Heinrich Hertz

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Heinrich Hertz
Heinrich Rudolf Hertz
Heinrich Rudolf Hertz

(1857-02-22)22 February 1857
Died1 January 1894(1894-01-01) (aged 36)
Alma materUniversity of Munich
University of Berlin
Known forContact mechanics
Electromagnetic radiation
Parabolic antenna
Photoelectric effect
Hertzian cone
Hertzian dipole antenna
Hertz vector
Hertz-Knudsen equation
Hertz's principle of least curvature
AwardsMatteucci Medal (1888)
Rumford Medal (1890)
Scientific career
Electrical engineering
Contact mechanics
InstitutionsUniversity of Kiel
University of Karlsruhe
University of Bonn
Doctoral advisorHermann von Helmholtz
Doctoral studentsVilhelm Bjerknes
Autograph of Heinrich Hertz.png

Heinrich Rudolf Hertz (/hɜːrts/ HURTS; German: [ˈhaɪnʁɪç ˈhɛʁts];[1][2] 22 February 1857 – 1 January 1894) was a German physicist who first conclusively proved the existence of the electromagnetic waves predicted by James Clerk Maxwell's equations of electromagnetism. The unit of frequency, cycle per second, was named the "hertz" in his honor.[3]


Heinrich Rudolf Hertz was born in 1857 in Hamburg, then a sovereign state of the German Confederation, into a prosperous and cultured Hanseatic family. His father was Gustav Ferdinand Hertz.[4]


In 1892, Hertz was diagnosed with an infection (after a bout of severe migraines) and underwent operations to treat the illness. He died after complications in surgery in attempts to fix his condition that was causing these migraines, which some consider to have been a malignant bone condition.[5] He died at the age of 36 in Bonn, Germany, in 1894, and was buried in the Ohlsdorf Cemetery in Hamburg.[6][7][8]

Hertz's wife, Elisabeth Hertz (née Doll; 1864–1941), did not remarry and he was survived by his daughters, Johanna (1887–1967) and Mathilde (1891–1975). Neither ever married or had children, hence Hertz has no living descendants.[9]

Scientific work[edit]

Electromagnetic waves[edit]

Hertz's 1887 apparatus for generating and detecting radio waves: a spark-gap transmitter (left) consisting of a dipole antenna with a spark gap (S) powered by high voltage pulses from a Ruhmkorff coil (T), and a receiver (right) consisting of a loop antenna and spark gap.
One of Hertz's radio wave receivers: a loop antenna with an adjustable spark micrometer (bottom).[10]

During Hertz's studies in 1879 Helmholtz suggested that Hertz's doctoral dissertation be on testing Maxwell's theory. Helmholtz had also proposed the "Berlin Prize" problem that year at the Prussian Academy of Sciences for anyone who could experimentally prove an electromagnetic effect in the polarization and depolarization of insulators, something predicted by Maxwell's theory.[11][12] Helmholtz was sure Hertz was the most likely candidate to win it.[12] Not seeing any way to build an apparatus to experimentally test this, Hertz thought it was too difficult, and worked on electromagnetic induction instead. Hertz did produce an analysis of Maxwell's equations during his time at Kiel, showing they did have more validity than the then prevalent "action at a distance" theories.[13]

In the autumn of 1886, after Hertz received his professorship at Karlsruhe, he was experimenting with a pair of Riess spirals when he noticed that discharging a Leyden jar into one of these coils produced a spark in the other coil. With an idea on how to build an apparatus, Hertz now had a way to proceed with the "Berlin Prize" problem of 1879 on proving Maxwell's theory (although the actual prize had expired uncollected in 1882).[14][15]

[[File:Hertz first oscillator.png|thumb|upright=3|center|Hertz's first radio transmitter: a capacitance loaded dipole resonator consisting of a pair of one meter copper wires with a 7.5 mm spark gap between them, ending in 30 cm zinc spheres.[10]

Between 1886 and 1889 Hertz conducted a series of experiments that would prove the effects he was observing were results of Maxwell's predicted electromagnetic waves. Starting in November 1887 with his paper "On Electromagnetic Effects Produced by Electrical Disturbances in Insulators", Hertz sent a series of papers to Helmholtz at the Berlin Academy, including papers in 1888 that showed transverse free space electromagnetic waves traveling at a finite speed over a distance.[15][16]

Hertz's directional spark transmitter (center), a half-wave dipole antenna made of two 13 cm brass rods with spark gap at center (closeup left) powered by a Ruhmkorff coil, on focal line of a 1.2 m x 2 m cylindrical sheet metal parabolic reflector.[17] It radiated a beam of 66 cm waves with frequency of about 450 MHz. Receiver (right) is similar parabolic dipole antenna with micrometer spark gap.
Hertz's demonstration of polarization of radio waves: the receiver does not respond when antennas are perpendicular as shown, but as receiver is rotated the received signal grows stronger (as shown by length of sparks) until it reaches a maximum when dipoles are parallel.[17]
Another demonstration of polarization: waves pass through polarizing filter to the receiver only when the wires are perpendicular to dipoles (A), not when parallel (B).[17]
Demonstration of refraction: radio waves bend when passing through a prism made of pitch, similarly to light waves when passing through a glass prism.[17]
Hertz' plot of standing waves created when radio waves are reflected from a sheet of metal

Hertz did not realize the practical importance of his radio wave experiments. He stated that,[18][19][20]

"It's of no use whatsoever[...] this is just an experiment that proves Maestro Maxwell was right—we just have these mysterious electromagnetic waves that we cannot see with the naked eye. But they are there."

Asked about the applications of his discoveries, Hertz replied,[18][21]

"Nothing, I guess."

Hertz's proof of the existence of airborne electromagnetic waves led to an explosion of experimentation with this new form of electromagnetic radiation, which was called "Hertzian waves" until around 1910 when the term "radio waves" became current. Within 10 years researchers such as Oliver Lodge, Ferdinand Braun, and Guglielmo Marconi employed radio waves in the first wireless telegraphy radio communication systems, leading to radio broadcasting, and later television. In 1909, Braun and Marconi received the Nobel Prize in physics for their "contributions to the development of wireless telegraphy".[22] Today radio is an essential technology in global telecommunication networks, and the communications medium used by modern wireless devices.[23][24]

Contact mechanics[edit]

[[Image:Büste von Heinrich Hertz in Karlsruhe.jpg|thumb|Memorial of Heinrich Hertz on the campus of the Karlsruhe Institute of Technology, which translates as At this site, Heinrich Hertz discovered electromagnetic waves in the years 1885–1889.]]

In 1881 and 1882, Hertz published two articles.[25][26][27]

To develop his theory Hertz used his observation of elliptical Newton's rings formed upon placing a glass sphere upon a lens as the basis of assuming that the pressure exerted by the sphere follows an elliptical distribution. He used the formation of Newton's rings again while validating his theory with experiments in calculating the displacement which the sphere has into the lens. Kenneth L. Johnson, K. Kendall and A. D. Roberts (JKR) used this theory as a basis while calculating the theoretical displacement or indentation depth in the presence of adhesion in 1971.[28] Hertz's theory is recovered from their formulation if the adhesion of the materials is assumed to be zero. Similar to this theory, however using different assumptions, B. V. Derjaguin, V. M. Muller and Y. P. Toporov published another theory in 1975, which came to be known as the DMT theory in the research community, which also recovered Hertz's formulations under the assumption of zero adhesion. This DMT theory proved to be premature and needed several revisions before it came to be accepted as another material contact theory in addition to the JKR theory. Both the DMT and the JKR theories form the basis of contact mechanics upon which all transition contact models are based and used in material parameter prediction in nanoindentation and atomic force microscopy. These models are central to the field of tribology and he was named as one of the 23 "Men of Tribology" by Duncan Dowson.[29] Despite preceding his great work on electromagnetism (which he himself considered with his characteristic soberness to be trivial[18]), Hertz's research on contact mechanics has facilitated the age of nanotechnology.


Hertz always had a deep interest in meteorology, probably derived from his contacts with Wilhelm von Bezold (who was his professor in a laboratory course at the Munich Polytechnic in the summer of 1878). As an assistant to Helmholtz in Berlin, he contributed a few minor articles in the field, including research on the evaporation of liquids,[30] a new kind of hygrometer, and a graphical means of determining the properties of moist air when subjected to adiabatic changes.[31]

Treatment by the Third Reich[edit]

Because Hertz's family converted from Judaism to Lutheranism two decades before his birth, his legacy ran afoul of the Nazi government in the 1930s, a regime that classified people by "race" instead of religious affiliation.[32][33]

Hertz's name was removed from streets and institutions and there was even a movement to rename the frequency unit named in his honor (hertz) after Hermann von Helmholtz instead, keeping the symbol (Hz) unchanged.[33]

Legacy and honors[edit]

Heinrich Hertz

Heinrich Hertz's nephew Gustav Ludwig Hertz was a Nobel Prize winner, and Gustav's son Carl Helmut Hertz invented medical ultrasonography. His daughter Mathilde Carmen Hertz was a well-known biologist and comparative psychologist. Hertz's grandnephew Hermann Gerhard Hertz, professor at the University of Karlsruhe, was a pioneer of NMR-spectroscopy and in 1995 published Hertz's laboratory notes.[34]

In 1969, in East Germany, a Heinrich Hertz memorial medal[35] was cast. The IEEE Heinrich Hertz Medal, established in 1987, is "for outstanding achievements in Hertzian waves [...] presented annually to an individual for achievements which are theoretical or experimental in nature".[citation needed]

Hertz is honored by Japan with a membership in the Order of the Sacred Treasure, which has multiple layers of honor for prominent people, including scientists.[36]

Heinrich Hertz has been honored by a number of countries around the world in their postage issues, and in post-World War II times has appeared on various German stamp issues as well.[citation needed]

On his birthday in 2012, Google honored Hertz with a Google doodle, inspired by his life's work, on its home page.[37][38]

See also[edit]


  • Ueber die Induction in rotirenden Kugeln (in German). Berlin: Schade. 1880.
  • Die Prinzipien der Mechanik in neuem Zusammenhange dargestellt (in German). Leipzig: Johann Ambrosius Barth. 1894.
  • Schriften vermischten Inhalts (in German). Leipzig: Johann Ambrosius Barth. 1895.


  1. ^ Krech, Eva-Maria; Stock, Eberhard; Hirschfeld, Ursula; Anders, Lutz Christian (2009). Deutsches Aussprachewörterbuch [German Pronunciation Dictionary] (in German). Berlin: Walter de Gruyter. pp. 575, 580. ISBN 978-3-11-018202-6.
  2. ^ Dudenredaktion; Kleiner, Stefan; Knöbl, Ralf (2015) [First published 1962]. Das Aussprachewörterbuch [The Pronunciation Dictionary] (in German) (7th ed.). Berlin: Dudenverlag. p. 440. ISBN 978-3-411-04067-4.
  3. ^ IEC History Archived 19 May 2013 at the Wayback Machine. Iec.ch.
  4. ^ "Biography: Heinrich Rudolf Hertz". MacTutor History of Mathematics archive. Retrieved 2 February 2013.
  5. ^ Robertson, O'Connor. "Heinrich Rudolf Hertz". MacTutor. University of Saint Andrews, Scotland. Retrieved 20 October 2020.
  6. ^ Hamburger Friedhöfe » Ohlsdorf » Prominente. Friedhof-hamburg.de. Retrieved 22 August 2014.
  7. ^ Plan Ohlsdorfer Friedhof (Map of Ohlsdorf Cemetery). friedhof-hamburg.de.
  8. ^ IEEE Institute, Did You Know? Historical ‘Facts’ That Are Not True Archived 10 January 2014 at the Wayback Machine
  9. ^ Susskind, Charles. (1995). Heinrich Hertz: A Short Life. San Francisco: San Francisco Press. ISBN 0-911302-74-3
  10. ^ a b Appleyard, Rollo (October 1927). "Pioneers of Electrical Communication part 5 – Heinrich Rudolph Hertz" (PDF). Electrical Communication. New York: International Standard Electric Corp. 6 (2): 63–77. Retrieved 19 December 2015.The two images shown are p. 66, fig. 3 and p. 70 fig. 9
  11. ^ Heinrich Hertz. nndb.com. Retrieved 22 August 2014.
  12. ^ a b Baird, Davis, Hughes, R.I.G. and Nordmann, Alfred eds. (1998). Heinrich Hertz: Classical Physicist, Modern Philosopher. New York: Springer-Verlag. ISBN 0-7923-4653-X. p. 49
  13. ^ Heilbron, John L. (2005) The Oxford Guide to the History of Physics and Astronomy. Oxford University Press. ISBN 0195171985. p. 148
  14. ^ Baird, Davis, Hughes, R.I.G. and Nordmann, Alfred eds. (1998). Heinrich Hertz: Classical Physicist, Modern Philosopher. New York: Springer-Verlag. ISBN 0-7923-4653-X. p. 53
  15. ^ a b Huurdeman, Anton A. (2003) The Worldwide History of Telecommunications. Wiley. ISBN 0471205052. p. 202
  16. ^ "The most important Experiments – The most important Experiments and their Publication between 1886 and 1889". Fraunhofer Heinrich Hertz Institute. Retrieved 19 February 2016.
  17. ^ a b c d Pierce, George Washington (1910). Principles of Wireless Telegraphy. New York: McGraw-Hill Book Co. pp. 51–55.
  18. ^ a b c "Heinrich Rudolph Hertz". History. Institute of Chemistry, Hebrew Univ. of Jerusalem website. 2004. Archived from the original on 25 September 2009. Retrieved 6 March 2018.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  19. ^ Capri, Anton Z. (2007) Quips, quotes, and quanta: an anecdotal history of physics. World Scientific. ISBN 9812709207. p 93.
  20. ^ Norton, Andrew (2000). Dynamic Fields and Waves. CRC Press. p. 83. ISBN 0750307196.
  21. ^ Heinrich Hertz (1893). Electric Waves: Being Researches on the Propagation of Electric Action with Finite Velocity Through Space. Dover Publications. ISBN 1-4297-4036-1.
  22. ^ "The Nobel Prize in Physics 1909". Nobel Foundation. Retrieved 18 January 2019.
  23. ^ "Heinrich Hertz | German physicist". Encyclopedia Britannica. Retrieved 21 May 2021.
  24. ^ "How Radio Works". HowStuffWorks. 7 December 2000. Retrieved 14 March 2019.
  25. ^ Hertz, Heinrich (1882). "Ueber die Berührung fester elastischer Körper". Journal für die reine und angewandte Mathematik. 1882 (92): 156–171. doi:10.1515/crll.1882.92.156. S2CID 123604617.
  26. ^ Hertz, Heinrich (1882). "Über die Berührung fester elastischer Körper und über die Härte". Verhandlungen des Vereins zur Beförderung des Gewerbefleißes. 1882: 449–463. Retrieved 9 February 2022.
  27. ^ Hertz, Heinrich (1986). Miscellaneous Papers. London: Macmillan and Co, Ltd. pp. 146–183. Retrieved 13 February 2022.
  28. ^ Johnson, K. L.; Kendall, K.; Roberts, A. D. (1971). "Surface energy and contact of elastic solids" (PDF). Proceedings of the Royal Society A. 324 (1558): 301–313. Bibcode:1971RSPSA.324..301J. doi:10.1098/rspa.1971.0141. S2CID 137730057.
  29. ^ Dowson, Duncan (1 April 1979). "Men of Tribology: Heinrich Rudolph Hertz (1857–1894) and Richard Stribeck (1861–1950)". Journal of Lubrication Technology. 101 (2): 115–119. doi:10.1115/1.3453287. ISSN 0022-2305.
  30. ^ Hertz, H. (1882). "Ueber die Verdunstung der Flüssigkeiten, insbesondere des Quecksilbers, im luftleeren Raume". Annalen der Physik. 253 (10): 177–193. Bibcode:1882AnP...253..177H. doi:10.1002/andp.18822531002. ISSN 1521-3889.
  31. ^ Mulligan, J. F.; Hertz, H. G. (1997). "An unpublished lecture by Heinrich Hertz: "On the energy balance of the Earth"". American Journal of Physics. 65 (1): 36–45. Bibcode:1997AmJPh..65...36M. doi:10.1119/1.18565.
  32. ^ Koertge, Noretta. (2007). Dictionary of Scientific Biography. New York: Thomson-Gale. ISBN 0-684-31320-0. Vol. 6, p. 340.
  33. ^ a b Wolff, Stefan L. (2008-01-04) Juden wider Willen – Wie es den Nachkommen des Physikers Heinrich Hertz im NS-Wissenschaftsbetrieb erging. Jüdische Allgemeine.
  34. ^ Hertz, H.G.; Doncel, M.G. (1995). "Heinrich Hertz's Laboratory Notes of 1887". Archive for History of Exact Sciences. 49 (3): 197–270. doi:10.1007/bf00376092. S2CID 121101068.
  35. ^ Heinrich Rudolf Hertz Archived 3 June 2013 at the Wayback Machine. Highfields-arc.co.uk. Retrieved 22 August 2014.
  36. ^ L'Harmattan: List of recipients of Japanese Order of the Sacred Treasure (in French)
  37. ^ Albanesius, Chloe (22 February 2012). "Google Doodle Honors Heinrich Hertz, Electromagnetic Wave Pioneer". PC Magazine. Retrieved 22 February 2012.
  38. ^ Heinrich Rudolf Hertz's 155th Birthday. Google (22 February 2012). Retrieved 22 August 2014.

Further reading[edit]

External links[edit]