Einstein (18 page)

Einstein’s impudence and contempt for convention, traits that were abetted by Mari
, were evident in his science as well as in his personal life in 1901. That year, the unemployed enthusiast engaged in a series of tangles with academic authorities.

The squabbles show that Einstein had no qualms about challenging those in power. In fact, it seemed to infuse him with glee. As he proclaimed to Jost Winteler in the midst of his disputes that year, “Blind respect for authority is the greatest enemy of truth.” It would prove a worthy credo, one suitable for being carved on his coat of arms if he had ever wanted such a thing.

His struggles that year also reveal something more subtle about Einstein’s scientific thinking: he had an urge—indeed, a compulsion—to unify concepts from different branches of physics. “It is a glorious feeling to discover the unity of a set of phenomena that seem at first to be completely separate,” he wrote to his friend Grossmann as he embarked that spring on an attempt to tie his work on capillarity to Boltzmann’s theory of gases. That sentence, more than any other, sums up the faith that underlay Einstein’s scientific mission, from his first paper until his last scribbled field equations, guiding him with the same sure sense that was displayed by the needle of his childhood compass.
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Among the potentially unifying concepts that were mesmerizing Einstein, and much of the physics world, were those that sprang from kinetic theory, which had been developed in the late nineteenth century by applying the principles of mechanics to phenomena such as heat transfer and the behavior of gases. This involved regarding a gas, for example, as a collection of a huge number of tiny particles—in this case, molecules made up of one or more atoms—that careen around freely and occasionally collide with one another.

Kinetic theory spurred the growth of statistical mechanics, which describes the behavior of a large number of particles using statistical
calculations. It was, of course, impossible to trace each molecule and each collision in a gas, but knowing the statistical behavior gave a workable theory of how billions of molecules behaved under varying conditions.

Scientists proceeded to apply these concepts not only to the behavior of gases, but also to phenomena that occurred in liquids and solids, including electrical conductivity and radiation. “The opportunity arose to apply the methods of the kinetic theory of gases to completely different branches of physics,” Einstein’s close friend Paul Ehrenfest, himself an expert in the field, later wrote.“Above all, the theory was applied to the motion of electrons in metals, to the Brownian motion of microscopically small particles in suspensions, and to the theory of blackbody radiation.”
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Although many scientists were using atomism to explore their own specialties, for Einstein it was a way to make connections, and develop unifying theories, between a variety of disciplines. In April 1901, for example, he adapted the molecular theories he had used to explain the capillary effect in liquids and applied them to the diffusion of gas molecules. “I’ve got an extremely lucky idea, which will make it possible to apply our theory of molecular forces to gases as well,” he wrote Mari
. To Grossmann he noted, “I am now convinced that my theory of atomic attractive forces can also be extended to gases.”
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Next he became interested in the conduction of heat and electricity, which led him to study Paul Drude’s electron theory of metals. As the Einstein scholar Jürgen Renn notes, “Drude’s electron theory and Boltzmann’s kinetic theory of gas do not just happen to be two arbitrary subjects of interest to Einstein, but rather they share an important common property with several other of his early research topics: they are two examples of the application of atomistic ideas to physical and chemical problems.”
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Drude’s electron theory posited that there are particles in metal that move freely, as molecules of gas do, and thereby conduct both heat and electricity. When Einstein looked into it, he was pleased with it in parts. “I have a study in my hands by Paul Drude on the electron theory, which is written to my heart’s desire, even though it contains some very sloppy things,” he told Mari
. A month later, with his usual lack of
deference to authority, he declared, “Perhaps I’ll write to Drude privately to point out his mistakes.”

And so he did. In a letter to Drude in June,Einstein pointed out what he thought were two mistakes.“He will hardly have anything sensible to refute me with,” Einstein gloated to Mari
, “because my objections are very straightforward.” Perhaps under the charming illusion that showing an eminent scientist his purported lapses is a good method for getting a job, Einstein included a request for one in his letter.
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Surprisingly, Drude replied. Not surprisingly, he dismissed Einstein’s objections. Einstein was outraged. “It is such manifest proof of the wretchedness of its author that no further comment by me is necessary,” Einstein said when forwarding Drude’s reply to Mari
. “From now on I’ll no longer turn to such people, and will instead attack them mercilessly in the journals, as they deserve. It is no wonder that little by little one becomes a misanthrope.”

Einstein also vented his frustration to Jost Winteler, his father figure from Aarau, in a letter that included his declaration about a blind respect for authority being the greatest enemy of truth. “He responds by pointing out that another ‘infallible’ colleague of his shares his opinion. I’ll soon make it hot for the man with a masterly publication.”
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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.
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That 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.”
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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.
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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.
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