and Peierls' wife Genia. Peierls was a fellow German physicist who had also been barred from academic positions in Germany because he was Jewish. This meant that Bethe had someone to speak to in German and he did not have to eat English food.{{sfn|Schweber|2012|pp=237–240}} Their relationship was professional as well as personal. Peierls aroused Bethe's interest in [[nuclear physics]].{{sfn|Schweber|2012|p=244}} After [[James Chadwick]] and [[Maurice Goldhaber]] discovered the [[photodisintegration]] of [[deuterium]],<ref>{{cite journal |doi=10.1038/134237a0 |title=A 'Nuclear Photo-effect': Disintegration of the Diplon by γ-Rays |date=1934 |last1=Chadwick |first1=J. |last2=Goldhaber |first2=M. |journal=Nature |volume=134 |issue=3381 |pages=237|bibcode = 1934Natur.134..237C |s2cid=4137231 |doi-access=free }}</ref> Chadwick challenged Bethe and Peierls to come up with a theoretical explanation of this phenomenon. This they did on the four-hour train ride from Cambridge back to Manchester.{{sfn|Brown|Lee|2009|p=9}} Bethe would investigate further in the years ahead.{{sfn|Schweber|2012|p=244}}

In 1933, the physics department at [[Cornell University]], [[New York (state)|New York]], was looking for a new theoretical physicist, and Lloyd Smith strongly recommended Bethe. This was supported by Bragg, who was visiting Cornell at the time. In August 1934, Cornell offered Bethe a position as an acting assistant professor. Bethe had already accepted a fellowship for a year to work with [[Nevill Mott]] at the [[University of Bristol]] for a semester, but Cornell agreed to let him start in the spring of 1935.{{sfn|Schweber|2012|pp=262–263}} Before leaving for the United States, he visited the [[Niels Bohr Institute]] in [[Copenhagen]] in September 1934, where he proposed to [[Hilde Levi]], who accepted. The match was opposed by Bethe's mother, who despite having a Jewish background, did not want him to marry a Jewish woman.{{sfn|Schweber|2012|p=279}} A few days before their wedding date in December, Bethe broke off their engagement.{{sfn|Schweber|2012|pp=272–275}} [[Niels Bohr]] and [[James Franck]] were so shocked by this action by Bethe that he was not invited to the institute again until after [[World War II]].{{sfn|Schweber|2012|p=279}}

== United States ==
Bethe arrived in the United States in February 1935, and joined the faculty at Cornell University on a salary of $3,000.{{sfn|Brown|Lee|2006|p=136}} Bethe's appointment was part of a deliberate effort on the part of the new head of its physics department, [[Roswell Clifton Gibbs]], to move into nuclear physics.{{sfn|Schweber|2012|pp=296–298}} Gibbs had hired [[Milton S. Livingston|Stanley Livingston]], who had worked with [[Ernest Lawrence]], to build a [[cyclotron]] at Cornell.{{sfn|Schweber|2012|pp=296–298}} To complete the team, Cornell needed an experimentalist, and, on the advice of Bethe and Livingston, recruited [[Robert Bacher]]. Bethe received requests to visit [[Columbia University]] from [[Isidor Isaac Rabi]], [[Princeton University]] from [[Edward Condon]], [[University of Rochester]] from [[Lee DuBridge]], [[Purdue University]] from [[Karl Lark-Horovitz]], the [[University of Illinois at Urbana–Champaign]] from [[Francis Wheeler Loomis]], and [[Harvard University]] from [[John Hasbrouck Van Vleck]]. Gibbs moved to prevent Bethe from being poached by having him appointed as a regular assistant professor in 1936, with an assurance that promotion to professor would soon follow.{{sfn|Schweber|2012|pp=305–307}}

Together with Bacher and Livingston, Bethe published a series of three articles,<ref>{{cite journal | last1=Bethe | first1=H. | last2=Bacher |first2=R |authorlink2=Robert Bacher | title=Nuclear Physics. A: Stationary States of Nuclei | date=1936 | journal=[[Reviews of Modern Physics]] | volume=8 | pages=82–229 | doi= 10.1103/RevModPhys.8.82 | bibcode=1936RvMP....8...82B | issue=2| url=https://authors.library.caltech.edu/51288/1/RevModPhys.8.82.pdf }}</ref><ref>{{cite journal | last=Bethe | first=H. | title=Nuclear Physics. B: Nuclear Dynamics, Theoretical | date=1937 | journal=[[Reviews of Modern Physics]] | volume=9 | pages=69–244 | doi= 10.1103/RevModPhys.9.69 | bibcode=1937RvMP....9...69B | issue=2}}</ref><ref>{{cite journal | last1=Bethe | first1=H. |last2=Livingston |first2=M. S. |authorlink2=Milton Stanley Livingston | title=Nuclear Physics. C: Nuclear Dynamics, Experimental | date=1937 | journal=[[Reviews of Modern Physics]] | volume=9 | pages=245–390 | doi= 10.1103/RevModPhys.9.245 | bibcode=1937RvMP....9..245L | issue=2}}</ref> which summarized most of what was known on the subject of nuclear physics until that time, an account that became known informally as "Bethe's Bible". It remained the standard work on the subject for many years. In this account, he also continued where others left off, filling in gaps in the older literature.{{sfn|Brown|Lee|2009|p=11}} Loomis offered Bethe a full professorship at the University of Illinois at Urbana–Champaign, but Cornell matched the position offered, and the salary of $6,000.{{sfn|Schweber|2012|p=313}} He wrote to his mother:

{{blockquote|I am about the leading theoretician in America. That does not mean the best. [[Eugene Wigner|Wigner]] is certainly better and [[Robert Oppenheimer|Oppenheimer]] and [[Edward Teller|Teller]] probably just as good. But I do more and talk more and that counts too.{{sfn|Schweber|2012|p=370}} }}

{{multiple image
| align     = right
| direction = vertical
| width     = 220
| image1    = Fusion in the Sun.svg
| caption1  = Illustration of the proton–proton chain reaction sequence
| image2    = CNO Cycle.svg
| caption2  = Overview of the CNO-I cycle – the helium nucleus is released at the top-left step
}}
On March 17, 1938, Bethe attended the [[Carnegie Institution for Science|Carnegie Institute]] and [[George Washington University]]'s fourth annual [[Washington Conference on Theoretical Physics]]. There were only 34 invited attendees, but they included [[Gregory Breit]], [[Subrahmanyan Chandrasekhar]], [[George Gamow]], [[Donald Menzel]], [[John von Neumann]], [[Bengt Strömgren]], [[Edward Teller]], and [[Merle Tuve]]. Bethe initially declined the invitation to attend, because the conference's topic, [[stellar nucleosynthesis|stellar energy generation]], did not interest him, but Teller persuaded him to go. At the conference, Strömgren detailed what was known about the temperature, density, and chemical composition of the Sun, and challenged the physicists to come up with an explanation. Gamow and [[Carl Friedrich von Weizsäcker]] had proposed in a 1937 paper that the Sun's energy was the result of a [[proton–proton chain reaction]]:{{sfn|Bernstein|1980|pp=45–47}}{{sfn|Schweber|2012|pp=345–347}}
: {|
|{{SubatomicParticle|link=yes|Proton}}&nbsp;||+&nbsp;||{{SubatomicParticle|link=yes|Proton}}||→&nbsp;||{{nuclide|link=yes|deuterium|2}}&nbsp;||+&nbsp;||{{SubatomicParticle|link=yes|Positron}}&nbsp;||+&nbsp;||{{SubatomicParticle|link=yes|Electron Neutrino}}
|}
But this did not account for the observation of elements heavier than helium. By the end of the conference, Bethe, working in collaboration with [[Charles Critchfield]], had come up with a series of subsequent nuclear reactions that explained how the Sun shines:{{sfn|Schweber|2012|p=347}}
: {|
|{{nuclide|link=yes|deuterium|2}}&nbsp;||+&nbsp;||{{SubatomicParticle|Proton|link=yes}}&nbsp;||→&nbsp;||{{nuclide|link=yes|helium|3}}&nbsp;||+&nbsp;||{{SubatomicParticle|link=yes|Gamma}}
|-
|{{nuclide|link=yes|helium|3}}&nbsp;||+&nbsp;||{{nuclide|link=yes|helium|4}}&nbsp;||→&nbsp;||{{nuclide|link=yes|beryllium|7}}&nbsp;||+&nbsp;||{{SubatomicParticle|link=yes|Gamma}}
|-
|{{nuclide|link=yes|beryllium|7}}&nbsp;||+&nbsp;||{{SubatomicParticle|link=yes|Electron}}&nbsp;||→&nbsp;||{{nuclide|link=yes|lithium|7}}&nbsp;||+&nbsp;||{{SubatomicParticle|link=yes|Electron Neutrino}}
|-
|{{nuclide|link=yes|lithium|7}}&nbsp;||+&nbsp;||{{SubatomicParticle|Proton|link=yes}}&nbsp;||→&nbsp;||2&nbsp;{{nuclide|link=yes|helium|4}}
|}

That this did not explain the processes in heavier stars was not overlooked. At the time there were doubts about whether the proton–proton cycle described the processes in the Sun, but more recent measurements of the Sun's core temperature and luminosity show that it does.{{sfn|Bernstein|1980|pp=45–47}} When he returned to Cornell, Bethe studied the relevant [[nuclear reaction]]s and reaction [[cross section (physics)|cross sections]], leading to his discovery of the [[CNO cycle|carbon-nitrogen-oxygen cycle (CNO cycle)]]:{{sfn|Schweber|2012|pp=348–350}}<ref>{{cite journal |title=Energy Production in Stars |first=H. A. |last=Bethe |journal=Physical Review |volume=55 |issue=5 |pages=434–456 |date=March 1, 1939 |doi=10.1103/PhysRev.55.434 |pmid=17835673 |bibcode=1939PhRv...55..434B |doi-access=free }}</ref>

: {|
|{{nuclide|link=yes|carbon|12}}&nbsp;||+&nbsp;||{{SubatomicParticle|Proton|link=yes}}&nbsp;||→&nbsp;||{{nuclide|link=yes|nitrogen|13}}&nbsp;||+&nbsp;||{{SubatomicParticle|link=yes|Gamma}}
|-
|{{nuclide|link=yes|nitrogen|13}}&nbsp;||&nbsp;||&nbsp;||→&nbsp;||{{nuclide|link=yes|carbon|13}}&nbsp;||+&nbsp;||{{SubatomicParticle|Positron|link=yes}}&nbsp;||+&nbsp;||{{SubatomicParticle|link=yes|Electron Neutrino}}
|-
|{{nuclide|link=yes|carbon|13}}&nbsp;||+&nbsp;||{{SubatomicParticle|Proton|link=yes}}&nbsp;||→&nbsp;||{{nuclide|link=yes|nitrogen|14}}&nbsp;||+&nbsp;||{{SubatomicParticle|Gamma|link=yes}}
|-
|{{nuclide|link=yes|nitrogen|14}}&nbsp;||+&nbsp;||{{SubatomicParticle|Proton|link=yes}}&nbsp;||→&nbsp;||{{nuclide|link=yes|oxygen|15}}&nbsp;||+&nbsp;||{{SubatomicParticle|Gamma|link=yes}}
|-
|{{nuclide|link=yes|oxygen|15}}&nbsp;||&nbsp;||&nbsp;||→&nbsp;||{{nuclide|link=yes|nitrogen|15}}&nbsp;||+&nbsp;||{{SubatomicParticle|Positron|link=yes}}&nbsp;||+&nbsp;||{{SubatomicParticle|Electron Neutrino|link=yes}}
|-
|{{nuclide|link=yes|nitrogen|15}}&nbsp;||+&nbsp;||{{SubatomicParticle|Proton|link=yes}}&nbsp;||→&nbsp;||{{nuclide|link=yes|carbon|12}}&nbsp;||+&nbsp;||{{nuclide|link=yes|helium|4}}
|}

The two papers, one on the proton–proton cycle, co-authored with Critchfield, and the other on the carbon-oxygen-nitrogen (CNO) cycle, were sent to the ''[[Physical Review]]'' for publication.{{sfn|Schweber|2012|pp=351–352}}

After ''[[Kristallnacht]]'', Bethe's mother had become afraid to remain in Germany. Taking advantage of her Strasbourg origin, she was able to emigrate to the United States in June 1939 on the French quota, rather than the German one, which was full.{{sfn|Bernstein|1980|p=39}} Bethe's graduate student [[Robert Marshak]] noted that the [[New York Academy of Sciences]] was offering a $500 prize for the best unpublished paper on the topic of solar and stellar energy. So Bethe, in need of $250 to release his mother's furniture, withdrew the CNO cycle paper and sent it in to the New York Academy of Sciences. It won the prize, and Bethe gave Marshak $50 finder's fee and used $250 to release his mother's furniture. The paper was subsequently published in the ''Physical Review'' in March. It was a breakthrough in the understanding of the stars, and would win Bethe the [[Nobel Prize in Physics]] in 1967.{{sfn|Bernstein|1980|pp=51–52}}{{sfn|Schweber|2012|pp=351–352}} In 2002, at age 96, Bethe sent a handwritten note to [[John N. Bahcall]] congratulating him on the use of solar neutrino observations to show that the CNO cycle accounts for approximately 7% of the Sun's energy; the neutrino observations had started with [[Raymond Davis Jr.]], whose experiment was based on Bahcall's calculations and encouragement, and the note led to Davis's receiving a share of the 2002 Nobel Prize.{{sfn|Brown|Lee|2006|p=149}}

Bethe married Rose Ewald, the daughter of [[Paul Peter Ewald|Paul Ewald]], on September 13, 1939, in a simple civil ceremony.{{sfn|Bernstein|1980|pp=54–55}} She had emigrated to the United States and was a student at Duke University and they met while Bethe was lecturing there in 1937. They had two children, Henry and Monica.<ref name="Nobel" /> (Henry was a [[contract bridge]] expert and former husband of [[Kitty Munson Cooper]].)<ref>{{cite news |author-link=Alan Truscott|last=Truscott |first=Alan |url=https://www.nytimes.com/1988/02/24/nyregion/bridge-son-of-nobel-prize-winner-is-famed-in-his-own-right.html |title=Bridge: Son of Nobel Prize Winner Is Famed in His Own Right |newspaper=[[The New York Times]] |date=February 24, 1988 |access-date=April 11, 2015}}</ref>

Bethe became a [[naturalized citizen]] of the United States in March 1941.{{sfn|Schweber|2012|p=382}} Writing to Sommerfeld in 1947, Bethe confided that "I am much more at home in America than I ever was in Germany. As if I was born in Germany only by mistake, and only came to my true homeland at 28."{{sfn|Brown|Lee|2006|p=143}}

== Manhattan Project ==
[[File:Bethe-hans a.jpg|right|thumb|Bethe's [[Los Alamos National Laboratory|Los Alamos Laboratory]] ID badge]]
When the Second World War began, Bethe wanted to contribute to the war effort,{{sfn|Bernstein|1980|p=61}} but was unable to work on classified projects until he became a citizen. Following the advice of the [[Caltech]] [[aerodynamicist]] [[Theodore von Kármán]], Bethe collaborated with his friend Edward Teller on a theory of shock waves that are generated by the passage of a projectile through a gas. Bethe considered it one of their most influential papers. He also worked on a theory of armor penetration, which was immediately classified by the army, thus making it impossible for Bethe (who was not an American citizen at the time) to access further research on the theory.{{sfn|Brown|Lee|2009|pp=13–14}}

After receiving security clearance in December 1941, Bethe joined the [[MIT Radiation Laboratory]], where he invented the [[Bethe-hole directional coupler]], which is used in [[microwave]] [[waveguide]]s such as those used in [[radar]] sets.{{sfn|Brown|Lee|2009|p=13}} In Chicago in June 1942, and then in July at the [[University of California, Berkeley]], he participated in a series of meetings at the invitation of Robert Oppenheimer, which discussed the first designs for the [[atomic bomb]]. They went over the preliminary calculations by [[Robert Serber]], [[Stan Frankel]], and others, and discussed the possibilities of using [[uranium-235]] and [[plutonium]]. (Teller then raised the prospect of a thermonuclear device, [[Teller's "Super" bomb]]. At one point Teller asked if the nitrogen in the atmosphere could be set alight. It fell to Bethe and [[Emil Konopinski]] to perform the calculations demonstrating the virtual impossibility of such an occurrence.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=42–47}}) "The fission bomb had to be done," he later recalled, "because the Germans were presumably doing it."<ref name="New York Times">{{cite news |newspaper=[[The New York Times]] |title=Hans Bethe Dies; Nobel Prize Winner Worked on A-Bomb |first=Martin |last=Weil |date=March 8, 2005 |page=B06 |url=https://www.nytimes.com/2005/03/07/science/hans-bethe-father-of-nuclear-astrophysics-dies-at-98.html |access-date=December 30, 2024}}</ref>

When Oppenheimer was put in charge of forming a secret weapons design laboratory, [[Los Alamos National Laboratory|Los Alamos]], he appointed Bethe director of the T (Theoretical) Division, the laboratory's smallest, but most prestigious division. This move irked the equally qualified, but more difficult to manage Teller and [[Felix Bloch]], who had coveted the job.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=92–83}}{{sfn|Szasz|1992|pp=19–20}} A series of disagreements between Bethe and Teller between February and June 1944 over the relative priority of Super research led to Teller's group being removed from T Division and placed directly under Oppenheimer. In September it became part of Fermi's new F Division.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=204, 246}}

Bethe's work at Los Alamos included calculating the [[critical mass]] and efficiency 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 bomb's explosive yield.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=179–184}} After August 1944, when the laboratory was reorganized and reoriented to solve the problem of the [[Implosion (mechanical process)|implosion]] of the [[plutonium]] bomb, Bethe spent much of his time studying the hydrodynamic aspects of implosion, a job that he continued into 1944.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|p=129}} In 1945, he worked on the [[neutron]] initiator, and later, on radiation propagation from an exploding atomic bomb.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=308–310}} The [[Trinity nuclear test]] validated the accuracy of T Division's results.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=344–345}} When it was detonated in the New Mexico desert on July 16, 1945, 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."<ref>{{cite journal |journal= [[Nature (journal)|Nature]] |date=March 8, 2005 |doi=10.1038/news050307-7 |title=Hans Bethe – Nuclear physicist dies at 98 |first=Mark |last=Peplow }}</ref>

== Hydrogen bomb ==
After the war, Bethe argued that a crash project for the [[hydrogen bomb]] should not be attempted,<ref>{{Cite journal |last=McCoy |first=Alfred W. |date=2020 |title=How an Article about the H-Bomb Landed Scientific American in the Middle of the Red Scare |url=https://www.scientificamerican.com/article/how-an-article-about-the-h-bomb-landed-scientific-american-in-the-middle-of-the-red-scare/ |journal=Scientific American |volume=323 |issue=3 |pages=73 |doi=10.1038/scientificamerican0920-73 |pmid=39014692 |issn=0036-8733|url-access=subscription }}</ref> nevertheless after President [[Harry Truman]] announced the beginning of such a project and the outbreak of the [[Korean War]], Bethe signed up and played a key role in the weapon's development. Although he saw the project through to its end, Bethe had hoped that it would be impossible to create the hydrogen bomb.{{sfn|Bernstein|1980|pp=92–96}} He later remarked in 1968 on the apparent contradiction in his stance, having first opposed the development of the weapon and later helping to create it:

{{blockquote|Just a few months before, the Korean war had broken out, and for the first time I saw direct confrontation with the [[communist]]s. It was too disturbing. The [[Cold War|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]].{{sfn|Schweber|2000|p=166}} }}

As for his own role in the project and its relation to the [[History of the Teller–Ulam design#Ulam's and Teller's contributions|dispute over who was responsible for the design]], Bethe later said that:

{{blockquote|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 [[Stanislaw Ulam|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]].{{sfn|Schweber|2000|p=166}} }}

In 1954, Bethe testified on behalf of [[J. Robert Oppenheimer]] during the [[Oppenheimer security hearing]]. Specifically, Bethe argued that Oppenheimer's stances against developing the hydrogen bomb in the late 1940s had not hindered its development, a topic which was seen as a key motivating factor behind the hearing. Bethe contended that the developments that 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 persuade [[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 prewar years, the conflict between them during the [[Manhattan Project]], and especially during the Oppenheimer episode, permanently marred their relationship.{{sfn|Bernstein|1980|pp=97–99}}

== Later work ==

=== Lamb shift ===
[[File:Bethe hans.jpg|thumb|Hans Bethe lecturing at [[Dalhousie University]], 1978]]
After the war ended, Bethe returned to Cornell. In June 1947, he participated in the [[Shelter Island Conference]]. Sponsored by the [[National Academy of Sciences]] and held at the Ram's Head Inn on [[Shelter Island (town), New York|Shelter Island, New York]], the conference on the "Foundations of Quantum Mechanics" was the first major physics conference held after the war. It was a chance for American physicists to come together, pick up where they had left off before the war, and establish the direction of post-war research.{{sfn|Brown|Lee|2006|pp=157–158}}{{sfn|Brown|Lee|2009|p=15}}

A major talking point at the conference was the discovery by [[Willis Lamb]] and his graduate student, [[Robert Retherford]], shortly before the conference began that one of the two possible quantum states of hydrogen atoms had slightly more energy than that predicted by the theory of [[Paul Dirac]]; this became known as the [[Lamb shift]]. Oppenheimer and Weisskopf suggested that this was a result of [[quantum fluctuation]]s of the electromagnetic field, which gave the electron more energy. According to pre-war [[quantum electrodynamics]] (QED), the energy of the electron consisted of the bare energy it had when uncoupled from an electromagnetic field, and the self-energy resulting from the electromagnetic coupling, but both were unobservable, since the electromagnetic field cannot be switched off. QED gave infinite values for the self-energies; but the Lamb shift showed that they were both real and finite. [[Hans Kramers]] proposed [[renormalization]] as a solution, but no one knew how to do the calculation.{{sfn|Brown|Lee|2006|pp=157–158}}<ref name="Bethe 1947">{{cite journal| author=H. Bethe| year=1947| title=The Electromagnetic Shift of Energy Levels| journal=[[Physical Review]]| volume=72 | pages=339–341| doi=10.1103/PhysRev.72.339 |bibcode = 1947PhRv...72..339B | issue=4 | s2cid=120434909}}</ref>

Bethe managed to perform the calculation on the train from New York to [[Schenectady]], where he was working for [[General Electric]]. He did so by realising that it was a non-relativistic process, which greatly simplified the calculation. The bare energy was easily removed as it was already included in the observed mass of the electron. The self energy term now increased logarithmically instead of linearly, making it mathematically convergent. Bethe arrived at a value for the Lamb shift of 1040&nbsp;MHz, extremely close to that obtained experimentally by Lamb and Retherford. His paper, published in the ''Physical Review'' in August 1947, was only three pages long and contained just twelve mathematical equations, but was enormously influential. It had been presumed that the infinities indicated that QED was fundamentally flawed, and that a new, radical theory was required; Bethe demonstrated that this was not necessary.<ref name="Bethe 1947" />{{sfn|Brown|Lee|2006|pp=158–159}} 

His calculation of the Lamb shift has been called "the most important discovery in the history of the theory of quantum electrodynamics" by the physicist [[Richard Feynman]], while physicist Paul Dirac called it "the most important calculation in physics for decades".<ref name=":0" />

One of Bethe's most famous papers is one he never wrote: the 1948 [[Alpher–Bethe–Gamow paper]].<ref>{{cite journal |last1=Alpher |first1=R. A. |authorlink1=Ralph Asher Alpher |first2=H. |last2=Bethe |authorlink2=Hans Bethe |first3=G. |last3=Gamow |authorlink3=George Gamow |date=April 1, 1948 |title=The Origin of Chemical Elements |journal=[[Physical Review]] |volume=73 |issue=7 |pages=803–804 |doi=10.1103/PhysRev.73.803 |pmid=18877094 |bibcode=1948PhRv...73..803A |doi-access=free }}</ref> [[George Gamow]] added Bethe's name (in absentia) without consulting him, knowing that Bethe would not mind, and against [[Ralph Alpher]]'s wishes. This was apparently a reflection of Gamow's sense of humor, wanting to have a paper title that would sound like the first three letters of the Greek alphabet. As one of the ''Physical Review''{{'}}s reviewers, Bethe saw the manuscript and struck out the words "in absentia".{{sfn|Bernstein|1980|p=46}}

=== Astrophysics ===
Bethe believed that the [[atomic nucleus]] was like a [[Semi-empirical mass formula#The liquid drop model and its analysis|quantum liquid drop]]. He investigated the [[nuclear matter]] problem by considering the work conducted by [[Keith Brueckner]] on [[perturbation theory (quantum mechanics)|perturbation theory]]. Working with [[Jeffrey Goldstone]], he produced a solution for the case where there was an infinite hard-core potential. Then, working with Baird Brandow and Albert Petschek, he came up with an approximation that converted the [[scattering theory|scattering]] equation into an easily  solved [[differential equation]]. This then led him to the Bethe-Faddeev equation, a generalisation of [[Ludvig Faddeev]]'s approach to three-body scattering. He then used these techniques to examine the [[neutron stars]], which have densities similar to those of nuclei.{{sfn|Brown|Lee|2006|pp=165–171}}

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 E. Brown]] of [[Stony Brook University]]. In 1978, Brown proposed that they collaborate on supernovae. These were reasonably well understood by this time, but the calculations were still a problem. Using techniques honed from decades of working with nuclear physics, and some experience with calculations involving nuclear explosions, Bethe tackled the problems involved in stellar [[gravitational collapse]], and the way in which various factors affected a supernova explosion. Once again, he was able to reduce the problem to a set of differential equations, and to solve them.<ref>{{cite web |url=http://aps.org/programs/honors/prizes/prizerecipient.cfm?name=Gerald%20E%2E%20Brown&year=2001 |title=Hans A. Bethe Prize winners |publisher=American Physical Society |access-date=July 7, 2013}}</ref>{{sfn|Brown|Lee|2006|pp=176–180}}

At age 85, Bethe wrote an important article about the [[solar neutrino problem]], in which he helped establish the conversion mechanism for [[electron neutrino]]s into [[muon neutrino]]s proposed by [[Stanislav Mikheyev]], [[Alexei Yuryevich Smirnov|Alexei Smirnov]], and [[Lincoln Wolfenstein]] to explain a vexing discrepancy between theory and experiment. Bethe argued that physics beyond the [[Standard Model]] was required to understand the solar neutrino problem, because it presumed that neutrinos have no mass, and therefore, cannot metamorphosize into each other; whereas the MSW effect required this to occur. Bethe hoped that corroborating evidence would be found by the [[Sudbury Neutrino Observatory]] (SNO) in [[Ontario, Canada|Ontario]] by his 90th birthday, but he did not get the call from SNO until June 2001, when he was nearly 95.{{sfn|Brown|Lee|2006|pp=151–153}}<ref>{{cite journal |first1=J.N. |last1=Bahcall |author-link=John N. Bahcall |first2=H.A. |last2=Bethe |title=A solution of the solar neutrino problem |journal=Physical Review Letters  |volume=65 |pages=2233–2235 |date=1990 |doi=10.1103/PhysRevLett.65.2233 |pmid=10042492 |bibcode = 1990PhRvL..65.2233B |issue=18 }}</ref>

In 1996, [[Kip Thorne]] approached Bethe and Brown about [[LIGO]], the Laser Interferometer Gravitational-Wave Observatory designed to detect the gravitational waves from merging neutron stars and black holes. Since Bethe and Brown were good at calculating things that could not be seen, could they look at the mergers? The 90-year-old Bethe quickly became enthused and soon began the required calculations. The result was a 1998 paper on the "Evolution of Binary Compact Objects Which Merge", which Brown regarded as the best that the two produced together.{{sfn|Brown|Lee|2006|p=182}}<ref>{{cite journal |journal=Astrophysical Journal |issue=2 |volume=506 |pages=780–789 |date=1998 |doi=10.1086/306265 |arxiv = astro-ph/9802084 |bibcode = 1998ApJ...506..780B |title=Evolution of Binary Compact Objects That Merge |last1=Bethe |first1=Hans A. |last2=Brown |first2=G. E. |s2cid=17502739 }}</ref>

== Political stances ==
[[File:Hans Albrecht Bethe (1906-2005).jpg|thumb|Bethe being interviewed by journalists]]
In 1968, Bethe, along with IBM physicist [[Richard Garwin]], published an article criticising in detail the anti-[[ICBM]] defense system proposed by the [[United States Department of Defense|Department of Defense]]. The two physicists described in the article that nearly any measure taken by the United States would be easily thwarted with the deployment of relatively simple decoys.<ref>{{cite journal | last=Garwin | first=R. L. |author2=Bethe, H.A. | title=Anti-Ballistic Missile Systems | journal=Scientific American | volume=218 | issue=3 | pages=21–31 | doi= 10.1038/scientificamerican0368-21|date=March 1968|bibcode = 1968SciAm.218c..21G }}</ref> 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.{{sfn|Bernstein|1980|pp=107–112}}

During the 1980s and 1990s, Bethe campaigned for the peaceful use of [[Nuclear power|nuclear energy]]. After the [[Chernobyl disaster]], Bethe was part of a committee of experts who analysed the incident. They concluded that the reactor suffered from a fundamentally faulty design and also that human error had contributed significantly to the accident. "My colleagues and I established," he explained "that the Chernobyl disaster tells us about the deficiencies of the Soviet political and administrative system rather than about problems with nuclear power."<ref>{{cite web |url=https://www.pbs.org/wgbh/pages/frontline/shows/reaction/readings/chernobyl.html |first=Richard |last=Rhodes |author-link=Richard Rhodes |title=Chernobyl |publisher=PBS |access-date=July 6, 2013 }}</ref> Throughout his life Bethe remained a strong advocate for electricity from nuclear energy, which he described in 1977 as "a necessity, not merely an option."{{sfn|Brown|Lee|2006|p=266}}

In the 1980s he and other physicists opposed the [[Strategic Defense Initiative]] missile system conceived by the [[Ronald Reagan]] administration.{{sfn|Bethe|1991|pp=113–131}} 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.<ref>{{cite web |url=http://www.nuclearfiles.org/menu/library/biographies/bio_bethe-hans.htm |title=Hans Albrecht Bethe |publisher=Nuclear Age Peace Foundation |access-date=July 6, 2013 |archive-date=April 19, 2013 |archive-url=https://web.archive.org/web/20130419084517/http://www.nuclearfiles.org/menu/library/biographies/bio_bethe-hans.htm |url-status=dead }}</ref> In 2004, he joined 47 other [[Nobel laureate]]s in signing a letter endorsing [[John Kerry]] for President of the United States as someone who would "restore science to its appropriate place in government".<ref>{{cite web |url=http://www.gwu.edu/~action/2004/kerry/kerrynobel062104.html |publisher=[[George Washington University]] |title=48 Nobel Winning Scientists Endorse Kerry-June 21, 2004 |access-date=July 6, 2013}}</ref>

Historian [[Gregg Herken]] wrote:
{{blockquote|When Oppenheimer died, Oppie's long-time friend, Hans Bethe, assumed the mantle of the scientist of conscience in this country. Like Jefferson and Adams, Teller and Bethe would live on into the new century which they and their colleagues had done so much to shape.{{sfn|Herken|2002|p=334}} }}

== Personal life ==
[[File:Bethe-rose.jpg|thumb|upright=0.7|Rose Bethe Los Alamos badge]]
Bethe's hobbies included a passion for stamp-collecting.{{sfn|Schweber|2012|p=44}} He loved the outdoors and was an enthusiastic hiker all his life, exploring the [[Alps]] and the [[Rocky Mountains|Rockies]].{{sfn|Brown|Lee|2006|pp=126–128}} He died in his home in [[Ithaca, New York]], on March 6, 2005, of congestive heart failure.<ref name="New York Times" /> He was survived by his wife, Rose Ewald Bethe, and their two children.<ref>{{cite news |url=https://www.theguardian.com/life/science/story/0,12996,1432583,00.html |title=Obituary: Hans Bethe |newspaper=[[The Guardian Newspaper|The Guardian]] |date=March 8, 2005 |first=Anthony |last=Tucker}}</ref> At the time of his death, he was the John Wendell Anderson Professor of Physics, Emeritus, at [[Cornell University]].<ref>{{cite web |url=http://www.aip.org/history/acap/biographies/bio.jsp?betheh |title=Hans Bethe |publisher=Array of Contemporary Physicists |access-date=July 7, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20100830074606/http://www.aip.org/history/acap/biographies/bio.jsp?betheh |archive-date=August 30, 2010 }}</ref>

== Honors and awards ==
Bethe received numerous honors and awards in his lifetime and afterward. He became a [[Honorary fellow|Fellow]] of the [[American Academy of Arts and Sciences]] in 1947,<ref name=AAAS>{{cite web|title=Book of Members, 1780–2010: Chapter B|url=http://www.amacad.org/publications/BookofMembers/ChapterB.pdf|publisher=American Academy of Arts and Sciences|access-date=June 24, 2011}}</ref> and that year, he also received the [[United States National Academy of Sciences|National Academy of Sciences]]'s [[Henry Draper Medal]]<ref name="Draper">{{cite web|title=Henry Draper Medal|url=http://www.nasonline.org/site/PageServer?pagename=AWARDS_draper|publisher=National Academy of Sciences|access-date=February 24, 2011|archive-url=https://web.archive.org/web/20120722010759/http://nas.nasonline.org/site/PageServer?pagename=AWARDS_draper|archive-date=July 22, 2012}}</ref> and was elected to the [[American Philosophical Society]].<ref>{{Cite web |title=APS Member History |url=https://search.amphilsoc.org/memhist/search?creator=Hans+Bethe&title=&subject=&subdiv=&mem=&year=&year-max=&dead=&keyword=&smode=advanced |access-date=2023-03-16 |website=search.amphilsoc.org}}</ref> He was awarded the [[Max Planck Medal]] in 1955, the [[Franklin Medal]] in 1959, the [[Royal Astronomical Society]] [[Eddington Medal]] and the [[United States Atomic Energy Commission]] [[Enrico Fermi Award]] in 1961,{{sfn|Brown|Lee|2009|p=17}} the [[Rumford Prize]] in 1963,<ref name=Rumford>{{cite web|title=Past Recipients of the Rumford Prize|url=http://www.amacad.org/about/rumford.aspx|publisher=American Academy of Arts and Sciences|access-date=February 24, 2011|archive-url=https://web.archive.org/web/20120927075008/http://www.amacad.org/about/rumford.aspx|archive-date=September 27, 2012}}</ref> the [[Nobel Prize in Physics]] in 1967,<ref name="Nobel">{{cite web |url=https://www.nobelprize.org/nobel_prizes/physics/laureates/1967/bethe-bio.html |title=Hans Bethe – Biographical |publisher=The Nobel Foundation |access-date=July 7, 2013 }}</ref> the [[National Medal of Science]] in 1975,<ref>{{cite web |url=https://www.nsf.gov/od/nms/recip_details.cfm?recip_id=42 |title=The President's national Medal of Science |publisher=National Science Foundation}}</ref> the [[Oersted Medal]] in 1993,<ref>{{cite web |url=http://www.aapt.org/Programs/awards/oersted.cfm |title=Oersted Medal |access-date=July 7, 2013 }}</ref> the [[Bruce Medal]] in 2001,<ref>{{cite web|title=Past Winners of the Catherine Wolfe Bruce Gold Medal|url=http://astrosociety.org/membership/awards/pastbruce.html|publisher=Astronomical Society of the Pacific|access-date=February 24, 2011|archive-url=https://web.archive.org/web/20110721092933/http://astrosociety.org/membership/awards/pastbruce.html|archive-date=July 21, 2011|url-status=dead}}</ref> and posthumously in 2005, the [[Benjamin Franklin Medal (American Philosophical Society)|Benjamin Franklin Medal for Distinguished Achievement in the Sciences]] by the [[American Philosophical Society]].<ref name="franklinscience_recipients">{{cite web|url=http://www.amphilsoc.org/prizes/franklinscience |title=Benjamin Franklin Medal for Distinguished Achievement in the Sciences Recipients |publisher=[[American Philosophical Society]] |access-date=November 26, 2011}}</ref>

Bethe was elected [[List of Fellows of the Royal Society elected in 1957|Foreign Member of the Royal Society (ForMemRS) in 1957]],<ref name=frs/> and he gave the 1993 [[Bakerian Lecture]] at the Royal Society on the Mechanism of Supernovae.<ref>{{cite journal
| journal = Philos. Trans. R. Soc. Lond.
| title = Mechanism of Supernovae
| year = 1994
| last = Bethe
| first = Hans A.
 | volume = A 346
| pages = 251–258
}}</ref>
In 1978 he was elected a Member of the [[German Academy of Sciences Leopoldina]].<ref>{{cite web|url=http://www.leopoldina.org/en/members/list-of-members/member/1956/|title=List of Members|website=www.leopoldina.org|access-date=October 8, 2017|archive-date=October 8, 2017|archive-url=https://web.archive.org/web/20171008180726/http://www.leopoldina.org/en/members/list-of-members/member/1956/|url-status=dead}}</ref>

Cornell named the third of five new [[residential college]]s, each of which is named after a distinguished former member of the Cornell faculty, as the [[Cornell West Campus|Hans Bethe House]] after him.<ref>{{cite web |url=https://www.hansbethehouse.cornell.edu/ |title=Hans Bethe House |publisher=[[Cornell University]] |access-date=July 7, 2013 }}</ref> Similarly named after him is the Hans Bethe Center, 322 Fourth Street NE, Washington, D.C., home to the [[Council for a Livable World]], where Bethe was a longtime board member,<ref>{{cite web |url=http://www.livableworld.org/who/legacy/ |title=Council for a Livable World, Our Legacy |access-date=July 7, 2013 }}</ref> as well as the Bethe Center for Theoretical Physics at [[University of Bonn]] in Germany.<ref>{{cite web |url=http://www.kroha.uni-bonn.de/research/bctp |title=Bethe Center for Theoretical Physics |access-date=July 7, 2013 }}</ref> An [[asteroid]], [[30828 Bethe]], that was discovered in 1990 was named after him.<ref>{{cite web |url=http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=30828+Bethe |title=JPL Small-Body Database Browser on 30828 Bethe |publisher=[[NASA]] |access-date=July 7, 2013 }}</ref> The [[American Physical Society]] [[Hans Bethe Prize]] was named after him as well.<ref>{{cite web |url=http://www.aps.org/programs/honors/prizes/bethe.cfm |title=Hans A. Bethe Prize Prize for astrophysics, nuclear physics, nuclear astrophysics and related fields |access-date=July 7, 2013 |publisher=American Physical Society}}</ref>

== Selected publications ==
* Bethe, H. A. [https://www.osti.gov/biblio/4415436-theory-high-frequency-rectification-silicon-crystals "Theory of High Frequency Rectification by Silicon Crystals"], [[Massachusetts Institute of Technology]] (MIT) Radiation Laboratory, [[United States Department of Energy]] (through predecessor agency the [[United States Atomic Energy Commission|Atomic Energy Commission]]), (October 29, 1942).
* Bethe, H. A. [https://www.osti.gov/biblio/4347017-theoretical-estimate-maximum-possible-nuclear-explosion "Theoretical Estimate of Maximum Possible Nuclear Explosion"], Knolls Atomic Power Laboratory-Schenectady, N.Y., [[United States Department of Energy]] (through predecessor agency the [[United States Atomic Energy Commission|Atomic Energy Commission]]), (January 31, 1950).
* Bethe, H. A.; Rajaraman, R. [https://www.osti.gov/biblio/4505584-three-body-problem-nuclear-matter "Three-body Problem in Nuclear Matter"], University of Southern California-Los Angeles, [[United States Department of Energy]] (through predecessor agency the [[United States Atomic Energy Commission|Atomic Energy Commission]]), (1967).
* Bethe, H. A. [https://www.osti.gov/biblio/4619112-note-inverse-bremsstrahlung-strong-electromagnetic-field "Note on Inverse Bremsstrahlung in a Strong Electromagnetic Field"], [[Los Alamos National Laboratory]] (LANL), [[United States Department of Energy]] (through predecessor agency the [[United States Atomic Energy Commission|Atomic Energy Commission]]), (September 1972).
* Bethe, H. A. [https://www.osti.gov/biblio/4584652-pauli-principle-pion-scattering "Pauli Principle and Pion Scattering"], [[Los Alamos National Laboratory]] (LANL), [[United States Department of Energy]] (through predecessor agency the [[United States Atomic Energy Commission|Atomic Energy Commission]]), (October 1972).
* Bethe, H. A. [https://www.osti.gov/biblio/5601384-fusion-hybrid-reactor "Fusion Hybrid Reactor"], [[Sandia National Laboratories]], [[United States Department of Energy]], (August 1981).

== See also ==
* [[Hydrogen anion]]
* [[List of Jewish Nobel laureates]]

== Notes ==
{{notelist-ua}}

== Citations ==
{{Reflist|30em}}

== References ==
* {{cite book |last=Bernstein |first=Jeremy |author-link=Jeremy Bernstein |title=Hans Bethe, Prophet of Energy |location=New York |publisher=Basic Books |date=1980 |isbn=978-0-465-02903-7}}
* {{cite book |last=Bethe |first=Hans A. |title=The Road from Los Alamos |location=New York |publisher=American Institute of Physics |date=1991 |isbn=978-0-88318-707-4|url-access=registration |url=https://archive.org/details/roadfromlosalamo00beth }}
* {{cite book |last=Brian |first=Denis |author-link=Denis Brian |title=The Voice Of Genius: Conversations With Nobel Scientists And Other Luminaries|date=2001|publisher=Perseus Pub |location= Cambridge, Massachusetts  |isbn=978-0-7382-0447-5}}
* {{cite book |first1=Gerald E. |last1=Brown |author-link=Gerald E. Brown |first2=Sabine |last2=Lee |url=https://www.nasonline.org/wp-content/uploads/2024/06/bethe-hans.pdf |access-date=13 January 2025 |publisher=National Academy of Sciences |series=Biographical Memoirs |title=Hans Albrecht Bethe |location=Washington, D.C. |date=2009}}
* {{cite book |editor-last=Brown |editor-first=Gerald E. |editor-link=Gerald E. Brown |editor2-first=Chang-Hwan|editor2-last=Lee |publisher=World Scientific Publishing |title=Hans Bethe and his Physics |location=New Jersey |date=2006 |isbn=981-256-609-0}}
* {{cite book |last=Herken |first=Gregg |title=Brotherhood of the Bomb: The Tangled Lives and Loyalties of Robert Oppenheimer, Ernest Lawrence, and Edward Teller |url=https://archive.org/details/brotherhoodofbom0000herk |url-access=registration |location=New York |publisher=Henry Holt and Company |date=2002 |isbn=0-8050-6588-1}}
* {{cite book |last1=Hoddeson |first1=Lillian|author-link=Lillian Hoddeson|first2=Paul W. |last2=Henriksen |first3=Roger A. |last3=Meade |first4=Catherine L. |last4=Westfall|author4-link= Catherine Westfall|title=Critical Assembly: A Technical History of Los Alamos During the Oppenheimer Years, 1943–1945 |location=New York |publisher=Cambridge University Press |date=1993 |isbn=0-521-44132-3 |oclc=26764320|url-access=registration |url=https://archive.org/details/criticalassembly0000unse }}
* {{cite book | last=Schweber | first=Silvan S. | author-link=Silvan S. Schweber | title=In the Shadow of the Bomb: Bethe, Oppenheimer, and the Moral Responsibility of the Scientist | location=Princeton | publisher=Princeton University Press | date=2000 | isbn=978-0-691-04989-2| url-access=registration | url=https://archive.org/details/inshadowofbombbe00schw }}
* {{cite book |last=Schweber |first=Silvan S. |title=Nuclear Forces: The Making of the Physicist Hans Bethe  |location=Cambridge, Massachusetts |publisher=Harvard University Press |date=2012 |isbn=978-0-674-06587-1}}
* {{cite book | last = Szasz |first=Ferenc Morton |date=1992 |title=British Scientists and the Manhattan Project: the Los Alamos Years |location=New York |publisher=St. Martin's Press |isbn=978-0-312-06167-8 |oclc=23901666}}

== External links ==
{{Commons category}}
{{Wikiquote}}
{{Wikinews|Nobel Laureate Hans Bethe passes away at age of 98}}
*[http://openvault.wgbh.org/catalog/V_4883F5B3D049498CA208AFD5B9545FCC 1986 Video Interview] War and Peace in the Nuclear Age
*[http://manhattanprojectvoices.org/oral-histories/hans-bethes-interview 1993 Audio Interview with Hans Bethe by Richard Rhodes] Voices of the Manhattan Project
*[http://manhattanprojectvoices.org/oral-histories/hans-bethes-interview-1982 1982 Audio Interview with Hans Bethe by Martin Sherwin] Voices of the Manhattan Project
*[http://manhattanprojectvoices.org/oral-histories/rose-bethes-interview 2014 Video Interview with Rose Bethe by Cynthia C. Kelly] Voices of the Manhattan Project
* [https://bethe.cornell.edu/index.html Three Lectures by Hans Bethe], from the Cornell University
* [http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1961QJRAS...2..107. Text of the Eddington Medal award speech]
* [[Obituary|Obituaries]]
** [http://www.economist.com/people/displayStory.cfm?story_id=3764700 Hans Bethe obituary] from [[The Economist]] magazine
** [https://www.theguardian.com/life/science/story/0,12996,1432583,00.html Hans Bethe obituary] from [[The Guardian]] Newspaper
* [https://web.archive.org/web/20060426205017/http://alsos.wlu.edu/qsearch.aspx?browse=people%2FBethe%2C+Hans Annotated bibliography for Hans Bethe from the Alsos Digital Library for Nuclear Issues]
* [https://www.aip.org/history-programs/niels-bohr-library/oral-histories/4503 Oral History interview transcript with Hans Bethe on 17 January 1964, American Institute of Physics, Niels Bohr Library and Archives] – interviewed by [[Thomas Kuhn|Thomas S. Kuhn]] in [[Dwinelle Hall]] at [[University of California, Berkeley|UC Berkeley]]
* [https://www.aip.org/history-programs/niels-bohr-library/oral-histories/4504-1 Oral History interview transcript with Hans Bethe on 27 October 1966, American Institute of Physics, Niels Bohr Library and Archives] – Session I, interviewed by Charles Weiner and [[Jagdish Mehra]] at [[Cornell University]]
* [https://www.aip.org/history-programs/niels-bohr-library/oral-histories/4504-2 Oral History interview transcript with Hans Bethe on 17 November 1967, American Institute of Physics, Niels Bohr Library and Archives] – Session II, interviewed by Charles Weiner at [[Cornell University]]
* [https://www.aip.org/history-programs/niels-bohr-library/oral-histories/4504-3 Oral History interview transcript with Hans Bethe on 8 May 1972, American Institute of Physics, Niels Bohr Library and Archives] – Session III, interviewed by Charles Weiner at [[Cornell University]]
* [https://www.aip.org/history-programs/niels-bohr-library/oral-histories/4505 Oral History interview transcript with Hans Bethe on 29 April 1981, American Institute of Physics, Niels Bohr Library and Archives] – interviewed by [[Lillian Hoddeson]] in [[Sicily]]
* [http://osulibrary.orst.edu/specialcollections/events/1995paulingconference/video-s4-1-schweber.html Video of a talk entitled "Writing the Biography of a Living Scientist: Hans Bethe,"] {{Webarchive|url=https://web.archive.org/web/20130514123204/http://osulibrary.orst.edu/specialcollections/events/1995paulingconference/video-s4-1-schweber.html |date=May 14, 2013 }} delivered by S.S. Schweber
* [http://webofstories.com/gl/hans.bethe Hans Bethe tells his life story] at [[Web of Stories]]
* {{MacTutor Biography|id=Bethe|ref=none}}
* {{MathGenealogy|id=48688}}
* {{cite web|last1=Bowley|first1=Roger|title=αβγ – The Alpha Beta Gamma Paper|url=http://www.sixtysymbols.com/videos/alphabetagamma.htm|work=Sixty Symbols|publisher=[[Brady Haran]] for the [[University of Nottingham]] |last2=Merrifield|first2=Michael |last3=Padilla|first3=Antonio (Tony) |ref=none}}
* {{Nobelprize}}

{{Nobel Prize in Physics Laureates 1951–1975}}
{{1967 Nobel Prize winners}}
{{Presidents of the American Physical Society}}
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