Heinrich Rudolf Hertz

"I do not think that the wireless waves I have discovered will have any practical application."
Born	February 22, 1857 Hamburg, Germany
Died	January 1, 1894 Bonn, Germany
Residence	Germany
Nationality	German
Field	Physicist and Electronic Engineer
Institutions	University of Kiel University of Karlsruhe University of Bonn
Alma mater	University of Munich University of Berlin
Academic advisor	Hermann von Helmholtz
Known for	Electromagnetic radiation

Heinrich Rudolf Hertz (February 22, 1857 - January 1, 1894) was the German physicist and mechanician for whom the hertz, an SI unit, is named. In 1888, he was the first to satisfactorily demonstrate the existence of electromagnetic radiation by building an apparatus to produce and detect UHF radio waves. Download high resolution version (700x906, 99 KB)This is Heinrich Rudolf Hertz, from Oliver Heaviside: Sage in Solitude (ISBN 0-87942-238-6), p. ... This article or section is in need of attention from an expert on the subject. ... For other uses, see Radio (disambiguation). ... February 22 is the 53rd day of the year in the Gregorian calendar. ... 1857 was a common year starting on Thursday (see link for calendar). ... This article is about the city in Germany. ... January 1 is the first day of the calendar year in both the Julian and Gregorian calendars. ... 1894 (MDCCCXCIV) was a common year starting on Monday (see link for calendar). ... Map of Germany showing Bonn Watershed of the Rhine river Bonn is a city in Germany (Population (2002 est): 310 930, the 19th largest city in Germany), in the Bundesland of North Rhine-Westphalia, located ca. ... Image File history File links Flag_of_Germany. ... Image File history File links Flag_of_Germany. ... ... Electronic engineering is a professional discipline that deals with the behavior and effects of electrons (as in electron tubes and transistors) and with electronic devices, systems, or equipment. ... The University of Kiel, in full the Christian-Albrechts-Universität zu Kiel (in short: CAU), is a university in the city of Kiel, Germany. ... The Universität Karlsruhe (TH) is a mainly technical university in the city of Karlsruhe, Germany and is a leading research university: It is among the five universities in Germany with the strongest effort in research. ... The main building, viewed from the Hofgarten. ... With approximately 48,000 students, the Ludwig-Maximilians-University Munich (German: Ludwig-Maximilians-Universität München or LMU) is one of the largest universities in Germany. ... There is no institution called the University of Berlin, but there are four universities in Berlin, Germany: Humboldt University of Berlin (Humboldt-Universität zu Berlin) Technical University of Berlin (Technische Universität Berlin) Free University of Berlin (Freie Universität Berlin) Berlin University of the Arts (Universität der... Hermann Ludwig Ferdinand von Helmholtz (August 31, 1821 – September 8, 1894) was a German physician and physicist. ... It has been suggested that this article or section be merged with light. ... February 22 is the 53rd day of the year in the Gregorian calendar. ... 1857 was a common year starting on Thursday (see link for calendar). ... January 1 is the first day of the calendar year in both the Julian and Gregorian calendars. ... 1894 (MDCCCXCIV) was a common year starting on Monday (see link for calendar). ... ... A mechanician is an engineer or a scientist working in the field of mechanics, or in a related or sub-field: engineering or computational mechanics, applied mechanics, geomechanics, biomechanics, and mechanics of materials. ... The hertz (symbol: Hz) is the SI unit of frequency. ... Look up si, Si, SI in Wiktionary, the free dictionary. ... Year 1888 (MDCCCLXXXVIII) was a leap year starting on Sunday (click on link for calendar) of the Gregorian calendar (or a leap year starting on Tuesday of the 12-day slower Julian calendar). ... It has been suggested that this article or section be merged with light. ... This article is about the radio frequency. ...

Biography

Early years

Heinrich Rudolf Hertz was born in Hamburg, Germany on February 22, 1857, to Gustav Ferdinand Hertz, whose father converted from Judaism to Lutheranism and married into a Lutheran family, and Anna Elisabeth Pfefferkorn, herself a Lutheran. His father was an advisor in Hamburg, his mother the daughter of a doctor. While going to school at the University 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. He was a student of Gustav R. Kirchhoff and Hermann von Helmholtz. He obtained his PhD in 1880, and remained a pupil of Helmholtz until 1883 when he took a post as a lecturer in theoretical physics at the University of Kiel. In 1885 he became a full professor at the University of Karlsruhe where he discovered electromagnetic waves. Hamburg from above Hamburgs motto: May the posterity endeavour with dignity to conserve the freedom, which the forefathers acquired. ... Hamburg from above Hamburgs motto: May the posterity endeavour with dignity to conserve the freedom, which the forefathers acquired. ... Arabic ( or just ) is the largest living member of the Semitic language family in terms of speakers. ... The Sanskrit language ( , for short ) is an old Indo-Aryan language from the Indian Subcontinent, the classical literary language of the Hindus of India[1], a liturgical language of Hinduism, Buddhism, and Jainism, and one of the 23 official languages of India. ... For other uses, see Dresden (disambiguation). ... Munich (German: , pronounced  ; Austro-Bavarian: Minga; Italian: Monaco; Latin language: Monacum) is the capital of the German Federal State of Bavaria (German: ). Munich is Germanys third largest city and one of Europes most prosperous. ... Berlin is the capital city and one of the sixteen states of the Federal Republic of Germany. ... Gustav Robert Kirchhoff (March 12, 1824 - October 17, 1887), a German physicist who contributed to the fundamental understanding of electrical circuits, spectroscopy, and the emission of black-body radiation by heated objects. ... Hermann Ludwig Ferdinand von Helmholtz (August 31, 1821 – September 8, 1894) was a German physician and physicist. ... PhD usually refers to the academic title Doctor of Philosophy PhD can also refer to the manga Phantasy Degree This is a disambiguation page — a list of pages that otherwise might share the same title. ... Year 1880 (MDCCCLXXX) was a leap year starting on Thursday (link will display the full calendar). ... The University of Kiel, in full the Christian-Albrechts-Universität zu Kiel (in short: CAU), is a university in the city of Kiel, Germany. ... The Universität Karlsruhe (TH) is a mainly technical university in the city of Karlsruhe, Germany and is a leading research university: It is among the five universities in Germany with the strongest effort in research. ...

Meteorology

Hertz had always had a deep interest in meteorology probably derived from his contacts with Willhelm von Bezold (he 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 for some early articles as an assistant to Helmholtz in Berlin, including research on the evaporation of liquids, a new kind of hygrometer, and a graphical means of determining the properties of moist air when subjected to adiabatic changes. ^[1] Satellite image of Hurricane Hugo with a polar low visible at the top of the image. ... Berlin is the capital city and one of the sixteen states of the Federal Republic of Germany. ... This article or section is in need of attention from an expert on the subject. ... A liquid will usually assume the shape of its container A liquid is one of the main states of matter. ... The interior of a Stevenson screen showing a motorized psychrometer Hygrometers are instruments used for measuring humidity. ... This article covers adiabatic processes in thermodynamics. ...

Contact mechanics

In 1881–1882, Hertz published two articles on what was to become known as the field of contact mechanics. Hertz is generally 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. Boussinesq published 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. But it was natural to neglect adhesion in that age as there were no experimental methods by which they could test for adhesion. 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 in the Journal of Colloid and Interface Science in 1971. 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.

Electromagnetic research

Hertz helped establish the photoelectric effect (which was later explained by others) 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. A diagram illustrating the emission of photoelectrons from a metal plate, requiring energy gained from an incoming photon to be more than the work function of the material. ... Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... Annalen der Physik is one of the best-known and oldest (it was founded in 1799) physics journals worldwide. ... A spark plug. ...

1887 experimental setup of Hertz's apparatus.

When removed, the spark length would increase. He observed no decrease in spark length when he substituted quartz for glass, as quartz does 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. Image File history File links Hertz_schematic0. ... Image File history File links Hertz_schematic0. ... Quartz is one of the most common minerals in the Earths continental crust. ...

Earlier in 1886, Hertz developed a dipole antenna. This antenna is a center-fed driven element for transmitting or receiving radio frequency energy. 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 equations to 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. A simple half-wave dipole antenna that a shortwave listener might build. ... His signature. ... Year 1881 (MDCCCLXXXI) was a common year starting on Saturday (link will display the full calendar). ... 1887 (MDCCCLXXXVII) is a common year starting on Saturday (click on link for calendar) of the Gregorian calendar or a common year starting on Monday of the Julian calendar. ... The Michelson-Morley experiment, one of the most important and famous experiments in the history of physics, was performed in 1887 by Albert Michelson and Edward Morley at what is now Case Western Reserve University, and is considered by some to be the first strong evidence against the theory of... The luminiferous aether: it was hypothesised that the Earth moves through a medium of aether that carries light In the late 19th century luminiferous aether (light-bearing aether) was the term used to describe a medium for the propagation of light. ... In electromagnetism, Maxwells equations are a set of equations developed in the latter half of the nineteenth century by James Clerk Maxwell. ... An induction coil or spark coil (archaically known as a Ruhmkorff coil) is a type of disruptive discharge coil. ... A solid-state, analog shortwave receiver Shortwave radio operates between the frequencies of 3,000 kHz and 30 MHz (30,000 kHz) [1] and came to be referred to as such in the early days of radio because the wavelengths associated with this frequency range were shorter than those commonly...

Through experimentation, he proved that transverse free space electromagnetic waves can travel over some distance. This had been predicted by James Clerk Maxwell and 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 zinc reflecting 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 intensity and polarity was also measured by Hertz. Image File history File links TransverseEMwave. ... A light wave is an example of a transverse wave. ... In physics, free space is a concept of electromagnetic theory, corresponding roughly to the vacuum, the baseline state of the electromagnetic field, or the replacement for the electromagnetic aether. ... Electromagnetic radiation is a propagating wave in space with electric and magnetic components. ... James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematician and theoretical physicist. ... Michael Faraday, FRS (September 22, 1791 – August 25, 1867) was an English chemist and physicist (or natural philosopher, in the terminology of that time) who contributed significantly to the fields of electromagnetism and electrochemistry. ... General Name, Symbol, Number zinc, Zn, 30 Chemical series transition metals Group, Period, Block 12, 4, d Appearance bluish pale gray Standard atomic weight 65. ... A standing wave, also known as a stationary wave, is a wave that remains in a constant position. ... The metre, or meter (symbol: m) is the SI base unit of length. ... Amplitude is a nonnegative scalar measure of a waves magnitude of oscillation, that is, magnitude of the maximum disturbance in the medium during one wave cycle. ... Electric Field :Electric field intensity is known as the space surrounding a charge particle in which any other particle feels a force of attraction or repulsion. ... The polarity of an object is, in general, its physical alignment of atoms. ...

The Hertzian cone was first described by Hertz as a type of wave-front propagation through various media. His experiments help expand the field of electromagnetism 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. This was key to radar and was investigated and exploited later by others. Hertz did not understand the practical importance of his experiments. He stated that, A Hertzian cone is cone of force that propagates through a brittle, amorphous or cryptocrystalline solid material from a point of impact, eventually removing a full or partial cone; this result is familiar to anyone who has seen what happens to a plate-glass window when struck by a small... // For the controversy about who invented radio, see Invention of radio. ... This long range radar antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll. ...

"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." ^[2]

Asked about the ramifications of his discoveries, Hertz replied,

"Nothing, I guess." ^[2]

His discoveries would later be more fully understood by others and be part of the new "wireless age". In bulk, Hertz' experiment explain reflection, refraction, polarization, interference, and velocity of electric waves. This article or section is in need of attention from an expert on the subject. ... Reflection in electricity is the result of impedance mismatch in electrical signals. ... The straw seems to be broken, due to refraction of light as it emerges into the air. ... In electrodynamics, polarization (also spelled polarisation) is the property of electromagnetic waves, such as light, that describes the direction of their transverse electric field. ... Interference of two circular waves - Wavelength (decreasing bottom to top) and Wave centers distance (increasing to the right). ... The velocity of an object is its speed in a particular direction. ... Electromagnetism is the force observed as static electricity, and causes the flow of electric charge (electric current) in electrical conductors. ...

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 Helmholtz formulated 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. General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Standard atomic weight 26. ... Philipp Eduard Anton von Lénárd, (June 7, 1862 in Preßburg, Austria-Hungary (today Bratislava, Slovakia)–May 20, 1947 in Messelhausen, Germany) was a Hungarian-German physicist and the winner of the Nobel Prize for Physics in 1905 for his research on cathode rays and the discovery of... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Hermann Ludwig Ferdinand von Helmholtz (August 31, 1821 – September 8, 1894) was a German physician and physicist. ... Wilhelm Conrad Röntgen (in English: William Conrad Roentgen) (March 27, 1845 – February 10, 1923) was a German physicist, of the University of Würzburg, who, on November 8, 1895, produced and detected electromagnetic radiation in a wavelength range today known as x-rays or Röntgen Rays, an achievement...

Death and afterwards

Hertz's autograph

In 1892, an infection was diagnosed (after a bout of severe migraines) and Hertz underwent some operations to correct the illness. He died of blood poisoning at the age of 36 in Bonn, Germany. His nephew Gustav Ludwig Hertz was a Nobel Prize winner, and Gustav's son Carl Hellmuth Hertz invented medical ultrasonography. Image File history File links This is Heinrich Rudolf Hertzs autograph, from Oliver Heaviside: Sage in Solitude (ISBN 0-87942-238-6), p. ... Image File history File links This is Heinrich Rudolf Hertzs autograph, from Oliver Heaviside: Sage in Solitude (ISBN 0-87942-238-6), p. ... 1892 (MDCCCXCII) was a leap year starting on Friday (see link for calendar). ... Blood poisoning, also known as septicaemia, is a bacterial infection that occurs when bacteria get into the bloodstream and multiply rapidly. ... Bonn is the 19th largest city in Germany, located about 20 kilometres south of Cologne on the river Rhine in the Federal State of North Rhine-Westphalia. ... Gustav Ludwig Hertz (July 22, 1887, Hamburg – October 30, 1975, Berlin) was a German physicist, and a nephew of Heinrich Rudolf Hertz. ... The Nobel Prizes (Swedish: ) are awards in Physics, Chemistry, Literature, Peace, Physiology or Medicine and Economics. ... Carl Hellmuth Hertz (1920-1990) was the son of Gustav Ludwig Hertz. ... Medical ultrasonography (sonography) is an ultrasound-based diagnostic imaging technique used to visualize muscles and internal organs, their size, structures and possible pathologies or lesions. ...

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)). In 1969 (East Germany), there was cast a Heinrich Hertz memorial medal. 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". It was adopted by the CGPM (Conférence générale des poids et mesures) in 1964. A crater that lies on the far side of the Moon, just behind the eastern limb, is named in his honor. FreQuency is a music video game developed by Harmonix and published by SCEI. It was released in November 2001. ... GDR redirects here. ... Tycho crater on Earths moon. ... Far side of the Moon. ... Apparent magnitude: up to -12. ... Hertz is a lunar crater that lies on the far side of the Moon, just behind the eastern limb. ...

See also

The main building, viewed from the Hofgarten. ... The Universität Karlsruhe (TH) is a mainly technical university in the city of Karlsruhe, Germany and is a leading research university: It is among the five universities in Germany with the strongest effort in research. ...

Further reading

• Appleyard, Rollo, "Pioneers of electrical communication". London, Macmillan and co., limited, 1930. LCCN 30011090 //r87 ( ed. memoirs were published in Electrical communication.)
• Bodanis, David. Electric Universe: How Electricity Switched on the Modern World. New York: Three Rivers Press, 2005. ISBN 0-307-33598-4
• Buchwald, Jed Z., "The creation of scientific effects : Heinrich Hertz and electric waves". Chicago : University of Chicago Press, c1994. ISBN 0-226-07887-6 (alk. paper) ISBN 0-226-07888-4 (pbk.; alk. paper) LCCN 93041783
• Susskind, Charles, "Heinrich Hertz : a short life". San Francisco, CA : San Francisco Press, c1995. ISBN 0-911302-74-3
• Lodge, Oliver, "The work of Hertz and his successors : being a description of signalling across space without wires by electric waves, "The Electrician" series. Signalling without wires. London : "The Electrician" Printing and Pub. Co., [1897?], 2nd ed.
• Bryant, John H., "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 : Institute of Electrical and Electronics Engineers ; Piscataway, NJ : IEEE Service Center, Single Publication Sales Dept. [distributor], c1988. ISBN 0-87942-710-8 LCCN 88176362 (ed. 1988 IEEE/MTT-S Hertz Centennial Celebration exhibition at the 1988 MTT-S International Microwave Symposium)
• Baird, Davis. (ed.), Hughes, R. I. G. (ed.), and Nordmann, Alfred, (ed.), "Heinrich Hertz : classical physicist, modern philosopher". Boston studies in the philosophy of science. v. 198, Dordrecht ; Boston : Kluwer Academic Publishers, c1998. ISBN 0-7923-4653-X (hardcover; alk. paper) LCCN 97023406
• Ducretet, E., "La télégraphie hertzienne sans fils : expériences de Henri Hertz" (Tr., Hertzian telegraphy without wire: experiments of Henri Hertz). Guise (Aisne) : s.n., 1898 (Baré)
• Maugis, D., "Contact, Adhesion and Rupture of Elastic Solids". ISBN 3-540-66113-1, (Springer-Verlag)

References, external links, and other articles

Citations

1. ^ J. F. Mulligan and H. G. Hertz, "On the energy balance of the Earth", American Journal of Physics, vol. 65, pp 36-45
2. ^ ^{a b} Eugenii Katz, "Heinrich Rudolf Hertz". Biographies of Famous Electrochemists and Physicists Contributed to Understanding of Electricity, Biosensors & Bioelectronics.

Websites

Wikimedia Commons has media related to:

Heinrich Hertz

• Kim Breitfelder (Program Manager) and Mike Geselowitz, (Director), "Heinrich Hertz". IEEE History Center, IEEE 2006.
• John D. Jenkins, "The Discovery of Radio Waves - 1888; Heinrich Rudolf Hertz (1847-1894)". sparkmuseum.com.
• Francesco Errante, "Hertzian Radiation, (better known as radio-waves) : what it is and how it happens". Radiondistics.com.
• Russell Naughton, "Heinrich Rudolph (alt: Rudolf) Hertz, Dr : 1857 - 1894". Adventures in CyberSound.
• "Heinrich Rudolf Hertz". Institute of Experimental Physics, University of Debrecen.
• Wilhelm Mosel, "Buildings Integral to the Former Life and/or Persecution of Jews in Hamburg - Eimsbüttel/Rotherbaum". Deutsch-Jüdische Gesellschaft, Hamburg.
• "Heinrich Hertz". The First Electronic Church of America.
• "Heinrich Rudolph Hertz (1857 - 1894)". Corrosion-doctors.org.
• Struan Robertson, "Heinrich Hertz (1857 - 1894)". uni-hamburg.de. (ed. Hertz' portrait in the Hamburg City Hall.)
• Electric waves: being researches on the propagation of electric action with finite velocity through space by Heinrich Rudolph Hertz. Cornell University Library Historical Monographs Collection. {Reprinted by} Cornell University Library Digital Collections