Background

Lenard was born on June 7, 1862, in Pressburg, Kingdom of Hungary (today Bratislava, Slovakia), the son of a wealthy winemaker and wholesaler, Philipp von Lenardis (1812-1896). His mother, the former Antonie Baumann, died young, and Lenard, an only child, was raised by an aunt who subsequently married his father.

Education

Lenard was at first educated at home, but when he was nine he entered the cathedral school, Pozsonyi Királyi Katolikus Gimnázium, in Pressburg and the later the Realschule. For him, mathematics and physics were “oases in the desert” of other subjects, and he studies these two subjects by himself with the aid of college textbooks. In addition, he carried out chemistry and physics experiments on his own. He once devoted his summer vacation entirely to study of the new field of photography.

In 1880 he studied physics and chemistry in Vienna and in Budapest. In Heidelberg he studied under the illustrious Robert Bunsen, interrupted by one semester in Berlin with Hermann von Helmholtz, and obtained his doctoral degree in 1886.

Career

Since Lenard returned to Pressburg on university vacations, he was able to devote greater effort to the work he had begun while a student with his Gymnasium teacher Virgil Klatt. Their joint undertaking opened up for Lenard an important field of research, phosphoresences, in which he carried out investigations for more than forty years. As Klatt gradually withdrew from the work, Lenard played an increasingly large role. when, toward the end of his life, three volumes of his planned four volume Wissenschaftliche Abhandlungen were published, the entire second volume was devoted to this topic. As early as 1889 he had discovered that phosphorescence is caused by the presence of very small quantities of copper, bismuth, or manganese in what were previously thought to be pure alkaline earth sulfides.

After three years as an assistant at Heidelberg, Lenard spent half a year in England, where he worked in the electromagnetic and engineering laboratories of the “City and guides of the London Central Institution.” Afterwards he was an assistant for a semester at Breslau and then came to Bonn on April 1, 1891, to work in the same capacity under Hertz, who was already famous for his discovery of electromagnetic waves. Lenard was a great admirer of Hertz, yet his hypersensitivity, which later became pathological, caused him to feel neglected and pushed aside even by Hertz. When Hertz died unexpectedly on 1 January 1894, at the age of thirty-six, Lenard took charge of the publication of the three-volume Gesammelte Werke. He had to sacrifice much time for this task, especially for the Prinzipien der Mechanik, which, although complete, required editing. More than two decades later Lenard published a literary monument to Hertz in Grosse Naturforscher. In the meantime, however, Lenard had developed his racial ideology and he felt obliged to reveal that he had detected a split personality in Hertz, whose father’s family was Jewish. Hertz’s theoretical works, especially the Prinzipien der Mechanik, seemed to Lenard a characteristic product of his Jewish inheritance.

Lenard qualified as a lecturer in 1892 with a work on hydroelectricity, but he was principally engaged in continuing the cathode ray experiments that Hertz had begun. Cathode rays had been Lenard’s favorite topic since 1880 when he had read Sir William Crookes’s paper “Radiant Matter or the Fourth Physical State.”

Lenard utilized Hertz’s discovery that thin metal sheets transmit cathode rays, and at the end of 1892 he constructed a tube with a “Lenard window.” With this device, he was able to direct the rays out of the discharge space and into either open-air or a second evacuated space, where they could be further examined independently of the discharge process.

Like Jean Perrin, Willy Wien, and J. J. Thomson, Lenard established that cathode rays consist of negatively charged particles. In harsh priority disputes, especially with Thomson, Lenard claimed, on the basis of his 1898 publication “Über die electrostatischen Eigenschaften der Kathodenstrahlen,” to have made the first “incontestable, convincing determination of what were soon called ’electrons.’”

Lenard was, in fact, able to infer from the absorption of the cathode rays by matter the correct conclusion that the effective center of the atom is concentrated in a tiny fraction of the atomic volume previously accepted in the kinetic theory of gases. Lenard’s “dynamide” was an important predecessor of the atomic model of Rutherford, who in 1910-1911, on the basis of the deflections of α particles, drew the same conclusion as Lenard had earlier from the scattering of electrons.

At Hertz’s untimely death, Lenard was also obliged to act as a director of the laboratory. At the initiative of Friedrich Theodor Althoff, of the Prussian Ministry of Education, he obtained his first offer of a tenured position, an associate professorship at Breslau (October 1894). Since hardly any possibility of experimental work existed at Breslau, Lenard gave up this post after a year in favor of a nontenured lectureship at the Technische Hochschule in Aachen - as an assistant to Adolph Wüllner.

In October 1896 Lenard accepted an offer of an extraordinary professorship at Heidelberg. Two years later he went to Kiel-as a full professor and director of the physics laboratory. After a few years, he was able to build a new laboratory. In 1902 Lenard succeeded in discovering important properties of the photoelectric effect. He found that as the intensity of the light increases the number of electrons set free rises, but their velocity remains unaffected: the velocity depends solely on the wavelength. The interpretation of this relationship was provided in 1905 by Albert Einstein’s hypothesis of light quanta.

In 1905 Lenard received the Nobel Prize in physics for his cathode ray experiments; and in 1907 he succeeded Quincke as professor and director of the physics and radiology laboratory at the University of Heidelberg. Once more a new laboratory was constructed, on a splendid site on Philosophenweg, above the city; it was completed just before the outbreak of World War I. The laboratory was renamed the Philipp Lenard Laboratory in 1935.

After the murder of Walther Rathenau, a state funeral and full cessation of work was decreed for 27 June 1922. Lenard protested by having the physics laboratory remain open. After the Heidelberg memorial service, where it became known that Lenard had stated he would not give his students time off because of a dead Jew, a crowd of hundreds of angry students and workers, led by the future Social Democratic Reichstag deputy, Carlo Mierendorff, stormed the laboratory. Lenard was taken into protective custody by police officials called to the scene and was released a few hours later. The incident attracted great attention throughout the country, and passionate stands were taken on both sides.

Lenard’s anti-Semitism and nationalism increased. He attributed the turmoil in the newspapers about the general theory of relativity to an agreement between Einstein and the Jewish press. When the so-called Arbeitsgemeinschaft deutscher Naturforscher zur Erhaltung reiner Wissenschaft, founded by nationalistic and anti-Semitic demagogues, began a slander campaign against Einstein in Berlin in the summer of 1920, Lenard volunteered to head the movement.

The growing conflict broke into the open on 9 September 1920 at the eighty-sixth conference of the Deutsche Naturforscher und Ärzte in Bad Nauheim. The debate over the general theory of relativity turned into a dramatic duel between Einstein and Lenard. Fortunately, Max Planck, who was presiding over the debate, was able to prevent an uproar.

Along with personal antagonisms, another cause of Lenard’s deep dissatisfaction - which often expressed itself in unusual aggression - was that mathematically difficult theories were attaining a decisive position in physics. Lenard, whose strength lay in experimentation, could not and did not want to follow this path. His anti-Semitism, joined with this disinclination for the new physical theories, led him to contrast the “dogmatic Jewish physics” with a pragmatic “German physics,” in which experiments were paramount. In 1936-1937 Lenard published four volumes of experimental physics with the title Deutsche Physik, based on his lectures of the preceding decades.

Only a very few of his colleagues (notably Stark) took Lenard’s side, and his efforts remained, despite the support of the Third Reich, fruitless.

Lenard was among the ealiest adherents of National Socialism, and on 29 February 1924 he concluded his lectures for the winter semester with a reference to Hitler as the “true philosopher with a clear mind” on 8 May his appeal to Hitler, consigned by Stark, appeared in the Grossdeutsche Zeitung; and on 19 December of the same year he expressed the hope, also in a lecture, that Hitler would soon be released from prison. On 15 May 1926 Lenard traveled to a party meeting in Heilbronn, in order to meet Adolf Hitler in person. Further meetings followed, and throughout his life Hitler prized, even revered, this Noble laureate who, unlike the other German scientists who treated Hitler as someone only half educated, had followed him unconditionally from the beginning.

Lenard became Hitler’s authority in physics, teaching him, as Albert Speer reports in his memoirs, that in nuclear physics and relativity theory the Jews exercised a destructive influence. Hitler thus occasionally referred to nuclear physics as “Jewish Physics,” which resulted in delays in support for nuclear research. This ideological blindness and the expulsion of Jewish scientists from the Third Reich could only have had a damaging, perhaps fatal, effect on any German efforts to develop nuclear weapons - despite the early commanding lead of German physics.

After World War II, Lenard was not arrested (he was eighty-three), but he left Heidelberg, probably on orders, to live in the small village of Messelhausen, where he died.

Achievements

• Lenard's most important contribution 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. His results had important implications for the development of electronics and nuclear physics.

Works

More photos

• book

  • Über Energie Und Gravitation

    (German Edition)

    1929
  • Uber Kathodenstrahlen

    (German Edition)

  • Miscellaneous Papers; With an Introduction by Philipp Lenard
  • Great Men of Science 1933

Politics

Philipp von Lenard was a nationalist and anti-Semite; as an active proponent of the Nazi ideology, he had supported Adolf Hitler in the 1920s and was an important role model for the "Deutsche Physik" movement during the Nazi period.

In August 1914 Lenard was swept along by the wave of patriotism and nationalism. Most scientists eventually found their way back to a more sober view, but Lenard persisted in his position of supernationalism. He composed the libelous England und Deutschland zur Zeit des grossen Krieges, in which he asserted that the work of German researchers was systematically hidden and plagiarized by their British colleagues. Congratulating Stark on the new advances on the effect that he had discovered, Lenard wrote (14 July 1915) with anger (which Stark shared) about the Dutch physicists whose sympathies were with the Allies: “Knowledge of the atoms is thus progressing well. That this now can happen among us cannot be put forth even by the ‘neutralists’ themselves as an English achievement.”

After Germany’s defeat, Lenard felt himself called upon, as a teacher, to incite student youth against the ruling parties of the Weimar Republic, whom he despised for their democratic and anti-militaristic views. His final lecture for 1919 ended with the words: “We are a dishonorable nation, because we are a disarmed nation. He who does not offer resistance is worth nothing. To whom do we owe our dishonor? To the present rulers. Work, as I believe you will, so that next year we will have another government.”

Views

Following Roentgen’s discovery of X rays at the end of 1895, Lenard was deeply depressed that he, in the course of his constant experimenting with cathode ray tubes, had not achieved this success himself. Moreover, before the discovery was made, Lenard had provided Roentgen, at the latter’s request, with a “reliable” tube and Roentgen did not reveal whether or not the discovery was made with this tube. Thus Lenard felt that his contribution should have been acknowledged in Roentgen’s “Über eine neue Art von Strahlen.” The affair left a permanent scar, and Lenard never used the term Röntgenstrahlen, although it became standard usage in Germany. He spoke only of “high frequency radiation.”

Membership

• Royal Swedish Academy of Sciences , Sweden

  1905

• Hungarian Academy of Sciences , Hungary

  1907

Personality

Lenard is said to be hypersensitive, which later became pathological, and caused him to feel neglected and pushed aside even by his colleagues.

In 1909, Adolf von Harnack, in the famous memorandum which led to the founding of the Kaiser Wilhelm Society, called Lenard the “most celebrated scientist” in the field of physical research. The initiated had a different opinion. In the summer of 1910, Einstein wrote to his friend Johann Jakob Laub, who was working as Lenard’s assistant at Heidelberg: “Lenard must be very ’unevenly developed’ in many things. His recent lecture on the abstruse ether [Über Äther und Materie (Heidelberg, 1910)] seems to me almost infantile. Moreover, the investigation that he has forced upon you … borders very closely on the ludicrous. I am sorry that you have to waste your time with such stupidities.”

Quotes from others about the person

• In 1909, Adolf von Harnack, in the famous memorandum which led to the founding of the Kaiser Wilhelm Society, called Lenard the “most celebrated scientist” in the field of physical research. The initiated had a different opinion. In the summer of 1910, Einstein wrote to his friend Johann Jakob Laub, who was working as Lenard’s assistant at Heidelberg: “Lenard must be very ’unevenly developed’ in many things. His recent lecture on the abstruse ether [Über Äther und Materie (Heidelberg, 1910)] seems to me almost infantile. Moreover, the investigation that he has forced upon you … borders very closely on the ludicrous. I am sorry that you have to waste your time with such stupidities.”

Interests

• Politicians

  Adolf Hitler

Connections

Nothing is known of Lenard's family.

Father:

Philipp von Lenardis

Mother:

Antonie Baumann

colleague:

Heinrich Hertz

colleague:

Albert Einstein

ally:

Adolf Hitler

References

• Dictionary of Scientific Biography Volume 7
  1973
• The Man Who Stalked Einstein: How Nazi Scientist Philipp Lenard Changed the Course of History
  2015
• Philipp Lenard: Erinnerungen eines Naturforschers
  2009
• Albert Einstein und Philipp Lenard: Antipoden im Spannungsfeld von Physik und Zeitgeschichte
  2000