His research has had major significance fortheoretical physics as well as purely mathematical disciplines such asnumber theory. He was one of the most influential mathematicians of the twentieth century, and an important member of theInstitute for Advanced Study during its early years.[5][6]
Hermann Weyl was born inElmshorn, a small town nearHamburg, inGermany, and attended theGymnasiumChristianeum inAltona.[9] His father, Ludwig Weyl, was a banker; whereas his mother, Anna Weyl (née Dieck), came from a wealthy family.[10]
In September 1913, in Göttingen, Weyl marriedFriederike Bertha Helene Joseph (30 March 1893[11] – 5 September 1948[12]) who went by the name Helene (nickname "Hella"). Helene was a daughter of Dr.Bruno Joseph (13 December 1861 – 10 June 1934), a physician who held the position of Sanitätsrat inRibnitz-Damgarten, Germany. Helene was a philosopher (she was a disciple of phenomenologistEdmund Husserl) and a translator of Spanish literature into German and English (especially the works of Spanish philosopherJosé Ortega y Gasset).[13] It was through Helene's close connection with Husserl that Hermann became familiar with (and greatly influenced by) Husserl's thought. Hermann and Helene had two sons,Fritz Joachim Weyl (19 February 1915 – 20 July 1977) andMichael Weyl (15 September 1917 – 19 March 2011),[14] both of whom were born in Zürich, Switzerland. Helene died in Princeton, New Jersey, on 5 September 1948. A memorial service in her honor was held in Princeton on 9 September 1948. Speakers at her memorial service included her son Fritz Joachim Weyl and mathematiciansOswald Veblen andRichard Courant.[15] In 1950. Hermann married sculptorEllen Bär (née Lohnstein) (17 April 1902 – 14 July 1988),[16] who was the widow of professorRichard Josef Bär (11 September 1892 – 15 December 1940)[17] of Zürich.
After taking a teaching post for a few years, Weyl left Göttingen in 1913 for Zürich to take the chair of mathematics[18] at theETH Zürich, where he was a colleague ofAlbert Einstein, who was working out the details of the theory ofgeneral relativity. Einstein had a lasting influence on Weyl, who became fascinated by mathematical physics. In 1921, Weyl metErwin Schrödinger, a theoretical physicist who at the time was a professor at theUniversity of Zürich. They were to become close friends over time. Weyl had some sort of childless love affair with Schrödinger's wife Annemarie (Anny) Schrödinger (née Bertel), while at the same time Anny was helping raise an illegitimate daughter of Erwin's named Ruth Georgie Erica March, who was born in 1934 inOxford, England.[19][20]
Weyl left Zürich in 1930 to become Hilbert's successor at Göttingen, leaving when theNazis assumed power in 1933, particularly as his wife wasJewish. He had been offered one of the first faculty positions at the newInstitute for Advanced Study inPrinceton, New Jersey, but had declined because he did not desire to leave his homeland. As the political situation in Germany grew worse, 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 8 December 1955, while living in Zürich.
Weyl was cremated in Zürich on 12 December 1955.[28] His ashes remained in private hands[unreliable source?] until 1999, at which time they were interred in an outdoor columbarium vault in thePrinceton Cemetery.[29] The remains of Hermann's son Michael Weyl (1917–2011) are interred right next to Hermann's ashes in the same columbarium vault.
In 1911 Weyl publishedÜber die asymptotische Verteilung der Eigenwerte (On the asymptotic distribution of eigenvalues) in which he proved that theeigenvalues of theLaplacian in a compact domain are distributed according to the so-calledWeyl law. In 1912 he suggested a new proof, based on variational principles. Weyl returned to this topic several times, considered elasticity system and formulated theWeyl conjecture. These works started an important domain—asymptotic distribution of eigenvalues—of modern analysis.
In 1913, Weyl publishedDie Idee der Riemannschen Fläche (The Concept of a Riemann Surface), which gave a unified treatment ofRiemann surfaces. In it Weyl utilizedpoint set topology, in order to make Riemann surface theory more rigorous, a model followed in later work onmanifolds. He absorbedL. E. J. Brouwer's early work in topology for this purpose.
Weyl, as a major figure in the Göttingen school, was fully apprised of Einstein's work from its early days. He tracked the development ofrelativity physics in hisRaum, Zeit, Materie (Space, Time, Matter) from 1918, which reached its 4th edition in 1922. In 1918, he introduced the notion ofgauge, and gave the first example of what is now known as agauge theory. Weyl's gauge theory was an unsuccessful attempt to model theelectromagnetic field and thegravitational field as geometrical properties ofspacetime. The Weyl tensor inRiemannian geometry is of major importance in understanding the nature ofconformal geometry.
His overall approach in physics was based on thephenomenological philosophy ofEdmund Husserl, specifically Husserl's 1913Ideen zu einer reinen Phänomenologie und phänomenologischen Philosophie. Erstes Buch: Allgemeine Einführung in die reine Phänomenologie (Ideas of a Pure Phenomenology and Phenomenological Philosophy. First Book: General Introduction). Husserl had reacted strongly toGottlob Frege's criticism of his first work on the philosophy of arithmetic and was investigating the sense of mathematical and other structures, which Frege had distinguished from empirical reference.[citation needed]
Topological groups, Lie groups and representation theory
These results are foundational in understanding the symmetry structure ofquantum mechanics, which he put on a group-theoretic basis. This includedspinors. Together with themathematical formulation of quantum mechanics, in large measure due toJohn von Neumann, this gave the treatment familiar since about 1930. Non-compact groups and their representations, particularly theHeisenberg group, were also streamlined in that specific context, in his 1927Weyl quantization, the best extant bridge betweenclassical and quantum physics to date. From this time, and certainly much helped by Weyl's expositions,Lie groups andLie algebras became a mainstream part both ofpure mathematics andtheoretical physics.
Shortly after publishingThe Continuum Weyl briefly shifted his position wholly to theintuitionism of Brouwer. InThe Continuum, the constructible points exist as discrete entities. Weyl wanted acontinuum that was not an aggregate of points. He wrote a controversial article proclaiming, for himself andL. E. J. Brouwer, a "revolution."[31] This article was far more influential in propagating intuitionistic views than the original works of Brouwer himself.
George Pólya and Weyl, during a mathematicians' gathering in Zürich (9 February 1918), made a bet concerning the future direction of mathematics. Weyl predicted that in the subsequent 20 years, mathematicians would come to realize the total vagueness of notions such asreal numbers,sets, andcountability, and moreover, that asking about thetruth or falsity of theleast upper bound property of the real numbers was as meaningful as asking about truth of the basic assertions ofHegel on the philosophy of nature.[32] Any answer to such a question would be unverifiable, unrelated to experience, and therefore senseless.
However, within a few years Weyl decided that Brouwer's intuitionism did put too great restrictions on mathematics, as critics had always said. The "Crisis" article had disturbed Weyl'sformalist teacher Hilbert, but later in the 1920s Weyl partially reconciled his position with that of Hilbert.
After about 1928 Weyl had apparently decided that mathematical intuitionism was not compatible with his enthusiasm for thephenomenological philosophy ofHusserl, as he had apparently earlier thought. In the last decades of his life Weyl emphasized mathematics as "symbolic construction" and moved to a position closer not only to Hilbert but to that ofErnst Cassirer. Weyl however rarely refers to Cassirer, and wrote only brief articles and passages articulating this position.
By 1949, Weyl was thoroughly disillusioned with the ultimate value of intuitionism, and wrote: "Mathematics with Brouwer gains its highest intuitive clarity. He succeeds in developing the beginnings of analysis in a natural manner, all the time preserving the contact with intuition much more closely than had been done before. It cannot be denied, however, that in advancing to higher and more general theories the inapplicability of the simple laws ofclassical logic eventually results in an almost unbearable awkwardness. And the mathematician watches with pain the greater part of his towering edifice which he believed to be built of concrete blocks dissolve into mist before his eyes." As John L Bell puts it: "It seems to me a great pity that Weyl did not live to see the emergence in the 1970s of smooth infinitesimal analysis, a mathematical framework within which his vision of a true continuum, not “synthesized” from discrete elements, is realized. Although the underlying logic of smooth infinitesimal analysis is intuitionistic — thelaw of excluded middle not being generally affirmable — mathematics developed within avoids the “unbearable awkwardness” to which Weyl refers above."
In 1929, Weyl proposed an equation, known as theWeyl equation, for use in a replacement to theDirac equation. This equation describes masslessfermions. A normal Dirac fermion could be split into two Weyl fermions or formed from two Weyl fermions.Neutrinos were once thought to be Weyl fermions, but they are now known to have mass. Weyl fermions are sought after for electronics applications.Quasiparticles that behave as Weyl fermions were discovered in 2015, in a form of crystals known asWeyl semimetals, a type of topological material.[33][34][35]
The question for the ultimate foundations and the ultimate meaning of mathematics remains open; we do not know in which direction it will find its final solution nor even whether a final objective answer can be expected at all. "Mathematizing" may well be a creative activity of man, like language or music, of primary originality, whose historical decisions defy complete objective rationalization.
—Gesammelte Abhandlungen—as quoted inYear book – The American Philosophical Society, 1943, p. 392
In these days the angel of topology and the devil of abstract algebra fight for the soul of each individual mathematical domain.
Whenever you have to do with a structure-endowed entity S try to determine its group of automorphisms, the group of those element-wise transformations which leave all structural relations undisturbed. You can expect to gain a deep insight into the constitution of S in this way.
—Symmetry, Princeton Univ. Press, p. 144; 1952
Beyond the knowledge gained from the individual sciences, there remains the task ofcomprehending. In spite of the fact that the views of philosophy sway from one system to another, we cannot dispense with it unless we are to convert knowledge into a meaningless chaos.
—Space-Time-Matter, 4th edition (1922), English translation, Dover (1952) p. 10; Weyl’s boldfaced highlight.
1925. (publ. 1988 ed. K. Chandrasekharan)Riemann's Geometrische Idee.
1927.Philosophie der Mathematik und Naturwissenschaft, 2d edn. 1949.Philosophy of Mathematics and Natural Science, Princeton 0689702078. With new introduction byFrank Wilczek, Princeton University Press, 2009,ISBN978-0-691-14120-6.
The Theory of Groups and Quantum Mechanics (translated from the second, revised German edition byHoward P. Robertson)1929. "Elektron und Gravitation I",Zeitschrift Physik, 56, pp 330–352. – introduction of thevierbein intoGR
^abFreeman Dyson (10 March 1956)."Prof. Hermann Weyl, For.Mem.R.S."Nature.177 (4506):457–458.Bibcode:1956Natur.177..457D.doi:10.1038/177457a0.S2CID216075495.He alone could stand comparison with the last great universal mathematicians of the nineteenth century, Hilbert and Poincaré. ... Now he is dead, the contact is broken, and our hopes of comprehending the physical universe by a direct use of creative mathematical imagination are for the time being ended.
^[1] Hermann Weyl Collection (AR 3344) (Sys #000195637), Leo Baeck Institute, Center for Jewish History, 15 West 16th Street, New York, NY 10011. The collection includes a typewritten document titled "Hellas letzte Krankheit" ("Hella's Last Illness"); the last sentence on page 2 of the document states: "Hella starb am 5. September [1948], mittags 12 Uhr." ("Hella died at 12:00 Noon on September 5 [1948]"). Helene's funeral arrangements were handled by the M. A. Mather Funeral Home (now named the Mather-Hodge Funeral Home), located at 40 Vandeventer Avenue, Princeton, New Jersey. Helene Weyl was cremated on 6 September 1948, at the Ewing Cemetery & Crematory, 78 Scotch Road, Trenton (Mercer County), New Jersey.
^For additional information on Helene Weyl, including a bibliography of her translations, published works, and manuscripts, see the following link:"In Memoriam Helene Weyl"Archived 5 February 2020 at theWayback Machine by Hermann Weyl. This document, which is one of the items in the Hermann Weyl Collection at the Leo Baeck Institute in New York City, was written by Hermann Weyl at the end of June 1948, about nine weeks before Helene died on 5 September 1948, inPrinceton, New Jersey. The first sentence in this document reads as follows: "Eine Skizze, nicht so sehr von Hellas, als von unserem gemeinsamen Leben, niedergeschrieben Ende Juni 1948." ("A sketch, not so much of Hella's life as of our common life, written at the end of June 1948.")
^[2] Ruth Georgie Erica March was born on 30 May 1934 in Oxford, England, but—according to the records presented here—it appears that her birth wasn't "registered" with the British authorities until the 3rd registration quarter (the July–August–September quarter) of the year 1934. Ruth's actual, biological father was Erwin Schrödinger (1887–1961), and her mother was Hildegunde March (née Holzhammer) (born 1900), wife of Austrian physicistArthur March (23 February 1891 – 17 April 1957). Hildegunde's friends often called her "Hilde" or "Hilda" rather than Hildegunde. Arthur March was Erwin Schrödinger's assistant at the time of Ruth's birth. The reason Ruth's surname is March (instead of Schrödinger) is because Arthur had agreed to be named as Ruth's father on her birth certificate, even though he wasn't her biological father. Ruth married the engineer Arnulf Braunizer in May 1956, and they have lived in Alpbach, Austria for many years. Ruth has been very active as the sole administrator of the intellectual (and other) property of her father Erwin's estate, which she manages from Alpbach.
^137: Jung, Pauli, and the Pursuit of a Scientific Obsession (New York and London: W. W. Norton & Company, 2009), by Arthur I. Miller (p. 228).
^Hermann Weyl's cremains (ashes) are interred in an outdoorcolumbarium vault in thePrinceton Cemetery at this location: Section 3, Block 04, Lot C1, Grave B15.
^Hermann Weyl; Peter Pesic (20 April 2009). Peter Pesic (ed.).Mind and Nature: Selected Writings on Philosophy, Mathematics, and Physics. Princeton University Press. p. 12.ISBN9780691135458.To use the apt phrase of his son Michael, 'The Open World' (1932) contains "Hermann's dialogues with God" because here the mathematician confronts his ultimate concerns. These do not fall into the traditional religious traditions but are much closer in spirit to Spinoza's rational analysis of what he called "God or nature," so important for Einstein as well. ...In the end, Weyl concludes that this God "cannot and will not be comprehended" by the human mind, even though "mind is freedom within the limitations of existence; it is open toward t///he infinite." Nevertheless, "neither can God penetrate into man by revelation, nor man penetrate to him by mystical perception."
^Gurevich, Yuri."Platonism, Constructivism and Computer Proofs vs Proofs by Hand",Bulletin of the European Association of Theoretical Computer Science, 1995. This paper describes a letter discovered by Gurevich in 1995 that documents the bet. It is said that when the friendly bet ended, the individuals gathered cited Pólya as the victor (withKurt Gödel not in concurrence).
ed. K. Chandrasekharan,Hermann Weyl, 1885–1985, Centenary lectures delivered by C. N. Yang, R. Penrose, A. Borel, at the ETH Zürich Springer-Verlag, Berlin, Heidelberg, New York, London, Paris, Tokyo – 1986, published for the Eidgenössische Technische Hochschule, Zürich.
Deppert, Wolfgang et al., eds.,Exact Sciences and their Philosophical Foundations. Vorträge des Internationalen Hermann-Weyl-Kongresses, Kiel 1985, Bern; New York; Paris: Peter Lang 1988,
Thomas Hawkins,Emergence of the Theory of Lie Groups, New York: Springer, 2000.
Kilmister, C. W. (October 1980), "Zeno, Aristotle, Weyl and Shuard: two-and-a-half millennia of worries over number",The Mathematical Gazette,64 (429), The Mathematical Gazette, Vol. 64, No. 429:149–158,doi:10.2307/3615116,JSTOR3615116,S2CID125725659.
In connection with the Weyl–Pólya bet, a copy of the original letter together with some background can be found in:Pólya, G. (1972). "Eine Erinnerung an Hermann Weyl".Mathematische Zeitschrift.126 (3):296–298.doi:10.1007/BF01110732.S2CID118945480.
Erhard Scholz; Robert Coleman; Herbert Korte; Hubert Goenner; Skuli Sigurdsson; Norbert Straumann eds.Hermann Weyl's Raum – Zeit – Materie and a General Introduction to his Scientific Work (Oberwolfach Seminars) (ISBN3-7643-6476-9) Springer-Verlag New York, New York, N.Y.
Skuli Sigurdsson. "Physics, Life, and Contingency: Born, Schrödinger, and Weyl in Exile." In Mitchell G. Ash, and Alfons Söllner, eds.,Forced Migration and Scientific Change: Emigré German-Speaking Scientists and Scholars after 1933 (Washington, D.C.: German Historical Institute and New York: Cambridge University Press, 1996), pp. 48–70.
Weyl, Hermann (2012), Peter Pesic (ed.),Levels of Infinity / Selected Writings on Mathematics and Philosophy, Dover,ISBN978-0-486-48903-2
