Physicist Who Put Bang in Cosmos Seeking Other Universes
Entering the Massachusetts Institute of Technology’s Center for Theoretical Physics by the front door, one passes more than a dozen well-used blackboards, meeting areas and offices before finding Alan Guth’s.
So when Harvard University astrophysicist John M. Kovac in February wanted to secretly meet with Guth, the originator of a key theory explaining the cosmos, he climbed up a stairway of MIT’s Building 6 and slipped through a back door on the third floor. Kovac, 43, then revealed a discovery that has since made Guth a star theoretical physicist.
“He didn’t want to send rumors around the rumor mill,” Guth, 67, said about the evidence backing his theory. “He was discreet, but he didn’t wear a disguise.”
Guth’s colleagues at MIT in Cambridge, Massachusetts knew Kovac had been running an experiment to find evidence of the origin of the Big Bang, the birth of the universe 14 billion years ago. Guth is the originator of the inflation theory, which holds that the universe underwent a period of rapid acceleration outward at its very beginning. These ideas, modified by Stanford University physicist Andrei Linde, have led researchers to believe that our universe is one of many.
Scientists had predicted that, if Guth was correct, the Big Bang would have left a ripple pattern in polarized cosmic radiation, called B-modes. Kovac’s team had detected those ancient ripples. Using a radiation-sensitive telescope stationed in the arid, pristine South Pole, Kovac’s team of scientists had spotted the impact of a burst of gravitational energy released less than an instant -- a trillionth of a trillionth of a trillionth of a second -- after the universe began.
Guth grilled Kovac on the results for an hour and a half, going step by step and figure by figure through the calculations. The findings were highly statistically significant; there was almost no chance they were a fluke.
Both men knew it was the most convincing evidence of how the Big Bang had occurred, and it suggested that the universe continues to expand infinitely. Guth, however, had already moved forward to understand the wider implications of the theory he put forth 34 years ago, including the possibility that there are multiple universes, or a multiverse.
“There’s nothing in physics that happens only once,” he said. “It’s very natural to expect that, once we have a physical description of how our universe began, it’s going to happen again and again.”
The findings announced March 17 sent shock waves through the scientific world, and Guth began to be mentioned as a leading candidate for a Nobel Prize. They bolstered his contention that the Big Bang was powered by a gravitational force that was different from the force that binds our feet to the ground.
First posited by Albert Einstein, this was a kind of negative gravity that was not attractive, but repulsive. And while we normally think of gravity as a force exerted by large masses like planets and stars, the gravity that launched the Big Bang was created by intense pressure, Guth said.
“Pressure can create gravitational fields just as well as mass,” he said in an interview in his office. “Most people don’t know that.”
Some scientists remain skeptical of Kovac’s findings. Paul Steinhardt, a Princeton University theoretical physicist who has proposed that the universe’s expansion is cyclic rather than constant, cautioned that the results of the Harvard-led experiment, called BICEP2, need verification.
“One should take some time to scrutinize the results and see if they are convinced,” he said in a telephone interview. “It is too early to reach a conclusion today.”
Guth is spending a lot of time these days explaining such notions to people who aren’t familiar with either particle physics, which is his specialty, or with the origins of the universe, which he started thinking about in 1978 while at Cornell University in Ithaca, New York.
Like many physicists, he often talks while drawing pictures and graphs on a blackboard as he discusses predictions, probabilities, and guesses -- seldom certainties -- about the universe. At 67 years old, he retains a patient, youthful smile as he launches into extended, multipart expositions of concepts that are opaque to most non-scientists.
While he says he does his best thinking at night, it’s not because he’s staring up at the sky to observe stars, planets and galaxies. Night is time, he said, “to think consecutive thoughts without being interrupted.”
“I wouldn’t know the center of the galaxy if you pointed me towards it,” Guth said, waving an arm.
To Guth, the universe is a series of interlocking and related equations, most of which involve energy. A few hours of sleep sometimes bring him even nearer to a problem’s solution.
“I never get bored,” he said. “It’s exciting.
While most people tend to think of the universe as everything that exists, Guth sees the existence of other universes, each with its own Big Bang. The idea that new universes are born and growing all the time suggests that a redefinition is in order, Guth said.
‘‘We should probably think about a universe as everything that emanates from one Big Bang,’’ he said.
One of the most important questions today facing scientists who study the universe is rooted in the vast blackness of empty space. Scientists know that a vacuum -- whether it’s between two atoms or the Earth and the moon -- contains energy.
While scientists have observed some of that so-called dark energy, they haven’t been able to detect nearly as much as they think should be there. String theory, a concept of mass and energy in which particles like electrons are replaced by one-dimensional strings, suggests a possible solution, Guth said.
Ocean of Energy
According to string theory, there are trillions and trillions of possible energy states in a vacuum. Therefore, other universes might contain roaring oceans of energy that disrupt the formation of planets and stars, while ours may be a comparatively quiet tide pool where life forms like ourselves can flourish.
‘‘The hypothesis is that we’re living in a rare vacuum with rare low vacuum energy,” Guth said. “We like to explain why we’re special, instead of just assuming we’re special.”
If universes behave as math and physics suggest, with new Big Bangs occurring all the time that then grow without end, there’s a chance that they would bump up against one another, Guth said. Such a collision might send another signal, not unlike B-modes, which could be detected by scientists here on Earth, he said.
Armed with even more sensitive telescopes than those that found the rippled B-modes, Kovac’s team is continuing to map patterns of cosmic background radiation. The work may lead to evidence of a crash between universes, Kovac said.
“If there were such a collision, it would show up in some way,” he said.
Whether or not those experiments pan out, Guth has already seen something he once thought impossible in his own lifetime: ripples in light from the birth of the universe 14 billion years ago.
“I’m sort of amazed and mystified that you can create a model of the universe that is a construct of one’s own brain, and then you can make predictions about it that can be verified in the real universe,” he said. “I find that flabbergasting.”
With assistance from Robert Langreth in New York.
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