Hermann Weyl

Hermann Klaus Hugo Weyl was a German mathematician, theoretical physicist, and philosopher. Although much of his working life was spent in Zürich, Switzerland, and then Princeton, New Jersey, he is associated with the University of Göttingen tradition of mathematics, represented by Carl Friedrich Gauss, David Hilbert, and Hermann Minkowski. His research has had major significance for theoretical physics and purely mathematical disciplines such as number theory. 

He was one of the most influential mathematicians of the twentieth century and an important member of the Institute for Advanced Study during its early years. Weyl contributed to an exceptionally wide range of mathematical fields, including works on space, time, matter, philosophy, logic, symmetry, and the history of mathematics. He was one of the first to conceive of combining general relativity with the laws of electromagnetism. 

Freeman Dyson wrote that Weyl alone bore comparison with the "last great universal mathematicians of the nineteenth century," Poincaré and Hilbert. Michael Atiyah, in particular, has commented that whenever he examined a mathematical topic, he found that Weyl had preceded him. Hermann Weyl was born in Elmshorn, a small town near Hamburg, in Germany, and attended the Gymnasium Christianeum in Altona. His father, Ludwig Weyl, was a banker, whereas his mother, Anna Weyl (née Dieck), came from a wealthy family.

From 1904 to 1908, he studied mathematics and physics in Göttingen and Munich. His doctorate was awarded at the University of Göttingen under the supervision of David Hilbert, whom he greatly admired. In September 1913, in Göttingen, Weyl married Friederike Bertha Helene Joseph, who was named Helene (nickname "Hella"). Helene was the daughter of Dr. Bruno Joseph (December 13, 1861 – June 10, 1934), a physician who held the position of Sanitätsrat in Ribnitz-Damgarten, Germany. 

Helene was a philosopher (she was a disciple of phenomenologist Edmund Husserl) and a translator of Spanish literature into German and English (especially the works of Spanish philosopher José Ortega y Gasset). Through Helene's close connection with Husserl, Hermann became familiar with (and greatly influenced by) Husserl's thoughts. Hermann and Helene had two sons, Fritz Joachim Weyl (February 19, 1915 – July 20, 1977) and Michael Weyl (September 15, 1917 – March 19, 2011), who were born in Zürich, Switzerland. 

Helene died in Princeton, New Jersey, on September 5, 1948. A memorial service in her honor was held in Princeton on September 9, 1948. Speakers at her memorial service included her son Fritz Joachim Weyl and mathematicians Oswald Veblen and Richard Courant. In 1950 Hermann married sculptress Ellen Bär (née Lohnstein) (April 17, 1902 – July 14, 1988), who was the widow of professor Richard Josef Bär (September 11, 1892 – December 15, 1940) of Zürich.

After taking a teaching post for a few years, Weyl left Göttingen in 1913 for Zürich to take the chair of mathematics at the ETH Zürich, where he was a colleague of Albert Einstein, who was working out the details of the theory of general relativity. Einstein had a lasting influence on Weyl, who became fascinated by mathematical physics. In 1921 Weyl met Erwin Schrödinger, a theoretical physicist who at the time was a professor at the University of Zürich. They were to become close friends over time. 

Weyl had a childless love affair with Schrödinger's wife, Annemarie (Anny) Schrödinger (née Bertel). At the same time, Anny was helping raise an illegitimate daughter of Erwin's named Ruth Georgie Erica March, who was born in 1934 in Oxford, England. Weyl was a Plenary Speaker of the International Congress of Mathematicians (ICM) in 1928 at Bologna and an Invited Speaker of the ICM in 1936 at Oslo. He was elected a fellow of the American Physical Society in 1928 and a National Academy of Sciences member in 1940.

For the academic year 1928–1929, he was a visiting professor at Princeton University. He wrote a paper, "On a problem in the theory of groups arising in the foundations of infinitesimal geometry," with Howard P. Robertson. Weyl left Zürich in 1930 to become Hilbert's successor at Göttingen, leaving when the Nazis assumed power in 1933, particularly as his wife was Jewish. He had been offered one of the first faculty positions at the new Institute for Advanced Study in Princeton, New Jersey, but had declined because he did not desire to leave his homeland. 

As Germany's political situation worsened, he changed his mind and accepted when offered the position again. He remained there until his retirement in 1951. Together with his second wife Ellen, he spent his time in Princeton and Zürich and died from a heart attack on December 8, 1955, while living in Zürich. Weyl was cremated in Zürich on December 12, 1955. 

His ashes remained in private hands until 1999 when they were interred in an outdoor columbarium vault in the Princeton Cemetery. Hermann's son, Michael Weyl's (1917–2011) 's remains are interred right next to Hermann's ashes in the same columbarium vault. Weyl was a pantheist.