In early 1924, before he sent his article to Einstein, Bose had applied to Dacca university for a grant to spend two years studying in Europe. The school officials took their time considering such an expensive idea. Apart from the cost of two years living at European prices, Bose would need travel money and a supplementary grant to ensure a living for his wife and family. Any officialdom worthy of its stamp pads can delay indefinitely a costly proposal like that, but the cavalry suddenly arrived in the unexpected form of a postcard written in Einstein’s own hand. “The smartest man in the world” had written from Berlin to an obscure physics teacher (not even the head of his department) in Bengal to say that he (Einstein) considered Bose’s work to be an important contribution to quantum physics, and that he would see that the article was published. Good-bye, bureaucratic delay. Dacca University promptly voted a generous stipend. The German consulate, after one look at Einstein’s postcard, gave Bose an immediate visa and waived the standard fee.

Bose then traveled by railway across India’s breadth and set sail from Bombay for the wonders of Europe. Arriving in Paris several months after his article had appeared, he discovered that his name was already known to France’s leading physicists. Maurice de Broglie put him to work in his lab, and Bose stayed in Paris for almost a year. That

was the Paris of expatriate fame. William Faulkner was there that year, living the bohemian life with no money. Aleksandr Kerensky, the revolutionary democrat whom Lenin had chased into exile, had landed in Paris, too. It was the city where Stravinsky composed, Picasso painted, and Gertrude Stein collected.

In physics it was the home of Madame Curie and Paul Langevin. Bose met both of them and he corresponded with Einstein, letting him know that he was in Europe and hoped to meet him in Berlin. Einstein encouraged Bose to come and talk. Yet Bose hesitated to move on. Accounts of Bose’s travels tend to express puzzlement over his long stay in Paris before pushing on to Einstein. Perhaps those head-scratchers should read Hemingway’s A Moveable Feast to get a sense of the pleasures and excitement that held Bose in France. He finally arrived in Berlin a year later, in October 1925, only to find that Einstein was away on his annual visit to Leiden, so Bose had several weeks on his own to look about and explore the German capital.

The city he found was much different from the tormented stadt of two years earlier. The hyperinflation had become a bad memory, and even the war promised finally to recede into history. An armistice had ended the fighting in 1918 but had resolved nothing else, not even the military blockade. The Treaty of Versailles ended the blockade but kept the hatred at full boil. Even Germany’s borders had remained unsettled. Now, in the fall of 1925, another agreement, called the Treaty of Locarno, was negotiated, this time settling Germany’s western borders with France and Belgium. Einstein hoped this new “spirit of Locarno” meant that Germany would at last be welcomed into the League of Nations.

Clearly too, in this recovered world, Berlin would become almost as grand as Paris. Bose found in Berlin a cosmopolis that had already become a greater center of modern art than it had ever been before. The grand talents that were once scattered over many German-speaking cities and regions had begun moving into Berlin, the way geniuses of the Renaissance had swarmed on Rome. Berthold Brecht had been Munich’s leading playwright, but he was now in Berlin. Heinrich Mann (brother of Thomas Mann), long considered Germany’s finest prose writer, had also left Munich for the new center. Arnold

Schönberg moved there from Vienna, bringing the most radical new music with him. Alban Bern was there too, rehearsing his opera Wozzeck for its world premiere in December. Young artists whose careers would span the remaining century were in town. Yehudi Menuhin played the violin while, around the block, Vladimir Horowitz performed on piano.

And Berliners appreciated what they had. “I loved the rapid, quick-witted reply of the Berlin woman above everything, the keen, clear reaction of the Berlin audience in the theater, in the cabaret, on the street and in the café, that taking-nothing-solemnly yet taking-seriously of things,” recalled a film critic of that era. Bose absorbed the sights and sounds until Einstein’s return from the Netherlands. When the two men at last came face to face, Einstein expected to meet a theoretical physicist and greeted him as such.

“How did you discover your method of deriving Planck’s formula,” Einstein wondered.

“Well,” Bose replied, “I recognized the logical contradictions in both Planck’s and your own derivations of the formula and I applied the statistics in my own way.”

Einstein moved in to challenge Bose. Did he think that these statistics meant something new about the interaction of quanta? And could he work out the details of those interactions?

With that question, Einstein had brought Bose to the frontier of quantum physics. The great need was for a coherent, intelligible theory that would describe how quantum mobiles, to use de Broglie’s term, acted on one another. In particular, of course, Einstein would have welcomed any insights useful in predicting the direction taken by a newborn photon.

Bose, however, had no notions on extending his statistics toward a quantum mechanics. He was, in fact, not really a practicing scientist of the sort Einstein usually dealt with. By vocation and imagination, Bose was a great teacher. He did not strive to understand nature so much as he struggled for ways to help his students understand the achievements of others. He had devised his new way of deriving Planck’s formula because both Planck’s and Einstein’s derivations seemed to him to mingle classic and quantum ideas as injudiciously as a bar-

tender mixing whiskeys. As a teacher, Bose could not ask his students to pretend to understand something that was fundamentally illogical, so he had looked for a better explanation that would satisfy his most alert students. That effort had given Bose’s letter to Einstein its odd tone of crackpot supplicant. Bose had written to Einstein as one teacher to another (“we are all your pupils”) while Einstein had responded as one physicist to another. In Berlin, however, it became apparent that the two men could not really help one another directly. Although he taught many people, Einstein lacked a teacher’s ambition to convert people to a way of thinking, while Bose, despite his enduring contribution to theoretical physics, was not driven by a scientific imagination. Einstein did give Bose letters of introduction and commendation that allowed him to enter all science doors in Berlin and Göttingen, but the two men did not become collaborators.

In a world where teaching is devalued, even viewed with contempt, this turn of events is seen to reflect ill on Bose. Even Bose himself spoke rather slightingly of his career, saying, “On my return to India I wrote some papers. I did something on statistics and then again on relativity theory, a sort of mixture, a medley. They were not so important. I was not really in science any more. I was like a comet, a comet which came once and never returned again.” Yet in India he continued teaching, inspiring generations of students through the legend of his meeting with Einstein, and in the way he clarified physics by demanding that the students see an idea’s rough spots and find their way through it. “Never accept an idea as long as you yourself are not satisfied with its consistency and the logical structure on which the concepts are based. Study the masters. These are the people who have made significant contributions to the subject. Lesser authorities cleverly bypass the difficult points.”

So the unexpected voice from India was not going to rescue Einstein from the puzzle patch that physics had become. In December, following his encounter with Bose, Einstein returned to the Netherlands to

join in celebrating the 50th anniversary of Lorentz’s doctorate. Europe’s leading theorists came to honor one of the founders of their field. Ehrenfest served as host. Bohr had come down from Copenhagen. Madame Curie and Arthur Eddington were there too, along with dignitaries from outside the scientific world. Queen Wilhelmina attended the ceremony and presented Lorentz with a medal.

The biggest surprise in physics during Lorentz’s 50 years as a doctor of philosophy had surely been the ruin of perhaps the oldest idea in scientific materialism—the belief that matter was ultimately composed of indivisible little particles that moved exactly the way larger particles moved. The giants celebrating Lorentz’s career, and the guest of honor himself, had put an end to that notion. Lorentz had predicted and coined the name “electron” for a particle smaller than an atom that somehow was part of an atom. The initial assumption, of course, had been that electrons themselves were tiny indivisible particles that moved according to the laws of classical mechanics.

Bohr, smoking his pipe and enjoying the Lorentz celebration, had shown that electron motions did not match perfectly with classical ones. And Einstein, with de Broglie and Bose, had recently brought the story even further, showing that electrons are not pure particles but some sort of wave-particle duality. When Max Born (absent from the festival because he was taking advantage of American lecture fees) organized a meeting to discuss de Broglie’s paper, one of his students proposed an experiment to test the idea that electrons showed wave properties. “Not necessary,” said Max Born’s colleague, James Franck. He reported that an American researcher at AT&T had already performed experiments that gave de Broglie’s predicted results.

The world was not as the materialists had expected, but how could it be? Materialists had not anticipated the existence of a second fundamental reality: energy. If you reduced all matter to indivisible particles, you still would not have accounted for the energy running all those steam and internal-combustion engines that powered the industrial world. There had to be more to the story than the classical atoms and their endless, random motions.

Einstein had shown in 1905 that the story was going to become irretrievably strange. In the spring of that year he had proved that

atoms were real, and in the fall he concluded that energy and matter are different forms of the same thing. Matter can be metamorphosed into energy. The old image of atoms as solid specks of grit was not going to work. Inevitably you were going to find that when you got down to fundamentals—down to apparently indivisible specks like photons and electrons—you were going to meet ambiguities. Specks of energy had particle-like natures, while specks of matter had wave-like properties.

Lorentz, cheered and congratulated, had kept abreast of those changes and proved his continuing nimble-mindedness by remaining knowledgeable, articulate and inventive about the many new ideas that had appeared since he had become Dr. Lorentz. The relativity of time, the quantum of action, the electron jump—he had absorbed them all, while staying faithful to the basic scientific ambition of understanding natural phenomena in nature’s own terms. For the young and middle-aged physicists at the celebration, this demand for perpetual agility was the promise and challenge of a scientific career. If they could remain as fleet-footed as Lorentz, they could keep moving toward the pot at the rainbow’s end where a full understanding of nature lay.

An example of the demands and rewards of science was visible at the celebration itself. Ehrenfest showed off two of his bright students, who had just discovered a third property of electrons. Besides mass and charge, electrons have a “spin.” They rotate around themselves the way the earth does. It was typical of Ehrenfest’s two sides—great teacher, neurotic self-doubter—that he was producing precocious students even while he worried that the new physics was eluding him.

Bohr was dubious of this latest idea. How does an electron’s magnetic field survive the picture of a spinning electron?

Elementary my dear Bohr, Ehrenfest told him. This was the basic stuff of relativity. A rotating electron is, from the electron’s point of view, standing still while its electric field appears to rotate about it. And when you have a rotating electric field you have a rotating magnetic one as well.

Ah, it clicked for Bohr, and he saw that physics had taken another stride.

That roomful of savants—talking gossip, talking science, disputing and finding common footing—had characterized science throughout Lorentz’s career. It had the look of an enterprise that would go on that way forever. In fact, however, this proved the last gathering of the old scientific order. Lorentz’s celebration was like the funeral of England’s Edward VII on the eve of the Great War. Kings and potentates had turned out to show the strength of the international system, but really they were bidding it farewell.