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photoelectrical effect has been extremely rigorously tested by the American Millikan* and his pupils and passed the test brilliantly,” he said.<br />
“Einstein’s law has become the basis of quantitative photo-chemistry in the same way as Faraday’s law is the basis of electro-chemistry.” 13<br />
Einstein gave his official acceptance speech the following July at a Swedish science conference with King Gustav Adolf V in attendance. He<br />
spoke not about the photoelectric effect, but about relativity, and he concluded by emphasizing the importance of his new passion, finding a unified<br />
field theory that would reconcile general relativity with electromagnetic theory and, if possible, with quantum mechanics. 14<br />
The prize money that year amounted to 121,572 Swedish kronor, or $32,250, which was more than ten times the annual salary of the average<br />
professor at the time. As per his divorce agreement with Mari , Einstein had part of it sent directly to Zurich to reside in a trust for her and their<br />
sons, and the rest went into an American account with the interest directed for her use.<br />
This prompted another row. Hans Albert complained that the trust arrangement, which had previously been agreed to, made only the interest on<br />
the money accessible to the family. Once again, Zangger intervened and calmed the dispute. Einstein jokingly wrote to his sons, “You all will be so<br />
rich that some fine day I may ask you for a loan.”The money was eventually used by Mari to buy three homes with rental apartments in Zurich. 15<br />
Newton’s Bucket and the Ether Reincarnated<br />
“Anything truly novel is invented only during one’s youth,” Einstein lamented to a friend after finishing his work on general relativity and cosmology.<br />
“Later one becomes more experienced, more famous—and more blockheaded.” 16<br />
Einstein turned 40 in 1919, the year that the eclipse observations made him world-famous. For the next six years, he continued to make<br />
important contributions to quantum theory. But after that, as we shall see, he would begin to seem, if not blockheaded, at least a bit stubborn as he<br />
resisted quantum mechanics and embarked on a long, lonely, and unsuccessful effort to devise a unified theory that would subsume it into a more<br />
deterministic framework.<br />
Over the ensuing years, researchers would discover new forces in nature, besides electromagnetism and gravity, and also new particles. These<br />
would make Einstein’s attempts at unification all the more complex. But he would find himself less familiar with the latest data in experimental<br />
physics, and he thus would no longer have the same intuitive feel for how to wrest from nature her fundamental principles.<br />
If Einstein had retired after the eclipse observations and devoted himself to sailing for the remaining thirty-six years of his life, would science have<br />
suffered? Yes, for even though most of his attacks on quantum mechanics did not prove to be warranted, he did serve to strengthen the theory by<br />
coming up with a few advances and also, less intentionally, by his ingenious but futile efforts to poke holes in it.<br />
That raises another question: Why was Einstein so much more creative before the age of 40 than after? Partly, it is an occupational hazard of<br />
mathematicians and theoretical physicists to have their great breakthroughs before turning 40. 17 “The intellect gets crippled,” Einstein explained to<br />
a friend, “but glittering renown is still draped around the calcified shell.” 18<br />
More specifically, Einstein’s scientific successes had come in part from his rebelliousness. There was a link between his creativity and his<br />
willingness to defy authority. He had no sentimental attachment to the old order, thus was energized by upending it. His stubbornness had worked to<br />
his advantage.<br />
But now, just as he had traded his youthful bohemian attitudes for the comforts of a bourgeois home, he had become wedded to the faith that<br />
field theories could preserve the certainties and determinism of classical science. His stubbornness henceforth would work to his disadvantage.<br />
It was a fate that he had begun fearing years before, not long after he finished his famous flurry of 1905 papers. “Soon I will reach the age of<br />
stagnation and sterility when one laments the revolutionary spirit of the young,” he had worried to his colleague from the Olympia Academy, Maurice<br />
Solovine. 19<br />
Now, many triumphs later, there were young revolutionaries who felt this fate had indeed befallen him. In one of his most revealing remarks about<br />
himself, Einstein lamented, “To punish me for my contempt of authority, Fate has made me an authority myself.” 20<br />
Thus it is not surprising that, during the 1920s, Einstein found himself scaling back on some of his bolder earlier ideas. For example, in his 1905<br />
special relativity paper he had famously dismissed the concept of the ether as “superfluous.” But after he finished his theory of general relativity, he<br />
concluded that the gravitational potentials in that theory characterized the physical qualities of empty space and served as a medium that could<br />
transmit disturbances. He began referring to this as a new way to conceive of an ether.“I agree with you that the general relativity theory admits of<br />
an ether hypothesis,” he wrote Lorentz in 1916. 21<br />
In a lecture in Leiden in May 1920, Einstein publicly proposed a reincarnation, though not a rebirth, of the ether. “More careful reflection teaches<br />
us, however, that the special theory of relativity does not compel us to deny ether,” he said. “We may assume the existence of an ether, only we<br />
must give up ascribing a definite state of motion to it.”<br />
This revised view was justified, he said, by the results of the general theory of relativity. He made clear that his new ether was different from the<br />
old one, which had been conceived as a medium that could ripple and thus explain how light waves moved through space. Instead, he was<br />
reintroducing the idea in order to explain rotation and inertia.<br />
Perhaps he could have saved some confusion if he had chosen a different term. But in his speech he made clear that he was reintroducing the<br />
word intentionally:<br />
To deny the ether is ultimately to assume that empty space has no physical qualities whatever. The fundamental facts of mechanics do not<br />
harmonize with this view . . . Besides observable objects, another thing, which is not perceptible, must be looked upon as real, to enable<br />
acceleration or rotation to be looked upon as something real . . . The conception of the ether has again acquired an intelligible content,<br />
although this content differs widely from that of the ether of the mechanical wave theory of light ... According to the general theory of relativity,<br />
space is endowed with physical qualities; in this sense, there exists an ether. Space without ether is unthinkable; for in such space there not<br />
only would be no propagation of light, but also no possibility of existence for standards of space and time (measuring-rods and clocks), nor<br />
therefore any spacetime intervals in the physical sense. But this ether may not be thought of as endowed with the qualities of ponderable<br />
media, as consisting of parts which may be tracked through time. The idea of motion may not be applied to it. 22<br />
So what was this reincarnated ether, and what did it mean for Mach’s principle and for the question raised by Newton’s bucket?* Einstein had<br />
initially enthused that general relativity explained rotation as being simply a motion relative to other objects in space, just as Mach had argued. In<br />
other words, if you were inside a bucket that was dangling in empty space, with no other objects in the universe, there would be no way to tell if you<br />
were spinning or not. Einstein even wrote to Mach saying he should be pleased that his principle was supported by general relativity.<br />
Einstein had asserted this claim in a letter to Schwarzschild, the brilliant young scientist who had written to him from Germany’s Russian front