Paul Peter Ewald
Encyclopedia
Paul Peter Ewald was a German
-born U.S. crystallographer
and physicist
, a pioneer of X-ray diffraction methods.
, where he learned to speak Greek, French, and English, in addition to his native language of German.
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
. 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. 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 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.
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.
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 to send him a special assistant for physics. Sommerfeld sent Ewald, who was dubbed as “Hilbert’s tutor for physics,” 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.
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.
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. 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. 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, and became a Privatdozent
there, while remaining as an assistant to Sommerfeld.
In 1921, while still at LMU, Ewald published a paper on the theta function method of analyzing dipole fields in crystals, an offshoot from his earlier work on the dynamical theory of optics and X-rays in crystals, which appeared in three journal publications. 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. 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, by Max Born
and Kun Huang.
let it be known that he was leaving his position as extraordinarius professor at the Stuttgart
Technische Hochschule
, to go to the University of Breslau, Ewald was called and accepted the position in 1921. In 1922, he was called to the University of Münster
. Ewald used the offer to better his position at Stuttgart to ordinarius professor; however, while Ewald was promoted to ordinarius professor, the established position was actually retained as an extraordinarius professorship. From 1922 Erwin Fues
, also a former doctoral student of Sommerfeld, did postgraduate work at the Stuttgart Technische Hochschule, under Ewald; Fues completed his Habilitation in 1924. Also in that year, Ewald became co-editor of Zeitschrift für Kristallographie. In 1929, he received a call to the Technische Hochschule Hanover
. Again, he used this call to better his position at Stuttgart by negotiating for a second assistant, the permanent conversion of his position to that of ordinarius professor, and a separate building for his activities. The building was formally opened in 1930 as the Institute for Theoretical Physics, with Ewald as director. The institute was modeled after Sommerfeld’s Institute for Theoretical Physics at Munich, in that it would conduct theoretical work as well as have space and equipment for experimental work. In 1931, Ewald was appointed Director of the Physical Science Division.
At Göttingen, Richard Courant
had taken Hilbert’s
lecture notes which were available in the Lesezimmer, edited them and added to them to write a two-volume work. The first volume, Methoden der mathematischen Physik I, was published in 1924. Upon seeing the book, Ewald was compelled to write a detailed review describing it as providing mathematical tools, characterized by eigenvalues and eigenfunctions, for the theoretical physics then being developed. The Courant-Hilbert book fortuitously contained the mathematics necessary for the development of the Heisenberg
-Born
matrix mechanics
formulation of quantum mechanics
and also for Schrödinger’s
wave mechanics formulation, both put forward in 1925!
The main thrust of Ewald’s work was X-ray crystallography, and Ewald was the eponym
of Ewald construction and the Ewald sphere, both useful constructs in that field.
In 1929, in order to remove confusion from the proliferation of crystallographic data, Ewald proposed review and collection of the best data into a single publication. The results were published in 1935 as the Internationale Tabellen zur Bestimmung von Kristallstrukturen. Another contribution by Ewald, published in 1931, Strukturbericht Volume I (1913-1928) was edited by Ewald and C. Hermann.
Ewald was elected Rector at Stuttgart in 1932. However, due to increasing difficulties with faculty who were members of National Socialism in Germany, he resigned his position in the spring of 1933, one year before his term was due to expire. Ewald continued on with his other activities. However, over increasing problems with the Dozentenbund, Wilhelm Stortz, University Rector, asked Ewald to leave. He emigrated to England in 1937 and took a research position in Cambridge
, until he was offered and accepted a lectureship at Queen's University Belfast, in 1939. He later became a professor of mathematical physics.
While lecturing at Duke University
in 1937, Hans Bethe
, who got his doctorate under Sommerfeld in 1928, bumped into Rose Ewald, who had already emigrated to the United States and was attending the school. They were married in September 1939. Thus Bethe became son-in-law to Paul Peter Ewald.
Near the end of World War II
, Sommerfeld organized his lecture notes and began writing the six-volume Lectures on Theoretical Physics. While at the Polytechnic Institute of Brooklyn, Ewald wrote a Foreword to Sommerfeld’s Course, which appeared in the English translation of Sommerfeld’s work.
Also, toward the end of World War II
, Ewald was concerned that peace would result in the establishment of multiple, competing national journals of crystallography. So, in 1944, at Oxford, he proposed the establishment of an International Union of Crystallography
(IUCr) that would have sole responsibility for publishing crystallographic research. In 1946, he was elected Chairman of the Provisional International Crystallographic Committee, in a London meeting of crystallographers, from 13 countries; he served in this capacity until 1948, when the Union was formed. The Committee also nominated him Editor of the journal to be published by the Union. The first issue of Acta Crystallographica
was published in 1948, the same year that Ewald chaired the first General Assembly and International Congress of the IUCr, which was held at Harvard University
.
In 1952, Ewald was elected President of the American Crystallographic Association. He served on the IUCr Executive Committee from its foundation until 1966, and he was its Vice-President in 1957 and President in 1960, a position he held until 1963. His editorship of its journal Acta Crystallographica extended from its inception in 1948 to 1959.
A decade after moving to Belfast, Ewald moved to the USA in 1949 and took a position at the Polytechnic Institute of Brooklyn, as a professor and head of the Physics Department. He retired as head of the department in 1957 and from teaching in 1959.
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
-born U.S. crystallographer
Crystallography
Crystallography is the experimental science of the arrangement of atoms in solids. The word "crystallography" derives from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and grapho = write.Before the development of...
and physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
, a pioneer of X-ray diffraction methods.
Education
Ewald received his early education in the classics at the Gymnasium in Berlin and PotsdamPotsdam
Potsdam is the capital city of the German federal state of Brandenburg and part of the Berlin/Brandenburg Metropolitan Region. It is situated on the River Havel, southwest of Berlin city centre....
, where he learned to speak Greek, French, and English, in addition to his native language of German.
Ewald began his higher education in physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
, chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
, and mathematics
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...
at Gonville and Caius College in Cambridge
Cambridge
The city of Cambridge is a university town and the administrative centre of the county of Cambridgeshire, England. It lies in East Anglia about north of London. Cambridge is at the heart of the high-technology centre known as Silicon Fen – a play on Silicon Valley and the fens surrounding the...
, 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
Felix Klein
Christian Felix Klein was a German mathematician, known for his work in group theory, function theory, non-Euclidean geometry, and on the connections between geometry and group theory...
, David Hilbert
David Hilbert
David Hilbert was a German mathematician. He is recognized as one of the most influential and universal mathematicians of the 19th and early 20th centuries. Hilbert discovered and developed a broad range of fundamental ideas in many areas, including invariant theory and the axiomatization of...
, and Hermann Minkowski
Hermann Minkowski
Hermann Minkowski was a German mathematician of Ashkenazi Jewish descent, who created and developed the geometry of numbers and who used geometrical methods to solve difficult problems in number theory, mathematical physics, and the theory of relativity.- Life and work :Hermann Minkowski was born...
. 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
Ernst Hellinger
Ernst David Hellinger was a German mathematician.-Early years:Ernst Hellinger was born on September 30, 1883 in Striegau, Silesia, Germany to Emil and Julie Hellinger. He grew up in Breslau, attended school and graduated from the Gymnasium there in 1902...
– and then prepare a clean copy for the Lesezimmer – the mathematics reading room. In 1907, he continued his mathematical studies at the Ludwig Maximilians University of Munich
Ludwig Maximilians University of Munich
The Ludwig Maximilian University of Munich , commonly known as the University of Munich or LMU, is a university in Munich, Germany...
(LMU), under Arnold Sommerfeld
Arnold Sommerfeld
Arnold Johannes Wilhelm Sommerfeld was a German theoretical physicist who pioneered developments in atomic and quantum physics, and also educated and groomed a large number of students for the new era of theoretical physics...
at his Institute for Theoretical Physics. He was granted his doctorate 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.
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
Max von Laue
Max Theodor Felix von Laue was a German physicist who won the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals...
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
Max von Laue
Max Theodor Felix von Laue was a German physicist who won the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals...
, Paul Knipping and Walter Friedrich at LMU, for which Laue would be awarded the Nobel Prize in Physics
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...
, in 1914.
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 to send him a special assistant for physics. Sommerfeld sent Ewald, who was dubbed as “Hilbert’s tutor for physics,” and he performed this function until 1913, when Sommerfeld sent another one of his students, Alfred Landé
Alfred Landé
Alfred Landé was a German-American physicist known for his contributions to quantum theory. He is responsible for the Landé g-factor an explanation of the Zeeman Effect.-Life and Achievements:...
. 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
Max Born
Max Born was a German-born physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a number of notable physicists in the 1920s and 30s...
, at Göttingen, solved the problem.
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
Max Born
Max Born was a German-born physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a number of notable physicists in the 1920s and 30s...
(a Privatdozent) and Hans Bolza (a physics student), “Ka” for Theodore von Kármán
Theodore von Karman
Theodore von Kármán was a Hungarian-American mathematician, aerospace engineer and physicist who was active primarily in the fields of aeronautics and astronautics. He is responsible for many key advances in aerodynamics, notably his work on supersonic and hypersonic airflow characterization...
(a Privatdozent), and “Re” for Albrecht Renner (a medical student). Richard Courant
Richard Courant
Richard Courant was a German American mathematician.- Life :Courant was born in Lublinitz in the German Empire's Prussian Province of Silesia. During his youth, his parents had to move quite often, to Glatz, Breslau, and in 1905 to Berlin. He stayed in Breslau and entered the university there...
, a mathematician and Privatdozent, called these people the “in group.” It was here that Ewald met Ella Philippson, who was to become his wife.
In the spring of 1913, Niels Bohr
Niels Bohr
Niels Henrik David Bohr was a Danish physicist who made foundational contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922. Bohr mentored and collaborated with many of the top physicists of the century at his institute in...
, of the Institute for Theoretical Physics at the University of Copenhagen
University of Copenhagen
The University of Copenhagen is the oldest and largest university and research institution in Denmark. Founded in 1479, it has more than 37,000 students, the majority of whom are female , and more than 7,000 employees. The university has several campuses located in and around Copenhagen, with the...
, submitted his theory of the Bohr atomic model
Bohr model
In atomic physics, the Bohr model, introduced by Niels Bohr in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system, but with electrostatic forces providing attraction,...
for publication. 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. 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
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
, 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
Habilitation
Habilitation is the highest academic qualification a scholar can achieve by his or her own pursuit in several European and Asian countries. Earned after obtaining a research doctorate, such as a PhD, habilitation requires the candidate to write a professorial thesis based on independent...
in 1917, and became a Privatdozent
Privatdozent
Privatdozent or Private lecturer is a title conferred in some European university systems, especially in German-speaking countries, for someone who pursues an academic career and holds all formal qualifications to become a tenured university professor...
there, while remaining as an assistant to Sommerfeld.
In 1921, while still at LMU, Ewald published a paper on the theta function method of analyzing dipole fields in crystals, an offshoot from his earlier work on the dynamical theory of optics and X-rays in crystals, which appeared in three journal publications. According to Ewald, the impetus for the method came from a skiing holiday in Mittenwald
Mittenwald
Mittenwald is a German municipality in the district of Garmisch-Partenkirchen, in Bavaria.-Geography:Mittenwald is located approx. 16 kilometers to the south-east of Garmisch-Partenkirchen...
, 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. 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
Peter Debye
Peter Joseph William Debye FRS was a Dutch physicist and physical chemist, and Nobel laureate in Chemistry.-Early life:...
, 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, by Max Born
Max Born
Max Born was a German-born physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a number of notable physicists in the 1920s and 30s...
and Kun Huang.
Career
When Erwin SchrödingerErwin Schrödinger
Erwin Rudolf Josef Alexander Schrödinger was an Austrian physicist and theoretical biologist who was one of the fathers of quantum mechanics, and is famed for a number of important contributions to physics, especially the Schrödinger equation, for which he received the Nobel Prize in Physics in 1933...
let it be known that he was leaving his position as extraordinarius professor at the Stuttgart
Stuttgart
Stuttgart is the capital of the state of Baden-Württemberg in southern Germany. The sixth-largest city in Germany, Stuttgart has a population of 600,038 while the metropolitan area has a population of 5.3 million ....
Technische Hochschule
Technische Hochschule
Technische Hochschule is what an Institute of Technology used to be called in German-speaking countries, as well as in the Netherlands, before most of them changed their name to Technische Universität or Technische Universiteit in the 1970s and in the...
, to go to the University of Breslau, Ewald was called and accepted the position in 1921. In 1922, he was called to the University of Münster
University of Münster
The University of Münster is a public university located in the city of Münster, North Rhine-Westphalia in Germany. The WWU is part of the Deutsche Forschungsgemeinschaft, a society of Germany's leading research universities...
. Ewald used the offer to better his position at Stuttgart to ordinarius professor; however, while Ewald was promoted to ordinarius professor, the established position was actually retained as an extraordinarius professorship. From 1922 Erwin Fues
Erwin Fues
Erwin Richard Fues was a German theoretical physicist who made contributions to atomic physics and molecular physics, quantum wave mechanics, and solid-state physics.-Education and career:...
, also a former doctoral student of Sommerfeld, did postgraduate work at the Stuttgart Technische Hochschule, under Ewald; Fues completed his Habilitation in 1924. Also in that year, Ewald became co-editor of Zeitschrift für Kristallographie. In 1929, he received a call to the Technische Hochschule Hanover
Hanover
Hanover or Hannover, on the river Leine, is the capital of the federal state of Lower Saxony , Germany and was once by personal union the family seat of the Hanoverian Kings of Great Britain, under their title as the dukes of Brunswick-Lüneburg...
. Again, he used this call to better his position at Stuttgart by negotiating for a second assistant, the permanent conversion of his position to that of ordinarius professor, and a separate building for his activities. The building was formally opened in 1930 as the Institute for Theoretical Physics, with Ewald as director. The institute was modeled after Sommerfeld’s Institute for Theoretical Physics at Munich, in that it would conduct theoretical work as well as have space and equipment for experimental work. In 1931, Ewald was appointed Director of the Physical Science Division.
At Göttingen, Richard Courant
Richard Courant
Richard Courant was a German American mathematician.- Life :Courant was born in Lublinitz in the German Empire's Prussian Province of Silesia. During his youth, his parents had to move quite often, to Glatz, Breslau, and in 1905 to Berlin. He stayed in Breslau and entered the university there...
had taken Hilbert’s
David Hilbert
David Hilbert was a German mathematician. He is recognized as one of the most influential and universal mathematicians of the 19th and early 20th centuries. Hilbert discovered and developed a broad range of fundamental ideas in many areas, including invariant theory and the axiomatization of...
lecture notes which were available in the Lesezimmer, edited them and added to them to write a two-volume work. The first volume, Methoden der mathematischen Physik I, was published in 1924. Upon seeing the book, Ewald was compelled to write a detailed review describing it as providing mathematical tools, characterized by eigenvalues and eigenfunctions, for the theoretical physics then being developed. The Courant-Hilbert book fortuitously contained the mathematics necessary for the development of the Heisenberg
Werner Heisenberg
Werner Karl Heisenberg was a German theoretical physicist who made foundational contributions to quantum mechanics and is best known for asserting the uncertainty principle of quantum theory...
-Born
Max Born
Max Born was a German-born physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a number of notable physicists in the 1920s and 30s...
matrix mechanics
Matrix mechanics
Matrix mechanics is a formulation of quantum mechanics created by Werner Heisenberg, Max Born, and Pascual Jordan in 1925.Matrix mechanics was the first conceptually autonomous and logically consistent formulation of quantum mechanics. It extended the Bohr Model by describing how the quantum jumps...
formulation of quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...
and also for Schrödinger’s
Erwin Schrödinger
Erwin Rudolf Josef Alexander Schrödinger was an Austrian physicist and theoretical biologist who was one of the fathers of quantum mechanics, and is famed for a number of important contributions to physics, especially the Schrödinger equation, for which he received the Nobel Prize in Physics in 1933...
wave mechanics formulation, both put forward in 1925!
The main thrust of Ewald’s work was X-ray crystallography, and Ewald was the eponym
Eponym
An eponym is the name of a person or thing, whether real or fictitious, after which a particular place, tribe, era, discovery, or other item is named or thought to be named...
of Ewald construction and the Ewald sphere, both useful constructs in that field.
In 1929, in order to remove confusion from the proliferation of crystallographic data, Ewald proposed review and collection of the best data into a single publication. The results were published in 1935 as the Internationale Tabellen zur Bestimmung von Kristallstrukturen. Another contribution by Ewald, published in 1931, Strukturbericht Volume I (1913-1928) was edited by Ewald and C. Hermann.
Ewald was elected Rector at Stuttgart in 1932. However, due to increasing difficulties with faculty who were members of National Socialism in Germany, he resigned his position in the spring of 1933, one year before his term was due to expire. Ewald continued on with his other activities. However, over increasing problems with the Dozentenbund, Wilhelm Stortz, University Rector, asked Ewald to leave. He emigrated to England in 1937 and took a research position in Cambridge
Cambridge
The city of Cambridge is a university town and the administrative centre of the county of Cambridgeshire, England. It lies in East Anglia about north of London. Cambridge is at the heart of the high-technology centre known as Silicon Fen – a play on Silicon Valley and the fens surrounding the...
, until he was offered and accepted a lectureship at Queen's University Belfast, in 1939. He later became a professor of mathematical physics.
While lecturing at Duke University
Duke University
Duke University is a private research university located in Durham, North Carolina, United States. Founded by Methodists and Quakers in the present day town of Trinity in 1838, the school moved to Durham in 1892. In 1924, tobacco industrialist James B...
in 1937, Hans Bethe
Hans Bethe
Hans Albrecht Bethe was a German-American nuclear physicist, and Nobel laureate in physics for his work on the theory of stellar nucleosynthesis. A versatile theoretical physicist, Bethe also made important contributions to quantum electrodynamics, nuclear physics, solid-state physics and...
, who got his doctorate under Sommerfeld in 1928, bumped into Rose Ewald, who had already emigrated to the United States and was attending the school. They were married in September 1939. Thus Bethe became son-in-law to Paul Peter Ewald.
Near the end of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, Sommerfeld organized his lecture notes and began writing the six-volume Lectures on Theoretical Physics. While at the Polytechnic Institute of Brooklyn, Ewald wrote a Foreword to Sommerfeld’s Course, which appeared in the English translation of Sommerfeld’s work.
Also, toward the end of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, Ewald was concerned that peace would result in the establishment of multiple, competing national journals of crystallography. So, in 1944, at Oxford, he proposed the establishment of an International Union of Crystallography
International Union of Crystallography
The International Union of Crystallography is a member of the International Council for Science and exists to serve the world community of crystallographers....
(IUCr) that would have sole responsibility for publishing crystallographic research. In 1946, he was elected Chairman of the Provisional International Crystallographic Committee, in a London meeting of crystallographers, from 13 countries; he served in this capacity until 1948, when the Union was formed. The Committee also nominated him Editor of the journal to be published by the Union. The first issue of Acta Crystallographica
Acta Crystallographica
Acta Crystallographica refers to a family of scientific journals, with peer-reviewed articles about crystallography, published by the International Union of Crystallography...
was published in 1948, the same year that Ewald chaired the first General Assembly and International Congress of the IUCr, which was held at Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
.
In 1952, Ewald was elected President of the American Crystallographic Association. He served on the IUCr Executive Committee from its foundation until 1966, and he was its Vice-President in 1957 and President in 1960, a position he held until 1963. His editorship of its journal Acta Crystallographica extended from its inception in 1948 to 1959.
A decade after moving to Belfast, Ewald moved to the USA in 1949 and took a position at the Polytechnic Institute of Brooklyn, as a professor and head of the Physics Department. He retired as head of the department in 1957 and from teaching in 1959.
Honors
- 1958 – Fellow of the Royal Society
- 1978 – Deutsche Physikalische GesellschaftDeutsche Physikalische GesellschaftThe Deutsche Physikalische Gesellschaft is the world's largest organization of physicists. The DPG's worldwide membership is cited as 60,000, as of 2011...
Max Planck medalMax Planck medalThe Max Planck medal is an award for extraordinary achievements in theoretical physics. It is awarded annually by the Deutsche Physikalische Gesellschaft , the world's largest organization of physicists.-List of recipients:... - 1986 – The International Union of Crystallography established the Ewald Prize for outstanding contributions to the science of crystallography.
Books
- Paul Peter Ewald Kristalle und Röntgenstrahlen (Springer, 1923)
- Paul Peter Ewald, Theodor Pöschl, Ludwig Prandtl; authorized translation by J. Dougall and W.M. Deans The Physics of Solids and Fluids: With Recent Developments (Blackie and Son, 1930)
- Paul Peter Ewald Der Weg der Forschung (insbesondere der Physik) (A. Bonz'erben, 1932)
- Peter Paul Ewald, editor 50 Years of X-Ray Diffraction (Reprinted in pdf format for the IUCr XVIII Congress, Glasgow, Scotland, 1962, 1999 International Union of Crystallography)
- Peter Paul Ewald On the Foundations of Crystal Optics (Air Force Cambridge Research Laboratories, 1970)