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Paul Peter Ewald (surname pronounced "Ay-vald"), FRS〔 (January 23, 1888 in Berlin, Germany – August 22, 1985 in Ithaca, New York) was a German crystallographer and physicist, a pioneer of X-ray diffraction methods. ==Education== Ewald received his early education in the classics at the Gymnasium in Berlin and Potsdam, where he learned to speak Greek, French, and English, in addition to his native language of German.〔(Ewald ) – Memorial〕 Ewald began his higher education in physics, chemistry, and mathematics at Gonville and Caius College in Cambridge, during the winter of 1905. Then in 1906 and 1907 he continued his formal education at the University of Göttingen, where his interests turned primarily to mathematics. At that time, Göttingen was a world-class center of mathematics under the three “Mandarins” of Göttingen: Felix Klein, David Hilbert, and Hermann Minkowski.〔Greenspan, 2005, pp. 26-34.〕 While studying at Göttingen, Ewald was taken on by Hilbert as an ''Ausarbeiter'', a paid position as a scribe, i.e., he would take notes in Hilbert’s classes, have the notes approved by Hilbert’s assistant – at that time Ernst Hellinger – and then prepare a clean copy for the ''Lesezimmer'' – the mathematics reading room.〔Constance ''Hilbert'' p. 109.〕 In 1907, he continued his mathematical studies at the Ludwig Maximilians University of Munich (LMU), under Arnold Sommerfeld at his Institute for Theoretical Physics. He was granted his doctorate〔(Paul Peter Ewald ) – Mathematics Genealogy Project. Ewald’s 1912 dissertation title: ''Dispersion und Doppelbrechung von Elektronengittern''.〕 in 1912. His doctoral thesis developed the laws of propagation of X-rays in single crystals. After earning his doctorate, he was an assistant to Sommerfeld.〔〔(Author Index: Ewald ) – American Philosophical Society〕 During the 1911 Christmas recess and in January 1912, Ewald was finishing the writing of his doctoral thesis. It was on a walk through ''Englischer Garten'' in Munich, in January, that Ewald was telling Max von Laue about his thesis topic. The wavelengths of concern to Ewald were in the visible region of the spectrum and hence much larger than the spacing between the resonators in Ewald’s crystal model. Laue seemed distracted and wanted to know what would be the effect if much smaller wavelengths were considered. It was not until June of that year that Ewald heard Sommerfeld report to the ''Physikalische Gesellschaft'' of Göttingen on the successful diffraction of X-rays by Max von Laue, Paul Knipping and Walter Friedrich at LMU, for which Laue would be awarded the Nobel Prize in Physics, in 1914.〔Ewald ''50 Years of X-Ray Diffraction'' Chapter 4, pp. 37-42.〕〔Jungnickel, Volume 2, 1990, pp. 284-285.〕 With the rise of theoretical physics in the early part of the Twentieth Century and its foundation in mathematics, David Hilbert decided to lend an organizing hand to formalizing the sciences, starting with physics. In 1912, Hilbert asked his friend and colleague Arnold Sommerfeld〔Both Hilbert and Minkowski, then at Göttingen, had gotten their doctorates under Ferdinand von Lindemann at the University of Königsberg, as had Sommerfeld.〕 to send him a special assistant for physics. Sommerfeld sent Ewald, who was dubbed as “Hilbert’s tutor for physics,”〔Reid ''Courant'', 1996, p. 43.〕 and he performed this function until 1913, when Sommerfeld sent another one of his students, Alfred Landé. The first problem assigned Ewald was to review the controversy in the literature on the constants of elasticity in crystals and report back. A few years later, Max Born, at Göttingen, solved the problem.〔 〔Reid ''Hilbert'', 1996, pp. 129-133.〕 During Ewald’s stay in Göttingen, he was often a visitor at ''El BoKaReBo'', a boarding house run by Sister Annie at Dahlmannstrasse 17. The name was derived from the first letters of the last names of its boarders: “El” for Ella Philippson (a medical student), “Bo” for Max Born (a Privatdozent) and Hans Bolza (a physics student), “Ka” for Theodore von Kármán (a Privatdozent), and “Re” for Albrecht Renner (a medical student). Richard Courant, a mathematician and Privatdozent, called these people the “in group.” It was here that Ewald met Ella Philippson, who was to become his wife.〔Greenspan, 2005, p. 53.〕 In the spring of 1913, Niels Bohr, of the Institute for Theoretical Physics at the University of Copenhagen, submitted his theory of the Bohr atomic model for publication.〔(Bohr ) - ''On the Constitution of Atoms and Molecules''〕 Later that year, Ewald attended the Birmingham meeting of the British Association where he heard accounts and discussions of James Jeans’ review on radiation theory and Bohr’s model.〔Paul Peter Ewald ''Bericht über die Tagung der British Association in Birmingham'', ''Phys. Zs.'' 14 1298-1307 (1913). Received 19 October 1913. – Paper cited in: Mehra, Volume 1, Part 1, p. 202 and Mehra, Volume 1, Part 2, 2001, p. 770.〕 This ignited a major new area of research for Sommerfeld and his students – the study and interpretation of atomic spectra and molecular band spectroscopy and theoretical modeling of atomic and molecular structure. During World War I, Ewald served in the German military as a medical technician. When he could, he continued to think about the physics of his doctoral thesis, and he developed the dynamical theory of X-ray diffraction, which he was later to use in his Habilitationsschrift. At the conclusion of the war, he returned to LMU as an assistant to Sommerfeld. He completed his Habilitation in 1917,〔Mehra, Volume 5, Part 1, 2001, p. 249.〕 and became a Privatdozent there, while remaining as an assistant to Sommerfeld.〔〔Ewald ''50 Years of X-Ray Diffraction'' Chapter 20, p. 456-457.〕 In 1921, while still at LMU, Ewald published a paper on the theta function method of analyzing dipole fields in crystals,〔Paul Peter Ewald ''Die Berechnung optischer und elektrostatischer Gitterpotentiale'', ''Ann. Phys.'' 64 253-287 (1921), as cited in (Ewald ) – University of Pennsylvania.〕 an offshoot from his earlier work on the dynamical theory of optics and X-rays in crystals, which appeared in three journal publications.〔Paul Peter Ewald ''Zur Begründung der Kristalloptik. Teil I'', ''Ann. Phys.'' 49 1-38 (1916), as cited in (Ewald ) – University of Pennsylvania.〕〔Paul Peter Ewald ''Zur Begründung der Kristalloptik. Teil II'', ''Ann. Phys.'' 49 117-143 (1916), as cited in (Ewald ) – University of Pennsylvania.〕〔Paul Peter Ewald ''Zur Begründung der Kristalloptik. Teil III'', ''Ann. Phys.'' 54 519-597 (1917), as cited in (Ewald ) – University of Pennsylvania.〕 According to Ewald, the impetus for the method came from a skiing holiday in Mittenwald, at Easter, in 1911. It was Sommerfeld’s practice to take his students and assistants on skiing outings in the winter and mountain climbing outings in the summer, where the discussions of physics were as hard as the physical exertion of the outings.〔Jungnickel, Volume 2, 1990, p. 284, quoting from references given in Footnote 100 on the page.〕 Ewald, was having trouble subtracting out of his calculations the field of the test dipole. The solution was provided by Sommerfeld’s assistant and former doctoral student, Peter Debye, in a discussion that took no more than 15 minutes. Ewald’s paper has been widely cited in the literature as well as scientific books, such as ''Dynamical Theory of Crystal Lattices'',〔Max Born and Kun Huang ''Dynamical Theory of Crystal Lattices'' (Oxford, Clarendon Press, 1954)〕 by Max Born and Kun Huang.〔(Ewald ) – University of Pennsylvania.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Paul Peter Ewald」の詳細全文を読む スポンサード リンク
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