Einstein

by Philipp Frank

  The situation is similar in the case of radiation enclosed in a box. We can imagine this box to be divided into a number of cells of equal volume and consider the distribution of the energy of radiation in these cells. If the portions of radiation are large, the variations of energy among the cells will be large, and if they are small, these variations will be small. From the empirical law of distribution it follows that the variations in the violet light are greater than in the red light. Einstein drew the conclusions that violet light consists of a few large portions, while red light consists of many small ones. Exact calculations showed that the magnitude of the portions must be hv. Thus Einstein found that not only did emission and absorption of radiation take place in discrete amounts, but light itself must consist of definite portions. The name “photon” has since been given to the quantum of radiation.

  To this conclusion, which Einstein derived theoretically, he was able to point out an experimental verification. It had been known for some time that when light shines on certain metals, electrons are given off. Electrons are fundamental particles in physics which carry a negative electric charge and constitute the outer portion of the atom. In 1902 the German physicist Philipp Lenard discovered a very startling result of this emission of electrons. He found that the intensity of light falling on the metal had no effect on the energy with which the electrons are ejected from the metal, but that this energy depends only on the color or frequency of the light. No matter how far the source of light is moved away from the metal, the electrons are still ejected with the same velocity, though of course the number ejected is smaller. But when violet light is used instead of red, the velocity of the electrons is much greater.

  According to Einstein’s view, the explanation is quite simple. No matter what distance light of a certain color has traveled from the source, it still consists of the same portions of energy, the only difference being that, farther away from the source, the individual portions are spread out thinner. The ejection of an electron occurs when a whole quantum of radiation is absorbed by a single electron, which then comes off with the energy of the photon. Thus the distance between the source and the metal has no effect on the energy of the single electron emitted. Furthermore, the difference between violet and red light is that a different amount of energy is possessed by the photon. Hence an electron that absorbs a violet photon naturally comes off with higher velocity than one that absorbs a red photon.

  To form another analogy, let us consider the bombardment of a fortification by machine guns and by heavy artillery. Even if the total weight of projectiles fired is the same in both cases, the effects produced are of a very different character. The machine-gun bullets make a very large number of small dents, while the artillery shells make a few big holes. Moreover, the average intensity of gunfire has very little effect on the magnitude of the holes, but only on their number.

  With his hypothesis on the discontinuous nature of light Einstein threw doubt on the entire conception of a continuous field of force. If light consists of photons, the electric and magnetic fields cannot fill all space continuously, and the whole of the electromagnetic theory of light based on this concept has to be re-examined. The discontinuous structure is apparently inconsistent, however, with some observed phenomena, in particular with interference and diffraction of light, which are explained so well by the theory of continuous waves. Einstein, who was well aware of this difficulty, looked upon his assumption only as a provisional hypothesis, without any lasting value. He therefore entitled the paper in which he presented his discovery: “On a Heuristic Point of View Regarding the Production and Transformation of Light.”

  It is interesting to note that Einstein’s new quantum theory of light was based upon the research of two German physicists who were later to play important roles in his life. Max Planck was first to advocate the significance of Einstein’s theory of relativity, and Philipp Lenard was to oppose it most vehemently on philosophical, political, and racial grounds.

  IV

  EINSTEIN AT PRAGUE

  1. Professor at the University of Zurich

  The researches whose results Einstein published at Bern in 1905 were so unusual that to the physicists of the Swiss universities they seemed incompatible with the assigned work of a minor official of the patent office. Attempts were soon made to bring Einstein to teach at the University of Zurich. At this time Professor Kleiner was the leading personality in physics there. He was a man who realized that Einstein’s papers revealed an unusual talent, but who did not really understand them. He felt it his duty to do the best for his university and endeavored to appoint Einstein professor at Zurich.

  According to the regulations in force at Zurich as well as at other Germanic universities, no one could be appointed professor at a university unless he had previously been a Privatdozent. This is a position for which there is no analogue in the universities of western Europe and America. A young man with scientific achievements may apply for permission to teach at a university. He has no obligations and can lecture as much or as little as he desires, but receives no remuneration except the usually very small fees paid by students who attend his lectures. Since for this reason the number of Privatdozenten does not have to be restricted, this system has the advantage that every young scientist has an opportunity to show his teaching abilities and the universities have a large number of candidates to choose from in appointing their professors. The disadvantage, of course, is that in practice only persons with private means or another position which supports them can enter this career. With his position at the patent office, Einstein was in the latter situation.

  Professor Kleiner advised him to become a Privatdozent at the university of Bern, so that after a short while he could then be eligible for a professorship at Zurich. Although he did not like the idea of giving regular lectures, Einstein followed the advice. Consequently his lectures were not very well prepared, and since the students were not obliged to attend them, only a few friends came. Furthermore, Einstein was then in the midst of a veritable maelstrom of new discoveries and it was difficult to arrange his material in a way appropriate to the capacities of the average student. Professor Kleiner once came to Bern to hear Einstein lecture and afterward remarked to him that such lectures did not seem on a level fitted for the students. Einstein answered: “I don’t demand to be appointed professor at Zurich.”

  At that time the professorship of theoretical physics at the University of Zurich became vacant, but the board of education of the canton of Zurich, which was in charge of the university, had its own plans for this position. The majority of the board of education belonged to the Social Democratic Party, and they had in Zurich a party comrade who appeared to be a suitable candidate, from both the political and the scientific viewpoint. This man was Friedrich Adler, Einstein’s former fellow student at the Zurich Polytechnic, who was then a Privatdozent at the University of Zurich. As the son of the leader of the Austrian Social Democrats, he was held in high esteem by the party members in Zurich. Friedrich Adler was a man imbued with a fanatical love of truth and was interested in physics chiefly because of its philosophical aspects. He was in every respect a man who would not shrink from uttering what he regarded as the truth even if it was to his own disadvantage. Learning that it was possible to obtain Einstein for the university, he told the board of education: “If it is possible to obtain a man like Einstein for our university, it would be absurd to appoint me. I must quite frankly say that my ability as a research physicist does not bear even the slightest comparison to Einstein’s. Such an opportunity to obtain a man who can benefit us so much by raising the general level of the university should not be lost because of political sympathies.”

  So in 1909, despite the political leaning of the board of education and the leading professor’s disapproval of his mode of lecturing, Einstein was appointed professor “extraordinary” at the University of Zurich.

  The call to Zurich gave Einstein for the first time a position with a certain pu
blic prestige. Most Privatdozenten feel that they have become important persons when they attain professorial rank, for then they can lord it over the Dozenten instead of being passive objects to be dealt with by the university administration. For Einstein this was naturally no cause for satisfaction. He had not suffered in any way while a Privatdozent, and he did not have any desire to dominate others. Besides, he had not been anxious enough for the position to derive any great pleasure from its attainment.

  From the financial point of view, the position of a professor “extraordinary” was not very lucrative. His income was no larger than it had been at the patent office and, moreover, he could no longer lead an inexpensive and pleasant bohemian life now that he had acquired a certain social status in the city. Though he kept expenses at a minimum, he had to spend money for things from which he derived no pleasure, but which were required by his social position. In order to improve the financial situation, his wife took in students to board. He once said jokingly: “In my relativity theory I set up a clock at every point in space, but in reality I find it difficult to provide even one clock in my room.”

  Einstein loved the city of Zurich, which had become his home. His wife also felt more at home here than anywhere else. Collaboration with students and colleagues, which was now possible, was a great stimulus to Einstein. Administrative duties and regular teaching, however, had few attractions and in certain respects many difficulties. This was due not only to the constraint a person of such great creative ability finds himself under when required to expend his efforts on tasks that do not appear important, but also to Einstein’s paradoxical relation to society, arising from his personality.

  The immediate impression that Einstein made on his environment was a conflicting one. He behaved in the same way to everybody. The tone with which he talked to the leading officials of the university was the same as that with which he spoke to his grocer or to the scrubwoman in the laboratory. As a result of his great scientific discoveries, Einstein had already acquired a profound inner feeling of security. The pressure that had often burdened his youth was gone. He now saw himself in the midst of the work to which he was going to devote his life and to which he felt himself equal. Alongside this work the problems of daily life did not appear very important. Actually he found it very difficult to take them seriously. His attitude in intercourse with other people, consequently, was on the whole one of amusement. He saw everyday matters in a somewhat comical light, and something of this attitude manifested itself in every word he spoke; his sense of humor was readily apparent. When someone said something funny, whether intentionally or not, Einstein’s response was very animated. The laughter that welled up from the very depth of his being was one of his characteristics that immediately attracted one’s attention. To those about him his laughter was a source of joy and added to their vitality. Yet sometimes one felt that it contained an element of criticism, which was unpleasant for some. Persons who occupied an important social position frequently had no desire to belong to a world whose ridiculousness in comparison to the greater problems of nature was reflected in this laughter. But people of lesser rank were always pleased by Einstein’s personality.

  Einstein’s conversation was often a combination of inoffensive jokes and penetrating ridicule, so that some people could not decide whether to laugh or to feel hurt. Often the joke was that he presented complicated relationships as they might appear to an intelligent child. Such an attitude often appeared to be an incisive criticism and sometimes even created an impression of cynicism. Thus the impression Einstein made on his environment vacillated between the two poles of childish cheerfulness and cynicism. Between these two poles lay the impression of a very entertaining and vital person whose company left one feeling richer for the experience. A second gamut of impression varied from that of a person who sympathized deeply and passionately with the fate of every stranger, to that of a person who, upon closer contact, immediately withdrew into his shell.

  2. Appointment to Prague

  In the fall of 1910 there occurred a vacancy in the chair of theoretical physics at the German University in Prague. Such appointments were made at the recommendation of the faculty by the Emperor of Austria, who exercised his right through the Ministry of Education. The decisive man in the selection of the candidate was the physicist Anton Lampa, a man of very progressive tendencies as far as education was concerned. All his life he fought for the introduction of modern pedagogical methods, for the freedom of teaching from reactionary influences, and for the extension of scientific and artistic education to the largest possible number of the population. There was a considerable gap between his high aspirations and his scientific capacities, however, and as a result he was animated by an ambition he could not satisfy. Since he was a man of high ethical ideals, he consciously sought to suppress this ambition, but the result was that it played an even greater role in his subconscious life. His philosophical Weltanschauung was for the most part determined by the positivistic philosophy of the physicist Ernst Mach, whose student he had been. It was Lampa’s life goal to propagate Mach’s views and to win adherents for them.

  When the question of filling the chair of theoretical physics came up, Lampa thought that here was an opportunity to appoint someone who would teach physics in the spirit of Mach. In addition, it had always been his dream to enter the realm of the extraordinary and of the genius, and he wanted an outstanding scientist, not an average professor. Even though he realized that he himself was not so gifted, he was just enough to accept the presence of an outstanding man.

  Lampa had in mind two physicists who he thought would teach in the spirit of Mach and were acknowledged to have extraordinary capacities. The first was Gustav Jaumann, a professor at the Technical Institute in Brno, and the second was Einstein. Jaumann followed Mach in some peculiarities, chief among which was his aversion to the introduction of atoms and molecules in physics. Even when the atomic constitution of matter had been generally accepted as giving the best and simplest presentation of physical phenomena, Jaumann retained Mach’s predilection and tried to build up a theory of continuously distributed matter. Since he had a great natural talent and imagination, he considered himself a neglected genius and developed an excessive vanity and sensitivity. Einstein, on the other hand, was influenced more by the spirit than by the letter of Mach’s teachings. We have already seen in his work on Brownian motion that Einstein did not follow Mach’s rejection of the atom.

  Since the regulations provided that the names of the proposed candidates be listed on the basis of their achievements, Einstein, whose writings in the years from 1905 to 1910 had already made a strong impression on the scientific world, was placed first and Jaumann second. Nevertheless, the Ministry of Education first offered the position to Jaumann. The Austrian government did not like to appoint foreigners and preferred Austrians. But the ministry had not taken Jaumann’s vanity and touchiness into account. He said: “If Einstein has been proposed as first choice because of the belief that he has greater achievements to his credit, then I will have nothing to do with a university that chases after modernity and does not appreciate true merit.” Upon Jaumann’s rejection of the offer, the government overcame its aversion to foreigners and offered the position to Einstein. He had some qualms about going to a foreign country, and his wife did not want to leave Zurich, but eventually he accepted it. One deciding factor was the circumstance that for the first time in his life he was to have a full professorship with adequate salary.

  There was one peculiar difficulty to be overcome, however, in taking up the position. The octogenarian Emperor Franz Josef was of the opinion that only a man who belonged to a recognized church should be a teacher at a university, and he refused to confirm the appointment of anyone who did not conform to this rule. Einstein’s friends at the university who had proposed his appointment informed him of this circumstance. Since leaving the gymnasium in Munich, Einstein had not been an official member of any religious community, but in order t
o avoid this difficulty, he indicated that he was an adherent of the Jewish religion, to which he had belonged as a child. He did not go through any formal ceremony, but in the questionnaire that he had to fill out he simply wrote his religion was “Mosaic,” as the Jewish creed was then called in Austria.

  When Einstein arrived in Prague he looked more like an Italian virtuoso than a German professor, and he had, moreover, a Slav wife. He was certainly unlike the average professor at the German University. Since he had been preceded by the reputation of being not an ordinary physicist but an extraordinary genius, everyone was curious to meet him.

  In Prague it was the custom for a newly arrived member of the faculty to pay a call on all his colleagues. In his good-natured way Einstein was ready to accept the advice of his friends and make the necessary calls, which numbered some forty. He also decided to take advantage of this opportunity to see various sections of the romantic old city of Prague, and so he began to make his visits according to the location of the houses. All who made his personal acquaintance were immediately pleased by his naturalness, his hearty laughter, and the friendly and at the same time dreamy look in his eyes. But Einstein soon began to find the calls rather a nuisance. He felt that it was a waste of time to carry on conversations about trivialities and suddenly he stopped his visits. The professors upon whom he had not called were puzzled and offended at this neglect. Some people began to regard him as either proud or capricious, when the true explanation was that these colleagues lived in sections of the city that did not interest Einstein, or their names were too far back in the faculty directory.