Hermann von Helmholtz

"Helmholtz" redirects here. For the lunar impact crater, see Helmholtz (lunar crater).
For the American nuclear physicist, see A. Carl Helmholz.
Hermann von Helmholtz
Born Hermann Ludwig Ferdinand von Helmholtz
(1821-08-31)August 31, 1821
Potsdam, Kingdom of Prussia
Died September 8, 1894(1894-09-08) (aged 73)
Charlottenburg, German Empire
Residence Germany
Nationality German
Fields

Physics

Institutions
Alma mater Royal Friedrich-Wilhelm Institute
Doctoral advisor Johannes Peter Müller[1]
Doctoral students
Other notable students
Known for
Influences Johann Gottlieb Fichte
Kant
Influenced Ludwig Wittgenstein[2]
Notable awards Matteucci Medal (1868)
Copley Medal (1873)
Albert Medal (1888)

Hermann Ludwig Ferdinand von Helmholtz (August 31, 1821 – September 8, 1894) was a German physician and physicist who made significant contributions to several widely varied areas of modern science. In physiology and psychology, he is known for his mathematics of the eye, theories of vision, ideas on the visual perception of space, color vision research, and on the sensation of tone, perception of sound, and empiricism. In physics, he is known for his theories on the conservation of energy, work in electrodynamics, chemical thermodynamics, and on a mechanical foundation of thermodynamics. As a philosopher, he is known for his philosophy of science, ideas on the relation between the laws of perception and the laws of nature, the science of aesthetics, and ideas on the civilizing power of science. The largest German association of research institutions, the Helmholtz Association, is named after him.[3]

Biography

Early years

Helmholtz was the son of the Potsdam Gymnasium headmaster, Ferdinand Helmholtz, who had studied classical philology and philosophy, and who was a close friend of the publisher and philosopher Immanuel Hermann Fichte. Helmholtz's work is influenced by the philosophy of Johann Gottlieb Fichte and Immanuel Kant. He tried to trace their theories in empirical matters like physiology.

As a young man, Helmholtz was interested in natural science, but his father wanted him to study medicine at the Charité because there was financial support for medical students.

Trained primarily in physiology, Helmholtz wrote on many other topics, ranging from theoretical physics, to the age of the Earth, to the origin of the solar system.

University posts

Helmholtz's first academic position was associate professor of physiology at the Prussian University of Königsberg, where he was appointed in 1849. In 1855 he accepted a full professorship of anatomy and physiology at the University of Bonn. He was not particularly happy in Bonn, however, and three years later he transferred to the University of Heidelberg, in Baden, where he served as professor of physiology. In 1871 he accepted his final university position, as professor of physics at the University of Berlin.

Research

Helmholtz in 1848

Mechanics

His first important scientific achievement, an 1847 treatise on the conservation of energy, was written in the context of his medical studies and philosophical background. He discovered the principle of conservation of energy while studying muscle metabolism. He tried to demonstrate that no energy is lost in muscle movement, motivated by the implication that there were no vital forces necessary to move a muscle. This was a rejection of the speculative tradition of Naturphilosophie which was at that time a dominant philosophical paradigm in German physiology.

Drawing on the earlier work of Sadi Carnot, Émile Clapeyron and James Prescott Joule, he postulated a relationship between mechanics, heat, light, electricity and magnetism by treating them all as manifestations of a single force (energy in modern terms[4]). He published his theories in his book Über die Erhaltung der Kraft (On the Conservation of Force, 1847).[5] Whether or not Helmholtz knew of Julius Robert von Mayer's discovery of the law of conservation of energy in the beginning of the 1840s is a point of controversy. Helmholtz did not quote Mayer in his work and was accused by contemporaries of plagiarism.

In the 1850s and 60s, building on the publications of William Thomson, Helmholtz and William Rankine popularized the idea of the heat death of the universe.

In fluid dynamics, Helmholtz made several contributions, including Helmholtz's theorems for vortex dynamics in inviscid fluids.

Sensory physiology

The sensory physiology of Helmholtz was the basis of the work of Wilhelm Wundt, a student of Helmholtz, who is considered one of the founders of experimental psychology. He, more explicitly than Helmholtz, described his research as a form of empirical philosophy and as a study of the mind as something separate. Helmholtz had, in his early repudiation of Naturphilosophie, stressed the importance of materialism, and was focusing more on the unity of "mind" and body.[6]

Ophthalmic optics

In 1851, Helmholtz revolutionized the field of ophthalmology with the invention of the ophthalmoscope; an instrument used to examine the inside of the human eye. This made him world famous overnight. Helmholtz's interests at that time were increasingly focused on the physiology of the senses. His main publication, entitled Handbuch der Physiologischen Optik (Handbook of Physiological Optics or Treatise on Physiological Optics), provided empirical theories on depth perception, color vision, and motion perception, and became the fundamental reference work in his field during the second half of the nineteenth century. In the third and final volume, published in 1867, Helmholtz described the importance of unconscious inferences for perception. The Handbuch was first translated into English under the editorship of James P. C. Southall on behalf of the Optical Society of America in 1924-5. His theory of accommodation went unchallenged until the final decade of the 20th century.

Helmholtz continued to work for several decades on several editions of the handbook, frequently updating his work because of his dispute with Ewald Hering who held opposite views on spatial and color vision. This dispute divided the discipline of physiology during the second half of the 1800s.

Nerve physiology

In 1849, while at Königsberg, Helmholtz measured the speed at which the signal is carried along a nerve fibre. At that time most people believed that nerve signals passed along nerves immeasurably fast.[7] He used a recently dissected sciatic nerve of a frog and the calf muscle to which it attached. He used a galvanometer as a sensitive timing device, attaching a mirror to the needle to reflect a light beam across the room to a scale which gave much greater sensitivity.[7] Helmholtz reported[8][9] transmission speeds in the range of 24.6 - 38.4 meters per second.[7]

Acoustics and aesthetics

The Helmholtz resonator (i) and instrumentation

In 1863, Helmholtz published On the Sensations of Tone, once again demonstrating his interest in the physics of perception. This book influenced musicologists into the twentieth century. Helmholtz invented the Helmholtz resonator to identify the various frequencies or pitches of the pure sine wave components of complex sounds containing multiple tones.[10]

Helmholtz showed that different combinations of resonator could mimic vowel sounds: Alexander Graham Bell in particular was interested in this but, not being able to read German, misconstrued Helmholtz' diagrams as meaning that Helmholtz had transmitted multiple frequencies by wire—which would allow multiplexing of telegraph signals—whereas, in reality, electrical power was used only to keep the resonators in motion. Bell failed to reproduce what he thought Helmholtz had done but later said that, had he been able to read German, he would not have gone on to invent the telephone on the harmonic telegraph principle.[11][12][13][14]

Helmholtz in 1876
(portrait by Franz von Lenbach)

The translation by Alexander J. Ellis was first published in 1875 (the first English edition was from the 1870 third German edition; Ellis's second English edition from the 1877 fourth German edition was published in 1885; the 1895 and 1912 third and fourth English editions were reprints of the second).[15]

Electromagnetism

Helmholtz studied the phenomena of electrical oscillations from 1869 to 1871, and in a lecture delivered to the Naturhistorisch-medizinischen Vereins zu Heidelberg (Natural History and Medical Association of Heidelberg) on April 30, 1869 titled On Electrical Oscillations he indicated that the perceptible damped electrical oscillations in a coil joined up with a Leyden jar were about 1/50th of a second in duration.[16]

In 1871, Helmholtz moved from Heidelberg to Berlin to become a professor in physics. He became interested in electromagnetism and the Helmholtz equation is named for him. Although he did not make major contributions to this field, his student Heinrich Rudolf Hertz became famous as the first to demonstrate electromagnetic radiation. Oliver Heaviside criticised Helmholtz's electromagnetic theory because it allowed the existence of longitudinal waves. Based on work on Maxwell's equations, Heaviside pronounced that longitudinal waves could not exist in a vacuum or a homogeneous medium. Heaviside did not note, however, that longitudinal electromagnetic waves can exist at a boundary or in an enclosed space.[17]

There is even a topic by the name "Helmholtz optics", based on the Helmholtz equation.[18][19][20]

Quotations

Whoever, in the pursuit of science, seeks after immediate practical utility may rest assured that he seeks in vain. — Academic Discourse (Heidelberg 1862)[21]

Students and associates

Other students and research associates of Helmholtz at Berlin included Max Planck, Heinrich Kayser, Eugen Goldstein, Wilhelm Wien, Arthur König, Henry Augustus Rowland, Albert A. Michelson, Wilhelm Wundt, Fernando Sanford and Michael I. Pupin. Leo Koenigsberger, who was his colleague 1869–1871 in Heidelberg, wrote the definitive biography of him in 1902.

Honours and legacy

Helmholtz's statue in front of Humboldt University in Berlin
Decree awarding Helmholtz the French Legion of Honour

Works

See also

General
People

References

Citations
  1. ↑ Physics Tree profile Hermann von Helmholtz
  2. ↑ Patton, Lydia, 2009, "Signs, Toy Models, and the A Priori: from Helmholtz to Wittgenstein," Studies in the History and Philosophy of Science, 40 (3): 281–289.
  3. 1 2 Cahan, David (1993). Hermann von Helmholtz and the Foundations of Nineteenth-Century Science. University of California Press. ISBN 0-520-08334-2.
  4. ↑ The usage of terms such as work, force, energy, power, etc. in the 18th and 19th centuries by scientific workers does not necessarily reflect the standardised modern usage.
  5. ↑ English translation published in Scientific memoirs, selected from the transactions of foreign academies of science, and from foreign journals: Natural philosophy (1853), p. 114; trans. by John Tyndall. Google Books, HathiTrust
  6. ↑ Peter J. Bowler and Iwan Rhys Morus (2005). Making Modern Science: A Historical Survey. University of Chicago Press. p. 177. ISBN 978-0-226-06861-9.
  7. 1 2 3 Glynn, Ian (2010). Elegance in Science. Oxford: Oxford University Press. pp. 147–150. ISBN 978-0-19-957862-7.
  8. ↑ Vorläufiger Bericht über die Fortpflanzungs-Geschwindigkeit der Nervenreizung. In: Archiv für Anatomie, Physiologie und wissenschaftliche Medicin. Jg. 1850, Veit & Comp., Berlin 1850, S. 71-73. MPIWG Berlin
  9. ↑ Messungen über den zeitlichen Verlauf der Zuckung animalischer Muskeln und die Fortpflanzungsgeschwindigkeit der Reizung in den Nerven. In: Archiv für Anatomie, Physiologie und wissenschaftliche Medicin. Jg. 1850, Veit & Comp., Berlin 1850, S. 276-364. MPIWG Berlin
  10. ↑ Helmholtz, Hermann von (1885), On the sensations of tone as a physiological basis for the theory of music, Second English Edition, translated by Alexander J. Ellis. London: Longmans, Green, and Co., p. 44. Retrieved 2010-10-12.
  11. ↑ "PBS, American Experience: The Telephone -- More About Bell".
  12. ↑ MacKenzie 2003, p. 41.
  13. ↑ Groundwater 2005, p. 31.
  14. ↑ Shulman 2008, pp. 46–48.
  15. ↑ Hermann L. F. Helmholtz, M.D. (1912). On the Sensations of Tone as a Physiological Basis for the Theory of Music (Fourth ed.). Longmans, Green, and Co.
  16. ↑ Hermann von Helmholtz by Leo Koenigsberger, 1906; p268
  17. ↑ John D. Jackson, Classical Electrodynamics, ISBN 0-471-30932-X.
  18. ↑ Kurt Bernardo Wolf and Evgenii V. Kurmyshev, Squeezed states in Helmholtz optics, Physical Review A 47, 3365–3370 (1993).
  19. ↑ Sameen Ahmed Khan, Wavelength-dependent modifications in Helmholtz Optics, International Journal of Theoretical Physics, 44(1), 95-125 (January 2005).
  20. ↑ Sameen Ahmed Khan, A Profile of Hermann von Helmholtz, Optics & Photonics News, Vol. 21, No. 7, pp. 7 (July/August 2010).
  21. ↑ Science, Volume 55 By American Association for the Advancement of Science; pp408
  22. ↑ "History of the name in the About section of Helmholtz Association website". Retrieved 30 April 2012.
Bibliography

Further reading

External links

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