Arnold Johannes Wilhelm Sommerfeld

Sommerfeld was born on 5 December 1868 in Königsberg, (now Kaliningrad, Russia). His father Franz Sommerfeld was a medical doctor who came from a leading Königsberg family and mother was Cäcile Matthias. Franz was 48 years old when Arnold was born while his wife Cäcile was 29; they had been married for six years. The family was protestant; and although Sommerfeld was not religious he never renounced his faith. He wrote autobiographical notes in around 1917, describing about his parents, "My father, the practicing physician, was a passionate collector of natural objects (amber, shells, minerals, beetles, etc.) and a great friend of the natural sciences. ... To my energetic and intellectually vigorous mother I owe an infinite debt".

Sommerfeld entered the Altstädtisches Gymnasium in Königsberg in 1875. At this High School, he excelled in all his subjects and he was not sure what subject he should pursue further. He was almost more interested in literature and history than in the exact sciences; but he was equally good in all subjects including the classical languages. In 1886 he took his final examination in the high school and decided to concentrate on Mathematics as he entered University of Königsberg. Although Mathematics was his main subject, he followed his all round interests by attending lectures in Natural Sciences, Philosophy, and Political Economy as well. The Mathematics Department at Königsberg at this time was remarkable for the talented staff and after attending a course by on the theory of ideal numbers, he felt that abstract pure Mathematics was the right subject for him.

Sommerfeld finished his Doctorate in 1891, his thesis was, "The Arbitrary Functions in Mathematical ". He passed his teaching diploma examinations in 1892 which would let him teach Mathematics and Physics at a Gymnasium. Then he went to the military service for a year in the reserve regiment in Königsberg and for the following eight years continued to undertake voluntary eight week military exercises. In 1893 Sommerfeld went to Göttingen spending a year as an assistant in the Mineralogical Institute. His job was to manage the Mathematical reading room and write out 's lectures.

In March 1895 Sommerfeld presented his thesis “The mathematical theory of “ to Göttingen and became a privatdozent in Mathematics. From October 1897 Sommerfeld became a full professor of Mathematics at the Mining Academy where he met with Johanna Höpfner, daughter of Ernst Höpfner who was the curator of University of Göttingen. The marriage between Sommerfeld and Johanna Höpfner produced three sons and one daughter. At Clausthal, Sommerfeld applied his extraordinary ingenuity in boundary-value problems to the propagation of electromagnetic waves along wires of finite diameter and to the diffraction of X-rays by a wedge-shaped slit. In 1900 he moved to Technical University Aachen, surprisingly not for Mathematics, but for Technical . In 1901 Sommerfeld proposed a special way of denoting vectors, vector calculus and the electromagnetic magnitudes, which became obligatory for all contributors. In September 1903 he took part of a "vector commission" which aim was to create a unified vector symbolism and calculus. In 1906 he became professor of at . There an institute was set up for him, with rooms for seminars, rooms for assistants, and laboratories for experimental work, determined to check his own theories. In total he supervised nearly 30 students at Munich including , Peter Ewald, , , and .

Sommerfeld met Einstein for the first time in 1909 and they felt an immediate attraction despite of the background and talents. They spent a full week at Zurich for solving the problem of and relativity theory. In 1913 when Bohr's quantum theory of atomic structure was published, Sommerfeld applied the Zeeman Effect on the Bohr's model by extending the theory and including elliptical paths for . This extraordinary extension, enrichment and precision on the Mathematical development of the Quantum- Theoretical atomic model led him to write books in 1919, which became the bible of .

Although Sommerfeld never received a , from 1917 on, a steady stream of honors, prizes, memberships in foreign academics, honorary doctorates flowed to him. Einstein wrote a letter to Sommerfeld saying "What I specially admire about you is the way, at a stamp of your foot, a great number of talented young theorists spring up out of the ground." He was offered the chair of Theoretical Physics at the University of Vienna which brought the title Geheimrat and a substantial increase in salary. In 1927, University of Berlin offered him for the same post for the success on Planck's Theory, which made a great deal of publicity for him and doubling his institute grant, and a far increase in personal income. Despite of his ethnic background, he openly sided with Einstein and was against anti-semitism. He continued the Directorship of the Institute of Theoretical Physics, till he was forced by the government to retire in 1940. He was politically involved during the Hitler's regime after his retirement. Sommerfeld died in a tragic accident on April 26, 1951, after being struck by a car while strolling with his grandchildren in Munich.

References Course Textbooks Introducing Quantum Theory Other Books The Historical Development of Quantum theory, by & Helmut Rechenberg Physics of The One-and-Two- Atoms, by F. Bopp & H. Kleinpoppen Historical Studies in the Physics, by Russell McCormmach The Story of , by Victor Guillemin Nature, Weekly Journal of Science Websites http://www.answers.com/topic/arnold-sommerfeld http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Sommerfeld.html www.chemie.uni-bremen.de/stohrer/biograph/sommer.htm www.lrz-muenchen.de/~Sommerfeld/