Editing Peter Debye (section)

==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|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>