- Heinrich Hertz
name = Heinrich Rudolf Hertz
image_width = 230px
birth_date = birth date|1857|2|22|mf=y
nationality = German
death_date = death date and age|1894|1|1|1857|2|22|mf=y
Physicistand Electronic Engineer
University of Kiel University of Karlsruhe University of Bonn
University of Munich University of Berlin
Hermann von Helmholtz
Heinrich Rudolf Hertz (
February 22, 1857– January 1, 1894) was a German physicist who clarified and expanded the electromagnetic theory of light that had been put forth by Maxwell. He was the first to satisfactorily demonstrate the existence of electromagnetic wavesby building an apparatus to produce and detect VHF or UHF radiowaves.
Hertz was born in
Hamburg, Germany, into a prosperous and cultured Hanseaticfamily. His father, Gustav Ferdinand Hertz, was a barrister and later a senator. His mother was the former Anna Elisabeth Pfefferkorn. He had three younger brothers and one younger sister.Koertge, Noretta. (2007). "Dictionary of Scientific Biography," Vol. 6, p. 340.] While studying at the gymnasium of Hamburg, he showed an aptitude for sciences as well as languages, learning Arabic and Sanskrit. He studied sciences and engineering in the German cities of Dresden, Munich and Berlin, where he studied under Gustav R. Kirchhoffand Hermann von Helmholtz.
In 1880, Hertz obtained his
PhDfrom the University of Berlin; and remained for post-doctoral study under Helmholtz.
In 1883, Hertz took a post as a lecturer in theoretical physics at the
University of Kiel.
In 1885, Hertz became a full professor at the
University of Karlsruhewhere he discovered electromagnetic waves.
Hertz always had a deep interest in
meteorologyprobably derived from his contacts with Wilhelm von Bezold(who was Hertz's professor in a laboratory course at the Munich Polytechnic in the summer of 1878). Hertz, however, did not contribute much to the field himself except some early articles as an assistant to Helmholtz in Berlin, including research on the evaporationof liquids, a new kind of hygrometer, and a graphical means of determining the properties of moist air when subjected to adiabaticchanges. [Mulligan, J. F., and H. G. Hertz, "On the energy balance of the Earth," "American Journal of Physics", Vol. 65, pp. 36-45.]
In 1881–1882, Hertz published two articles on what was to become known as the field of
contact mechanics. Hertz is well known for his contributions to the field of electrodynamics ("see below") however most papers that look into the fundamental nature of contact cite his two papers as a source for some important ideas. Joseph Valentin Boussinesqpublished some critically important observations on Hertz's work, nevertheless establishing this work on contact mechanics to be of immense importance. His work basically summarises how two axi-symmetric objects placed in contact will behave under loading, he obtained results based upon the classical theory of elasticity and continuum mechanics. The most significant failure of his theory was the neglect of any nature of adhesion between the two solids, which proves to be important as the materials composing the solids start to assume high elasticity. It was natural to neglect adhesion in that age as there were no experimental methods of testing for it.
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. K. 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 their landmark article "Surface energy and contact of elastic solids" published in 1971 in the Proceedings of the Royal Society (A324, 1558, 301-313). 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 rather 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. So Hertz's research from his days as a lecturer, preceding his great work on electromagnetism, which he himself considered with his characteristic soberness to be trivial, has come down to the age of nanotechnology.
Hertz helped establish the
photoelectric effect(which was later explained by Albert Einstein) when he noticed that a charged object loses its charge more readily when illuminated by ultraviolet light. In 1887, he made observations of the photoelectric effect and of the production and reception of electromagnetic (EM) waves, published in the journal Annalen der Physik. His receiver consisted of a coil with a spark gap, whereupon a spark would be seen upon detection of EM waves. He placed the apparatus in a darkened box in order to see the spark better; he observed, however, that the maximum spark length was reduced when in the box. A glass panel placed between the source of EM waves and the receiver absorbed ultraviolet radiation that assisted the electrons in jumping across the gap. When removed, the spark length would increase. He observed no decrease in spark length when he substituted quartz for glass, as quartzdoes not absorb UV radiation. Hertz concluded his months of investigation and reported the results obtained. He did not further pursue investigation of this effect, nor did he make any attempt at explaining how the observed phenomenon was brought about. Earlier in 1886, Hertz developed the Hertz antenna receiver. This is a set of terminals that is not electrically grounded for its operation. He also developed a transmitting type of dipole antenna, which was a center-fed driven element for transmission UHF radio waves. These antennas are the simplest practical antennas from a theoretical point of view. In 1887, Hertz experimented with radio waves in his laboratory. These actions followed Michelson's 1881 experiment (precursor to the 1887 Michelson-Morley experiment) which did not detect the existence of aether drift, Hertz altered the Maxwell's equationsto take this view into account for electromagnetism. Hertz used a Ruhmkorff coil-driven spark gap and one meter wire pair as a radiator. Capacity spheres were present at the ends for circuit resonance adjustments. His receiver, a precursor to the dipole antenna, was a simple half-wave dipole antenna for shortwaves.
Through experimentation, he proved that transverse
free space electromagnetic waves can travel over some distance. This had been predicted by James Clerk Maxwelland Michael Faraday. With his apparatus configuration, the electric and magnetic fields would radiate away from the wires as traverse waves. Hertz had positioned the oscillator about 12 meters from a zincreflecting plate to produce standing waves. Each wave was about four meters. Using the ring detector, he recorded how the magnitude and wave's component direction vary. Hertz measured Maxwell's waves and demonstrated that the velocity of radio waves was equal to the velocity of light. The electric field intensityand polarity was also measured by Hertz. (Hertz, 1887, 1888).
Hertzian conewas first described by Hertz as a type of wave-front propagation through various media. His experiments expanded the field of electromagnetic transmission and his apparatus was developed further by others in the history of radio. Hertz also found that radio waves could be transmitted through different types of materials, and were reflected by others, leading in the distant future to radar.
Hertz did not realise the practical importance of his experiments. He stated that, : "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." Institute of Chemistry, Hebrew University of Jerusalem: [http://chem.ch.huji.ac.il/history/hertz.htm Hertz biography, digitized photographs] ] Asked about the ramifications of his discoveries, Hertz replied, : "Nothing, I guess"." His discoveries would later be more fully understood by others and be part of the new "wireless age". In bulk, Hertz' experiments explain reflection,
refraction, polarization, interference, and velocityof electric waves.
In 1892, Hertz began experimenting and demonstrated that cathode rays could penetrate very thin metal foil (such as
aluminium). Philipp Lenard, a student of Heinrich Hertz, further researched this "ray effect". He developed a version of the cathode tube and studied the penetration by X-rays of various materials. Philipp Lenard, though, did not realize that he was producing X-rays. Hermann von Helmholtzformulated mathematical equations for X-rays. He postulated a dispersion theory before Röntgen made his discovery and announcement. It was formed on the basis of the electromagnetic theory of light ("Wiedmann's Annalen", Vol. XLVIII). However, he did not work with actual X-rays.
Death at age 36
In 1892, an infection was diagnosed (after a bout of severe
migraines) and Hertz underwent some operations to correct the illness. He died of Wegener's granulomatosisat the age of 36 in Bonn, Germany in 1894.
His wife, Elizabeth Hertz (maiden name: Elizabeth Doll) did not marry again. Heinrich Hertz left two daughters, Joanna and Mathilde. Subsequently, all three women left Germany in the 1930s to England, after the rise of
Adolf Hitler. Charles Susskind interviewed Mathilde Hertz in the 1960s and he later published a book on Heinrich Hertz. Heinrich Hertz's daughters never married and so he does not have any descendants, according to the book by Susskind.
Gustav Ludwig Hertzwas a Nobel Prizewinner, and Gustav's son Carl Hellmuth Hertzinvented medical ultrasonography.
The SI unit "
Hertz" (Hz) was established in his honor by the IEC in 1930 for frequency, a measurement of the number of times that a repeated event occurs per unit of time (also called "cycles per sec" (cps)). It was adopted by the CGPM (Conférence générale des poids et mesures) in 1964.
In 1969 (
East Germany), there was cast a Heinrich Hertz memorial medal. The IEEEHeinrich 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".
A crater that lies on the far side of the
Moon, just behind the eastern limb, is named in his honor. The Hertz market for radioelectronics products in Nizhny Novgorod, Russia, is named after him. The Heinrich-Hertz-Turmradio telecommunication tower in Hamburgis named after the city's famous son.
Although Hertz would not have considered himself Jewish, his "Jewish" portrait was removed by the
Nazis from its prominent position of honor in Hamburg's City Hall ("Rathaus") because of his partly " Jewishancestry." Hertz was a Lutheran; and although his father’s family had been Jewish, [see above] ] his father had been converted to Catholicism before marrying. [see above] ] One additional fact gives this historical moment a poignant clarity. By this point in German history, Hertz himself had been dead for 26 years. The painting has since been returned to public display.Robertson, Struan: [http://www1.uni-hamburg.de/rz3a035//hertz.html Hertz biography] ]
Hertz was honored by Japan with the
Order of the Sacred Treasure. [L'Harmattan: [http://www.editions-harmattan.fr/index.asp?navig=catalogue&obj=article&no=8245 List of recipients of Japanese Order of the Sacred Treasure (in French)] ]
Hans Christian Ørsted
* David Edward Hughes
Reginald Aubrey Fessenden
Gustav Ludwig Hertz
Hermann von Helmholtz
James Clerk Maxwell
Wilhelm Röntgen;Lists and histories
* Electromagnetism timeline
* Timeline of mechanics and physics
List of physicists
* Radio history
List of people on stamps of Germany
List of physics topics;Electromagnetic radiation
University of Bonn
University of Karlsruhe
* Hertz, H.R. "Ueber sehr schnelle electrische Schwingungen", "Annalen der Physik", vol. 267, no. 7, p. 421-448, May 1887. ( [http://www3.interscience.wiley.com/journal/5006612/home WILEY InterScience] )
* Hertz, H.R. "Ueber einen Einfluss des ultravioletten Lichtes auf die electrische Entladung", "Annalen der Physik", vol. 267, no. 8, p. 983-1000, June, 1887. ( [http://www3.interscience.wiley.com/journal/5006612/home WILEY InterScience] )
* Hertz, H.R. "Ueber die Einwirkung einer geradlinigen electrischen Schwingung auf eine benachbarte Strombahn", "Annalen der Physik", vol. 270, no. 5, p. 155-170, March, 1888. ( [http://www3.interscience.wiley.com/journal/5006612/home WILEY InterScience] )
* Hertz, H.R. "Ueber die Ausbreitungsgeschwindigkeit der electrodynamischen Wirkungen", "Annalen der Physik", vol. 270, no. 7, p. 551-569, May, 1888. ( [http://www3.interscience.wiley.com/journal/5006612/home WILEY InterScience] )
* Hertz, Heinrich Rudolph. (1893). "Electric waves: being researches on the propagation of electric action with finite velocity through space" (translated by David Evans Jones). Ithica, New York:
Cornell University Library. 10-ISBN 1-429-74036-1; 13-ISBN 978-1-429-74036-4
* IEEE ((Institute of Electrical and Electronics Engineers) Virtual Museum, IEEE History Center: [http://www.ieee-virtual-museum.org/collection/people.php?taid=&id=1234576&lid=1 "Heinrich Hertz" (retrieved 27 Jan 2007)]
* Jenkins, John D. [http://www.sparkmuseum.com/BOOK_HERTZ.HTM "The Discovery of Radio Waves - 1888; Heinrich Rudolf Hertz (1847-1894)" (retrieved 27 Jan 2008)]
* Koertge, Noretta. (2007). "Dictionary of Scientific Biography." New York:
Thomson-Gale. 10-ISBN 0-684-31320-0; 13-ISBN 978-0-684-31320-7
* Naughton, Russell. [http://www.acmi.net.au/AIC/HERTZ_BIO.html "Heinrich Rudolph (alt: Rudolf) Hertz, Dr : 1857 - 1894" (retrieved 27 Jan 2008)]
* Roberge, Pierre R. [http://www.corrosion-doctors.org/Biographies/HertzBio.htm "Heinrich Rudolph Hertz, 1857-1894" (retrieved 27 Jan 2008)]
* Robertson, Struan. [http://www1.uni-hamburg.de/rz3a035//bundesstrasse1.html "Buildings Integral to the Former Life and/or Persecution of Jews in Hamburg" (retrieved 27 Jan 2008)]
* Robertson, Struan. [http://www1.uni-hamburg.de/rz3a035//rathaus.html#4 "Heinrich Hertz, 1857-1894" (retieved 27 Jan 2007)]
* Appleyard, Rollo. (1930). "Pioneers of Electrical Communication". London:
Macmillan and Company. [reprinted by Ayer Company Publishers, Manchester, New Hampshire: 10-ISBN 0836-90156-8; 13-ISBN 978-0-836-90156-6 (cloth)]
* Baird, Davis, R.I.G. Hughes, and Alfred Nordmann, eds. (1998). 'Heinrich Hertz: Classical Physicist, Modern Philosopher." New York:
Springer-Verlag. 10-ISBN 0-792-34653-X; 13-ISBN 978-0-792-34653-1
* Bodanis, David. (2006). "Electric Universe: How Electricity Switched on the Modern World." New York:
Three Rivers Press. 10-ISBN 0-307-33598-4; 13-ISBN 978-0-307-33598-2
* Buchwald, Jed Z. (1994). "The Creation of Scientific Effects : Heinrich Hertz and Electric Waves." Chicago :
University of Chicago Press. 10-ISBN 0-226-07887-6; 13-ISBN 978-0-226-07887-8 (cloth) 10-ISBN 0-226-07888-4; 13-ISBN 978-0-226-07888-5 (paper)
* Bryant, John H. (1988). "Heinrich Hertz, the Beginning of Microwaves: Discovery of Electromagnetic Waves and Opening of the Electromagnetic Spectrum by Heinrich Hertz in the Years 1886-1892." New York : IEEE (Institute of Electrical and Electronics Engineers). 10-ISBN 0-879-42710-8; 13-ISBN 978-0-879-42710-8
* [http://www.acmi.net.au/aic/phd8030.html Lodge, Oliver Joseph. (1900). "Signalling Across Space without Wires by Electric Waves: Being a Description of the work of
HeinrichHertz and his Successors."] [reprinted by Arno Press, New York, 1974. 10-ISBN 0-405-06051-3
* Maugis, Daniel. (2000). "Contact, Adhesion and Rupture of Elastic Solids." New York:
Springer-Verlag. 10-ISBN 3-540-66113-1; 13-ISBN 978-3-54066113-9]
* Susskind, Charles. (1995)."Heinrich Hertz :a Short Life." San Francisco: San Francisco Press. 10-ISBN 0-911-30274-3; 13-ISBN 978-0-911-30274-5
* [http://www.esmartstart.com/_framed/250x/radiondistics/hertzian_radiation.htm Hertzian radiation - better known as radio waves: what it is and how it happens]
* "Encyclopedia Britannica" (1911): [http://www.1911encyclopedia.org/Heinrich_Rudolf_Hertz Hertz biography]
* Institute of Chemistry, Hebrew University of Jerusalem: [http://chem.ch.huji.ac.il/history/hertz.htm Hertz biography, several digitized photographs]
NAME= Hertz, Heinrich Rudolf
Physicistand Electronic Engineer
DATE OF BIRTH= birth date|1857|2|22|mf=y
PLACE OF BIRTH=
DATE OF DEATH= death date|1894|1|1|mf=y
PLACE OF DEATH=
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Heinrich Hertz — noun German physicist who was the first to produce electromagnetic waves artificially (1857 1894) • Syn: ↑Hertz, ↑Heinrich Rudolph Hertz • Derivationally related forms: ↑Hertzian (for: ↑Hertz) • Instance Hypernyms … Useful english dictionary
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