Editing Werner Heisenberg (section)

==Academic career==
===Göttingen, Copenhagen and Leipzig===
From 1924 to 1927, Heisenberg was a [[Privatdozent]] at [[Göttingen]], meaning he was qualified to teach and examine independently, without having a chair. From 17 September 1924 to 1 May 1925, under an International Education Board [[Rockefeller Foundation]] fellowship, Heisenberg went to do research with [[Niels Bohr]], director of the Institute of Theoretical Physics at the [[University of Copenhagen]]. On June 7, after weeks of failing to alleviate a severe bout of [[hay fever]] with aspirin and cocaine,<ref>{{cite book |last1=Rechenberg |first1=Helmut |title=Werner Heisenberg – Die Sprache der Atome. Leben und Wirken |date=2010 |publisher=Springer |isbn=978-3-540-69221-8 |page=322}}</ref> Heisenberg retreated to the pollen-free [[North Sea]] island of [[Heligoland|Helgoland]] to focus on quantum mechanics.<ref>{{Cite web|last=Prescod-Weinstein|first=Chanda |author-link=Chanda Prescod-Weinstein|date=2021-07-07|title=No man is an island – the early days of the quantum revolution|url=https://physicsworld.com/no-man-is-an-island/ |access-date=2022-02-03|website=[[Physics World]]|language=en-GB}}</ref><ref name=crease>{{cite web |last1=Crease |first1=Robert P. |author-link=Robert P. Crease |title=Return to Helgoland: celebrating 100 years of quantum mechanics |url=https://physicsworld.com/a/return-to-helgoland-celebrating-100-years-of-quantum-mechanics/ |website=[[Physics World]] |date=1 December 2024 |archive-url=https://web.archive.org/web/20241201152618/https://physicsworld.com/a/return-to-helgoland-celebrating-100-years-of-quantum-mechanics/ |archive-date=2024-12-01 |url-status=dead }}</ref><!-- [[Helgoland (book)]] --> His seminal paper, "[[Über quantentheoretische Umdeutung kinematischer und mechanischer Beziehungen]]" ("Quantum theoretical re-interpretation of kinematic and mechanical relations") also called the ''Umdeutung'' (reinterpretation) paper, was published in September 1925.<ref>Kragh, H. (2004) "[[Dirac, Paul Adrien Maurice]] (1902–1984)", ''[[Oxford Dictionary of National Biography]]'', Oxford University Press. {{doi|10.1093/ref:odnb/31032}}</ref> He returned to Göttingen and, with [[Max Born]] and [[Pascual Jordan]] over a period of about six months, developed the [[matrix mechanics]] formulation of [[quantum mechanics]]. On 1 May 1926, Heisenberg began his appointment as a university lecturer and assistant to Bohr in Copenhagen. It was in Copenhagen, in 1927, that Heisenberg developed his [[uncertainty principle]], while working on the mathematical foundations of quantum mechanics. On 23 February, Heisenberg wrote a letter to fellow physicist [[Wolfgang Pauli]], in which he first described his new principle.<ref>{{Cite journal | url=http://www.aps.org/publications/apsnews/200802/physicshistory.cfm | title=February 1927: Heisenberg's Uncertainty Principle | publisher=American Physics Society | journal=APS News | date=February 2008 | volume=17 | issue=2 | access-date=23 February 2011 | archive-url=https://web.archive.org/web/20110130195156/http://aps.org/publications/apsnews/200802/physicshistory.cfm | archive-date=30 January 2011 | url-status=live }}</ref> In his paper on the principle,<ref>{{harvnb|Heisenberg|1927}}, cited in {{harvnb|Mott|Peierls|1977|p=243}}</ref> Heisenberg used the word "''Ungenauigkeit''" (imprecision), not uncertainty, to describe it.<ref name=Biography/><ref name=Cassidy>{{harvnb|Cassidy|1992|loc=Appendix A}}</ref><ref>{{harvnb|Mott|Peierls|1977|p=224}}</ref>

In 1927, Heisenberg was appointed ''ordentlicher Professor'' (professor ordinarius) of theoretical physics and head of the department of physics at the [[Leipzig University|University of Leipzig]]; he gave his inaugural lecture there on 1 February 1928. In his first paper published from Leipzig,<ref>{{harvnb|Heisenberg|1928}}, as cited in {{harvnb|Mott|Peierls|1977|p=243}}</ref> Heisenberg used the [[Pauli exclusion principle]] to solve the mystery of [[ferromagnetism]].<ref name=Biography/><ref name=Hentschel/><ref name=Cassidy/><ref>{{harvnb|Mott|Peierls|1977|pp=226–227}}</ref>

At 25 years old, Heisenberg gained the title of the youngest full-time professor in Germany and professorial chair<ref name="Valiunas-2019">{{Cite journal |last=Valiunas |first=Algis |date=2019 |title=The Most Dangerous Possible German |url=https://www.jstor.org/stable/26609101 |journal=The New Atlantis |issue=57 |pages=36–74 |jstor=26609101 |issn=1543-1215}}</ref> of the Institute for Theoretical Physics at the University of Leipzig. He gave lectures that were attended by physicists like [[Edward Teller]] and [[Robert Oppenheimer]],<ref name="Valiunas-2019" /> who would later work on the [[Manhattan Project]]<ref name="Groves-1962" /> for the United States. 

During Heisenberg's tenure at Leipzig, the high quality of the doctoral students and [[Postgraduate education|post-graduate]] and research associates who studied and worked with him is clear from the acclaim that many later earned. They included [[Erich Bagge]], [[Felix Bloch]], [[Ugo Fano]], [[Siegfried Flügge]], [[William Vermillion Houston]], [[Friedrich Hund]], [[Robert S. Mulliken]], [[Rudolf Peierls]], [[George Placzek]], [[Isidor Isaac Rabi]], [[Fritz Sauter]], [[John C. Slater]], [[Edward Teller]], [[John Hasbrouck van Vleck]], [[Victor Frederick Weisskopf]], [[Carl Friedrich von Weizsäcker]], [[Gregor Wentzel]], and [[Clarence Zener]].<ref name=MottPeierls77_227>{{harvnb|Mott|Peierls|1977|p=227}}</ref>

In early 1929, Heisenberg and Pauli submitted the first of two papers laying the foundation for relativistic [[quantum field theory]].<ref>{{harvnb|Heisenberg|Pauli|1929}}, {{harvnb|Heisenberg|Pauli|1930}}, as cited in {{harvnb|Mott|Peierls|1977|p=243}}</ref> Also in 1929, Heisenberg went on a lecture tour of China, Japan, India, and the United States.<ref name=Cassidy/><ref name=MottPeierls77_227 /> In the spring of 1929, he was a visiting lecturer at the [[University of Chicago]], where he lectured on quantum mechanics.<ref>{{cite book|last1=Kursunoglu|first1=Behram N.|last2=Wigner|first2=Eugene P.|title=Paul Adrien Maurice Dirac: Reminiscences about a Great Physicist|date=26 April 1990|publisher=Cambridge University Press|isbn=978-0-521-38688-3|page=132}}</ref>

In 1928, the British [[Mathematical Physics|mathematical physicist]] [[Paul Dirac]] had derived his [[Dirac equation|relativistic wave equation]] of quantum mechanics, which implied the existence of positive electrons, later to be named [[positron]]s. In 1932, from a [[cloud chamber]] photograph of [[cosmic ray]]s, the American physicist [[Carl David Anderson]] identified a track as having been made by a [[positron]]. In mid-1933, Heisenberg presented his theory of the positron. His thinking on Dirac's theory and further development of the theory were set forth in two papers. The first, "Bemerkungen zur Diracschen Theorie des Positrons" ("Remarks on Dirac's theory of the positron") was published in 1934,<ref>{{harvnb|Heisenberg|1934}}</ref> and the second, "Folgerungen aus der Diracschen Theorie des Positrons" ("Consequences of Dirac's Theory of the Positron"), was published in 1936.<ref name=Cassidy/><ref>{{harvnb|Heisenberg|Euler|1936}}</ref><ref>{{cite book |first=Emilio G. |last=Segrè |author-link=Emilio G. Segrè |title=From X-rays to Quarks: Modern Physicists and Their Discoveries |publisher=W.H. Freeman |year=1980 |isbn=978-0-7167-1146-9 |url=https://archive.org/details/fromxraystoquark0000segr }}</ref> In these papers Heisenberg was the first to reinterpret the [[Dirac equation]] as a "classical" [[field equation]] for any point particle of [[Spin (physics)|spin]] ħ/2, itself subject to quantization conditions involving anti-[[commutator]]s. Thus reinterpreting it as a (quantum{{clarify|date=January 2021}}) field equation accurately describing electrons, Heisenberg put matter on the same footing as [[electromagnetism]]: as being described by relativistic quantum field equations which allowed the possibility of particle creation and destruction. ([[Hermann Weyl]] had already described this in a 1929 letter to [[Albert Einstein]].)

===Matrix mechanics and the Nobel Prize===
{{more citations needed|section|date=February 2017}}
<!-- Deleted image removed: [[File:Bohr heisen pauli.jpg|thumb|[[Niels Bohr]], Werner Heisenberg, and [[Wolfgang Pauli]], c. 1935]] -->

Heisenberg's [[Umdeutung paper|''Umdeutung'' paper]] that established modern quantum mechanics<ref>{{cite journal|author=Heisenberg, W. |title=Über quantentheoretishe Umdeutung kinematisher und mechanischer Beziehungen|journal=Zeitschrift für Physik|volume=33|pages= 879–893|year= 1925|issue=1|doi=10.1007/BF01328377|bibcode=1925ZPhy...33..879H|s2cid=186238950}} (received 29 July 1925). [English translation in: B.L. van der Waerden, editor, ''Sources of Quantum Mechanics'' (Dover Publications, 1968) {{ISBN|978-0-486-61881-4}} (English title: "Quantum-Theoretical Re-interpretation of Kinematic and Mechanical Relations").]</ref>{{efn|name=old}} has puzzled physicists and historians. His methods assume that the reader is familiar with [[Hans Kramers|Kramers]]-Heisenberg transition probability calculations. The main new idea, [[Matrix multiplication#Properties of matrix multiplication|non-commuting matrices]], is justified only by a rejection of unobservable quantities. It introduces the non-[[Commutativity|commutative]] multiplication of [[Matrix (mathematics)|matrices]] by physical reasoning, based on the [[correspondence principle]], despite the fact that Heisenberg was not then familiar with the mathematical theory of matrices. The path leading to these results has been reconstructed by MacKinnon,<ref>{{cite journal |last=MacKinnon |first=Edward |title=Heisenberg, Models, and the Rise of Quantum Mechanics |journal=Historical Studies in the Physical Sciences |volume=8 |pages=137–188 |year=1977 |jstor=27757370 |doi=10.2307/27757370}}</ref> and the detailed calculations are worked out by Aitchison and coauthors.<ref>{{cite journal |last1=Aitchison |first1=Ian J.R. |first2=David A. |last2=MacManus |first3=Thomas M. |last3=Snyder |s2cid=53118117 |title=Understanding Heisenberg's 'magical' paper of July 1925: A new look at the calculational details |journal=American Journal of Physics |volume=72 |issue=11 |pages=1370–1379 |date=November 2004 |doi=10.1119/1.1775243 |arxiv=quant-ph/0404009v1|bibcode=2004AmJPh..72.1370A }}</ref>

In Copenhagen, Heisenberg and [[Hans Kramers]] collaborated on a paper on dispersion, or the scattering from atoms of radiation whose wavelength is larger than the atoms. They showed that the successful formula Kramers had developed earlier could not be based on Bohr orbits, because the transition frequencies are based on level spacings which are not constant. The frequencies which occur in the [[Fourier transform]] of the classical [[sharp series]] orbits, by contrast, are equally spaced. But these results could be explained by a semi-classical [[virtual state]] model: the incoming radiation excites the valence, or outer, electron to a virtual state from which it decays. In a subsequent paper, Heisenberg showed that this virtual oscillator model could also explain the polarization of fluorescent radiation.

These two successes, and the continuing failure of the [[Bohr model|Bohr–Sommerfeld model]] to explain the outstanding problem of the anomalous Zeeman effect, led Heisenberg to use the virtual oscillator model to try to calculate spectral frequencies. The method proved too difficult to immediately apply to realistic problems, so Heisenberg turned to a simpler example, the [[anharmonic oscillator]].

The dipole oscillator consists of a [[simple harmonic oscillator]], which is thought of as a [[charged particle]] on a spring, perturbed by an external force, like an external charge. The motion of the oscillating charge can be expressed as a [[Fourier series]] in the frequency of the oscillator. Heisenberg solved for the quantum behavior by two different methods. First, he treated the system with the virtual oscillator method, calculating the transitions between the levels that would be produced by the external source.

He then solved the same problem by treating the anharmonic potential term as a perturbation to the harmonic oscillator and using the [[Perturbation theory|perturbation methods]] that he and Born had developed. Both methods led to the same results for the first and the very complicated second-order correction terms. This suggested that behind the very complicated calculations lay a consistent scheme.

So Heisenberg set out to formulate these results without any explicit dependence on the virtual oscillator model. To do this, he replaced the Fourier expansions for the spatial coordinates with matrices, matrices which corresponded to the transition coefficients in the virtual oscillator method. He justified this replacement by an appeal to Bohr's correspondence principle and the Pauli doctrine that quantum mechanics must be limited to observables.

On 9 July, Heisenberg gave Born this paper to review and submit for publication. When Born read the paper, he recognized the formulation as one which could be transcribed and extended to the systematic language of matrices,<ref>{{cite book |author-link=Abraham Pais |first=Abraham |last=Pais |title=Niels Bohr's Times in Physics, Philosophy, and Polity |publisher=Clarendon Press |year=1991 |isbn=978-0-19-852049-8 |pages=[https://archive.org/details/nielsbohrstimesi00pais_0/page/275 275–279] |url=https://archive.org/details/nielsbohrstimesi00pais_0/page/275 }}</ref> which he had learned from his study under [[Jakob Rosanes]]<ref>[http://nobelprize.org/nobel_prizes/physics/laureates/1954/born-lecture.pdf Max Born] {{Webarchive|url=https://web.archive.org/web/20121019194414/http://www.nobelprize.org/nobel_prizes/physics/laureates/1954/born-lecture.pdf |date=19 October 2012 }} ''The Statistical Interpretation of Quantum Mechanics'', Nobel Lecture (1954)</ref> at [[Breslau University]]. Born, with the help of his assistant and former student [[Pascual Jordan]], began immediately to make the transcription and extension, and they submitted their results for publication; the paper was received for publication just 60 days after Heisenberg's paper.<ref>{{cite journal |first1=M. |last1=Born |first2=P. |last2=Jordan |s2cid=186114542 |title=Zur Quantenmechanik |journal=Zeitschrift für Physik |volume=34 |issue=1 |pages=858–888 |year=1925 |doi=10.1007/BF01328531 |bibcode=1925ZPhy...34..858B }} (received 27 September 1925). [English translation in: {{harvnb|van der Waerden|1968|loc=[https://books.google.com/books?id=8KLMGqnZCDcC&pg=PA277 "On Quantum Mechanics"]}}]</ref> A follow-on paper was submitted for publication before the end of the year by all three authors.<ref>{{cite journal |first1=M. |last1=Born |last2=Heisenberg |first2=W. |first3=P. |last3=Jordan |s2cid=186237037 |title=Zur Quantenmechanik II |journal=Zeitschrift für Physik |volume=35 |pages=557–615 |year=1925 |bibcode=1926ZPhy...35..557B |doi=10.1007/BF01379806 |issue=8–9 }} The paper was received on 16 November 1925. [English translation in: {{harvnb|van der Waerden|1968|loc=[https://books.google.com/books?id=8KLMGqnZCDcC&pg=PA321 15 "On Quantum Mechanics II"]}}]</ref>

Up until this time, matrices were seldom used by physicists; they were considered to belong to the realm of [[pure mathematics]]. [[Gustav Mie]] had used them in a paper on electrodynamics in 1912 and Born had used them in his work on the lattice theory of crystals in 1921. While matrices were used in these cases, the algebra of matrices with their multiplication did not enter the picture as they did in the matrix formulation of quantum mechanics.<ref>Jammer, Max (1966) ''The Conceptual Development of Quantum Mechanics''. McGraw-Hill. pp. 206–207.</ref>

In 1928, Albert Einstein nominated Heisenberg, Born, and Jordan for the [[Nobel Prize in Physics]].<ref>{{harvnb|Bernstein| 2004|p= 1004}}</ref> The announcement of the Nobel Prize in Physics for 1932 was delayed until November 1933.<ref>{{cite book |last=Greenspan |first=Nancy Thorndike |title=[[The End of the Certain World|The End of the Certain World: The Life and Science of Max Born]] |publisher=Basic Books |year=2005 |isbn=978-0-7382-0693-6 |page=190}}</ref> It was at that time announced that Heisenberg had won the Prize for 1932 "for the creation of quantum mechanics, the application of which has, [[List of Latin phrases: I#inter alia|inter alia]], led to the discovery of the [[Spin isomers of hydrogen|allotropic forms of hydrogen]]".<ref name=nobelprize>[http://nobelprize.org/nobel_prizes/physics/laureates/1932/ The Nobel Prize in Physics 1932] {{Webarchive|url=https://web.archive.org/web/20080716011447/http://nobelprize.org/nobel_prizes/physics/laureates/1932/ |date=16 July 2008 }}. Nobelprize.org. Retrieved on 1 February 2012.</ref><ref name=ReferenceA>[[Nobel Prize in Physics]] and [http://nobelprize.org/nobel_prizes/physics/laureates/1933/press.html 1933] {{Webarchive|url=https://web.archive.org/web/20080715234807/http://nobelprize.org/nobel_prizes/physics/laureates/1933/press.html |date=15 July 2008 }}&nbsp;– Nobel Prize Presentation Speech.</ref>

===Interpretation of quantum theory===

The development of quantum mechanics, and the apparently contradictory implications in regard to what is "real" had profound philosophical implications, including what scientific observations truly mean. In contrast to Albert Einstein and [[Louis de Broglie]], who were realists who believed that particles had an objectively true momentum and position at all times (even if both could not be measured), Heisenberg was an anti-realist, arguing that direct knowledge of what is "real" was beyond the scope of science.<ref name=Einstein>{{Cite book|title=Einstein's unfinished revolution: the search for what lies beyond the quantum|last=Smolin |first=Lee |isbn=978-0-241-00448-7|location=London|pages=92–93|oclc=1048948576|date = 9 April 2019}}</ref> In his book ''The Physicist's Conception of Nature'',<ref name=Nature>{{Cite book|url=https://books.google.com/books?id=jYYGAQAAIAAJ|title=The Physicist's Conception of Nature|last=Heisenberg|first=Werner|date=1958|publisher=Harcourt, Brace|pages=15, 28–29|language=en}}</ref> Heisenberg argued that ultimately we only can speak of the ''knowledge'' (numbers in tables) which describes something about particles but we can never have any "true" access to the particles themselves:<ref name=Einstein/><blockquote>We can no longer speak of the behaviour of the particle independently of the process of observation. As a final consequence, the natural laws formulated mathematically in quantum theory no longer deal with the elementary particles themselves but with our knowledge of them. Nor is it any longer possible to ask whether or not these particles exist in space and time objectively ...

When we speak of the picture of nature in the exact science of our age, we do not mean a picture of nature so much as a ''picture of our relationships with nature''. ...Science no longer confronts nature as an objective observer, but sees itself as an actor in this interplay between man and nature. The scientific method of analysing, explaining and classifying has become conscious of its limitations, which arise out of the fact that by its intervention science alters and refashions the object of investigation. In other words, method and object can no longer be separated.<ref name=Einstein/><ref name=Nature/></blockquote>

===''SS'' investigation===
Shortly after the discovery of the [[neutron]] by [[James Chadwick]] in 1932, Heisenberg submitted the first of three papers<ref>{{harvnb|Heisenberg|1932a}}, {{harvnb|Heisenberg|1932b}}, {{harvnb|Heisenberg|1933}}, as cited by {{harvnb|Mott|Peierls|1977|p=244}}</ref> on his [[Neutron#Proton – neutron model of the nucleus|neutron-proton model of the nucleus]].<ref name=Cassidy/><ref>{{harvnb|Mott|Peierls|1977|p=228}}</ref> After [[Adolf Hitler]] came to power in 1933, Heisenberg was attacked in the press as a "White Jew" (i.e. an [[Aryan race|Aryan]] who acts like a Jew).<ref>{{cite web |title=Heisenberg&nbsp;– The Difficult Years: Professor in Leipzig, 1927–1942 |publisher=American Institute of Physics |url=http://www.aip.org/history/heisenberg/p10.htm |access-date=20 July 2008 |archive-url=https://web.archive.org/web/20080915073146/http://www.aip.org/history/heisenberg/p10.htm |archive-date=15 September 2008 |url-status=live }}</ref> Supporters of ''[[Deutsche Physik]]'', or German Physics (also known as Aryan Physics), launched vicious attacks against leading theoretical physicists, including Arnold Sommerfeld and Heisenberg.<ref name=Cassidy/> From the early 1930s onward, the [[anti-Semitic]] and anti-theoretical physics movement ''Deutsche Physik'' had concerned itself with quantum mechanics and the [[theory of relativity]]. As applied in the university environment, political factors took priority over scholarly ability,<ref>{{harvnb|Beyerchen|1977|pp=141–167}}</ref> even though its two most prominent supporters were the [[Nobel Prize in Physics|Nobel Laureates in Physics]] [[Philipp Lenard]]<ref>{{harvnb|Beyerchen|1977|pp=79–102}}</ref> and [[Johannes Stark]].<ref>{{harvnb|Beyerchen|1977|pp=103–140}}</ref><ref>{{Cite journal|title = Werner Heisenberg and Albert Einstein|journal = Physics Today|date = 12 January 2007|pages = 38–42|volume = 53|issue = 7|doi = 10.1063/1.1292474|first = Gerald|last = Holton|bibcode = 2000PhT....53g..38H|doi-access = free}}</ref>

There had been many failed attempts to have Heisenberg appointed as a professor at a number of German universities. His attempt to be appointed as successor to Arnold Sommerfeld failed because of opposition by the ''Deutsche Physik'' movement.<ref name=Macrakis172>{{harvnb|Macrakis|1993|p = 172}}</ref> On 1 April 1935, the eminent theoretical physicist Sommerfeld, Heisenberg's doctoral advisor at the [[Ludwig Maximilian University of Munich|Ludwig-Maximilians-Universität München]], achieved [[emeritus]] status. However, Sommerfeld stayed in his chair during the selection process for his successor, which took until 1 December 1939. The process was lengthy due to academic and political differences between the Munich Faculty's selection and that of the [[Reichserziehungsministerium|Reich Education Ministry]] and the supporters of ''Deutsche Physik''.

In 1935, the Munich Faculty drew up a list of candidates to replace Sommerfeld as ordinarius professor of theoretical physics and head of the Institute for Theoretical Physics at the University of Munich. The three candidates had all been former students of Sommerfeld: Heisenberg, who had received the [[Nobel Prize in Physics]]; [[Peter Debye]], who had received the [[Nobel Prize in Chemistry]] in 1936; and [[Richard Becker (physicist)|Richard Becker]]. The Munich Faculty was firmly behind these candidates, with Heisenberg as their first choice. However, supporters of ''Deutsche Physik'' and elements in the REM had their own list of candidates, and the battle dragged on for over four years. During this time, Heisenberg came under vicious attack by the ''Deutsche Physik'' supporters. One attack was published in ''[[Das Schwarze Korps]]'', the newspaper of the ''[[SS]]'', headed by [[Heinrich Himmler]]. In this, Heisenberg was called a "White Jew" who should be made to "disappear".<ref>{{harvnb|Hentschel|Hentschel|1996|pp=152–157 Document #55 [https://books.google.com/books?id=sl69XGiohsoC&pg=PA152 'White Jews' in Science (15 July 1937)]}}</ref> These attacks were taken seriously, as Jews were violently attacked and incarcerated. Heisenberg fought back with an editorial and a letter to Himmler, in an attempt to resolve the matter and regain his honour.

At one point, Heisenberg's mother visited Himmler's mother. The two women knew each other, as Heisenberg's maternal grandfather and Himmler's father were rectors and members of a Bavarian hiking club. Eventually, Himmler settled the Heisenberg affair by sending two letters, one to SS [[Gruppenführer]] [[Reinhard Heydrich]] and one to Heisenberg, both on 21 July 1938. In the letter to Heydrich, Himmler said Germany could not afford to lose or silence Heisenberg, as he would be useful for teaching a generation of scientists. To Heisenberg, Himmler said the letter came on the recommendation of his family and he cautioned Heisenberg to make a distinction between professional physics research results and the personal and political attitudes of the involved scientists.<ref name=Goudsmit117>{{harvnb|Goudsmit|1986|pp= 117–119}}</ref>

[[Wilhelm Müller (physicist)|Wilhelm Müller]] replaced Sommerfeld at the Ludwig Maximilian University of Munich. Müller was not a theoretical physicist, had not published in a physics journal, and was not a member of the [[Deutsche Physikalische Gesellschaft|German Physical Society]]. His appointment was considered a travesty and detrimental to educating theoretical physicists.<ref name=Goudsmit117/><ref>{{harvnb|Beyerchen|1977|pp=153–167}}</ref><ref>{{harvnb|Cassidy|1992|pp=383–387}}</ref><ref>{{harvnb|Powers|1993|pp=40–43}}</ref><ref>{{harvnb|Hentschel|Hentschel|1996|pp=152–157}} Document #55 ''[https://books.google.com/books?id=sl69XGiohsoC&pg=PA152 'White Jews' in Science (15 July 1937)] {{Webarchive|url=https://web.archive.org/web/20160101210718/https://books.google.com/books?id=sl69XGiohsoC&pg=PA152 |date=1 January 2016 }}''<br />pp. 175–176 Document #63 ''[https://books.google.com/books?id=sl69XGiohsoC&pg=PA175 Heinrich Himmler: Letter to Reinhard Heydrich &#91;21 July 1938&#93;] {{Webarchive|url=https://web.archive.org/web/20160521212342/https://books.google.com/books?id=sl69XGiohsoC&pg=PA175 |date=21 May 2016 }}''<br />pp. 176–177 Document #64 ''[https://books.google.com/books?id=sl69XGiohsoC&pg=PA176 Heinrich Himmler: Letter to Werner Heisenberg &#91;21 July 1938&#93;] {{Webarchive|url=https://web.archive.org/web/20160603004352/https://books.google.com/books?id=sl69XGiohsoC&pg=PA176 |date=3 June 2016 }}''<br />pp. 261–266 Document #85 ''Ludwig Prandtl: Attachment to the letter to Reich Marschal (sic) Hermann Göring [28 April 1941]'' <br />pp. 290–292 Document #93 ''[[Carl Ramsauer]]: The Munich Conciliation and Pacification Attempt [20 January 1942]''</ref>

The three investigators who led the SS investigation of Heisenberg had training in physics. Indeed, Heisenberg had participated in the doctoral examination of one of them at the [[University of Leipzig|Universität Leipzig]]. The most influential of the three was [[Johannes Juilfs]]. During their investigation, they became supporters of Heisenberg as well as his position against the ideological policies of the ''Deutsche Physik'' movement in theoretical physics and academia.<ref>{{harvnb|Cassidy|1992|pp=390–391}} Please note that Cassidy uses the alias Mathias Jules for Johannes Juilfs.</ref>