View source for Peter Debye

{{Short description|Dutch-American physical chemist (1884–1966)}}
{{Use mdy dates|date=August 2023}}
{{Infobox scientist
| honorific_suffix  = {{post-nominals|country=GBR|size=100%|ForMemRS}}
| name  = Peter Debye
| image = Debye100.jpg
| caption = Debye in 1912
| birth_date  = {{birth date|1884|3|24|mf=y}}
| birth_place = [[Maastricht]], Netherlands
| birth_name  = Petrus Josephus Wilhelmus Debije
| death_date  = {{death date and age|1966|11|2|1884|3|24}}
| death_place = [[Ithaca, New York]], U.S.
| citizenship = {{hlist|Netherlands|United States}}
| field =  {{hlist|[[Physics]]|[[chemistry]]}}
| work_institution = [[University of Zurich]] {{small|(1911–12)}}<br />[[University of Utrecht]] {{small|(1912–14)}}<br />
[[University of Göttingen]] {{small|(1914–20)}}<br />[[ETH Zurich]] {{small|(1920–27)}}<br />[[University of Leipzig]] {{small|(1927–34)}}<br />[[University of Berlin]] {{small|(1934–39)}}<br />[[Cornell University]] {{small|(1940–50)}}
| alma_mater       = [[RWTH Aachen]]<br />[[University of Munich]]
| doctoral_advisor  = [[Arnold Sommerfeld]]
| doctoral_students = [[Lars Onsager]]  <br />[[Paul Scherrer]]<br />[[George K. Fraenkel]]<br />[[Fritz Zwicky]]
| known_for  = {{hlist|[[Debye model]]|[[Debye relaxation]]|[[Debye frequency]]}}
| spouse = {{marriage|Mathilde Alberer|1913}} 
| children = 2
| prizes     = {{no wrap|[[Rumford Medal]] {{small|(1930)}}<br />[[Faraday Lectureship Prize]] {{small|(1933)}}<br />[[Lorentz Medal]] {{small|(1935)}}<br />[[Nobel Prize in Chemistry]] {{small|(1936)}}<br />[[Willard Gibbs Award]] {{small|(1949)}}<br />[[Max Planck Medal]] {{small|(1950)}}<br />[[William H. Nichols Medal]] {{small|(1961)}}<br />[[Priestley Medal]] {{small|(1963)}}<br />[[National Medal of Science]] {{small|(1965)}}}}
| signature = Solvay1933Signature Debye.jpg
}}

'''Peter Joseph William Debye''' {{post-nominals|post-noms=[[Foreign Member of the Royal Society|ForMemRS]]}}<ref name="frs">{{cite journal|doi=10.1098/rsbm.1970.0007|title=Peter Joseph Wilhelm Debye. 1884–1966|date=1970|last1=Davies|first1=M.|journal=Biographical Memoirs of Fellows of the Royal Society|volume=16|pages=175–232|doi-access=free}}</ref> ({{IPAc-en|d|ɪ|ˈ|b|aɪ}} {{respell|dib|EYE}};<ref>''[[Random House Dictionary]]'', Random House, 2013: "Debye".</ref> born '''Petrus Josephus Wilhelmus Debije''',{{efn|For Dutch use of "y" and "ij", see [[IJ (digraph)]].}} {{IPA|nl|ˈpeːtrʏz dəˈbɛiə|lang}}; March 24, 1884 – November 2, 1966)<ref>{{Cite web|title=The Nobel Prize in Chemistry 1936|url=https://www.nobelprize.org/prizes/chemistry/1936/debye/biographical/|access-date=2021-12-26|website=NobelPrize.org|language=en-US}}</ref><ref>{{Cite web|title=Peter Debye {{!}} American physical chemist {{!}} Britannica|url=https://www.britannica.com/biography/Peter-Debye|access-date=2021-12-26|website=www.britannica.com|language=en}}</ref> was a Dutch-American [[physicist]] and [[physical chemistry|physical chemist]], and [[List of Nobel laureates in Chemistry|Nobel laureate in Chemistry]].

==Biography==

===Early life===
Born in [[Maastricht]], Netherlands, Debye enrolled in the [[Aachen University of Technology]] in 1901. In 1905, he completed his first degree in [[electrical engineering]]. He published his first paper, a mathematically elegant solution of a problem involving [[eddy current]]s, in 1907. At Aachen, he studied under the theoretical physicist [[Arnold Sommerfeld]], who later claimed that his most important discovery was Peter Debye.

In 1906, Sommerfeld received an appointment at [[Ludwig Maximilian University of Munich|Munich]], [[Kingdom of Bavaria|Bavaria]], and took Debye with him as his assistant. Debye got his [[Doctor of Philosophy|Ph.D.]] with a dissertation on [[radiation pressure]] in 1908. In 1910, he derived the [[Planck's law|Planck radiation formula]] using a method which [[Max Planck]] agreed was simpler than his own.

In 1911, when [[Albert Einstein]] took an appointment as a professor at [[Charles University of Prague|Prague]], [[Bohemia]], Debye took his old professorship at the [[University of Zurich]], Switzerland. This was followed by moves to [[Utrecht University|Utrecht]] in 1912,<ref>Debye's predecessor in the chair of theoretical physics at Utrecht was Cornelis Wind, who died in 1911. Debye's successor at Utrecht was [[Leonard Ornstein]].</ref> to [[University of Göttingen|Göttingen]] in 1913, to [[ETH Zurich]] in 1920, to [[University of Leipzig]] in 1927, and in 1934 to [[Humboldt University of Berlin|Berlin]], where, succeeding Einstein, he became director of the [[Kaiser Wilhelm Institute for Physics]] (now named the Max-Planck-Institut) whose facilities were built only during Debye's era. He was awarded the [[Lorentz Medal]] in 1935. From 1937 to 1939 he was the president of the [[Deutsche Physikalische Gesellschaft]].

In May 1914 he became member of the [[Royal Netherlands Academy of Arts and Sciences]] and in December of the same year he became foreign member.<ref>{{cite web|url=http://www.dwc.knaw.nl/biografie/pmknaw/?pagetype=authorDetail&aId=PE00004770 |title=Peter Joseph Wilhelm Debije (1884–1966) |publisher=Royal Netherlands Academy of Arts and Sciences |access-date=27 July 2015}}</ref>

===Family and personal life===
Peter Debye was described as a martinet when it came to scientific principles, yet he was always approachable and made time for his students. His personal philosophy emphasized a fulfillment of purpose and enjoyment in one's work. Debye was an avid trout fisherman and gardener, collector of cacti, and was "always known to enjoy a nice cigar".<ref name=":0">{{Cite journal|last=Davies|first=Mansel|date=1970|title=Peter Joseph Wilhelm Debye. 1884–1966|journal=Biographical Memoirs of Fellows of the Royal Society|volume=16|pages=175–232|jstor=769588|doi=10.1098/rsbm.1970.0007|doi-access=free}}</ref>

While in Berlin as an assistant to [[Arnold Sommerfeld]], Debye became acquainted with Mathilde Alberer.<ref name=":1">{{Cite book|url=https://books.google.com/books?id=jEy67gEvIuMC&q=mathilde+debye&pg=PA230|title=Nobel Laureates in Chemistry, 1901–1992|last=Laylin|first=James K.|date=1993-10-30|publisher=Chemical Heritage Foundation|isbn=9780841226906|language=en}}</ref> Mathilde was the daughter of the proprietor of the boarding house in which Debye was staying.<ref name=":1" /> Mathilde would soon change her citizenship and in 1913, Debye married Mathilde Alberer.<ref name=":1" /><ref name=":2" /> Debye would enjoy working in his rose garden with Mathilde Alberer late into his years.<ref name=":0" /> They had a son, Peter P. Debye (1916–2012), and a daughter, Mathilde Maria (1921–1991).{{citation needed|date=July 2023}} Peter became a physicist and collaborated with Debye in some of his research,{{citation needed|date=July 2023}} and had a son who was also a chemist.<ref name=":2">[http://www.towson.edu/applications/dailydigest/databases/news/20091012_114742AM_joschmid_293.asp Towson University Daily Digest] {{Webarchive|url=https://web.archive.org/web/20111120112218/http://www.towson.edu/applications/dailydigest/databases/news/20091012_114742AM_joschmid_293.asp |date=2011-11-20 }}. Towson.edu. Retrieved on 2012-07-25.</ref>

Debye was a faithful Catholic<ref>{{Cite journal|doi = 10.1098/rsbm.1970.0007|title = Peter Joseph Wilhelm Debye, 1884-1966|journal = Biographical Memoirs of Fellows of the Royal Society|year = 1970|volume = 16|pages = 175–232|s2cid = 72952631|doi-access = free}}</ref> who insisted his family go to church.<ref>{{Cite book |last=Ginkel |first=G. van |title=Prof. Peter J. W. Debye (1884–1966) in 1935 – 1945: brilliant scientist – gifted teacher; an investigation of historical sources |date=2006 |publisher=RIPCN |isbn=978-90-393-4284-8 |location=s.l.}}</ref>

===Scientific contributions===
His first major scientific contribution was the application of the concept of [[Electric dipole moment|dipole moment]] to the [[electric charge|charge]] distribution in asymmetric [[molecule]]s in 1912, developing equations relating dipole moments to temperature and [[Relative static permittivity|dielectric constant]]. In consequence, the units of molecular dipole moments are termed ''debyes'' in his honor. Also in 1912, he extended [[Albert Einstein]]'s theory of [[Specific heat capacity|specific heat]] to lower temperatures by including contributions from low-frequency [[phonon]]s. See [[Debye model]].

In 1913, he extended [[Niels Bohr]]'s theory of [[atomic structure]], introducing elliptical orbits, a concept also introduced by [[Arnold Sommerfeld]]. In 1914–1915, Debye calculated the effect of temperature on [[X-ray scattering techniques|X-ray diffraction]] patterns of [[crystalline solid]]s with [[Paul Scherrer]] (the "[[Debye–Waller factor]]").
In 1923, together with his assistant [[Erich Hückel]], he developed an improvement of [[Svante Arrhenius]]' theory of electrical conductivity in [[electrolyte]] solutions. Although an improvement was made to the [[Debye–Hückel equation]] in 1926 by [[Lars Onsager]], the theory is still regarded as a major forward step in our understanding of [[Electrolyte|electrolytic]] solutions. Also in 1923, Debye developed a theory to explain the [[Compton effect]], the shifting of the frequency of [[X-ray]]s when they interact with [[electron]]s.

===Later work===
From 1934 to 1939 Debye was director of the physics section of the prestigious Kaiser Wilhelm Institute in [[Berlin]]. From 1936 onwards he was also professor of Theoretical Physics at the [[Humboldt University of Berlin|Frederick William University]] of Berlin. These positions were held during the [[Nazi regime]] in Germany and, from 1938 onward, [[Austria]].

In 1939 Debye traveled to the United States to deliver the Baker Lectures at [[Cornell University]] in [[Ithaca, New York]]. After leaving Germany in early 1940, Debye became a professor at Cornell, chaired the chemistry department for 10 years, and became a member of [[Alpha Chi Sigma]]. In 1946 he became an American citizen. Unlike the European phase of his life, where he moved from city to city every few years, in the United States Debye remained at Cornell for the remainder of his career. He retired in 1952, but continued research until his death.

Much of Debye's work at Cornell concerned the use of light-scattering techniques (derived from his X-ray scattering work of years earlier) to determine the size and [[molecular weight]] of [[polymer]] [[molecule]]s. This started as a result of his research during [[World War II]] on [[synthetic rubber]], but was extended to [[protein]]s and other [[macromolecule]]s.

In April 1966, Debye suffered a [[myocardial infarction|heart attack]], and in November of that year a second one proved fatal. He is buried in the Pleasant Grove Cemetery (Ithaca, New York, US).<ref>[http://chemindigest.com/peter-debye1884-1966-phenomenal-achievements-in-physical-chemistry/ ''Chemical Industry Digest'']</ref>

==War activities and controversies==

===2006 controversy===
In January 2006, a book (in Dutch) appeared in The Netherlands, written by [[Sybe I. Rispens|Sybe Rispens]], entitled  ''Einstein in the Netherlands.''<ref name="Rispens">Sybe Rispens, ''Einstein in Nederland. Een intellectuele biografie'' Ambo/Anthos '''2006''' {{ISBN|90-263-1903-7}}</ref> One chapter of this book discusses the relationship between [[Albert Einstein]] and Debye. Rispens discovered documents that, as he believed, were new and proved that, during his directorship of the [[Kaiser Wilhelm Society]], Debye was actively involved in cleansing German science institutions of Jewish and other "non-Aryan elements". Rispens records that on December 9, 1938, Debye wrote in his capacity as chairman of the ''Deutsche Physikalische Gesellschaft'' (DPG) to all the members of the DPG:

''In light of the current situation, membership by German Jews as stipulated by the Nuremberg laws, of the Deutsche Physikalische Gesellschaft cannot be continued. According to the wishes of the board, I ask of all members to whom these definitions apply to report to me their resignation. Heil Hitler!''

Many biographies<ref name="frs"/><ref>Stichting Edmond Hustinx and Christian Bremen (eds). Pie Debije-Peter Debye: 1884–1966. Gardez! Verlag (2000) {{ISBN|3897960486}}.</ref><ref>Williams, J. W. [http://www.nap.edu/openbook.php?record_id=569&page=22 "Peter Joseph Wilhelm Debye"]  Biographical Memoirs, Vol. 46 (1975) National Academy of Sciences U.S.</ref> published before Rispens' work, state that Debye moved to the US because he refused to accept German citizenship forced on to him by the Nazis. He planned his departure from Germany during a visit with his mother in [[Maastricht]] in late 1939, boarded a ship in Genoa in January 1940 and arrived in New York in early February 1940. He immediately sought a permanent position in the US and accepted such an offer from Cornell in June 1940. That month, he crossed the US border into Canada and returned within days on an immigration visa. He was able to get his wife out of Germany and to the US by December 1940. Although his son already was in the US before he departed, Peter Debye's 19-year-old daughter and his sister-in-law did not leave. They lived in his official residence in Berlin and were supported by Debye's official Berlin wages (he carefully maintained an official leave of absence for this purpose).

Further, Rispens<ref name="Rispens" /> alleges that Albert Einstein in the first half of 1940 tried to prevent Debye from being appointed in the United States at Cornell. Einstein allegedly wrote to his American colleagues: "I know from a reliable source that Peter Debye is still in close contact with the German (Nazi) leaders" and, according to Rispens, called upon his colleagues to do "what they consider their duty as American citizens". To support this, Rispens refers to a well-known{{citation needed|date=June 2021}} letter from Debye to Einstein and Einstein's response to it. Van Ginkel<ref name="Ginkel">G. van Ginkel, [http://www.theochem.ru.nl/~pwormer/Historical%20sources%20Debye%201935-1945.pdf ''Prof. Peter J. W. Debye in 1935–1945. An investigation of historical sources''], December 2006, {{ISBN|90-393-4284-9}}</ref> investigated 1940 FBI reports on this matter and traced the "reliable source" to a single letter directed to Einstein and written by someone whose name is lost. This person was not known personally to Einstein and, according to Einstein, probably did not know Debye personally either. Moreover, this accusatory letter did not reach Einstein directly but was intercepted by British censors who showed it to Einstein. Einstein sent the British agent with the letter to Cornell, and the Cornell authorities told Debye about the affair. Thereupon Debye wrote his well-known 1940 letter to Einstein to which Einstein answered. The latter two letters can be found in the published Einstein correspondence.

Rispens alleges that Debye sent a telegram to Berlin on 23 June 1941 informing his previous employers that he was able and willing to resume his responsibilities at the Kaiser Wilhelm Institut, presumably to maintain his leave of absence and keep the Berlin house and wages available for his daughter. A copy of this telegram has not been recovered thus far. In summer 1941, Debye filed his intent to become a US citizen and was quickly recruited in the US to participate in Allied war research.

It has been well documented in many biographies, and also in Rispens' book, that Debye and Dutch colleagues helped his Jewish colleague [[Lise Meitner]] in 1938–1939 (at great risk to himself and his family<ref>[[Ruth Lewin Sime|Sime, Ruth Lewin]]. ''Lise Meitner: A Life in Physics''. University of California Press (1997) {{ISBN|0520208609}}.</ref><ref>{{cite journal|doi=10.1119/1.16196|title=Lise Meitner's Escape from Germany|bibcode=1990AmJPh..58..262S|date=1990|last1=Sime|first1=Ruth Lewin|journal=American Journal of Physics|volume=58|issue=3|pages=262–267}}</ref>) cross the Dutch-German border to escape Nazi persecution and eventually obtain a position in Sweden.

Predating Rispens' work, and in contrast to it, an article by [[Helmut Rechenberg|Rechenberg]]<ref>{{Cite journal|last=Rechenberg|first=H.|author-link=Helmut Rechenberg|date=November 1988|title=Vor fünfzig Jahren|journal=[[Physik Journal|Physikalische Blätter]]|language=en|volume=44|issue=11|pages=418|doi=10.1002/phbl.19880441104|s2cid=121893768 |doi-access=free}}</ref> appeared 18 years earlier concerning Debye's letter. The article describes Debye's missive in more detail and presents a very favorable picture of Debye in his efforts to resist Nazi activists. Moreover, this article points out that [[Max von Laue]], well known for his anti-Nazi views, gave his approval to the letter from the DPG chairman.

===International response===
Debye's son, Peter P. Debye, interviewed in 2006 at age 89<ref>Interview given to Gooi & Eemlander newspaper (Dutch language) on 2 February 2006</ref> recollects that his father was completely apolitical and that in the privacy of their home politics were never discussed. According to his son, Debye just wanted to do his job at the Kaiser Wilhelm Institute and as long as the Nazis did not bother him was able to do so. He recalls that his mother urged him (the son) to stay in the US in the event of war. Debye's son had come to the US on a planned 2-month vacation during the summer of 1939 and never returned to Germany because war broke out.

In an opinion article published on the [[Debye Institute]] website, Dr. Gijs van Ginkel, until April 2007 Senior Managing Director of the VM Debye Instituut in Utrecht<ref>Gijs van Ginkel (2006) [http://www.debye.uu.nl/documents/Debye.htm AFSCHEID VAN DEBYE DOOR UTRECHT: EEN BESTUURLIJKE DWALING] {{webarchive|url=https://web.archive.org/web/20070225060816/http://www.debye.uu.nl/documents/Debye.htm |date=2007-02-25 }}. debye.uu.nl (in Dutch)</ref> deplored the decision to rename the institute. In his article he cites scholars who point out that the DPG was able to retain their threatened staff as long as could be expected under increasing pressure from the Nazis. He also puts forward the important argument that when Debye in 1950 received the [[Max Planck medal]] of the DPG, nobody objected, not even the known opponent of the national socialists [[Max von Laue]], who would have been in a position to object. Also Einstein, with his enormous prestige, was still alive, as were other Jewish scientists such as [[Lise Meitner]] and [[James Franck]] who both knew Debye intimately. None of them protested against Debye's receiving the highest German scientific distinction. In fact, Albert Einstein, after many years of not participating in the voting for the Max Planck Medal nominees, joined the process again to vote for Debye.

[[File:Maastricht, University hospital, Monument for Peter Debye.jpg|thumb|Monument for Peter Debye in the Maastricht square that bears his name: ''Dipole moments'' (Felix van de Beek, 1998)]]
[[Maastricht University]] also announced that it was reconsidering its position on the ''Peter Debye Prijs voor natuurwetenschappelijk onderzoek'' (Peter Debye Prize for scientific research).<ref>[http://www.unimaas.nl/default.asp?id=c62214CGV252615N3656&template=overig/pers_detail.htm&pid=429&jaar=2006&red=1 Opgeroepen beeld moeilijk verenigbaar met voorbeeldfunctie UM] {{Webarchive|url=https://web.archive.org/web/20121031090302/http://www.unimaas.nl/default.asp?id=c62214CGV252615N3656&template=overig%2Fpers_detail.htm&pid=429&jaar=2006&red=1 |date=2012-10-31 }}, Press release University of Maastricht, 16 February 2006</ref>

In a reply on the DPG website,<ref>Dieter Hoffmann and Mark Walker (March 2006). [http://www.dpg-physik.de/gliederung/fv/gp/debye_en.html Peter Debye: A Typical Scientist in an Untypical Time] {{webarchive|url=https://web.archive.org/web/20070927011325/http://www.dpg-physik.de/gliederung/fv/gp/debye_en.html |date=2007-09-27 }}. dpg-physik.de</ref> Dieter Hoffmann and Mark Walker also conclude that Debye was not a Nazi activist. They remark that Max von Laue also was required and obliged (as a civil servant) to sign letters with ''Heil Hitler''. They also state that the DPG was one of the last scientific societies to purge the Jewish members and only very reluctantly. They quote the response of the ''Reich University Teachers League'' (a National Socialist organization) to the Debye letter:

''Obviously the German Physical Society is still very backward and still clings tightly to their dear Jews. It is in fact remarkable that only "because of circumstances beyond our control" the membership of Jews can no longer be maintained''
 
In May 2006,<ref>{{cite web |url=http://home.hetnet.nl/~alchemilab/alchemie/DebyeV.htm |title=Veltman letter to the Utrecht University's Board of Directors |access-date=2006-07-11 |url-status=dead |archive-url=https://web.archive.org/web/20071223163548/http://home.hetnet.nl/~alchemilab/alchemie/DebyeV.htm |archive-date=December 23, 2007 }}. 5 May 2006. Home.hetnet.nl. Retrieved on 2012-07-25.</ref> the Dutch Nobel Prize winner [[Martinus Veltman]] who had written the foreword to the Rispen book, renounced the book's description of Peter Debye, withdrew his foreword, and asked the Board of Directors of Utrecht University to rescind their decision to rename the Debye Institute.

Various historical investigations, both in The Netherlands and in the US, have been carried out subsequent to the actions of the University of Maastricht. The earliest of these investigations, carried out by the Cornell University's department of Chemistry and Chemical Biology released a report<ref>{{cite web |url=http://home.hetnet.nl/~alchemilab/alchemie/DebyeCornell.htm |title=Decision Cornell University |first=Héctor D. |last=Abruña |author-link=Héctor D. Abruña |url-status=dead |archive-url=https://web.archive.org/web/20070109195333/http://home.hetnet.nl/~alchemilab/alchemie/DebyeCornell.htm |archive-date=January 9, 2007 |access-date=2012-07-25 |website=Home.hetnet.nl }}</ref> on 31 May 2006, which states that:

''Based on the information to-date, we have not found evidence supporting the accusations that Debye was a Nazi sympathizer or collaborator or that he held anti-Semitic views. It is important that this be stated clearly since these are the most serious allegations.''

It goes on to declare:

''Thus, based on the information, evidence and historical record known to date, we believe that any action that dissociates Debye's name from the Department of Chemistry and Chemical Biology at Cornell is unwarranted.''

In June 2006, it was reported<ref>{{cite journal | author=Enserink M | title=ETHICS: Blocking a Book, Dutch University Rekindles Furor Over Nobelist Debye | journal= Science | volume=312 | issue=5782 | date=2006 | page=1858 |doi=10.1126/science.312.5782.1858 | pmid=16809496| s2cid=6571440 }}</ref><ref>Arjan Dijkgraaf (20 June 2006) [http://www.c2w.nl/uu-weer-beschuldigd-van-censuur.74888.lynkx UU weer beschuldigd van censuur] {{Webarchive|url=https://web.archive.org/web/20160329220229/http://www.c2w.nl/uu-weer-beschuldigd-van-censuur.74888.lynkx |date=2016-03-29 }}. Chemisch Weekblad (in Dutch).</ref> that the scientific director of the (formerly) Debye Institute had been reprimanded by the board of directors of the [[University of Utrecht]] for a new publication on Debye's war years on the grounds that it was too personally biased with respect to the Institute's naming dispute. According to the board, the book should have been published not as a Debye Institute publication, but as a personal one. The book<ref name="Ginkel" /> was banned by the University of Utrecht and both Directors of the (former) Debye Institute were forbidden to have any further contact with the press. A dozen professors of the Physics Faculty, amongst whom [[Cornelis Dirk Andriesse|Cees Andriesse]], openly protested against the interventions of the Board and the censorship of their protest by the university.<ref>[[Volkskrant]], 24 March 2007.</ref>

In May 2007, the universities of Utrecht and Maastricht announced that a new committee headed by [[Jan Terlouw]] would advise them regarding the name change. Also, in the beginning of 2007 an official report was announced, to be published by the [[NIOD]] and authorized by the Dutch Education Ministry (then scheduled for fall 2007).<ref>[[NRC Handelsblad]], 19 May 2007.</ref>

===2007 NIOD report===

The report describes Rispens' presentation of Debye, as an opportunist who had no objection to the Nazis, as a caricature.

''[I]t can be stated that Debye was rightly called an opportunist after his arrival in the United States. We have seen that he showed himself to be loyal to the dominant political system, first in the Third Reich and then in the United States, while at the same time keeping the back door open: in the Third Reich by retaining his Dutch nationality, in the United States by attempting to secretly maintain some contacts with Nazi Germany via the Foreign Office.''

It concludes that Debye's actions in 1933–45 were based on the nineteenth-century positivist view of science which saw research in physics as generating blessings for humankind. The report states that, by his contemporaries, Debye was considered an opportunist by some and as a man of highest character by others. The report asserts that Debye was not coerced by the Nazis into writing the infamous DPG ''Heil Hitler'' letter and that he also did not follow the lead of other societies in doing so but, rather, other societies followed his lead.<ref>Note that this statement is in sharp contrast to the conclusion reached in a previous study of the DPG's relationship to the Third Reich which describes the DPG to be one of the last professional organizations in Germany to expel its Jewish members. Dieter Hoffmann (2001) [http://www.mpiwg-berlin.mpg.de/Preprints/P192.PDF Zwischen Autonomie und Anpassung: Die Deutsche Physikalische Gesellschaft im Dritten Reich]. Max Planck Institute for the History of Science</ref> The NIOD report also concludes that Debye felt obliged to send the letter and that it was, for him, simply a confirmation of an existing situation. The report argues that Debye, in the Third Reich, developed a survival method of ambiguity which allowed him to pursue his scientific career despite the political turmoil. Crucial to this survival method was the need to keep ready an escape hatch, for example in his secret dealings with the Nazis in 1941, if needed.

Yet, the report also states that the picture of Debye should not be oversimplified as Debye's actions were also motivated by his loyalty to his daughter, who had remained in Berlin. In general, Debye developed a survival method of ambiguity, that "could pull the wool over people's eyes".<ref>Eickhoff, Martijn "In the Name of Science?", Aksant, Amsterdam, 2008, p. 131.</ref>

===2008 Terlouw report===
In January 2008 the Terlouw Commission advised ''the Boards of Utrecht and Maastricht Universities to continue to use Peter Debye’s name for the chemistry and physics institute in Utrecht, and to continue awarding the science prize in Maastricht''.<ref>[http://www.uu.nl/EN/Current/Pages/TerlouwCommissionContinueusingDebyesname.aspx Terlouw Commission: ‘Continue using Debye’s name’]. Press release University of Utrecht. 17 January 2008.</ref> The Commission concluded that Debye was not a party member, was not an anti-semite, did not further Nazi propaganda, did not cooperate with the Nazi war machine, was not a [[Collaborationism|collaborator]], and yet also was not a resistance hero. He was a rather pragmatic, flexible, and brilliant scientist, idealistic with respect to the pursuit of science, but only superficially oriented in politics. With respect to sending out the DPG letter, the Commission concluded that Debye found the situation inescapable. The Commission pointed out that the Royal Dutch Academy of Sciences also took away Albert Einstein's honorary membership, emphasizing the circumstances in which these decisions had been taken. The Commission stated that now, seventy years later, no judgment can be made concerning the decision of Debye to sign this letter in the exceptionally difficult circumstances in which he then found himself. Nevertheless, the Commission describes the DPG letter as an extraordinarily unpleasant fact, forming a dark page in his life history. Finally, the Commission concluded that based on the NIOD report ''since no bad faith on Debye’s part has been demonstrated, his good faith must be assumed'' and recommended that the University of Utrecht retain the name of the Debye Institute of NanoMaterials Science and that the University of Maastricht continue to associate itself with the Peter Debye Prize. Utrecht University accepted the recommendation, Maastricht University did not. But in February 2008, the Hustinx Foundation (Maastricht), originator and sponsor of the Peter Debye Prize, announced that it will continue to have the prize awarded. The City of Maastricht, Debye's birthplace, declared that it sees no reason to change the names of Debye Street and Debye Square.

===Debye the spy===
In a 2010 publication Jurrie Reiding asserts that Debye may have been an [[MI6]] spy.<ref>{{cite journal|title=Letters defend Nobel laureate against Nazi charges|doi=10.1038/news.2010.656|date=2010|last1=Ball|first1=Philip | author-link = Philip Ball|journal=[[Nature (journal)|Nature]]}}</ref><ref>{{cite journal|title=Peter Debye: Nazi Collaborator or Secret Opponent?|doi=10.1179/174582310X12849808295706|date=2010|last1=Reiding|first1=Jurrie|journal=[[Ambix]]|volume=57|issue=3|pages=275–300|pmid=21465996|s2cid=45072312}}</ref> Reiding discovered that Debye was befriended by the well-documented spy [[Paul Rosbaud]]. They first met around 1930 when they were both working as editors for two scientific journals. They collaborated in the escape of Lise Meitner in 1938. According to Reiding, Debye was well connected in German scientific and industrial circles and could have provided MI6 with valuable information. For example, as board member of the German Academy for Aviation Research he was acquainted with [[Hermann Göring]]. Reiding also offers an explanation for Debye's hasty departure on 16 January 1940 for the United States: the date coincided with the planned (but later delayed) [[German invasion of the Netherlands]] a day later, information possibly provided to him by Rosbaud.

This hypothesis is contested by [[Philip Ball]], as he notes that friendship with Rosbaud is no gauge of Debye's political stance. Rosbaud was well-connected with many people and Debye, while he was a friend of Rosbaud's, seems to have also felt regard for geologist Friedrich Drescher-Kaden, an ardent Nazi.<ref>Philip Ball, Serving the Reich: The Struggle for the Soul of Physics under Hitler, 2014, {{ISBN|978-0-226-20457-4}}, page 141.</ref>

==Awards and honors==
*1927 – elected International Honorary Member of the [[American Academy of Arts and Sciences]]<ref>{{Cite web |date=2023-02-09 |title=Peter Joseph William Debye |url=https://www.amacad.org/person/peter-joseph-william-debye |access-date=2023-06-01 |website=American Academy of Arts & Sciences |language=en}}</ref>
*1930 – [[Rumford Medal]] for work relating to specific heats and X-ray spectroscopy
*1936 – [[Nobel Prize in Chemistry]] "for his contributions to the study of molecular structure," primarily referring to his work on dipole moments and X-ray diffraction
*1936 – elected member of the [[American Philosophical Society]]<ref>{{Cite web |title=APS Member History |url=https://search.amphilsoc.org/memhist/search?creator=Peter+Debye&title=&subject=&subdiv=&mem=&year=&year-max=&dead=&keyword=&smode=advanced |access-date=2023-06-01 |website=search.amphilsoc.org}}</ref>
*1937 – [[Franklin Medal]] from [[The Franklin Institute]]
*1947 – elected member of the United States [[National Academy of Sciences]]<ref>{{Cite web |title=Peter J. Debye |url=http://www.nasonline.org/member-directory/deceased-members/20001738.html |access-date=2023-06-01 |website=www.nasonline.org}}</ref>
*1963 – [[Priestley Medal]]
*1965 – [[National Medal of Science]]<ref>[https://www.nsf.gov/od/nms/recip_details.cfm?recip_id=101 National Science Foundation – The President's National Medal of Science]. Nsf.gov (1966-02-10). Retrieved on 2012-07-25.</ref>
*1982 – [[Alpha Chi Sigma]] Hall of Fame<ref>{{cite web|url=http://www.alphachisigma.org/page.aspx?pid=268|title=Fraternity – Awards – Hall of Fame – Alpha Chi Sigma|work=alphachisigma.org}}</ref>

==Eponyms==
{{see also|List of things named after Peter Debye}}
*[[Debye shielding]] – In [[plasma (physics)|plasmas]], [[semiconductor]]s and [[electrolyte]]s, the process by which a fixed electric charge is shielded by redistributing mobile charged particles around it.
*[[Debye length]] – The typical distance in a plasma required for full Debye shielding.
*[[Debye model]] – A model of the [[heat capacity]] of solids as a function of temperature
*[[Debye]] – a unit of electric dipole moment
*[[Debye frequency]] – a characteristic vibrational frequency of a crystalline lattice.
*[[Debye relaxation]] – The dielectric relaxation response of an ideal, noninteracting population of dipoles to an alternating external electric field.
*[[Debye sheath]] – The non-neutral layer, several Debye lengths thick, where a plasma contacts a material surface.
*[[Debye–Hückel equation]] – A method of calculating [[activity coefficient]]s
*[[Debye function]] – A function used in the calculation of [[heat capacity]].
*Debye–Scherrer method – A technique used in X-ray powder diffraction.
*[[Debye–Waller factor]] – A measure of disorder in a [[crystal lattice]].
*[[30852 Debye]] – A [[Meanings of asteroid names (30001-31000)|minor planet]] (originally named 1991 TR6).
*[[Mie theory|Lorenz–Mie–Debye theory]] Theory of light scattering by a spherical particle.
*[[Debye (crater)]] – A lunar crater located on the far side and in the northern hemisphere of the moon.

==See also==
*[[Electroacoustic phenomena]]
*[[Ion vibration current]]
*[[Magnetic refrigeration]]
*[[Method of steepest descent]]
*[[Rotational Brownian motion]]

==Notes==
{{Notelist}}

==References==
{{Reflist|30em}}

==Further reading==
*{{DSB
|first=Charles
|last=Smith
|title=Debye, Peter Joseph William
|volume=3
|pages=617–621
}}

==External links==
{{wikiquote}}
{{Commons category}}
* [https://web.archive.org/web/20061002071002/http://chem.ch.huji.ac.il/~eugeniik/history/debye.html Debye Biography] – Institute of Chemistry, [[Hebrew University]]
* {{Nobelprize}} including the Nobel Lecture, December 12, 1936 ''Methods to Determine the Electrical and Geometrical Structure of Molecules''
* [http://journals.iucr.org/q/issues/1967/06/00/a05589/a05589.pdf Debye Biography] – [[IUCr]]
* {{webarchive |url=https://web.archive.org/web/20080307154851/http://www.museumboerhaave.nl/ONDERWIJS/VOORTGEZET/2defase/ANW/pdf/nobelprijswinnaars.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.museumboerhaave.nl/ONDERWIJS/VOORTGEZET/2defase/ANW/pdf/nobelprijswinnaars.pdf |archive-date=2022-10-09 |url-status=live |date=March 7, 2008 |title=Negen Nederlandse Nobelprijswinnaars }} – [[Museum Boerhaave]]
* [https://archive.today/20060617232607/http://www.dpg-physik.de/dpg/organisation/fachlich/gp/debye_en.html Deutsche Physikalische Gesellschaft (DPG)]
* [http://www.debye.uu.nl/ Debye Institute]
* [https://www.aip.org/history-programs/niels-bohr-library/oral-histories/4568-1 Oral History interview transcript with Peter Debye on 3 May 1962, American Institute of Physics, Niels Bohr Library & Archives] – Session I
* [https://www.aip.org/history-programs/niels-bohr-library/oral-histories/4568-2 Oral History interview transcript with Peter Debye on 3 May 1962, American Institute of Physics, Niels Bohr Library & Archives] – Session II
* [https://www.aip.org/history-programs/niels-bohr-library/oral-histories/4568-3 Oral History interview transcript with Peter Debye on 4 May 1962, American Institute of Physics, Niels Bohr Library & Archives] – Session III
* {{PM20}}

{{Nobel Prize laureates from The Netherlands|state=collapsed}}
{{Nobel Prize in Chemistry Laureates 1926-1950}}
{{1936 Nobel Prize winners}}
{{Scientists whose names are used as non SI units}}

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