Physics & Math / Einstein

Moffat was accepted into the graduate program in mathematical and theoretical physics at Cambridge University, due in part to a suprisingly strong recommendation from Schrödinger. In 1958 Moffat became the first student in the 800-year history of the school to earn his Ph.D. without completing an undergraduate degree. He now works at the Perimeter Institute near Toronto—an iconoclastic veteran among some of the world’s best and brashest young physicists. If he was first drawn to Einstein by his mistakes, he has come to believe the old man may have been on the right path after all. He just started down it a few decades too soon.

In the 1930s, when Einstein began his work on a unified field theory, physicists believed that there were only two universal forces that the theory would have to unite: gravity and electromagnetism. They have since learned that there are two other fundamental forces as well, a strong force that binds together atomic nuclei and a weak force that governs radioactive decay. “Einstein defined what later became a fundamental problem in physics,” says Carlo Rovelli, a theoretical physicist at the University of the Mediterranean in Marseille, France. “But he was missing an ingredient.”

These days Einstein’s once-lonely quest engages thousands of physicists around the world, most of them working on an ambitious physics framework known as string theory. Although this work is grounded in quantum mechanics, it relies heavily on some of the same components that Einstein used. According to string theory, the fundamental constituents of the physical world are not pointlike particles but infinitesimal one-dimensional loops, or strings. All the particles and forces in the universe arise from these strings vibrating at different frequencies. But there’s a catch, one that no doubt would have made Einstein smile: The strings need 11 dimensions in which to vibrate, and those extra dimensions are described by essentially the same mathematics that Einstein used in his own unified field theory.

Moffat is not so sure that string theory is an improvement on Einstein’s ideas. On the other hand, he thinks there may still be some life in the master’s late equations. For much of the past decade he has returned to the theory that Einstein was working on when he died—the same one that prompted Moffat’s fateful letter. Moffat argues that the mathematics Einstein hoped would describe electromagnetism in his unified field theory instead gives rise to a slight repulsive force that reduces the strength of gravity. If so, that force might help solve certain long-standing puzzles in astronomy.

Two thousand light-years from Earth, for instance, two young blue stars in a system called DI Herculis whirl about each other every 101/2 days. Their paths shift slightly from one orbit to the next—a phenomenon known as precession—but when astronomers use general relativity to predict the amount of this shift, their answers are off by a factor of four. Most astronomers believe that a third star, unobserved as yet, is disturbing the orbit. Moffat has a different interpretation. In his modified version of Einstein’s later theory, the gravitational pull between the two stars is weakened just enough to slow the stars’ orbits down a bit. By his new calculations, the predicted precession agrees almost exactly with observations.

There’s no small historical irony to all of this. One of the first rigorous tests of general relativity was an observation of the precession of Mercury’s orbit around the sun. Before Einstein, most astronomers assumed, as with DI Herculis, that a third body would make the orbit conform to Newton’s equations. Some even claimed to have observed the mystery planet and named it Vulcan. Einstein’s general theory of relativity made the third planet unnecessary.

Could the third star in DI Herculis turn out to be as illusory as Vulcan? If so, it would be very big news. Moffat claims that his theory would also eliminate the need for dark matter and dark energy—two phenomena, as yet undetected, that physicists have invoked to account for the motions of galaxies and the expansion of the universe. It’s a long shot, Moffat says, but Einstein’s last theory may have some life in it yet.

One day, over lunch at a bistro near Moffat’s office, I asked him if we will ever see a physicist like Einstein again. He shook his head. “If you go and visit Chartres cathedral in France, you’ll realize that it took 150 years to build, and we don’t know the names of the artisans who built it. They’re anonymous. Maybe physics is going to become like this. We may one day have a great edifice for Western civilization, but it might take 200 years to build.” To claim there is an ultimate theory is “pure hubris,” Moffat said. “There’s always something new on the horizon, and then everything starts all over again.”

Einstein was the first victim of his own success, Giovanni Amelino-Camelia, a physicist at the University of Rome, likes to tell his students. He gave rise to the romantic notion that a genius who follows his intuition can create a perfect theory that explains all the data. And then he fell prey to that notion himself. “It’s a success which has really been a mixed blessing for theoretical physics,” Amelino-Camelia says. “If we didn’t have that one example, we would have no examples. And that would teach people how science is really done.”

Yet, once upon a time, Einstein did revolutionize physics, and he did succeed in large part because of his stubborn, independent, audacious spirit. The general theory of relativity was developed in defiance of centuries of physics. It consumed Einstein for 11 years—from 1905 to 1916—and in the end was proved triumphantly correct. It’s no wonder the memory of that achievement sustained him in later years. In 1953, when the letter from John Moffat found its way to Princeton, Einstein was still doing what he had always done—asking big questions and looking for big answers.

At lunch that day in Ontario, Moffat said that he had one more letter from Einstein to show me. He rummaged through a folder, pulled out a copy, and pointed to the date: May 25, 1953. Then he read the words that have guided him for more than half a century: “Every individual . . . has to retain his way of thinking if he does not want to get lost in the maze of possibilities. However, nobody is sure of having taken the right road, me the least.”