Philipp Lenard

Philipp Eduard Anton von Lenard (Template:IPA; 7 June 1862 – 20 May 1947) was a Hungarian–German experimental physicist who received the Nobel Prize in Physics in 1905 for his work on cathode rays.<ref name=Nobel1905>Template:Cite web</ref> This work led to his experimental realization of the photoelectric effect, discovering that the energy (speed) of the electrons ejected from a cathode depends only on the frequency, and not the intensity of light.

As an active proponent of the Nazi ideology, Lenard supported Adolf Hitler in the 1920s and was an important role model for the Template:Lang movement during the Nazi period. Notably, he labeled Albert Einstein's contributions to theoretical physics as "Jewish physics."

Biography

Philipp Eduard Anton von Lenard was born on 7 June 1862 in Pressburg (now Bratislava, Slovakia), then located in the Kingdom of Hungary, the son of Philipp von Lenard (1812–1896), a wine merchant in Pressburg, and Antonie Baumann (1831–1865).<ref>Neue deutsche biografie XIV, 1984 München</ref> His father's family had originally come from Tyrol, while his mother's family originated from Baden; both parents were German-speaking.<ref>Template:Cite book</ref> Among his mostly Germanic ancestors, he also had Hungarian ones.

Lenard attended the Pozsonyi Királyi Katolikus Főgymnasium (today Gamča), and as he records in his autobiography, this made a big impression on him (especially the personality of his teacher, Virgil Klatt).<ref name="Lenard">Template:Cite web</ref> In 1880, he studied physics and chemistry in Vienna and in Budapest.<ref name="Lenard"/> In 1882, he left Budapest and returned to Pressburg, but in 1883 moved to Heidelberg after his tender for an assistant's position at the University of Budapest was refused. At the University of Heidelberg, he studied under Robert Bunsen, interrupted by one semester in Berlin with Hermann von Helmholtz. He also studied under Georg Quincke, and received his Ph.D. in 1886.<ref name=NobelBio>Template:Cite web</ref><ref>Template:Cite web</ref> The following year, he worked as a demonstrator under Loránd Eötvös at Budapest.<ref name="Lenard"/>

In 1892, Lenard became a Template:Lang and an assistant to Heinrich Hertz at the University of Bonn; Lenard and Hertz conducted experiments with cathode rays, which led to him winning the 1905 Nobel Prize in Physics.<ref name=NobelBio/> After brief stays at the University of Breslau (1894–1895), RWTH Aachen (1895–1896), and the University of Heidelberg (1896–1898), he was appointed Professor Ordinarius at the University of Kiel in 1898. In 1907, he returned to Heidelberg, where he remained until his retirement in 1931.<ref>Template:Cite web</ref>

Lenard died on 20 May 1947 in Messelhausen at the age of 84.<ref name=NobelBio/>

Research

Cathode rays

The dynamid atomic model, by Philipp Lenard, 1903

Lenard's major contribution to physics was 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. He 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 and materials.<ref>Template:Cite journal</ref> In particular, he came to use pentadecylparatolylketone, which was very effective as a cathode ray detector but, unfortunately for Lenard, not fluorescent in X-rays. When Wilhelm Röntgen set out to reproduce Lenard's results, he was forced to use barium platinocyanide instead because Lenard had purchased all the available pentadecyl-para-tolyl ketone. The alternative was sensitive to both UV and X-rays allowing Röntgen to discover X-rays.<ref>Template:Cite web</ref>

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.<ref>Template:Cite web</ref> 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 him 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

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 observation was that the energy of the rays in the photoelectric effect was independent of the light intensity. His interpretation however imagined that the light released rays already moving inside of atoms and he made no connection between the energy of the light and the electron.<ref>Template:Cite journal</ref>

These latter observations were explained by Albert Einstein as a quantum effect. Each quantum of light with sufficient energy resulted in one photoelectron, so the light intensity affected the electron flux intensity but not its energy. This theory predicted that the plot of the cathode ray energy versus the frequency would be a straight line with a slope equal to the Planck constant, h. This was shown to be the case some years later. The photoelectric quantum theory was the work cited when Einstein was awarded the Nobel Prize in Physics in 1921. Suspicious of the general adulation of Einstein, he 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 X-rays.<ref>Template:Cite web</ref><ref>Template:Cite web</ref> Lenard wrote that he—not Röntgen—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.<ref>Template:Cite journal</ref>

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.<ref>Template:Cite web</ref><ref>Template:Cite book</ref>Template:Rp

Lenard 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.<ref> Template:Cite web</ref>

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.<ref name="Rydell2017">Template:Cite book</ref><ref name="Kojevnikov2011">Template:Cite book</ref><ref name="Steinhaus2016">Template:Cite book</ref> Lenard and fellow experimental physicist Johannes Stark were increasingly sidelined and ignored in the 1920's due to their rejection of the theory of relativity and of quantum mechanics.<ref>Template:Cite journal</ref> During the Nazi regime, he was the outspoken proponent of the idea that Germany should rely on "Template:Lang" 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).<ref>"How 2 Pro-Nazi Nobelists Attacked Einstein’s "Jewish Science". Scientific American. Retrieved 30 January 2021.</ref> Lenard became Chief of Aryan Physics under the Nazis.<ref>Nobel prize 1905</ref> In his foreword to his four volume science textbook Template:Lang he argued that like everything that man creates, science is determined by race.<ref>Template:Cite book</ref>

Lenard's book, Great Men in Science, A History of Scientific Progress, first published in English in 1933,<ref>Template:Cite book</ref> claimed these men were all "Aryan scientists".<ref>Template:Cite book</ref> The individual scientists selected for inclusion by Lenard do not include Einstein or Marie Curie, nor any other twentieth-century scientist. 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".

The ideologists of Nazism in Germany argued that the theory of relativity was inextricably linked to materialism and Marxism.<ref name="t356">Template:Cite book</ref> The most notable of them was Lenard.<ref name="t356"/> Lenard had become the head of Deutsche Physik ("Aryan physics"), a philosophy of science that dismissed the contributions of Albert Einstein and other Jewish physicists as "Jewish physics".<ref name="nobel">Template:Cite web</ref> Einstein had discovered the mechanism of the photoelectric effect, which Lenard had detected experimentally but could not explain theoretically.<ref name="nobel"/>

Lenard called Einstein's theories "Jewish fraud."<ref name="z006">Template:Cite book</ref> Lenard especially hated physics based on advanced mathematics.<ref name="i308">Template:Cite book</ref> Lenard, in particular, and in general the experimental physicists of that time did not understand advanced mathematics.<ref name="e521">Template:Cite book</ref> They described their laboratory observations in prose rather than mathematically.<ref name="e521"/>

Awards

Country	Year	Institute	Award	Citation	Template:Reference column heading
Template:Flagdeco United Kingdom	1896	Royal Society	Rumford Medal	"For their investigations of the phenomena produced outside a highly exhausted tube, through which an electrical discharge is taking place" (with Wilhelm Röntgen)	<ref>Template:Cite web</ref>
Template:Flagdeco Italy	1896	Accademia dei XL	Matteucci Medal		<ref>Template:Cite web</ref>
Template:Flag	1905	Royal Swedish Academy of Sciences	Nobel Prize in Physics	"For his work on cathode rays"	<ref name=Nobel1905/>
Template:Flag	1932	Franklin Institute	Franklin Medal	"For research of cathode rays and photoelectricity"	<ref>Template:Cite web</ref>

Legacy

Template:Lang had been named the Template:Lang from 1927 until 1945, when it was renamed by the Mayor of Heidelberg as part of the denazification process.<ref name="HGH1">Geierhaas, Theo. "Schulgeschichte". Helmholtz-Gymnasium Heidelberg. Retrieved 4 March 2019 Template:In lang.</ref>

Lenard crater near the north pole of the Moon was named in his honor from 2005 (approved in 2008) until 2020. When the International Astronomical Union learned of Lenard's Nazi connection, they decided to drop the name.<ref>Template:Cite web</ref><ref>Template:GPN</ref>

Cultural references

• Lenard's criticism of the theory of relativity and his crusade against Einstein and his theories was covered in an episode of Dark Matters: Twisted But True, in a segment entitled "Einstein's Revenge".
• The life of Lenard and the interrelationship between his work and that of Albert Einstein is the subject of the book The Man Who Stalked Einstein: How Nazi Scientist Philipp Lenard Changed the Course of History by Bruce J. Hillman, Birgit Ertl-Wagner and Bernd C. Wagner.
• Lenard was portrayed by actor Michael McElhatton in the 2017 National Geographic anthology period drama television series Genius.<ref>Template:Cite web</ref>
• Lenard featured as the villain in the seventh episode of Super Science Friends.

Bibliography

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• Lenard, Philipp (1931) (in German). Erinnerungen eines Naturforschers. New edition: Erinnerungen eines Naturforschers – Kritische annotierte Ausgabe des Originaltyposkriptes von 1931/1843 (Arne Schirrmacher, ed.). Springer Verlag, Heidelberg 2010, 344 pages, Template:ISBN, e-Template:ISBN.
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• Template:Cite book 1. Einleitung und Mechanik, 2. Akustik und Wärmelehre, 3. Optik, Elektrostatik und Anfänge der Elektrodynamik (or: 3. Optik und Elektrizitätslehre 1. Teil), 4. Magnetismus, Elektrodynamik und Anfänge von weiterem (or: Elektrizitätslehre 2. Teil). Later editions, 1943

See also

• Cavity magnetron
• Fluid thread breakup

References

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External links

• Template:Nobelprize including the Nobel Lecture, 28 May 1906 On Cathode Rays
• On Cathode Rays
• The Cathode Ray Tube site
• Template:MathGenealogy
• Template:PM20