“Let’s see if Einstein can solve our problem.” This was not an idea I had ever entertained, much less verbalized, during my previous twenty-six years doing research in quantum physics. Physicists don’t read the works of the great masters of earlier generations. We learn physics from weighty textbooks in which the ideas are stated with cold-blooded logical inevitability, and the history that is mentioned is sanitized to eliminate the passions, egos, and human frailties of the great “natural philosophers.” After all, since physical science (we believe) is a cumulative discipline, why shouldn’t we downplay or even censor the missteps and...

On the evening of Friday, October 19, 1900, Max Planck, the world’s leading expert on the science of heat, was experiencing a physicist’s worst nightmare. Little more than a year earlier, he had staked his considerable reputation on a theory that purported to solve the outstanding problem of his field: the relationship between heat and light. Tonight at this meeting of the German Physical Society, the hall filled by the men who had been Planck’s closest colleagues for over a decade, another scientist would announce publicly what Planck already knew—that the theory he had worked on for the past...

We do not know the exact moment when Heinrich Weber began to despise Albert Einstein. It definitely was not at first sight. Professor Weber was the head of the Physics Department of the Federal Institute of Technology, an up-and-coming engineering school in Zurich, Switzerland, now known worldwide as ETH Zurich. In 1895, when Weber and Einstein first met, the “Poly” (as it was called by the locals) had the immense advantage for the young Einstein that it did not require a high school diploma for admission. This was particularly pertinent for Einstein because he had rather recently and without the...

“This Einstein will one day be a very great man.” Although Einstein had finished college having made a poor impression on his professors, the opposite was true of his peers. Einstein already was a man of great charisma and charm, to go along with his penetrating intellect and deep understanding of science. The prediction of greatness came from Einstein’s classmate Marcel Grossmann, only a few days after their first meeting in 1898. Grossmann, according to Einstein, “was a model student, close to his teachers”; he would graduate at the top of their class and within a few years become a...

“About Max Planck’s studies on radiation, misgivings of a fundamental nature have arisen in my mind, so that I am reading his article with mixed feelings.” So Einstein wrote to his Dolly from Milan in April of 1901, a scant four months after Planck’s “act of desperation” in Berlin had saved his own reputation but failed to alert the physics community to the storm ahead. In the same letter Einstein ruefully admits, “soon I will have honored all physicists from the North Sea to the southern tip of Italy with my [job inquiry].” Emboldened by his first published article, which...

“The Boltzmann is magnificent,” Einstein wrote to Maric in September of 1900. “I am firmly convinced that the principles of his theory are right, . . . that in the case of gases we are really dealing with discrete particles of definite finite size which are moving according to certain conditions . . . the hypothetical forces between molecules are not an essential component of the theory, as the whole energy is kinetic. This is a step forward in the dynamical explanation of physical phenomena.” Einstein was reading Boltzmann’s Lectures on the Theory of Gases. The Viennese physicist Ludwig Boltzmann...

“I have again made the acquaintance of a sorry example of that species—one of the leading physicists of Germany. To two pertinent objections which I raised about one of his theories and which demonstrate a direct defect in his conclusions, he responds by pointing out that another (infallible) colleague of his shares his opinion. I will shortly give that man a kick up the backside with a hefty publication. Authority befuddled is the greatest enemy of truth.”

Such was the feisty mood of Einstein as he wrote in July of 1901 to an old friend, Jost Winteler. The object...

The tomb of Ludwig Boltzmann in Vienna is engraved with a very short and simple-looking equation, which, ironically, he never wrote down during his lifetime:

S = k log W.

S is the universal symbol for entropy, k is a fundamental constant of nature known as Boltzmann’s constant, and log W is the logarithm¹ of a number, W, relating to the physical system of interest, a number that Boltzmann called the number of “complexions.” (The number W can be so devilishly hard to calculate for many physical systems of interest that the greatest mathematical physicists of the twenty-first century, and...

One of the great open questions in the history of science is how Einstein came to the core idea of his paradigm-shifting paper of 1905. No, not his paper on special relativity or his paper proposing the famous equation E = mc². Einstein was asked over and over again how he had developed the key insights leading to the special and general theories of relativity, and he answered with various charming anecdotes that have become part of his legend. As far as we know, he never went on record as to how he came up with the basic conception for...

“The wave [Maxwell] theory of light . . . has proved itself splendidly in describing purely optical phenomena and probably will never be replaced by another theory. . . . [However] it is conceivable that . . . the [wave] theory of light may lead to contradictions with experience when it is applied to the phenomena of production and transformation of light. Indeed it seems to me that the observations regarding ‘blackbody radiation,’ photoluminescence, and [the photoelectric effect] . . . can be understood better if one assumes that the energy of light is discontinuously distributed in space. According to...

“I do not seek the meaning of the quantum of action (light quantum) in the vacuum but at the sites of absorption and emission, and assume that processes in vacuum are described exactly by Maxwell’s equations.” This was Max Planck’s first known response to Einstein’s heuristic theory of light quanta, sent to Einstein in a letter of July 6, 1907, more than two years after the publication of the “revolutionary” paper of 1905. Planck must surely have known of Einstein’s ideas much earlier, since he was the theory editor of the journal in which they were published, Annalen der Physik....

“The three of us are fine, as always. The little sprout has grown into quite an imposing impertinent fellow. As for my science, I am not all that successful at present. Soon I will reach the age of stagnation and sterility when one laments the revolutionary spirit of the young. My papers are much appreciated and are giving rise to further investigations. Professor Planck (Berlin) has recently written to me about that.”

Thus the twenty-seven-year-old Einstein wrote to his former Olympia Academy colleague Maurice Solovine in April 1906, in the aftermath of his miracle year. The “little sprout” he spoke...

In June of 1900, six months prior to Planck’s historic act of desperation and long before Einstein’s 1906 clarification of its meaning, John William Strutt, Lord and Third Baron Rayleigh, had noticed that something must be wrong with the Wien law. This was the law that was believed to describe blackbody radiation but would soon be found experimentally to fail at long wavelengths.

Lord Rayleigh, a member of the British nobility, had overcome his family’s disapproval of the plebeian study of nature to ascend to the very pinnacle of British science. He had been a sickly youth, bouncing from school...

Einstein’s nemesis in his student days, Professor Heinrich Weber, may have come close to depriving posterity of Einstein’s historic genius, but now Herr Weber would indirectly play a crucial role in the flowering of that genius. In 1875 the young Weber, then an assistant to Helmholtz in Berlin, had just completed the best experiments extant on the specific heat of solids. The effect he was studying was an apparent violation of the empirical law noted by Pierre Dulong and Alex Petit fifty-six years earlier in 1819. These French researchers had discovered that pretty much every solid they measured had the...

It was the fall of 1908, and Svante Augustus Arrhenius was determined to see that Max Planck received the Nobel Prize for Physics that year. Arrhenius, a scientist of impressively broad and bold speculations, had recently returned from a tour of Europe, where he was received warmly as befitted the first Swedish winner of the newly minted Nobel prizes. Arrhenius had won the Chemistry Prize in 1903 (two years after the establishment of the awards) for his groundbreaking work on electrolytic chemistry. He was widely recognized as a founder of the discipline of physical chemistry, which works at the boundary...

“So, now I too am an official member of the guild of whores.” Thus Einstein announced to a friend, Jakob Laub, his long-overdue acceptance into the Swiss professoriate. Einstein had been appointed extraordinary professor of theoretical physics at the University of Zurich on May 7, 1909, and was writing shortly thereafter to describe the last phase of his “hazing” before admission to the fraternity. This same Laub, a young Austrian physicist who had studied with Wien, had written Einstein fourteen months earlier, saying, “I must tell you quite frankly that I was surprised to read that you must sit in...

“I am very sorry if I have caused you distress by my careless behavior. I answered the congratulatory card your wife sent me on the occasion of my appointment too heartily and thereby reawakened the old affection we had for each other. But this was not done with impure intentions. The behavior of your wife, for whom I have the greatest respect, was totally honorable. It was wrong of my wife—and excusable only on account of extreme jealousy—to behave—without my knowledge—the way she did.” In June of 1909, Einstein sent this apology to someone he had...

Although in Salzburg it was clear to observers such as Max Born that “Einstein’s achievement received its seal [of approval] before the assembled world of scientists,” the achievement most recognized was his theory of relativity, which by then had been well confirmed by the fast-electron experiments of Alfred Bucherer in Bonn. As just noted, Einstein’s quantum hypotheses were regarded by all the leaders present in Salzburg as perhaps inventive, but certainly rash and premature. This impression was possibly facilitated by Einstein’s decision not to mention in his lecture his lesser-known work on the specific heat of solids. This work, showing...

A distinguished white-haired man, impeccably dressed, just over seventy, took the podium to explain his theory. In the small audience of twenty-four, listening attentively, were Einstein, Lorentz, Planck, Nernst, Wien, Rutherford, Madame Curie, Jean Perrin, and H. K. Onnes, all of whom were current or future Nobel laureates, as well as major scientific figures such as Sommerfeld, Rubens, Poincaré, and Jeans. The venue was a small meeting room in the elegant Hotel Metropole in Brussels.

I decided to take as my starting point the one general concept that could meet the demands of the most scrupulous, philosophical and constructive mind:...

Having decided that a true quantum theory was not yet attainable in 1911, even with his utmost exertion, Einstein devoted himself for the next four years primarily to his new theory of gravity, which arose as a natural generalization of his special theory of relativity and is hence termed the general relativity theory. The inspiration for his first work in this area, the special theory, had come from the properties of electromagnetic waves, arising from Maxwell’s equations. Gravity played no role at all in his thinking, and in fact prior to 1907, in contrast to his well-documented interest in atoms,...

Einstein had not only changed his domestic situation by moving to Berlin; he had radically changed his social and political environment. Within a month of his inaugural address at the Prussian Academy of Sciences he found himself surrounded by a flood of militaristic German nationalism, alone on a tiny island of pacifist universalism. The Great War had begun, and his admired German colleagues—Nernst, Haber, and even the mild-mannered Planck—rushed to show their devotion to the fatherland. They and many other academics signed an ill-conceived “Appeal to the Cultured World” denying documented German war crimes in Belgium and asserting...

“Why Planck and I engaged him just as you take on a butler, and now look what a mess he’s made of physics; one can’t turn one’s back for a minute.” This was Nernst’s sardonic appraisal of Einstein’s triumph with general relativity. The esteemed professors of the Prussian Academy had not brought Einstein to Berlin to monkey around with the law of gravity and the geometry of space-time; they were expecting him to lead them to victory in the race to understand the atom. Instead he had ceded the inside rail to the Dane Niels Bohr, and his English collaborators,...

“I have firmly decided to bite the dust with a minimum of medical assistance when my time has come, and up to then to sin to my wicked heart’s desire. Diet: smoke like a chimney, work like a horse, eat without thinking and choosing, go for walks only in really pleasant company, and thus only rarely, unfortunately, sleep irregularly, etc.” This was Einstein’s cheeky pronouncement to Elsa Einstein back in August 1913, before his arrival in Berlin and the monumental labors that occupied him between then and the completion of his new work on thermal radiation in 1916. Many historians...

While Einstein struggled to regain his vitality and refocus his efforts on understanding the atom during the years 1917 and 1918, a singular confluence of social forces was occurring that would change his life irrevocably. On November 9, 1918, the German Reich surrendered, the kaiser abdicated, and Germany was thrown into political turmoil. The Great War would leave a residue of hatred, resentment, and disillusionment, which would affect international scientific cooperation for a decade. Yet within less than a year a British scientific expedition would catapult Einstein to a level of global fame unprecedented in the history of science. Arthur...

This letter to Einstein from an unknown Indian scientist, received in early June, 1924, initiated one of the most extraordinary episodes in the modern history of science, culminating in Einstein’s final historic contribution to the structure of the new quantum theory. At the time of his writing, Satyendra Nath Bose was a thirty-year-old Reader (roughly equivalent to the rank of associate professor) at Dacca University in East Bengal. His previous five research papers had made no impact at all on contemporary research, and he had recently been informed that, due to a funding cutoff to the university, his appointment would...

Just under two years before Einstein’s famous rejection of the new quantum mechanics with the memorable phrase “I . . . am convinced that [God] is not playing at dice,” Einstein himself, inspired by Bose, changed the laws governing the playing of dice. Bose had unwittingly introduced a new method of counting the states of a physical system in order to derive the Planck law from direct consideration of a gas of light quanta, treated as particles, not waves. It was Einstein who would now explain and extend this new representation of the microscopic world to resolve long-standing paradoxes in...

“A younger brother of the de Broglie known to us has made a very interesting attempt to interpret the Bohr-Sommerfeld quantization rules in his dissertation. I believe that it is the first feeble ray of light to illuminate this, the worst of our physical riddles. I have also discovered something that supports his construction.” So Einstein wrote to Lorentz in December of 1924, just as he was completing his masterpiece on the quantum ideal gas. In the midst of his cogitations on the meaning of Bose statistics, during the summer of 1924, a second bolt from the blue singed his...

“When you began this work you had no idea that anything so clever would come out of it, had you?” This question was addressed to the Austrian theorist Erwin Schrödinger sometime in the fall of 1926. The questioner was a young female admirer of the thirty-nine-year-old physicist, whose unusual marriage allowed for many such “friendships.” The work in question was that leading to the most famous equation of quantum mechanics, the “wave equation,” named after its inventor. Schrödinger’s scientific colleagues were less restrained in their praise. The reserved Planck effused, “I have read your article the way an inquisitive child...

“I am convinced that you have made a decisive advance with your formulation of the quantum condition, just as I am equally convinced that the Heisenberg-Born route is off the track.” Thus Einstein wrote to Schrödinger in late April of 1926. The Heisenberg-Born route, a different approach to the “quantum conditions,” introduced the term “quantum mechanics” as a more rigorous replacement for the nebulous conceptual structure of “quantum theory.” This method had begun to bear fruit six months earlier than Schrödinger’s, and unlike his work it arose independently of Einstein’s recent successes with the quantum gas.

It represented the radical...

“Here I sit in order to write, at the age of 67, something like my own obituary . . . [this] does . . . not come easy—today’s person of 67 is by no means the same as was the one of 50, of 30 or of 20. Every reminiscence is colored by today’s being what it is, and therefore by a deceptive point of view.” Einstein, in the autobiographical sketch he thus begins, confirms his initial disclaimer. Readers hoping to learn from the man himself amusing anecdotes or details of his personal life were disappointed; the article of...