Philipp Lenard

Last updated
Philipp Lenard
Phillipp Lenard in 1900.jpg
Philipp Lenard in 1900
Philipp Eduard Anton von Lenard

(1862-06-07)7 June 1862
Pressburg, Kingdom of Hungary, Austrian Empire (present-day Bratislava, Slovakia)
Died20 May 1947(1947-05-20) (aged 84)
CitizenshipHungarian [1] (1862–1907)
German (1907–1947)
Alma mater University of Heidelberg
Known for Cathode rays
Photoelectric effect
Grid control
Lenard window
SpouseKatharina Schlehner
Awards Matteucci Medal (1896)
Rumford Medal (1896)
Nobel Prize for Physics (1905)
Franklin Medal (1932)
Scientific career
Fields Physics
Institutions University of Budapest
University of Breslau
University of Aachen
University of Heidelberg
University of Kiel
University of Berlin
Doctoral advisor R. Bunsen
G. H. Quincke
Doctoral students Edward Andrade
Walther Kossel

Philipp Eduard Anton von Lenard (German pronunciation: [ˈfɪlɪp ˈleːnaʁt] ( Loudspeaker.svg listen ); Hungarian : Lénárd Fülöp Eduárd Antal; 7 June 1862 – 20 May 1947) was a Hungarian-born German physicist and the winner of the Nobel Prize for Physics in 1905 for his work on cathode rays and the discovery of many of their properties. One of his most important contributions was the experimental realization of the photoelectric effect. He discovered that the energy (speed) of the electrons ejected from a cathode depends only on the wavelength, and not the intensity, of the incident light.


Lenard was a nationalist and anti-Semite; as an active proponent of the Nazi ideology, he supported Adolf Hitler in the 1920s and was an important role model for the "Deutsche Physik" movement during the Nazi period. Notably, he labeled Albert Einstein's contributions to science as "Jewish physics".

Early life and work

Philipp Lenard was born in Pressburg (Pozsony, today's Bratislava), on 7 June 1862 in the Kingdom of Hungary. The Lenard family had originally come from Tyrol in the 17th century, and the family-name indicates italian origin, while his mother's family originated from Baden, the parents were German-speaking. [2] His father, Philipp von Lenardis (1812–1896), was a wine-merchant in Pressburg. His mother was Antonie Baumann (1831–1865). [3] But he had also magyar ancestors among his mostly germanic ones. The young Lenard studied at the Pozsonyi Királyi Katolikus Főgymnasium (today Gamča), and as he writes it in his autobiography, this made a big impression on him (especially the personality of his teacher, Virgil Klatt). [4] In 1880, he studied physics and chemistry in Vienna and in Budapest. [4] In 1882, Lenard left Budapest and returned to Pressburg, but in 1883, he moved to Heidelberg after his tender for an assistant's position in the University of Budapest was refused. In Heidelberg, he studied under the illustrious Robert Bunsen, interrupted by one semester in Berlin with Hermann von Helmholtz, and he obtained a doctoral degree in 1886. [5] In 1887 he worked again in Budapest under Loránd Eötvös as a demonstrator. [4] After posts at Aachen, Bonn, Breslau, Heidelberg (1896–1898), and Kiel (1898–1907), he returned finally to the University of Heidelberg in 1907 as the head of the Philipp Lenard Institute. In 1905, Lenard became a member of the Royal Swedish Academy of Sciences, and in 1907, of the Hungarian Academy of Sciences. [4]

His early work included studies of phosphorescence and luminescence and the conductivity of flames.

Contributions to physics

Photoelectric investigations

The dynamid atomic model, by Philipp Lenard, 1903 The dynamid atomic model, by Philipp Lenard, 1903.gif
The dynamid atomic model, by Philipp Lenard, 1903

As a physicist, Lenard's major contributions were in the study of cathode rays, which he began in 1888. Prior to his work, cathode rays were produced in primitive, partially evacuated glass tubes that had metallic electrodes in them, across which a high voltage could be placed. Cathode rays were difficult to study using this arrangement, because they were inside sealed glass tubes, difficult to access, and because the rays were in the presence of air molecules. Lenard overcame these problems by devising a method of making small metallic windows in the glass that were thick enough to be able to withstand the pressure differences, but thin enough to allow passage of the rays. Having made a window for the rays, he could pass them out into the laboratory, or, alternatively, into another chamber that was completely evacuated. These windows have come to be known as Lenard windows. He was able to conveniently detect the rays and measure their intensity by means of paper sheets coated with phosphorescent materials. [6]

Lenard observed that the absorption of cathode rays was, to first order, proportional to the density of the material they were made to pass through. This appeared to contradict the idea that they were some sort of electromagnetic radiation. He also showed that the rays could pass through some inches of air of a normal density, and appeared to be scattered by it, implying that they must be particles that were even smaller than the molecules in air. He confirmed some of J. J. Thomson's work, which eventually arrived at the understanding that cathode rays were streams of negatively charged energetic particles. He called them quanta of electricity or for short quanta, after Helmholtz, while Thomson proposed the name corpuscles, but eventually electrons became the everyday term. [7] In conjunction with his and other earlier experiments on the absorption of the rays in metals, the general realization that electrons were constituent parts of the atom enabled Lenard to claim correctly that for the most part atoms consist of empty space. He proposed that every atom consists of empty space and electrically neutral corpuscules called "dynamids", each consisting of an electron and an equal positive charge.

Lenard window tube Lenard window tube labeled.svg
Lenard window tube

As a result of his Crookes tube investigations, he showed that the rays produced by irradiating metals in a vacuum with ultraviolet light were similar in many respects to cathode rays. His most important observations were that the energy of the rays was independent of the light intensity, but was greater for shorter wavelengths of light. [8]

These latter observations were explained by Albert Einstein as a quantum effect. This theory predicted that the plot of the cathode ray energy versus the frequency would be a straight line with a slope equal to Planck's constant, h. This was shown to be the case some years later. The photo-electric quantum theory was the work cited when Einstein was awarded the Nobel Prize in Physics in 1921. Suspicious of the general adulation of Einstein, Lenard became a prominent skeptic of relativity and of Einstein's theories generally; he did not, however, dispute Einstein's explanation of the photoelectric effect. Lenard grew extremely resentful of the credit accorded to Wilhelm Röntgen, who received the first Nobel Prize in physics in 1901, for the discovery of the X-ray, [9] [10] despite the fact that Röntgen was German and a non-Jew. Lenard wrote that he, not Roentgen, was the "mother of the X-rays," since he had invented the apparatus used to produce them. Lenard likened Röntgen's role to that of a "midwife" who merely assists with the birth.

Lenard received the 1905 Nobel Prize for Physics in recognition of this work.

Meteorological contributions

Lenard was the first person to study what has been termed the Lenard effect in 1892. This is the separation of electric charges accompanying the aerodynamic breakup of water drops. It is also known as spray electrification or the waterfall effect. [11]

He conducted studies on the size and shape distributions of raindrops and constructed a novel wind tunnel in which water droplets of various sizes could be held stationary for a few seconds. He was the first to recognize that large raindrops are not tear-shaped, but are rather shaped something like a hamburger bun. [12]

Deutsche Physik

Lenard is remembered today as a strong German nationalist who despised "English physics", which he considered to have stolen its ideas from Germany. [13] [14] [15] During the Nazi regime, he was the outspoken proponent of the idea that Germany should rely on "Deutsche Physik" and ignore what he considered the fallacious and deliberately misleading ideas of "Jewish physics", by which he meant chiefly the theories of Albert Einstein, including "the Jewish fraud" of relativity (see also criticism of the theory of relativity). [16] An advisor to Adolf Hitler, Lenard became Chief of Aryan Physics under the Nazis. [17]

Some measure of Lenard's views on certain scientists may be deduced through examination of Lenard's book, Great Men in Science, A History of Scientific Progress, first published in English in 1933. The book was translated into English by H. Stafford Hatfield with an introduction by his onetime student Edward Andrade of University College London, and was widely read in schools and universities after the Second World War.[ citation needed ] The individual scientists selected for inclusion by Lenard do not include Einstein or Marie Curie, nor any other twentieth-century scientist. Andrade noted that "A strong individuality like that of the writer of this book is bound to assert strongly individual judgements". [18] The publisher included what now appears to be a remarkable understatement on page xix of the 1954 English edition: "While Professor Lenard's studies of the men of science who preceded him showed not only profound knowledge but also admirable balance, when it came to men of his own time he was apt to let his own strong views on contemporary matters sway his judgment. In his lifetime he would not consent to certain modifications that were proposed in the last study of the series".

Later life

Lenard retired from Heidelberg University as professor of theoretical physics in 1931. He achieved emeritus status there, but he was expelled from his post by Allied occupation forces in 1945 when he was 83. The Helmholtz-Gymnasium Heidelberg had been named the Philipp Lenard Schule from 1927 until 1945. As part of the elimination of Nazi street names and monuments it was renamed in September 1945 by order of the military government. [19] Lenard died in 1947 in Messelhausen, Germany.

Honours and awards

Cultural references



  1. "Lénárd Fülöp (1862–1947)". Sulinet (in Hungarian). Archived from the original on 2007-11-16.
  2. Pöss, Ondrej (2012). "Karpatskí Nemci". In Nagy, Myrtil (ed.). Naše národnostné menšiny. Šamorín: Fórum inštitút pre výskum menšín. pp. 9–12. ISBN   978-80-89249-57-2.
  3. Neue deutsche biografie XIV, 1984 München
  4. 1 2 3 4 Palló, Gabriel (1997). "Fizikai Szemle; ELEKTRON ÉS ÉTERFIZIKA: LÉNÁRD FÜLÖP (1862–1947)" (in Hungarian). Hungarian Academy of Sciences, Physical Sciences Section. p. 116. Written in Hungarian by the autobiography of the famous physicist: Philipp Lenard, Erinnerungen eines Naturwissenschaftlers, der Kaiserreich, Judenschaft und Hitler erlebt hat. Geschrieben September 1930 bis Mrz 1931
  5. "Lénárd Fülöp". Retrieved 2013-07-13.
  6. Lenard, Philipp (1894). "Ueber Kathodenstrahlen in Gasen von atmosphärischem Druck und im äussersten Vacuum". Annalen der Physik. 287 (2): 225–267. Bibcode:1894AnP...287..225L. doi:10.1002/andp.18942870202.
  7. "Lenard's Nobel lecture (1906)" (PDF). Retrieved 2010-08-25.
  8. Wheaton, Bruce R. (1978). "Philipp Lenard and the Photoelectric Effect, 1889-1911". Historical Studies in the Physical Sciences. 9: 299–322. doi:10.2307/27757381. JSTOR   27757381.
  9. "When science gets ugly – the story of Philipp Lenard and Albert Einstein" . Retrieved 2018-08-25.
  10. "Science Gets Political, Einstein Gets Fired in Nat Geo's 'Genius'". . 9 May 2017.
  11. "American Meteorological Society Glossary". 2013-06-25. Archived from the original on 2012-02-05. Retrieved 2013-07-13.
  12. Volynets, Igor (2001). Elert, Glenn (ed.). "Diameter of a raindrop". The Physics Factbook. Retrieved 2019-08-19.
  13. Rydell, Anders (7 February 2017). The Book Thieves: The Nazi Looting of Europe's Libraries and the Race to Return a Literary Inheritance. Penguin. pp. 86–. ISBN   978-0-7352-2124-6.
  14. Kojevnikov, Alexei (2011). Weimar Culture and Quantum Mechanics: Selected Papers by Paul Forman and Contemporary Perspectives on the Forman Thesis. World Scientific. pp. 33–. doi:10.1142/7581. ISBN   978-981-4293-12-9.
  15. Steinhaus, Hugo (8 February 2016). Mathematician for All Seasons: Recollections and Notes, Vol. 2 (1945–1968). Birkhäuser. pp. 105–. ISBN   978-3-319-23102-0.
  16. "How 2 Pro-Nazi Nobelists Attacked Einstein’s "Jewish Science". Scientific American. Retrieved 30 January 2021.
  17. Nobel prize 1905
  18. Lenard, Philipp (1933). Great Men of Science. London: G. Bell and sons. p. xi. OCLC   1156317.
  19. Geierhaas, Theo. "Schulgeschichte". Helmholtz-Gymnasium Heidelberg. Retrieved 4 March 2019 (in German).
  20. Marie), Abbé Moigno (François Napoléon (1898). "Prix La Caze". Cosmos: Revue des Sciences et de Leurs Applications. 38 (678): 122.
  21. Ball, Philipp (26 June 2020). "Astronomers unknowingly dedicated moon craters to Nazis". Retrieved 26 June 2020.
  22. "Philipp Lenard". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.
  23. "Genius – Chapter One". Retrieved 2017-05-06.

See also

Related Research Articles

<span class="mw-page-title-main">Heinrich Hertz</span> German physicist (1857–1894)

Heinrich Rudolf Hertz 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.

<span class="mw-page-title-main">Max Planck</span> German theoretical physicist (1858–1947)

Max Karl Ernst Ludwig Planck was a German theoretical physicist whose discovery of energy quanta won him the Nobel Prize in Physics in 1918.

<span class="mw-page-title-main">Walther Bothe</span> German nuclear physicist and Nobel Prize shared with Max Born

Walther Wilhelm Georg Bothe was a German nuclear physicist, who shared the Nobel Prize in Physics in 1954 with Max Born.

<span class="mw-page-title-main">Max von Laue</span> German physicist

Max Theodor Felix von Laue was a German physicist who received the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals.

<span class="mw-page-title-main">Johannes Stark</span> German physicist and Nobel laureate

Johannes Stark was a German physicist who was awarded the Nobel Prize in Physics in 1919 "for his discovery of the Doppler effect in canal rays and the splitting of spectral lines in electric fields". This phenomenon is known as the Stark effect.

<i>Deutsche Physik</i> Nationalist movement in the German physics community in the early 1930s

Deutsche Physik or Aryan Physics was a nationalist movement in the German physics community in the early 1930s which had the support of many eminent physicists in Germany. The term was taken from the title of a four-volume physics textbook by Nobel laureate Philipp Lenard in the 1930s.

<span class="mw-page-title-main">Friedrich Hasenöhrl</span> Austrian physicist

Friedrich Hasenöhrl was an Austrian physicist.

Rudolf Seeliger was a German physicist who specialized in electric discharges in gases and plasma physics.

Ernst J. L. Gehrcke was a German experimental physicist. He was director of the optical department at the Reich Physical and Technical Institute. Concurrently, he was a professor at the University of Berlin. He developed the Lummer–Gehrcke method in interferometry and the multiplex interferometric spectroscope for precision resolution of spectral-line structures. As an anti-relativist, he was a speaker at an event organized in 1920 by the Working Society of German Scientists. He sat on the board of trustees of the Potsdam Astrophysical Observatory. After World War II, he worked at Carl Zeiss Jena, and he helped to develop and become the director of the Institute for Physiological Optics at the University of Jena. In 1949, he began work at the German Office for Materials and Product Testing. In 1953, he became the director of the optical department of the German Office for Weights and Measures.

<i>Annus mirabilis</i> papers Papers of Albert Einstein published in the scientific journal Annalen der Physik in 1905

The annus mirabilis papers are the four papers that Albert Einstein published in Annalen der Physik, a scientific journal, in 1905. These four papers were major contributions to the foundation of modern physics. They revolutionized science's understanding of the fundamental concepts of space, time, mass, and energy. Because Einstein published these remarkable papers in a single year, 1905 is called his annus mirabilis.

  1. The first paper explained the photoelectric effect, which established the energy of the light quanta , and was the only specific discovery mentioned in the citation awarding Einstein the Nobel Prize in Physics.
  2. The second paper explained Brownian motion, which established the Einstein relation and led reluctant physicists to accept the existence of atoms.
  3. The third paper introduced Einstein's theory of special relativity, which established the universal constant speed of light for all reference frames and a theory of spacetime.
  4. The fourth, a consequence of the theory of special relativity, developed the principle of mass-energy equivalence, expressed in the famous equation and which led to the discovery and use of atomic energy.

Bruno Jakob Thüring was a German physicist and astronomer.

<span class="mw-page-title-main">Kaufmann–Bucherer–Neumann experiments</span>

The Kaufmann–Bucherer–Neumann experiments measured the dependence of the inertial mass of an object on its velocity. The historical importance of this series of experiments performed by various physicists between 1901 and 1915 is due to the results being used to test the predictions of special relativity. The developing precision and data analysis of these experiments and the resulting influence on theoretical physics during those years is still a topic of active historical discussion, since the early experimental results at first contradicted Einstein's then newly published theory (1905), but later versions of this experiment confirmed it. For modern experiments of that kind, see Tests of relativistic energy and momentum, for general information see Tests of special relativity.

Jakob Johann Laub was a physicist from Austria-Hungary, who is best known for his work with Albert Einstein in the early period of special relativity.

Wolfgang Gentner was a German experimental nuclear physicist.

In physics, a quantum is the minimum amount of any physical entity involved in an interaction. The fundamental notion that a physical property can be "quantized" is referred to as "the hypothesis of quantization". This means that the magnitude of the physical property can take on only discrete values consisting of integer multiples of one quantum.

Rudolf Karl Anton Tomaschek was a German experimental physicist. His scientific efforts included work on phosphorescence, fluorescence, and (tidal) gravitation. Tomaschek was a supporter of deutsche Physik, which resulted in his suspension from his university posts after World War II. From 1948 to 1954, he worked in England for the Anglo-Iranian Oil Company (AIOC). In 1954, when AIOC became BP, he went to Germany and was president of the Permanent Tidal Commission.

Alfons Bühl (1900–1988) was a German physicist. From 1934 to 1945, he was director of the physics department at the Technische Hochschule Karlsruhe.

Criticism of the theory of relativity of Albert Einstein was mainly expressed in the early years after its publication in the early twentieth century, on scientific, pseudoscientific, philosophical, or ideological bases. Though some of these criticisms had the support of reputable scientists, Einstein's theory of relativity is now accepted by the scientific community.

<span class="mw-page-title-main">Klaus Hentschel</span> German physicist and historian of science

Klaus Hentschel is a German physicist, historian of science and Professor and head of the History of Science and Technology section in the History Department of the University of Stuttgart. He is known for his contributions in the field of the history of science.

<span class="mw-page-title-main">Helmholtz-Gymnasium Heidelberg</span> School in Heidelberg, Germany

Helmholtz-Gymnasium Heidelberg (HGH) is a state-funded gymnasium located on Rohrbacher Straße 102 in Heidelberg, Germany. Founded in 1835, it is now named Helmholtz-Gymnasium after Hermann von Helmholtz, but from 1927 until 1945 it was known as the Philipp Lenard Schule after Philipp Lenard. As of 2018, it had 891 pupils. In addition to its academic curriculum, it is designated by the German Olympic Sports Confederation as an "Eliteschule des Sports".