Einstein: His Life and Universe

But neither Lorentz nor Poincare made the full leap: that there is no need to posit an ether, that there is no absolute rest, that time is relative based on an observer’s motion, and so is space. Both men, the physicist Kip Thorne says, “were groping toward the same revision of our notions of space and time as Einstein, but they were groping through a fog of misperceptions foisted on them by Newtonian physics.”

Einstein, by contrast, was able to cast off Newtonian misconceptions. “His conviction that the universe loves simplification and beauty, and his willingness to be guided by this conviction, even if it meant destroying the foundations of Newtonian physics, led him, with a clarity of thought that others could not match, to his new description of space and time.”⁶⁶

Poincare never made the connection between the relativity of simultaneity and the relativity of time, and he “drew back when on the brink” of understanding the full ramifications of his ideas about local time. Why did he hesitate? Despite his interesting insights, he was too much of a traditionalist in physics to display the rebellious streak in-grained in the unknown patent examiner.⁶⁷ “When he came to the decisive step, his nerve failed him and he clung to old habits of thought and familiar ideas of space and time,” Banesh Hoffmann said of Poincare. “If this seems surprising, it is because we underestimate the boldness of Einstein in stating the principle of relativity as an axiom and, by keeping faith with it, changing our notion of space and time.”⁶⁸

A clear explanation of Poincare’s limitations and Einstein’s boldness comes from one of Einstein’s successors as a theoretical physicist at the Institute for Advanced Studies in Princeton, Freeman Dyson:

The essential difference between Poincare and Einstein was that Poincare was by temperament conservative and Einstein was by temperament revolutionary. When Poincare looked for a new theory of electromagnetism, he tried to preserve as much as he could of the old. He loved the ether and continued to believe in it, even when his own theory showed that it was unobservable. His version of relativity theory was a patchwork quilt. The new idea of local time, depending on the motion of the observer, was patched onto the old framework of absolute space and time defined by a rigid and immovable ether. Einstein, on the other hand, saw the old framework as cumbersome and unnecessary and was delighted to be rid of it. His version of the theory was simpler and more elegant. There was no absolute space and time and there was no ether. All the complicated explanations of electric and magnetic forces as elastic stresses in the ether could be swept into the dustbin of history, together with the famous old professors who still believed in them.

⁶⁹

As a result, Poincare expressed a principle of relativity that contained certain similarities to Einstein’s, but it had a fundamental difference. Poincare retained the existence of the ether, and the speed of light was, for him, constant only when measured by those at rest to this presumed ether’s frame of reference.⁷⁰

Even more surprising, and revealing, is the fact that Lorentz and Poincare never were able to make Einstein’s leap even after they read his paper. Lorentz still clung to the existence of the ether and its “at rest” frame of reference. In a lecture in 1913, which he reprinted in his 1920 book The Relativity Principle, Lorentz said, “According to Einstein, it is meaningless to speak of motion relative to the ether. He likewise denies the existence of absolute simultaneity. As far as this lecturer is concerned, he finds a certain satisfaction in the older interpretations, according to which the ether possesses at least some substantiality, space and time can be sharply separated, and simultaneity without further specification can be spoken of.”⁷¹

For his part, Poincare seems never to have fully understood Einstein’s breakthrough. Even in 1909, he was still insisting that relativity theory required a third postulate, which was that “a body in motion suffers a deformation in the direction in which it was displaced.” In fact, the contraction of rods is not, as Einstein showed, some separate hypothesis involving a real deformation, but rather the consequence of accepting Einstein’s theory of relativity.

Until his death in 1912, Poincare never fully gave up the concept of the ether or the notion of absolute rest. Instead, he spoke of the adoption of “the principle of relativity according to Lorentz.” He never fully understood or accepted the basis of Einstein’s theory. “Poincare stood steadfast and held to his position that in the world of perceptions there was an absoluteness of simultaneity,” notes the science historian Arthur I. Miller.⁷²

His Partner

“How happy and proud I will be when the two of us together will have brought our work on the relative motion to a conclusion!” Einstein had written his lover Mileva Mari back in 1901.⁷³ Now it had been brought to that conclusion, and Einstein was so exhausted when he finished a draft in June that “his body buckled and he went to bed for two weeks,” while Mari “checked the article again and again.”⁷⁴

Then they did something unusual: they celebrated together. As soon as he finished all four of the papers that he had promised in his memorable letter to Conrad Habicht, he sent his old colleague from the Olympia Academy another missive, this one a postcard signed by his wife as well. It read in full: “Both of us, alas, dead drunk under the table.”⁷⁵

All of which raises a question more subtle and contentious than that posed by the influences of Lorentz and Poincare: What was Mileva Mari’s role?

That August, they took a vacation together in Serbia to see her friends and family. While there, Mari was proud and also willing to accept part of the credit. “Not long ago we finished a very significant work that will make my husband world famous,” she told her father, according to stories later recorded there. Their relationship seemed restored, for the time being, and Einstein happily praised his wife’s help. “I need my wife,” he told her friends in Serbia.“She solves all the mathematical problems for me.”⁷⁶

Some have contended that Mari was a full-fledged collaborator, and there was even a report, later discredited,⁷⁷ that an early draft version of his relativity paper had her name on it as well. At a 1990 conference in New Orleans, the American Association for the Advancement of Science held a panel on the issue at which Evan Walker, a physicist and cancer researcher from Maryland, debated John Stachel, the leader of the Einstein Papers Project. Walker presented the various letters referring to “our work,” and Stachel replied that such phrases were clearly romantic politeness and that there was “no evidence at all that she contributed any ideas of her own.”

The controversy, understandably, fascinated both scientists and the press. Columnist Ellen Goodman wrote a wry commentary in the Boston Globe, in which she judiciously laid out the evidence, and the Economist did a story headlined “The Relative Importance of Mrs. Einstein.” Another conference followed in 1994 at the University of Novi Sad, where organizer Professor Rastko Magli contended that it was time “to emphasize Mileva’s merit in order to ensure a deserved place in the history of science for her.” The public discussion culminated with a PBS documentary, Einstein’s Wife, in 2003, that was generally balanced, although it gave unwarranted credence to the report that her name had been on the original manuscript.⁷⁸

From all the evidence, Mari was a sounding board, though not as important in that role as Besso. She also helped check his math, although there is no evidence that she came up with any of the mathematical concepts. In addition, she encouraged him and (what at times was more difficult) put up with