This principle is obviously a special case of Einstein’s law. If radiation is already contained in a body, its mass will decrease when the radiation is given off. Einstein’s law, however, is much more general. He says that the mass of a body, no matter what its nature, decreases if the body loses energy in any manner whatsoever.
Lenard and his group, however, were seeking a substitute for the name Einstein. There were several external factors that favored the choice of Hasenöhrl’s name. During the World War he had fought in the Austrian army — that is, on Germany’s side — and was killed in battle at the age of forty. He thus appeared to be an ideal figure in the view of Einstein’s enemies, a hero and model for German youth who was the very antithesis of the abstract speculator and international pacifist Einstein. Actually, Hasenöhrl was a honest and competent scientist and a sincere admirer of Einstein.
The legend originated with Lenard’s book Great Men of Science. The author presented a series of biographies of great men, such as Galileo, Kepler, Newton, Faraday, and others, and he concluded with one of Hasenöhrl. In order to link him with the preceding heroes Lenard said of him: “He loved music and his violin as Galileo his lute: he was very fond of his family and as extremely modest as Kepler.” Further on he says about Hasenöhrl’s conclusions: “The applications of this idea have already progressed very far today, although almost entirely in the names of other people.” “Other people” apparently means Einstein.
VIII
TRAVELS THROUGH EUROPE, AMERICA, AND ASIA
1. Holland
The vicious attacks on Einstein resulted in arousing interest in his theories among all classes of people in every country. Theories that were of no great significance to the masses and at that almost incomprehensible to them became the center of political controversies. At a time when political ideals had been shattered by the war and new philosophies and political systems were being sought, the public was puzzled and mysteriously attracted by the connection between Einstein’s scientific work and politics. The public interest was further increased by the appearance of articles by philosophers published in daily newspapers stating that Einstein’s theories might perhaps be of some importance in physics, but were certainly untrue philosophically.
The public wondered what sort of man was this Einstein, and they wanted to see and hear this famous scientist in person. From every country Einstein began to receive invitations to come and give lectures. He was amazed, but happy to comply with the people’s wishes. He enjoyed leaving the narrow circle of his professional colleagues and coming into contact with new people. It was also refreshing for him to leave Berlin and Germany, to go away from this tormented and harrowing atmosphere, and to see new countries.
These journeys and public appearances, however, added another cause for attacks on Einstein. Even some German scientists became annoyed, and one of them, a hard-working observer in the laboratory, wrote a brochure entitled The Mass Suggestion of the Relativity Theory. In it he gave an interpretation of Einstein’s travels from his own point of view. He wrote: “As soon as the erroneous character of the relativity theory became evident in scientific circles, Einstein turned more and more to the masses and exhibited himself and his theory as publicly as possible.”
The first instance of this “unscientific” publicity was Einstein’s lecture at the ancient and honorable University of Leiden in Holland. There he lectured before fourteen hundred students of this famous center of physical science on “Ether and the Relativity Theory.” This lecture led to many misinterpretations. Einstein, who had previously suggested that the term “ether” be dropped so as to prevent the rise of any idea that one is dealing with a material medium, discussed another proposal: namely, the word “ether” be used for “curved space,” or what amounts to the same thing, for the gravitational field present in space.
Einstein’s new proposal irritated some physicists and made others happy. Quite a few were unable to differentiate between a proposal to use a word in a certain sense and an assertion of a physical fact. They said: “For a long time efforts were made to convince us of the sensational fact that the ether had been got rid of, and now Einstein himself reintroduces it; this man is not to be taken seriously, he contradicts himself constantly.”
Einstein, however, was happy to be in the quiet, pleasant city of Leiden, among good friends and remote from the controversies of Berlin. He loved to carry on discussions with a physicist of this city, Paul Ehrenfest, a Viennese by birth who was married to a Russian physicist. Husband and wife were indefatigably ready to discuss with Einstein the most subtle questions regarding the logical relations of physical propositions.
Einstein was also appointed professor at Leiden, but he was required to lecture there only a few weeks throughout the year. It was a pleasant thought to look forward to this period of rest every year. And in Berlin there were constant speculations as to whether Einstein would move permanently to Holland. His opponents tried everything possible to make it unpleasant for him to remain in Berlin. Many Germans thought that they must be thankful to Einstein because by means of his great popularity abroad he was acting to increase Germany’s prestige after the lost war. His enemies, however, began a campaign against him, asserting that he was making propaganda abroad only for his own reputation, not for Germany.
Hänisch, the Prussian Minister of Education and a member of the Social Democratic Party, wrote an anxious letter to Einstein entreating him not to let himself be disturbed by these attacks and to remain in Germany. The government of the German Republic was very well aware how valuable he was for German culture and for its prestige throughout the world. The German government was even sorry that the great new theory of a German scientist had been studied and confirmed by English astronomers so that a large part of the ensuing fame had been lost to the Germans. The Minister requested Einstein to make use of the assistance of German observers and promised him governmental assistance.
Einstein, who appreciated greatly the significance of Berlin as a center of science and research, also understood very well that it was now important for all progressively minded elements to do everything possible to increase the prestige of the German Republic. He wrote a letter to the Minister in which he said: “Berlin is the place to which I am bound by the closest human and scientific ties.” He promised if possible to remain in Berlin and even applied for German citizenship, something that he had not wanted to accept from the Imperial government. He thus became a German citizen, a circumstance that later entailed only troubles for him.
2. Czechoslovakia
In Prague, which was now the capital of the new Czechoslovak Republic, a Urania society had been organized to arrange lectures for the German-speaking population, and in particular to acquaint them with the great personalities of the new republican Germany. The president of Urania, Dr. O. Frankel, also endeavored to induce Einstein to lecture in Prague. Einstein, who was fond of recalling the quiet times he had enjoyed when he was working in Prague, seized the opportunity to revisit his old university and friends. He was also interested in becoming acquainted with the new democratic state that had arisen under the leadership of President Masaryk on the ruins of the Habsburg monarchy. The psychological status of the German minority in Prague and in Czechoslovakia in general was approximately like that of the population of the defeated German Reich within Europe. Einstein’s visit increased the self-esteem of the Germans in Czechoslovakia, who were later called “Sudeten Germans,” and played a fateful role in the crisis that led to the second World War. When Einstein’s visit was announced, one of the papers of this minority wrote: “The whole world will now see that a race that has produced a man like Einstein, the Sudeten German race, will never be suppressed.” This was characteristic of the nationalistic thinking. On the one hand every effort was made to keep the race free of all foreign admixtures; on the other hand, when someone was needed, even one who had not spent two years among this race was counted as a member of the group.
Earl
y in 1921 Einstein returned to Prague, where I was then teaching as his successor. I had not seen him for years. I remembered only the great physicist, the man with an artistic and often jesting outlook on the world, who at that time had already enjoyed a great reputation among scientists. But during the years that had passed since then, he had become an international celebrity, a man whom everyone recognized from his photographs in the newspapers, whose opinions on politics and art were sought by every reporter, and whose autograph was wanted by every collector; in short, a man whose life no longer belonged entirely to himself. As so often happens in such cases, he had ceased to be an individual person in many respects; he had now become a symbol or banner upon which the gaze of masses of people was directed.
I was therefore very curious to meet him again, and was somewhat worried about how I could make it possible for him to live a halfway quiet life in Prague and prevent him from being overburdened by his obligations as a famous man. When I met him at the station, he had changed very little and still looked like an itinerant violin virtuoso, with the combination of childlikeness and self-assurance that attracted people to him, but that sometimes also offended them. I had been married only a short time then, and during this period shortly after the war it was so difficult to find an apartment that I lived with my wife in my office at the Physics Laboratory. It was the same room, with the many large windows looking out on the garden of the mental hospital, that had formerly been Einstein’s office. Since Einstein would have been exposed to curiosity-seekers in a hotel, I suggested that he spend the night in this room on a sofa. This was probably not good enough for such a famous man, but it suited his liking for simple living habits and situations that contravened social conventions. We told no one about this arrangement, and no journalist or anyone else knew where Einstein spent the night. My wife and I spent the night in another room. In the morning I came to Einstein and asked him how he had slept. He replied: “I felt as if I were in a church. It is a remarkable feeling to awake in such a peaceful room.”
We went first to police headquarters, where, as was common during the postwar period, every stranger had to report. Then we visited the Physics Laboratory of the Czech University. The professors there were pleasantly surprised by seeing Einstein, whose picture hung on the wall, appear in person in their room. By this visit Einstein wanted to express his sympathy for the new Czechoslovak Republic and its democratic policy under Masaryk’s leadership.
In Prague, as in all the cities that had belonged to the Austro-Hungarian monarchy, a large part of the social life took place in the cafés. There people read newspapers and magazines, met with friends and acquaintances, and discussed business problems and scientific, artistic, or political questions. New political parties, literary circles, or large business firms were founded in cafés. Often, however, people sat alone, studying books or doing their own writing. Many students prepared for their examinations there, because their rooms were too cold, too dark, or simply too dreary. Einstein wanted to visit such places and he said to me: “We ought to visit several cafés and look in to see what the various places frequented by different social classes look like.” Thus we paid rapid visits to several cafés; in one we saw Czech nationalists, in another German nationalists; here were Jews, there Communists, actors, university professors, and so forth.
On the way home Einstein said to me: “Now we must buy something for lunch so that your wife won’t have too much bother.” At that time my wife and I cooked our meals on a gas burner such as is used for experiments in chemical or physical laboratories, a so-called Bunsen burner. This took place in the same large room in which we lived and where Einstein had also slept. We came home bringing some calf’s liver that we had purchased. While my wife began to cook the liver on the gas burner, I sat with Einstein talking about all sorts of things. Suddenly Einstein looked apprehensively at the liver and jumped at my wife: “What are you doing there? Are you boiling the liver in water? You certainly know that the boiling-point of water is too low to be able to fry liver in it. You must use a substance with a higher boiling-point such as butter or fat.” My wife had been a college student until then and knew little about cooking. But Einstein’s advice saved the lunch; and we got a source of amusement for all our married life, because whenever “Einstein’s theory” was mentioned, my wife remembered his theory about frying calf’s liver.
That evening he lectured before the Urania association. It was Einstein’s first popular lecture that I had heard. The hall was dangerously overcrowded since everyone wanted to see the world-famous man who had overthrown the laws of the universe and proved the “curvature” of space. The ordinary public did not really know whether it was all a colossal humbug or a scientific achievement. Nevertheless, it was ready to marvel at both. As we were going in to the lecture, a very influential man in public life who had himself done a great deal to organize the meeting pushed through the crowd and said to me: “Please tell me quickly in one word, is there any truth in this Einstein or is this all bunk?” Einstein spoke as simply and clearly as possible. But the public was much too excited to understand the meaning of the lecture. There was less desire to understand, than to experience an exciting event.
After the lecture the chairman of the Urania gathered together a number of guests to spend the evening with Einstein. Several speeches were made. When Einstein’s turn came to answer, he said: “It will perhaps be pleasanter and more understandable if instead of making a speech I play a piece for you on the violin.” It was easier for him to express his feelings in this way. He played a sonata by Mozart in his simple, precise, and therefore doubly moving manner. His playing indicated something of his intense feeling for the complexity of the universe and simultaneously of the intellectual joy over the possibility of expressing it in simple formulas.
Einstein remained in Prague another evening to participate in a discussion of his theories that was to take place in the Urania before a large audience. Einstein’s main opponent was a philosopher of the Prague University, Oskar Kraus, an acute thinker in the philosophy of law, whose conception of scientific discussions, however, was more like that of a counsel at a trial. He made no attempt to explore the truth, but instead wanted only to refute his opponent by finding passages that were contradictory in the writings of Einstein’s supporters. In this he was successful. Anyone who wants to present a complex subject popularly must introduce some simplifications. But every author introduces them at different places according to his own taste or his opinion of his reader’s tastes. If every statement by a popularizer is then taken literally, contradictions must necessarily arise. But this has nothing to do with the correctness of Einstein’s theory.
Professor Kraus was a typical proponent of the idea that one can learn various things about the geometrical and physical behavior of bodies through simple “intuition.” Anything that contradicted this intuition he considered absurd. Among these absurdities he included Einstein’s assertion that Euclid’s geometry, which we all learned in school, might not be strictly correct. Since in Kraus’s opinion the truths of ordinary geometry must be clear to every normal person, it was a puzzle to him how a person like Einstein could believe the opposite. His wife reminded me not to speak to him about Einstein’s theory. She said that he often spoke about it in his sleep and he got excited over the idea that there were people who could “believe what is absurd.” It was tormenting for him to think that such a thing was possible.
This philosopher was the chief speaker against Einstein. I presided at this discussion and endeavored to direct it in halfway quiet paths. A number of people now appeared who wanted to take advantage of an opportunity that would probably never present itself to them again. They could now fling the opinions that they had formed privately directly at the famous Einstein; he was compelled to listen to them. As a result several comical things occurred. Thus a professor of mechanical engineering at the Institute of Technology made some remarks that were false, but sounded rather reasonable. After the lecture
Einstein said to me: “That laborer spoke naïvely, but not in an entirely foolish way.” When I replied that he was not a laborer, but a professor of engineering, he said: “In that case it was too naive.”
On the following day Einstein was to depart, but by early forenoon the news had already spread that Einstein was staying at the Physics Laboratory and many people hurried to speak to him. I had great difficulty in arranging a relatively quiet departure. For instance, a young man had brought a large manuscript. On the basis of Einstein’s equation E = mc2 he wanted to use the energy contained within the atom for the production of frightful explosives, and he had invented a kind of machine that could not possibly function. He told me that he had awaited this moment for years and in any case wanted to speak to Einstein personally. I finally prevailed upon Einstein to receive him. There was but little time left and Einstein said to him “Calm yourself. You haven’t lost anything if I don’t discuss your work with you in detail. Its foolishness is evident at first glance. You cannot learn any more from a longer discussion.” Einstein had already read about a hundred such “inventions.” But twenty-five years later, in 1945, the “real thing” exploded at Hiroshima.
3. Austria
From Prague Einstein went to Vienna, where he also had to give a lecture. The Vienna of this postwar period was completely different from the city that Einstein had visited in 1913. It was now no longer the capital of a great empire, but only that of a little republic.
Among Einstein’s acquaintances, too, changes were noticeable. His friend Friedrich Adler had become a public figure. During the war, when the Austrian government had refused to convene the parliament and to submit its course of action to the judgment of the people’s representatives, Friedrich Adler, imbued with a fanatical desire to achieve what he considered just, had shot the head of the government during a dinner in a fashionable hotel.
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