Philipp E. A. Lenard was a brilliant experimental physicist who made important contributions to the study of the photoelectric effect , the characterization of cathode rays, the nature of phosphorescence , ionization potentials, and other phenomena. He was awarded the 1905 Nobel Prize in physics primarily for his work on cathode rays. He taught and carried on research at a number of German universities, including Heidelberg, Bonn, Breslau, and Kiel, as well as at the Technische Hochschule in Aachen. In spite of his gifts as an experimentalist, Lenard is also remembered as an anti-Semite and enthusiastic proponent of National Socialism. His unwillingness to embrace many of the new developments in science taking place in the 1920s and 1930s is thought to be at least partially due to his political feelings that these ideas were false pronouncements from "Jewish science." By the end of his life, Lenard had lost the personal respect and professional esteem of the great majority of his colleagues in the scientific community.
Philipp Eduard Anton Lenard was born on June 7, 1862, in Pressburg, Hungary (now Bratislava, Slovakia). His father was Philipp Lenard, a prosperous wine merchant, and his mother, the former Antonia Baumann. Young Philipp was expected to take over his father's business, but was not enthusiastic about that prospect. He attended technical universities in Budapest and Hungary, and spent a year working for his father before a trip to Germany rekindled his desire to study science. After attending the lectures of German chemist Robert Bunsen, Lenard decided to study physics at the University of Heidelberg in Germany, in the winter of 1883. He remained there for four semesters, spending two more semesters at the University of Berlin before returning to Heidelberg, where he received a doctorate with high honors in 1886.
Takes Posts at Heidelberg, Bonn, Breslau, Aachen, and Kiel
Lenard was asked to stay on at Heidelberg as assistant to his former teacher, Georg Quincke. During his three years in that position, Lenard began research on phosphorescence, a topic that was to occupy him off and on for the next four decades. He was later to discover that phosphorescence occurs as a result of impurities in a material and that it attains some maximum intensity for a given concentration of impurity. After leaving Heidelberg in 1890, Lenard visited England where he worked at the electromagnetic and engineering laboratories of the City and Guilds of the London Central Institution. He soon came to dislike the English, however, and left after six months to take a post at the University of Breslau. After only one semester there, he accepted an appointment as an assistant to Heinrich Hertz at the University of Bonn, where he began to experiment with cathode rays.
When Hertz died unexpectedly in 1894 at the age of 36, Lenard became responsible for publishing Hertz's mammoth three-volume work Gesammelte Werke, interrupting his own research. He continued this task when he moved back to the University of Breslau in 1894 to become associate professor of physics. Once more, he remained at Breslau only briefly before taking consecutive posts at the Technische Hochschule in Aachen (1895-96) and the University of Heidelberg (1896-98). Finally, in 1898, he was appointed professor of physics and director of the physics laboratory at the University of Kiel, where he would remain for nine years.
Makes Important Discoveries about Cathode Rays and the Photoelectric Effect
In the years prior to 1914, Lenard made his most important scientific discoveries, particularly those relating to his studies of cathode rays and the photoelectric effect. Research on the former had been inspired by William Crookes's 1879 discovery of cathode rays, beams of charged particles produced during the discharge of electricity in vacuum tubes. Lenard was interested (as were other researchers) in finding a way to study cathode rays outside of vacuum tubes. Based on Hertz's discovery that cathode rays could permeate thin metal sheets, Lenard found, in 1892, that cathode rays can be made to pass out of a vacuum tube through a thin aluminum window. Using this arrangement, Lenard was able to make a number of observations regarding the properties of cathode rays.
As a result of these studies, Lenard came to the conclusion that matter--and, therefore, the atoms of which matter consists--is largely empty space. He suggested that an atom consists of neutral pairs of dynamids, one positively charged and the other negatively charged. Though incorrect, this concept presaged the nuclear model of the atom developed by Ernest Rutherford a decade later. It was for his work on cathode rays that Lenard was awarded the 1905 Nobel Prize in physics.
During the same period, Lenard also studied the photoelectric effect, the phenomenon that occurs when a beam of light strikes a metal plate, resulting in the emission of electrons from the plate. Lenard made the interesting discovery that the velocity of electrons emitted during this process was affected by the wavelength of the incident light, and that an increase in that light's intensity increased the number of electrons emitted, but not their speed. He was unable to explain this result, an anomaly unpredictable with the laws of classical physics. In fact, it was not until Albert Einstein applied the principles of quantum theory to this phenomenon that Lenard's results were correctly interpreted, an accomplishment that won for Einstein the 1921 Nobel Prize in physics.
Lenard was an enormously complex individual about whom a great deal has been written. He experienced a number of personal disillusionments, as when he failed to discover x rays only a short time before his countryman, Wilhelm Conrad Röntgen , did so. This disappointment was especially hard on Lenard since he had made substantial contributions to the theoretical and experimental aspects of Röntgen's discovery, contributions that Röntgen never acknowledged.
As Lenard grew older, he began to develop profound anti-Semitic feelings. In his unpublished autobiography, for example, quoted in Alan D. Beyerchen's Scientists under Hitler: Politics and the Physics Community in the Third Reich, Lenard describes the theory of relativity as "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." Ultimately, Lenard rejected the traditional notion that science is an international activity that transcends national boundaries. Instead, he wrote in his textbook on experimental physics, Deutsche Physik (German physics), "In reality, science, like everything man produces, is racially determined, determined by blood."
Before long, Lenard became one of the leaders of Aryan physics, an attempt to keep science pure of Jewish and other foreign influences, and he enthusiastically supported Adolf Hitler and his political agenda. When Hitler was named chancellor in 1933, Lenard wrote to him, offering his skills as a scientific adviser while pointing out how badly the nation's university system needed cleansing of Jewish influences.
In the decade after Hitler's ascent to power, Lenard was constantly involved in power struggles aimed at gaining control of the nation's scientific establishment, though, in his early seventies by then, he was probably too old to make many substantive contributions to the Nazi regime. In addition, he was defeated at nearly every turn by less-able, lesser-known scientific figures with more important contacts to inner circles of Nazi politics. Instead, he was given a number of awards and honorary appointments, such as the Eagle Shield of the Reich and election to the Executive Committee of the German Research Association. He survived the war, but was expelled from his post at the University of Heidelberg by Allied officials in 1945. After this disgrace, he settled in the village of Messelhausen, close to Heidelberg, where he died on May 20, 1947. Lenard had been married in 1897 to Katherine Schlehner. The one child of whom we know, Werner, died in February 1922, due to malnutrition brought on by wartime conditions in World War I.
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