The Man Who Stalked Einstein

by Hillman, Bruce J.

  Although Einstein’s charge of complicity in the evening’s events was true enough, Lenard very much resented being accused of involvement when he painstakingly had sought to conceal his role. In a September 8 letter to Stark, Lenard wrote,

  I am astonished by this personal element that Mr. Einstein and Mr. von Laue [a friend of Einstein and a 1914 Nobel Laureate who also published a critique of the Philharmonic events] hold in the matter and that they believe that they can turn against me. . . . My purely factual objections are to refute the generalized theory of relativity so that Einstein must precisely demonstrate it, instead of being naughty. . . . In short, I do not have the slightest desire to be in the company of Einstein unless. . . . I am a part of the whole that either passes or fails [his theories].

  Beginning shortly after the time Lenard became aware of Einstein’s newspaper speculations on his role in the Berlin Philharmonic episode, he became even more hostile toward Einstein, and his words and writings more openly anti-Semitic. What had been primarily a conflict of scientific positions had transformed into something pointedly personal.

  Among the pro-Einstein faction, there was concern that Einstein had incautiously let his emotions get the better of him, charging Lenard with actions he could not substantiate. Many of his friends and admirers worried that, out of either fear for his safety or a feeling of being unappreciated, Einstein might emigrate to any number of countries that would welcome him with open arms. It was common knowledge that Einstein’s friend, Paul Ehrenfest of the University of Leiden in the Netherlands, was particularly interested in bringing Einstein to Holland and had offered the likelihood of a professorship. Few doubted that there would be other bidders should Einstein express an interest in emigrating.

  It had been no easy matter six years previous to recruit Einstein to Berlin from his professorship in Zurich, where he had landed after a brief tenure at the Charles-Ferdinand University in Prague. Einstein’s star was rising on a meteoric trajectory. He had demanded and received unheard-of considerations to immigrate to Germany—the directorship of the Kaiser Wilhelm Institute of Physics, professorship at Humboldt University, and agreement that he would have only minimal teaching obligations. Now those who had invested so much in his recruitment feared the undoing of their efforts. Why, they wondered, should he put up with such grief when he had so many other choices?

  Despite the growing anti-Jewish sentiment in Berlin, Einstein probably did not seriously consider leaving Germany at this time. However, this fact may not have been apparent to his contemporaries. In an open letter to a number of Berlin newspapers, Max von Laue, Heinrich Rubens, and Walther Nernst implored him to continue in his current posts. Nobel laureate Max Planck, and president of the German Physical Society Arnold Sommerfeld, wrote personal letters emphasizing their support for Einstein’s continued presence in the capital. Sommerfeld, in particular, made an effort at reconciliation between the two scientists as a way of heading off open conflict at the upcoming Bad Nauheim meeting, to which Lenard had alluded in his August 2 letter to Stark.

  Sommerfeld was encouraged that a truce might be enacted when Einstein’s friend, physicist Max Born, shared a letter he had received from Einstein. The letter acknowledged, “Everyone needs to offer up his sacrifice at the altar of stupidity . . . and I did so in my article.” Sommerfeld asked Einstein to write a letter of apology to Lenard and to recant his accusations publicly if Lenard requested it. In return, he promised that he would ask Friedrich von Mueller, the chairman of the Bad Nauheim meeting, to feature as part of his opening address a warning against the kind of polemics in which Weyland had engaged. At the same time, Sommerfeld wrote a letter to Lenard informing him of the request he had made of Einstein.

  However, any hope of civility between the two scientists became moot when Lenard wrote back,

  The thought of an apology by Mr. Einstein to me, moreover the assumption of a suitable response to him on my part, to remain satisfactory, I must refuse with indignation. The comments by Mr. Einstein represent the characteristics which must belittle me in the eyes of the reader. They are a sign of personal contempt for me by Mr. Einstein, whose transformation into the required esteem based on some assurance by me would be very astonishing.

  In his stilted, overly formal style, Lenard revealed the stress imposed upon him over what he doubtlessly viewed as a public humiliation. Despite the fact that he actually did conspire with Weyland and others in organizing the evening’s events, he apparently felt that Einstein had unfairly singled him out:

  Mr. Einstein finds his words shameful and probably incorrect, as he has publicly withdrawn his statements. Otherwise he could not make up the wrong done to me to the extent that is even possible. The public release of such value judgments about a colleague, such as those made by Einstein . . . is, in my feeling, an improper arrogance and reveals an all time low of nobleness.

  Despite Lenard’s harsh assessment of his character and the failure of Sommerfeld’s efforts to negotiate a détente, Einstein privately celebrated what seemed to him a settling down of the uproar surrounding a series of unfortunate events. The embarrassing episode had passed, and with it the worry it had caused. The promised twenty lectures at the Berlin Philharmonic were aborted after the second installment, a lackluster and poorly attended presentation by the engineer, Ludwig Glaser. The other scheduled lecturer for the evening failed to appear. Weyland, a potentially dangerous antagonist, had lost face with his former allies. Gehrcke wrote to Lenard that Weyland was simply “one of the many dubious types that had been generated by the revolutionary, warlike city.” Lenard responded, “Weyland, unfortunately, has proven to be a fraud.”

  Reassured by the outpouring of support by his German colleagues and the retrenchment of the Working Society, it must have seemed to Einstein that the storm had passed. Einstein exulted to friends that perhaps the Working Society did not have the following it claimed. As it turned out, Einstein reckoned wrong. There was much more to come. What he took for fair weather was actually the eye of the storm.

  Chapter 5

  A Disagreement

  between Gentlemen

  Less than a month after the Working Group lectures at the Berlin Philharmonic, on the morning of September 19, 1920, the eighty-sixth meeting of the German Society of Natural Scientists and Physicians kicked off an ambitious, weeklong schedule of more than three hundred sessions. Held jointly with the meetings of the German Mathematical Society, the German Physical Society, and the Society of Technical Physics, a late change in venue to Bad Nauheim had presented logistical challenges. Violent political unrest, rampant at the time in the original choice of Frankfurt am Main, convinced the organizers to distance their conference to a more bucolic setting where unsavory elements were less likely to infringe on the business of science.

  Bad Nauheim was a very attractive alternative. The small spa town lies at the edge of the Taunus Mountains, only thirty-five kilometers from Frankfurt. Famous for its carbon dioxide–infused effervescent baths, sworn to be effective in treating heart and nervous conditions, patrons had enjoyed the restorative powers of the town’s briny waters for centuries. The red-roofed, “new baroque”–style main building, named the Sprudelhof, and eight similarly designed bath houses had been commissioned by the Grand Duke Ernst Ludwig of Hessen and by Rhine in 1904. Completed in 1912, the interiors were an art nouveau marvel of sea-themed, ornamental detail, featuring marine creatures, water nymphs, mermaids, and ocean waves. Numerous fountains and outdoor pools graced extensive parklike grounds. In sum, the facilities promised a positive environment that offered both sufficient space for formal events and informality conducive to more intimate conversation.

  Because the conference was the first major scientific meeting in Germany after the end of the war, interest was even greater than usual. As retribution for the war, German scientists were excluded from participation in scientific congresses throughout the rest of Europe. Many were concerned that their isolation disadvantaged them in the compet
ition that exists at the highest levels of science. These fears doubtlessly contributed to the strong turnout of more than 2600 scientists. Those attending knew that the eyes of the scientific world would be watching.

  In the audience for Chairman Mueller’s opening address were seventeen physicists, chemists, and mathematicians who already had been awarded or would eventually receive a Nobel Prize for their innovative research. Among them were Philipp Lenard and Johannes Stark, who applauded vigorously as the chair gave scant nod to his promise of condemning demagoguery before exhorting the gathered scientists to prove their German patriotism in word and deed. As the session progressed, a series of speakers followed suit. The tone of the conference was going Lenard’s way. It was time for him to step from the shadows and strike a second blow against the theory of relativity—one that he had reason to hope would make a large impact on the direction that German science might take in the future.

  For some time, Einstein had been proposing to the organizers of the conference that there be a session devoted to a general discussion of his theory of relativity. In the passion of the moment following the Berlin Philharmonic lectures, he raised the stakes by proposing a debate with his antagonists in open session: “Anyone willing to confront a professional forum can present his objections [to the theory of relativity] there.” The assembled academics expected Lenard and his supporters to take Einstein up on his challenge. As Lenard’s objections to relativity were well known, the expectations were that the critics of relativity would base their arguments on several frequently stated concerns, namely that the theory of relativity:

  Was mathematically deduced but did not actually exist in the physical realm.

  Was supported by only scant experimental evidence; what evidence did exist was explainable by error in observer measurements.

  Rejected the idea of there being an ether to explain how electromagnetic radiation, like light and X-rays, were propagated through space; the theory of relativity did not sufficiently address the mechanism of how this occurred to replace what its detractors claimed had worked well for centuries.

  Contradicted conventional notions of space and time; these conventions, dependent on Euclidian geometry, had served science well and should not be replaced by relativistic artifices.

  Moreover, Lenard intended to introduce a new wrinkle to these longstanding critiques. Specifically, given the abstract nature of the theory of relativity and the absence of supporting physical evidence, at Bad Nauheim and for years afterward, he would attack Einstein’s ideas on the grounds that they went against the principle of “sound common sense.” In Lenard’s mind, they lacked believability.

  Sessions featuring presentations on relativity occurring on September 23 and early in the morning on September 24 set the stage for the open discussion that would conclude the conference. Following the lectures on relativity of September 24, a single door opened to Bath House number 8, guarded on one side by a burly member of the German Mathematical Society and on the other by one from the German Physical Society. The members of these societies were given preferential admission. In all, six hundred scientists jammed into the capacious, richly decorated bath house waiting room; proceeded into the Schmuckhof, a monastery-like ornamental court; and lined the gallery. Afterward, what space remained was opened to a waiting line of members of the press and interested onlookers. Paul Weyland was among them. The crowd was restive; a softly murmured expectancy hung in the air. There was the expectation there would be blood.

  In such a charged atmosphere, it was a given that only one man could chair the session. Although Max Planck was generally known to be a supporter of Einstein, he had expressed concerns of his own on the subject of relativity. Most importantly, his gentility and sense of fairness were widely respected. On this occasion, the courtly physicist responsible for quantum theory appeared to onlookers to be unusually agitated. Planck had encouraged Einstein to stay in Germany in the face of Einstein’s mounting concerns about the bellicose posturing of extremist elements. So far, Einstein had stayed put, but Planck worried that events occurring during the session might cause Einstein to reconsider emigration.

  As it turned out, Planck need not have worried. Writing well after the debate, Einstein made it clear that he had no intention to abandon Germany at this time, noting, “It also would be an injurious act when in this time of stress and humiliation I would turn my back on Germany, given the great kindness that I have constantly experienced from the side of my German colleagues and authorities.” He concluded, “I therefore consider it my duty to endure in my position until outside circumstances render it practically impossible.”

  However, Planck was not privy to these sentiments as he prepared to open the session at Bad Nauheim. His major concern was Lenard, who it was rumored would take the lead among the reactionaries wishing to discredit Einstein. The intense dislike of Einstein and Lenard for one another now embroiled Planck and pushed him into the unwanted role of mediator.

  In principle, the session was to provide a forum for an open discussion of Einstein’s theories. However, it quickly devolved into a mano y mano confrontation between Lenard and Einstein. Although the tone was academic, and only intellectual blows were exchanged, it was apparent to all that the combatants were bitter foes who each bore a serious grudge against the other.

  Lenard soon got to his main points of disagreement with Einstein. Einstein’s work disdained the conventional explanation of ether as the medium of transit for electromagnetic radiation and the supportive element for gravitation. Lenard was not alone. Scientific conservatives frequently expressed concern over the abandonment of ether, despite the fact that two centuries of experimentation had failed to yield any indication of ether’s mass or energy.

  Lenard also disagreed with Einstein’s extension of the principle of relativity to all movements in space rather than just those in steady state. Lenard had earlier written that the theory of general relativity “must give up its universality and no longer claim the ‘relativity of all movements’ but restrict itself to those movements which proceed under the influence of mass proportional forces, such as gravitation.” Indeed, it was over the specific issue of gravitation that Lenard grew exercised.

  As reported in the journal Physikalische Zeitschrift, the exchange between the two physicists swung from the serious to the contemptuous to outright mocking.

  Lenard: I was delighted to have heard talks on the theory of gravitation through the ether today. I have to admit, however, that the simple mind of a natural scientist resents the theory [of relativity] as soon as one goes from gravitational theory to forces other than the mass proportional ones. I relate the example of a braking train. To make the relativity principal work, you add gravitational fields in the absence of mass proportional forces. I would first like to ask you, why is it that it is not differentiable whether the train itself brakes or the world around it slows down?

  Einstein: It is certain that we observe effects relative to the train, and we could interpret these as forces of inertia. The relativity theory could just as well interpret these as effects of the gravitational field. . . . You are convinced that this is the invention of the relativity theory people. However, this is no invention as it fulfills the same differential laws of physics as the effects of masses that we are used to understanding. It is correct that some parts of the solution remain arbitrary when one only looks at a limited scope of the world. I would like to briefly summarize that this field was not arbitrarily invented since it fulfills the general differential equations and since it can be deduced from the effects of all masses.

  Lenard: Mr. Einstein’s explanations did not reveal anything new to me. I am convinced that the gravitational fields that are added need to correspond to occurrences and that these experiences have not been experienced or observed.

  Einstein: I would like to emphasize that what mankind considers clear or apparently valid has changed. The perspective on clarity and apparent validity is somewhat a function of time
. I am convinced that physics should be conceptual rather than just apparently valid.

  Lenard: I have summarized my views in my printed publication, Relativity Theory, Ether, and Gravitation. I understand the usefulness of the relativity principle so long as it is only used with respect to gravitational forces. I view it as invalid when all forces are not proportional to mass.

  Einstein: It is in the nature of things that the validity of the relativity principle can only be postulated if it is valid for all laws of nature.

  Lenard: Only when you invent additional fields.

  What became known in scientific circles as the “Einsteindebatte” continued in this vein for some time, surely appearing to many in the audience as though two infants were bickering over a favorite toy. In the end, each man bore even greater resentment for his interlocutor than had been the case before the session began. There was no resolution, no tidy tying up of loose ends, no common ground to promote a better understanding of the utility of Einstein’s theories. Sensing the bad feelings, a number of physicists, including Einstein’s friends Walther Nernst and Max von Laue, tried to comfort Lenard. Von Laue made an effort at humor, exclaiming, “Einstein, after all, is only a child!” To which Lenard responded, “Children do not write in the Berliner Tageblatt.”

  As the crowd dispersed, Einstein attempted to speak with Lenard in the cloakroom. Lenard would have none of it, saying, “It is now too late,” while brusquely brushing off Einstein’s advance and leaving quickly. Gehrcke chased after him but arrived at the train station platform too late. He reported seeing Einstein through one of the departing train’s windows. There was no sign of Lenard.