WIENER, OTTO

(b. Karlsruhe, Germany, 15 June 1862; d Leipzig, Germany, 18 January 1927)

physics.

Wiener, whose ancestors included clergymen and jurists, was the son of Christian Wiener, a professor of descriptive geometry at the Technische Hochschule in Karlsruhe. His mother, the former Pauline Hausrath, was the sister of a Protestant theologian and died of typhus when Wiener was three.

Wiener studied physics first at Karlsruhe, then at Berlin, and finally at the University of Strasbourg, where he earned the Ph.D. in 1887 under August Kundt, whose private assistant he was. In 1890 he qualified as a lecturer with “Stehende Lichtwellen.” The following year he was named Dozent for physics at the Technische Hochshule in Aachen. and in 1894 he was promoted to extraordinary professor. In the same year he married Lina Fenner, daughter of Geheimrat Georg Fenner of Hesse-Homburg. In 1895 Wiener accepted an offer of a full professorship at the University of Giessen, where all his efforts were absorbed in the construction and organization of a new physics institute. His experience in this undertaking subsequently proved very useful, when he became involved in a similar project at Leipzig, upon succeeding Gustav Wiedemann as professor of physics.

Wiener reached the summit of his scientific career at its beginning and spent the second half pursuing what proved to be a mirage: “a fundamental law of nature,” as he put it, according to which all physical events could be derived from a universal ether and from the velocities and differences in velocities of its parts. In this view, even electrons and protons were considered to be only definite forms of motion: rotating ether rings. Wiener’s publications on this subject, more sketches than reports of results, brought more opposition and ridicule than recognition and made him seem an “anti-Einstein” to many of his colleagues.

Wiener’s name is linked with the experimental demonstration of standing light waves. In 1888 Heinrich Hertz, working in the physics institute of the Technische Hochschule of Karlsruhe, proved the existence of electromagnetic waves. Those he detected had lengths of about eight meters. A year later Wiener performed a similar experiment with light waves–electromagnetic waves–approximately ten million times shorter than those used by Hertz. In the simplest case these waves arise in front of a plane metal mirror from the interference of incident monochromatic waves with the reflected ones

Wiener’s research in this area was a result of the work he did for his doctoral dissertation, “Über die Phasenänderung des Lichtes bei der Reflexion und Methoden zur Dickenbestimmung dünner Blättchen” (1887). In the latter he had, at Kundt’s suggestion, measured light absorption in transparently thin metal plates, obtained by cathode-ray evaporation. In order to evaluate the measurements, however. it was necessary to know the thickness of the plates and the change in the vibration phase resulting from reflection. This change could be determined only when the light was obliquely incident. Through this research Wiener became a pioneer in the physics and techniques of thin plates, a field of great importance today.

A major question remained unanswered: how the vibration phase changes when light is incident perpendicularly. Inspired by Hertz’s work, Wiener hoped to find an answer and, if possible, to demonstrate standing light waves. He did, in fact, succeed in making visible nodes and antinodes separated by intervals of about 2 . 10^-5 centimeters in front of a plane silver plate on which monochromatic light shone perpendicularly. He achieved this with a suitably mounted photosensitive plate, like those used in photography, the thickness of which was about 1/30; the wavelengths. Wiener demonstrated conclusively that it was the nodes of the resulting light vibrations. and not antinodes. that lay in the mirror surface. Accordingly, the reflection of light must take place with phase inversion: this was the answer to his question. In addition the experiment revealed that only the electric portion of the electromagnetic light waves blackens the silver chloride in the photosensitive layer. Wiener’s amazing success was acknowledged as a masterpiece of experimentation.

The standing waves soon found an application in Gabriel Lippmann’s color photography. In this process the silver contained in suitably prepared photosensitive plates is separated into parallel planes by the standinglight waves. When viewed in daylight, these planes transmit to the eye only those colors having wavelengths that match the distances between the planes, while the other wavelengths are eliminated through interference. Wiener worked on color photography and proved that the color effects observed in the plates produced by Daguerre (silver plates with a silver iodide layer) arose in the same way they do in Lippmann’s plates. Wiener also had a predilection for technical problems, especially of bird flight, and was very interested in the developing subject of aeronautics.

BIBLIOGRAPHY

I. Original Works. A bibliography of Wiener’s writings is in Berichte. Sächsische Akademie der Wissenschaften, 79 (1927), 119–121. Among his works are “Uuml;ber die Phasenänderung des Lichts bei der Reflexion und Methoden zur Dickenbestimmung dünner Blättchen,” in Annalen der Physik und Chemie, n.s. 31 (1887), 629–672, his doctoral dissertation; “Stehende Lichtwellen und die Schwingungsrichtung polarisierten Lichts,” ibid., n.s. 40 (1890), 203–243, 744; and “Farbenphotographie durch Körperfarben und mechanische Farbenanpassung in der Natur,” ibid., n.s. 55 (1895), 225–281. The Saxon Academy of Sciences, Leipzig, possesses more than 1,000 pages of a MS “Grundgesetz der Natur.”

II. Secondary Literature. See K. Lichtenecker, “Otto Wiener,” in Physikalische Zeitschrift, 29 (1928)73–78, with portrait; W. Möbius, “Otto Wiener gestorben,” in Zeitschrift fär technische Physik, 8 (1927), 129– 131: and L. Sächsische Akademie der Wissenschaften, 79 (1927), 107–120, with portrait and bibliography.

Fritz Fraunberger