VOIGT, WOLDEMAR

(b. Leipzig, Germany, 2 September 1850; d. Göttingen, Germany, 13 December 1919), physics.

Voigt graduated from the Nikolaischule at Leipzig in 1868. He then entered the University of Leipzig, but in 1870 his studies were interrupted by service in the Franco-Prussian War. He resumed his studies in 1871, this time at Königsberg. At first Voigt was undecided between a career in physics and a career in music, for the latter had always played a large role in his life: Felix Mendelssohn and Robert Schumann had been frequent visitors to his parents’ house. His musical ear was highly trained; and while in the army he would often pass the time while marching by reciting, note for note, the complete orchestration of entire symphonic pieces. He finally decided on a career in physics, on the ground that, unlike music, in physics there is a reasonable mean, not simply highs and lows.

While at Königsberg, Voigt came under the influence of Franz Neumann, his deep respect and love for whom largely determined his career, in terms of subject matter, the style of his research, and the manner in which he presented his work to the physics community. His dissertation on the elastic constants of rock salt was completed in 1874. He then returned to Leipzig, where he taught at the the Nikolaischule, but in 1875 was called back to Königsberg as extraordinary professor of physics. In 1883 Voigt was appointed ordinary professor of theoretical physics at Göttingen, with the promise that he and Eduard Reike were to have a new physical institute (which was not ready until 1905). His chief research interests centered on the understanding of crystals, but near the turn of the century he became more and more concerned with the Zeeman effect and the electron theory.

Voigt’s interest in crystals was closely related to Neumann’s work. At Königsberg, Neumann had worked in both the physics department and the department of mineralogy, so it was quite natural that he should do extensive work on the optical properties of crystals. Neumann had developed a mechanical theory of light propagation that assumed that light oscillations had a mechanical-elastic nature. The oscillations were transmitted through an ether conceived of as an elastic solid. He had not restricted his activities in physics to theoretical work, however, and had initiated a great number of experimental studies; his students spent many hours in his laboratories studying the properties of crystals.

Voigt brought this tradition of theoretical and experimental work to Göttingen. Although for many years he was hampered by lack of adequate facilities, he not only pursued theoretical studies of the properties of crystals but also undertook a host of very delicate experimental investigations in which the physical properties of many crystalline substances were measured.

According to the theories of Poisson and Cauchy, which were based on special molecular assumptions, certain relationships must exist between the constants of a crystal regardless of its classification. Voigt determined the elastic constants for a wide variety of crystals and showed that the predicted relationships were not at all satisfied. While some felt that this work vindicated those who objected to forming special hypotheses about the nature of crystals, Voigt did not accept this point of view and in many of his publications indicated the direction that must be taken in amending the molecular hypothesis.

In 1887, in a paper on the Doppler effect in which he analyzed the differential equations for oscillations in an incompressible elastic medium, Voigt established a set of transformation equations that later became known as the Lorentz transformations.

Voigt’s extensive theoretical and physical researches on the nature of crystals were summarized in Magneto- und Elektro-Optik (1908) and Kristallphysik (1910). These treatises reveal the elegance of his mathematical treatments and the great orderliness that has research had bought to the understanding of crystals. The elastic, thermal, electric, and magnetic properties of crystals were ordered in magnitudes of three types; scalar, vector, and tensor. In fact, it was Voigt who in 1898 had introduced the term “tensor” into the vocabulary of mathematical physics.

Even though Voigt devoted considerable time to his research and his students, and even though he acquired more administrative responsibility at Göttingen, he never gave up an active interest in music and musicology. He was recognized as an expert on Bach’s vocal works and in 1911 published a book on Bach’s church cantatas. Voigt often referred to the study of physics in musical terms. To him the region of science that represented the highest degree of orchestration and that possessed the utmost in rhythm and melody was crystal physics. It was altogether fitting that on 15 December 1919 his funeral bier was carried from his house to its final resting place to the strains of a Bach chorale.

BIBLIOGRAPHY

I. Original Works. There is no comprehensive catalog of Voigt’s more than 200 publications. Among his most significant works are “Allgemeine Formeln für die Bestimmung der Elasticityäts constantan von Krystallen durch die Beobachtung der Biegung undd Drillung von Prismen,” in Annalen der Physik.16 (1882), 273–310, 398–415; “Volumen und Winkeländerung krystallinischen Körper bei all-oder einseitigen Druck,” ibid., 416–426; “Theorie des Lihtes für vollkommen durchschtige Media,” ibid.,19 (1883), 873–908; “Zur Theorie des Lichtes,” ibid.,20 (1883), 444–452; “Theorie der absorbirenden isotropen Medien insbesonder Theorie der optischen Eigenschaften der Metalle,” ibid.,23 (1884), 104–147; “Theorie der electromagnetischen Drehung der Polarisationseben,” ibid., 493–511; “Zur Theorie des Lichtes für absorbirende isotrope Medien,” ibid.,31 (1887), 233–242; and “Zur Erklärung der elliptischen Polarisation bei Reflexion an durchsichtigen Medien,” ibid.,32 (1887), 526–528.

Also see “Ueber das Doppler’sche Princip,” in Nachrichten von der Königlichen Gesellschaft der Wissenschaften zu Göttingen (1887), 44–51; “Theorie des Lichtes für bewegte Medien,” in Annalen der Physik, 35 (1888), 370–396; 524–551; “Zur Theorie des Lichtes,” ibid.,43 (1891), 410–437; “Ueber einen einfachen Apparat zur Bestimmung der thermischen Dilation fester Körper, special der Krystalle,” ibid., 831–834; “Bestimmung der Elasticitätsconstanten einiger quasiisotroper Metalle durch langsame Schwingungen von Stäben,” ibid.,48 (1893), 674–707; “Bestimmung der Constanten der thermische-Dilation und des thermische-Druckers für eingie quasi-isotrope Metalle,” ibid.,49 (1893), 697–708; “Die specifischen Wärmen c_p and c_n einiger quasi-isotroper Metalle,” ibid., 709–718; “Beiträge zur molecularen Theorie der Piëzoelectricität,” ibid.,51 (1894), 638–660; “Ueber Medien ohne innere Kräfte und über eine durch sie gelieferte mechanische Deutung der MAxwell-Hertz’schen Gleichungen,” ibid.52 (1894), 665–672; and “Beiträge zur geometrischen Darstellung der physickalischen Eigenschaften der Krystalle,” ibid.,63 (1897), 376–385.

Additional works are “Zur kinetischen Theirie idealer Flüssigkeiten,” in Nachrichten von der Königlichen Gesellschaft der Wissenschaften zu Göttingen (1897), 19–47, 261–272; “Lässt sich die Pyroelectricität der Krystalle vollständig auf Piëzoelectrische Wirkungen zuruckführen?” in Annalen der Physik,66 (1898), 1030-1060; “Doppelbrechung von im Magnetfelde befindlichen Natriumdampf in der Richtung normal zu den Kraftlinien,” in Nachrichten von der Königlichen Gesellschaft der Wissenschaften zu Göttingen (1898), 355–359; “Ueber das bei der sogenannten totalen Reflextion in des zweite Medium eindringende Licht,” in Annalen der Physik, 67 (1899), 185–200; “Zur Theorie der magneto-optischen Erscheinungen,” ibid., 345–365; “Ueber die Proportionalität von Emissions- und Absorptionsvermögen,” ibid., 366–387; “Weiteres zur Theorie der Zeemaneffectes,” ibid.,68 (1899), 352–364; “Neuere Untersuchungen über die optischen Wirkungen eines Magnetfeldes,” in Physikalische Zeitschrift, 1 (1899), 116–120, 128–131, 138–143; “Zur Festigkeitlehre,” in Annalen der Physik, 4 (1901), 567–591; “Beiträge zur Elektronentheorie des Lichtes,” ibid.,6 (1901), 459–505; “Elektronenhypothese und Theorie des Magnetisums,” in Nachrichten von der Königlichen Gesellshaft der Wissenschaften zu Göttingen (1901), 169–200; and “Ueber einige neuere Beobachtugen von magneto-optischen Wirkungen,” in Annalen der Physcik, 8 (1902), 872–889.

Further, see “Ueber das optische Verhalten von Kristallen der hemiëdrischen Gruppe des monokinen Systemes,” in Physikalische Zeitschrift, 7 (1906), 267–269; “Betrachtungen über die komplizierteren Formen des Zeemaneffektes,” in Annalen der Physik, 24 (1907), 193–224; “Beobachtungen über natürliche und magnetische Drehung der Polarisationsebene in Krystallen von K. Honda,” in physikalische Zeitschrift, 9 (1908), 585–590; Magneto- und Elektro-Optik (Leipzig, 1908); Kristallphysik (Leipzig-Berlin, 1910; 2nd ed., 1926); “Zur Theorie der komplizierteren Zeemaneffecte,” in Annalen der Phyesik, 36 (1911), 873–906; “Allgemeines über Emission und Absorption in zusammenhang mitder Frage der Intensitätsmessungen beim Zeeman-Effect,” in Nachrichten von der Königlichen Gesellschaft der Wissenschaften zu Göttingen (1911), 71–97; “Ueber Emission und Absorption schichtenweise stetig inhomogener Körper,” in Annalen der Physcik, 39 (1912), 1381-1407; “Weiteres zur Polarisation des Rowaland Gitterbn gebeugten Lichtes,” in Nachrichten von der Königlichen Geselleschaft der Wissenschaften zu Göttingen (1912), 385–417, written wtih P.Collet; “Ueber die anormalesn Zeeman-effekte der Wasserstofflinien,” in Annalen der Physick40 (1913), 368–380; “Weiteres zum Ausbau der Koppelungstheorie der Zeemanneffekte,” ibid., 41 (1913), 403–440; “Ueber die zeemaneffekte bei mehrafachen Serienlinien besonders auch beidem O-Triplet ? =3947,” ibid.,43 (1914), 1137-1164; and “Ueber sekundäre Wirkungen bei piëzoelktrischen vorgängen, insbesondere im Falle der Drillung und Biegung eines Krieszylinders” ibid.,48 (1915), 433–448.

II. Secondary Literature. See E.T.Whittaker, A History of the Theories of Aether and Electricity, 2 vols. (New York, 1960), I, 333, 415; II, 33, 160, 238–239. Obituary notices are by H.L[amb?], in Preceedings of the Royal Society, 99A (1921), XXiX-XXX; and by C. Runge in Physikalische Zeitschrift,21 (1920), 81–82; and in Nachrichten von der Königlichen Gesellschaft Zu Göttingen: Geschäftliche Mitteilungen aus dem Jahare 1920 (Göttingen, 1920), 47–52.

Stanley Goldbers