Walter Isaacson - Einstein - His Life and Universe

The published papers of Einstein do not identify this “infallible” colleague cited by Drude, but some sleuthing by Renn has turned up a letter from Mari that declares it to be Ludwig Boltzmann. 46That explains why Einstein proceeded to immerse himself in Boltzmann’s writings. “I have been engrossed in Boltzmann’s works on the kinetic theory of gases,” he wrote Grossmann in September, “and these last few days I wrote a short paper myself that provides the missing key-stone in the chain of proofs that he started.” 47

Boltzmann, then at the University of Leipzig, was Europe’s master of statistical physics. He had helped to develop the kinetic theory and defend the faith that atoms and molecules actually exist. In doing so, he found it necessary to reconceive the great Second Law of Thermodynamics. This law has many equivalent formulations. It says that heat flows naturally from hot to cold, but not the reverse. Another way to describe the Second Law is in terms of entropy, the degree of disorder and randomness in a system. Any spontaneous process tends to increase the entropy of a system. For example, perfume molecules drift out of an open bottle and into a room but don’t, at least in our common experience, spontaneously gather themselves together and all drift back into the bottle.

The problem for Boltzmann was that mechanical processes, such as molecules bumping around, could each be reversed, according to Newton. So a spontaneous decrease in entropy would, at least in theory, be possible. The absurdity of positing that diffused perfume molecules could gather back into a bottle, or that heat could flow from a cold body to a hot one spontaneously, was flung against Boltzmann by opponents, such as Wilhelm Ostwald, who did not believe in the reality of atoms and molecules. “The proposition that all natural phenomena can ultimately be reduced to mechanical ones cannot even be taken as a useful working hypothesis: it is simply a mistake,” Ostwald declared. “The irreversibility of natural phenomena proves the existence of processes that cannot be described by mechanical equations.”

Boltzmann responded by revising the Second Law so that it was not absolute but merely a statistical near-certainty. It was theoretically possible that millions of perfume molecules could randomly bounce around in a way that they all put themselves back into a bottle at a certain moment, but that was exceedingly unlikely, perhaps trillions of times less likely than that a new deck of cards shuffled a hundred times would end up back in its pristine rank-and-suit precise order. 48

When Einstein rather immodestly declared in September 1901 that he was filling in a “keystone” that was missing in Boltzmann’s chain of proofs, he said he planned to publish it soon. But first, he sent a paper to the Annalen der Physik that involved an electrical method for investigating molecular forces, which used calculations derived from experiments others had done using salt solutions and an electrode. 49

Then he published his critique of Boltzmann’s theories. He noted that they worked well in explaining heat transfer in gases but had not yet been properly generalized for other realms. “Great as the achievements of the kinetic theory of heat have been in the domain of gas theory,” he wrote, “the science of mechanics has not yet been able to produce an adequate foundation for the general theory of heat.” His aim was “to close this gap.” 50

This was all quite presumptuous for an undistinguished Polytechnic student who had not been able to get either a doctorate or a job. Einstein himself later admitted that these papers added little to the body of physics wisdom. But they do indicate what was at the heart of his 1901 challenges to Drude and Boltzmann. Their theories, he felt, did not live up to the maxim he had proclaimed to Grossmann earlier that year about how glorious it was to discover an underlying unity in a set of phenomena that seem completely separate.

In the meantime, in November 1901, Einstein had submitted an attempt at a doctoral dissertation to Professor Alfred Kleiner at the University of Zurich. The dissertation has not survived, but Mari told a friend that “it deals with research into the molecular forces in gases using various known phenomena.” Einstein was confident. “He won’t dare reject my dissertation,” he said of Kleiner, “otherwise the shortsighted man is of little use to me.” 51

By December Kleiner had not even responded, and Einstein started worrying that perhaps the professor’s “fragile dignity” might make him uncomfortable accepting a dissertation that denigrated the work of such masters as Drude and Boltzmann. “If he dares to reject my dissertation, then I’ll publish his rejection along with my paper and make a fool of him,” Einstein said. “But if he accepts it, then we’ll see what good old Herr Drude has to say.”

Eager for a resolution, he decided to go see Kleiner personally. Rather surprisingly, the meeting went well. Kleiner admitted he had not yet read the dissertation, and Einstein told him to take his time. They then proceeded to discuss various ideas that Einstein was developing, some of which would eventually bear fruit in his relativity theory. Kleiner promised Einstein that he could count on him for a recommendation the next time a teaching job came up. “He’s not quite as stupid as I’d thought,” was Einstein’s verdict.“Moreover, he’s a good fellow.” 52

Kleiner may have been a good fellow, but he did not like Einstein’s dissertation when he finally got around to reading it. In particular, he was unhappy about Einstein’s attack on the scientific establishment. So he rejected it; more precisely, he told Einstein to withdraw it voluntarily, which permitted him to get back his 230 franc fee. According to a book written by Einstein’s stepson-in-law, Kleiner’s action was “out of consideration to his colleague Ludwig Boltzmann, whose train of reasoning Einstein had sharply criticized.” Einstein, lacking such sensitivity, was persuaded by a friend to send the attack directly to Boltzmann. 53

Lieserl

Marcel Grossmann had mentioned to Einstein that there was likely to be a job at the patent office for him, but it had not yet materialized. So five months later, he gently reminded Grossmann that he still needed help. Noticing in the newspaper that Grossmann had won a job teaching at a Swiss high school, Einstein expressed his “great joy” and then plaintively added, “I, too, applied for that position, but I did it only so that I wouldn’t have to tell myself that I was too faint-hearted to apply.” 54

In the fall of 1901, Einstein took an even humbler job as a tutor at a little private academy in Schaffhausen, a village on the Rhine twenty miles north of Zurich. The work consisted solely of tutoring a rich English schoolboy who was there. To be taught by Einstein would someday seem a bargain at any price. But at the time, the proprietor of the school, Jacob Nüesch, was getting the bargain. He was charging the child’s family 4,000 francs a year, while paying Einstein only 150 francs a month, plus providing room and board.

Einstein continued to promise Mari that she would “get a good husband as soon as this becomes feasible,” but he was now despairing about the patent job. “The position in Bern has not yet been advertised so that I am really giving up hope for it.” 55

Mari was eager to be with him, but her pregnancy made it impossible for them to be together in public. So she spent most of November at a small hotel in a neighboring village. Their relationship was becoming strained. Despite her pleas, Einstein came only infrequently to visit her, often claiming that he did not have the spare money. “You’ll surely surprise me, right?” she begged after getting yet another note canceling a visit. Her pleadings and anger alternated, often in the same letter: