Celebrating the Eclipse That Let Einstein Shine

Before 1919, cosmology was as subjective as art criticism. A solar eclipse, and a patent clerk’s equations, changed everything.

The New York Times, May 28, 2019

PRINCETON — A century ago, on May 29, 1919, the universe was momentarily perturbed, and Albert Einstein became famous.

On Wednesday at the Institute for Advanced Study, Einstein’s intellectual home from 1932 until his death in 1955, scholars celebrated the centenary with an afternoon symposium titled “The Universe Speaks in Numbers.” The premise: that nature reveals itself through patterns, which can be described with numbers and probed through problems posed by mathematicians and physicists alike. The event’s name was borrowed from the title of a new book by Graham Farmelo, who gave the introductory talk.

“This is actually a good story,” said Helmut Hofer, a mathematician at the Institute, sitting in his office. Behind him, on the wall, hung an axiom that his wife had found and framed:

“Mathematics is such a drama queen. It can’t seriously have that many problems.”

Having the right mathematicians in the company of the right physicists can be quite helpful in solving problems, said Dr. Hofer.

Einstein himself apparently had no special plans for what he knew could be a momentous day. He was home in Berlin. He wrote a letter admitting a “blunder” in an ongoing debate with Theodor Kaluza, a German mathematician with a new notion of space-time that required five dimensions.

He betrayed no jitters about the fact that, on that day in May, two scientific expeditions were finally putting his theory of general relativity to the test. In Sobral, Brazil, and on Príncipe Island, off the western coast of Africa, two teams were viewing a total solar eclipse; in measuring the deflection of starlight by the sun’s gravitational field, they proved Einstein right.

Einstein first received word of their preliminary results in September, and wrote his mother with the “happy news.” The confirmation was officially announced in November at the Royal Astronomical Society in London, triggering headlines about the ensuing excitement. (“Men of Science More or Less Agog Over Results of Eclipse Observations,” one headline in The Times noted.) Einstein bought himself a congratulatory violin.

One hundred years later, relativists the world over are rejoicing, each in their own way.

Katharine Leney, a physicist at CERN, in Switzerland, and the purveyor of @PhysicsCakes on Twitter, created a rotating solar eclipse diorama, featuring cake pops of the sun, Earth and moon.

On Wednesday, two actors, Ben Livingstone, playing Einstein, and Colin Uttley, as Arthur Eddington, the astrophysicist who led the Príncipe expedition, gave a special performance at the Royal Astronomical Society in London.

And there are weeklong conferences in Sobral and Príncipe featuring lectures, seminars, parades, dancing and fine dining. (The scientific gatherings merged on Wednesday for a special joint session via teleconference.)

In Sobral, at an international meeting hosted by the Brazilian Society for the Advancement of Science, a lecture by Luis Crispino, a physicist at the Federal University of Pará, in Brazil, aimed to set the record straight about the importance of the Brazilian expedition.

The Sobral measurements commonly are assumed to have played a minimal role in verifying Einstein’s theory, in part because the photographic plates from the main Sobral instrument were blurry. But in fact, the backup Sobral instrument provided the crucial images, because many of Eddington’s photographs from Príncipe were obscured by clouds and revealed few stars.

The Sobral photographs allowed Frank Dyson, the astronomer and co-organizer of the expeditions, to conclude that the results favored general relativity, said Dr. Crispino: “This is common sense to everybody in Brazil. Outside Brazil it is not.”

Dr. Crispino and Daniel Kennefick, of the University of Arkansas, recently laid out this argument in a paper in Nature Physics. “The role of other astronomers involved has been, so to speak, eclipsed by Eddington’s (and Einstein’s) fame,” they wrote.

Dr. Kennefick also is the author of a new book on the subject, “No Shadow of a Doubt,” and on Wednesday, at a conference in Paris, he offered a similar retelling. A day earlier, Anna Curir, from the Turin Astrophysical Observatory in Italy, gave a talk titled, “Arthur Eddington and the Gestalt theory,” that explored the role of the storyteller in the formulation of physical laws.

On Príncipe Island, there was a multinational extravaganza, coordinated by the Portuguese Society for Relativity and Gravitation; the presidents of Portugal and of São Tomé and Príncipe were in attendance. The event included release parties for two new books on the Eddington expedition, one a children’s comic strip.

And there was a miniature version of the Laser Interferometer Gravitational-Wave Observatory experiment, “complete with interferometry,” noted one of the organizers, Vitor Cardoso, in an email. “To show that Einstein’s predictions go beyond light deflection, and that we can test them. This also shows how human ingenuity takes us to amazing new places in science.”

Earlier in the week, a select group of about 20 relativists gathered on Bom Bom beach to discuss a century’s worth of exploration about Einstein’s equations of general relativity.

“His equations allowed cosmology to become a science,” John Barrow, the cosmologist, wrote in an email. “Before him, cosmology was like a branch of art history. You could imagine any type, shape or form of universe you liked.”

But Einstein’s equations, he added, “are more sophisticated than any others in science. They describe whole universes. Every solution of Einstein’s equations describes an entire possible universe that is consistent with the laws of physics.” Since 1916, Dr. Barrow noted, Einstein’s equations — matched to astronomical observations — have revealed static universes, expanding universes, accelerating universes, and universes that are rotating, oscillating, cyclic, distorted, irregular, chaotic, inflationary, and eternal.

Alessandra Buonanno, a director at the Max Planck Institute for Gravitational Physics in Potsdam, was also on the beach in Príncipe, where she discussed gravitational waves, another prediction of general relativity.

“The waves are like fingerprints of the gravitational-wave sources,” she said. Dr. Buonanno’s research focuses on improving the accuracy of the models of the fingerprints for upcoming observations with the Laser Interferometer Gravitational-Wave Observatory and Virgo detectors, and for future gravitational-wave detectors, such as with the Laser Interferometer Space Antenna, or LISA, which will be launched in 2034.

“LISA seems very far into the future,” she said. “But theoretical models and the required hardware and software need to be developed from now.”

The Príncipe proceedings opened with a talk by Clifford Will, a mathematical physicist at the University of Florida, who in 1986 published the popular book “Was Einstein Right?” His centenary talk was titled, “Is Einstein still right?”

Ever more so, it seems. The past few decades have seen “an amazing array of experimental tests of general relativity, all of them in agreement with the predictions,” Dr. Will said. But the quest continues: “There are still things we don’t fully understand. And that’s probably likely always to be the case.”

“The more we keep testing it, the more confidence we have in the theory,” he said. “And of course on the other hand, any sort of deviations from his predictions would surely tell us that there is something new to be investigated.”

Back on the Princeton campus on Wednesday, scholars at the Institute for Advanced Study paused their own investigations to contemplate the numerical nature of the universe.

“We are just a bunch of human beings muddling along in a world that’s very hard to understand,” said mathematician Karen Uhlenbeck, the recent winner of the Abel Prize. She was speaking with Freeman Dyson, the mathematical physicist, and Natalie Wolchover, a writer for Quanta.

“We put together ideas in our mind and somehow make rules and order,” Dr. Uhlenbeck said. “We create mathematics as a language in response to external stimuli.”

Dr. Dyson likened studying the cosmos to visiting “a zoo full of wonderful creatures.”

He added: “Most of the mathematicians are busy admiring the architecture, while the physicists are admiring the animals. Which is more important isn’t, to me, the interesting question. The interesting question is, Why do they fit together so well?”

Edward Witten, Nima Arkani-Hamed, Robbert Dijkgraaf and others debated which method of investigation, experimental or mathematical, was better.

Those in favor of experiments have been known to regard the hard-core mathematical approach as “mathematical masturbation,” Dr. Farmelo said — “self-indulgent, without an obvious payoff for understanding the real world.” And the mathematical cosmologists traditionally have viewed their opposites as “ambulance chasers,” rabidly pursuing every new experimental clue at the expense of overarching physical ideas.

“Einstein was convinced that the royal road to the laws of physics was not through looking at experimental data, but by developing the mathematical content of well-established theories,” said Dr. Farmelo.