Lenard, Philipp

views updated May 23 2018

Lenard, Philipp

(b. Pressburg, Austria-Hungary [now Bratislava, Czechoslovakia], 7 June 1862; d. Messelhausen, Germany, 20 May 1947)

Physics.

Lenard was the son of a wealthy wine maker and wholesaler. His mother, the former Antonie Baumann, died young, and Lenard, an only child, was raised by an aunt who subsequently married his father.

Lenard was at first educated at home, but when he was nine he entered the cathedral school 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In his unpublished autobiography Lenard wrote, “When school days ended, a painful void came into my life”. His father, who wanted him to carry on the wine business, permitted him, after long arguments, to continue his studies, but only at the Technische Hochsculen in Vienna and Budapest; moreover, he was to occupy himself primarily with the chemistry of wine. After a few dreary semesters Lenard joined his father’s business.

In the summer of 1883, Lenard used the savings from a year of work for a trip to Germany. In Heidelberg he met Robert Bunsen, a figure who had long been a “secret object of worship.” Bunsen’s lectures were a revelation to Lenard, who was now firmly resolved to become a scientist; he matriculated at Heidelberg in the winter semester 1883-1884.

Lenard studied physics for four semesters at Heidelberg and two at Berlin. From Helmholtz he received the idea for his dissertation: “Über die Schwingungen fallender Tropfen.” He began work on it at Berlin in the summer of 1885 and completed it at Heidelberg in 1886. He received his doctorate summa cum laude and thereupon became an assistant to Quincke at Heidelberg.

Since Lenard still returned to Pressburg on university vacations, he was now 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.” Afterward he was an assistant for a semester at Breslau and then came to Bonn on 1 April 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. As Lenard said later, “For the first time completely pure experiments were now possible.”

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.’”

In order to prove absorption Lenard utilized a phosphorescent screen that lit up as soon as it was struck by cathode rays:

If we employ a phosphorescent screen, we find that it shines dazzlingly when placed right next to the window; … at a distance of about 8 cm the screen remains completely dark; obviously air at full atmosspheric pressure is not at all permeable to cathode rays, not nearly as much as it is, for example, to light. Therefore, these rays must be extraordinarily short, so short that the molecular structure of matter, which vanishes in comparison with light waves—which are after all very small-becomes very appreciable in comparison with them. Naturally it then becomes possible, with the aid of these rays, to obtain information concerning the constitution of molecules and atoms [Über Kathodenstrahlen,p. 10].

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.

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.”

At Hertz’s untimely death, Lenard was also obliged to act as 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.)

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.”

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 antimilitaristic 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.”

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. As Max Born recounted it, Lenard directed “sharp, malicious attacks against Einstein, with an unconcealed anti-Semitic bias.” 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. The preface begins with the author’s war cry:

“German physics?” one will ask.—I could also have said Aryan physics or physics of the Nordic man, physics of the reality explorers, of the truth seekers, the physics of those who have founded natural science.—“Science is and remains international!” someone will reply to me. He, however, is in error. In reality science, like everything man produces, is racially determined, determined by blood.

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.

BIBLIOGRAPHY

I. Original Works, For Lenard’s writings, see Über Kathodenstrahlen (Leipzig, 1906; 2nd ed., Leipzig, 1920); Über Äther und Materie (Heidelberg, 1910; 2nd ed., Heidelberg, 1911); England und Deutschland zur Zeit des grossen Krieges (Heidelberg, 1914); Über Relativitätsprinzip, Äther,Gravitation (Leipzig, 1918; 3rd ed., Leipzig, 1921); Über Äther und Uräther (Leipzig, 1921; 2nd ed., Leipzig, 1922); “Kathodenstrahlen,” in Handbuch der Experimentalphysik,14 , pt.1 (Leipzig, 1927), written with August Becker; “Phosphoreszenz und Fluoreszenz,” in Handbuch der Experimentalphysik,23, pt. 1 (Leipzig, 1928), written with Ferdinand Schmidt and Rudolf Tomaschek; and “Lichtelektrische Wirkung,” in Handbuch der Experimentalphysik,23, pt. 2 (Leipzig, 1928), written with August Becker.

For further reference, see Grosse Naturforscher. Eine Geschichte der Naturforschung in Lebensbeschreibungen (Munich, 1929; 4th ed., Munich, 1941); Deutsche Physik, 4 vols. (Munich-Berlin, 1936-1937); Wissenschaftliche Abhandlungen aus den Jahren 1886-1932, 3 vols. (Leipzig,1942-1944); “Erinnerungen eines Naturforschers” (unpublished typewritten MS, completed in 1943. There is a copy in the Lehrstuhl für Geschichte der Naturwisenschaften und Technik der Universität Stuttgart); some of Lenard’s instruments are in the possession of the Deutsches Museum in Munich. A list of them can be found in the Museum’s library under no. 1962 B 350.

II. Secondary Literature. For information on Lenard’s life and work, see August Becker, ed., Naturforschung im Aufbruch. Reden und Vorträge zur Einweihungsfeier des Philipp Lenard-Institutes der Universität Heidelberg am 14. u. 15. December 1935 (Munich, 1936), also including Johannes Stark, “Philipp Lenard als deutscher Naturforscher,” pp. 10-15; Philipp Lenard, der deutsche Naturforscher. Sein Kampf um nordische Forschung … Heraugegeben im Auftrag des Reichstudenten führers (Munich-Berlin, 1937) ; “Philipp Lenard, der Vorkämpfer der Deutschen Physik,” in Karlsruher Akademische Reden,17 (Karlsruhe, 1937); and Zum 80. Geburtstag von … Philipp Lenard und zum 70. Geburtstag von Reichspostminister Dr. Ing, e.h.wilhelm Ohnesorge (Vienna, 1942).

See also Ernst Brüche and H. Marx, “Der Fall Philipp Lenard-Mensch und ’Politiker,’” in Physikalische Blätter,23 (1967), 262-267; Carl Ramsauer, Physik-Technik-Pädagogik. Erfahrungen und Erinnerungen (Karlsruhe, 1949), pp. 102, 106-119; “Zum zehnten Todestag. Philipp Lenard 1862-1947,” in Physikalische Blätter,13 (1957), 219-222; Charlotte Schmidt-Schönbeck, “300 Jahre Physik und Astronomie an der Universität Kiel,” Ph.D. dissertation (University of Kiel, 1965); and Franz Wolf, “Zue 100. Wiederkehr des Geburtstages von Philipp Lenard,” in Naturwissenschaften,49 (1962), 245-247.

Armin Hermann

Complete Dictionary of Scientific Biography

Lenard, Philipp

views updated May 23 2018

Philipp Lenard

German physicist Philipp Lenard (1862–1947) won the 1905 Nobel Prize for his research into the properties of cathode rays. His reputation was later tarnished, however, thanks to his support of Germany's National Socialist (Nazi) Party and its racial–superiority theories. In the 1920s, Lenard broke with the international scientific community over Albert Einstein's theory of relativity. From his post as professor of physics at the esteemed University of Heidelberg, he derided Einstein's breakthrough as spurious "Jewish science."

Disliked Wine Business

The future Nobel winner was born Philipp Eduard Anton von Lenard on June 7, 1862, in Pressburg, the Slovakian city that later became Bratislava. His family was of Austrian heritage, from the Tyrol, and lived comfortably from the income of his father's business as a wine merchant. It was hoped that Lenard, too, would enter into the wine trade and someday take over the family business, but he favored the science experiment over the business deal. He took some courses in Pressburg and also at the technical university in Budapest, Hungary, and then agreed to work for his father for a year. Afterward, he traveled through Germany, and at one point attended a series of lectures given by Robert Bunsen, the German chemist after whom the ubiquitous chemistry–lab gas burner is named. The lectures sparked Lenard's determination to pursue a scientific career in earnest.

Lenard studied at the universities of Heidelberg and Berlin, earning his doctorate with high honors in 1886 from the former. He remained in the city for the next three years, taking a position as assistant to his professor, Georg Quincke, but was able to conduct his own research experiments. As a youngster, he had been fascinated by the way fluorine crystals began to glow when heated. His earliest projects concluded that such phosphorescence was a result of impurities in the material. Calcium sulphide, for example, was thought to be self–luminous, but Lenard's work showed that traces of heavy metals, such as copper and bismuth, formed crystals that caused the substance to glow.

Worked with Heinrich Hertz

From Heidelberg, Lenard went to England in 1890 for a job at the electromagnetic and engineering laboratories of the City and Guilds of the London Central Institution. He remained there less than a year, however, and came away with a lifelong disdain for the country and even its scientific community. Over the next decade, Lenard switched jobs several times, taking posts at the universities of Breslau, Bonn, and Heidelberg, and at the technical college of Aachen. It was during this period that he made the significant advances in cathode ray research, which had progressed out of his work in phosphorescence. Discovered in 1879, cathode rays were essentially light beams of charged particles produced as a result of the discharge of electricity in vacuum tubes. Scientists were eager to find a way to study their properties outside of the vacuum tubes.

Some of Lenard's work was done under the auspices of Heinrich Hertz at the University of Bonn, to whom he served as an assistant. The scientific designation for frequency (Hz), used commonly in radio communication, is named in Hertz's honor. One day in 1892, according to the official Nobel Prize Website, "Hertz called him to see the discovery he had made that a piece of uranium glass covered with aluminum foil and put inside the discharge tube became luminous beneath the aluminum foil when the cathode rays struck it." Hertz conceived an experiment whereby the two spaces could be separated via a thin aluminum plate, "one in which the cathode rays were produced in the ordinary way and the other in which one could observe them in a pure state, which had never been done. Hertz was too busy to do this and gave Lenard permission to do it and it was then that he made the great discovery of the 'Lenard window,' " the Nobel Prize essay noted.

The cathode–ray work led Lenard to theorize about matter, the basic element of the physical world, and the atoms of which it consists. He concluded that the atom contains neutral pairs of what he called dynamids, one positively charged and the other negatively charged. He was not entirely correct, but it would be another decade before a nuclear model of the atom would be correctly assembled by Ernest Rutherford, the New Zealand–born Nobel Prize winner who made several notable scientific advances while at the Universities of Cambridge and Manchester in England. Rutherford was the 1908 winner in chemistry, while Lenard was awarded the 1905 Nobel Prize in physics for his cathode ray work.

Theorized about Atoms

Lenard's other significant contribution to science involved the photoelectric effect, or what happens when a beam of light strikes a metal plate. Electrons are emitted from the plate, and Lenard found that their intensity was dependent on the brightness of the incident light. He also found that the speed of the electrons remained unchanged. Explaining why this occurred, however, was beyond the grasp of science at the time, and could not be proved by correlating experiments using the current laws of physics. Only in 1905, when Albert Einstein published a paper that discussed what he termed "light quanta," or photons, could the photoelectric effect be accurately explained by science.

After several years as a professor at the University of Kiel, Lenard was offered a professorship at his alma mater, the University of Heidelberg, in 1907. He remained there for the rest of his career, and proved a popular, enthusiastic teacher and mentor to a generation of students. He also became head of the physics institute at the esteemed university. He was said to have been disappointed that Einstein did not acknowledge his contributions to the study of the photoelectric effect, especially when Einstein was awarded the 1921 Nobel Prize in physics. A German Jew who was by then serving as the director of the Kaiser Wilhelm Institute of Physics in Berlin, Einstein was widely hailed as a genius and the theorist who single–handedly pushed modern science into a new and exciting future. In an unpublished autobiography, Lenard later dismissed Einstein's groundbreaking theory of relativity, calling it "a Jewish fraud, which one could have suspected from the first with more racial knowledge than was then disseminated, since its originator Einstein was a Jew," he declared, according to Alan D. Beyerchen's Scientists under Hitler: Politics and the Physics Community in the Third Reich.

Lenard was not alone in the scientific community with his objections to Einstein's work. The charge was initially led by the Work Group of German Scientists for the Preservation of Pure Scholarship, which even held a few anti–Einstein rallies in 1920. These activities prompted Einstein to respond in the press, and he attacked Lenard in one of his letters published in a German newspaper. Over the next few years, Lenard personally campaigned against Einstein's theories in various scientific papers, at conferences of German physicists, and in the press. Originally, he questioned only the methods used by Einstein and other theoretical physicists, but the attacks took on a shriller, anti–Semitic tone.

Suffered Several Personal Setbacks

This shift occurred around the same time that Lenard's son, Werner—from his 1897 marriage to Katherine Schlehner—died from the aftereffects of malnutrition in February of 1922. Several years earlier, during World War I, England had blockaded Germany, cutting off food supplies, and it was the youngest Germans who suffered most. Werner never fully recovered, and had been Lenard's only son. The tragedy likely further fueled the frustration he felt and injustices perceived. A conservative in outlook, Lenard was by then middle–aged and like many of his contemporaries, felt adrift with the end of imperial Germany after World War I. Economic difficulties compounded his attitude. The newly installed constitutional democracy, commonly called the Weimar government after the city where the constitution was drafted, had a difficult time managing the country's dire economic predicament, and inflation skyrocketed. After the war, Lenard had exchanged his savings for government bonds, which became worthless; he and other Germans worried that the money had actually been stolen by the Weimar government, which had some prominent Jewish politicians amongst its leaders.

The assassination of Germany's Foreign Minister, Walther Rathenau, in June of 1922 instigated a professional crisis for Lenard. Rathenau was a wealthy Jewish industrialist before he served in the Weimar government, and heir to the AEG electric fortune. Right–wing extremists in Germany accused him of using his post to secretly collude with the Soviets in what was deemed a "Jewish–Communist conspiracy." A day of mourning was declared on the day of Rathenau's funeral, but Lenard refused to close his physics institute at the University of Heidelberg or fly its flag at half–mast. Protesters gathered outside, stormed the building after water was dumped on them from above, and marched Lenard by force to the local union hall, where city authorities took him into custody for a few hours for his own protection. The University's academic senate suspended him, but students loyal to him protested and he was exonerated.

Praised Hitler in Newspaper Articles

The incident served to crystallize Lenard's belief that his country was becoming clearly divided by ideology, and he wholeheartedly threw his support to conservative side—the emerging Nazi Party, which called for the removal of Jews from German political, social, and cultural institutions. When Nazi Party leader Adolf Hitler began serving a jail sentence in April of 1924 for a failed coup in Munich known as the Beer Hall Putsch, Lenard penned an article for a Bavarian newspaper, Grossdeutsche Zeitung, commending Hitler. He asserted that the Nazis "appear to us as gifts of God from a long darkened earlier time when races were still purer, persons still greater, spirits still less fraudulent."

It is known that Hitler and his deputy, Rudolf Hess, later paid a visit to Lenard at his Heidelberg home in 1928. When Hitler became chancellor in 1933, Lenard wrote him and offered his services as scientific advisor to the new Reich. In the letter, he suggested that the esteemed German university system was unduly riddled with Jewish influence. By then he had retired from the University of Heidelberg, and in 1935 its physics institute was renamed in his honor in 1935. He was the recipient of several other official honors, including the Eagle Shield of the Reich, but his actual role in guiding Nazi policy during the 1933–45 era was negligible. At World War II's end and the defeat of Hitler, Allied authorities discussed subjecting him to a denazification trial, but a rector at the university intervened. Lenard was in his early eighties by then, and spent the remaining years of his life in a nearby town called Messelhausen, where he died on May 20, 1947.

The cathode–ray research Lenard conducted early in his career helped pave the way for the cathode ray tube, or CRT, which was the essential element in the development of television. The CRT was standard in the television manufacturing industry for nearly 50 years after Lenard's death, until it was replaced by liquid–crystal display technology. In the end, however, Lenard's scientific legacy was tarnished by his support for "Aryan physics" and "German science," which rejected foreign influence on German research and progress. He dismissed the standard notion that science is an international activity where nationalism has no place. In the 1936 textbook he wrote, Deutsche Physik (German Physics), he asserted instead that "science, like everything man produces, is racially determined, determined by blood."