Perimeter’s Heart

Turok’s challenge in balancing his two interests was evident on his first day at work. Before attending the Penrose lecture, he had given a talk of his own to a group of eminent physicists who had gathered at Perimeter to discuss quantum mechanics and the nature of time. After hearing Penrose speak at the high school nearby, Turok returned once again to Perimeter, this time for a late-evening conference dinner hosted in the urbane Black Hole Bistro on the fourth floor. As the attendees dined on a meal featuring osso buco, parmesan risotto, and pumpkin brûlée, Turok divided his attention between his fellow physicists and the steady stream of government officials and other guests periodically introduced to him by Perimeter’s director of external relations and outreach, John Matlock.

“Neil’s been given the keys to the kingdom, and he knows exactly what he wants to do with them,” Matlock said. “He’s out to find the next Einstein.” Turok looked a little tired, his hair askew — but he firmly shook every proffered hand, radiating enthusiasm. “We’ve got big plans,” he told me, smiling widely. “Very big plans.”

The big bang is one of those canonical bits of science we’ve all internalized. First there was nothing, then there was a massive explosion, and then there was a universe composed of the shrapnel from that explosion. Or something like that. There are some very good reasons to believe in the big bang — two of the best being Edwin Hubble’s observations, in 1929, that all galaxies are moving away from us, and that the more distant galaxies are moving away more quickly; and the 1964 discovery of the cosmic microwave background, a faint radio signal that comes to us from all directions, which scientists interpret as radiation left over from the aftermath of the initial bang, nearly 14 billion years ago.

Some questions about the big bang theory persist, though, including the one Turok’s favourite childhood teacher put to him a few years ago: “What banged?” Knowing that the universe is expanding, we can extrapolate backwards in time to a point when the universe was infinitely small and infinitely dense. At that singularity, the math breaks down: the theory simply can’t tell us anything about what banged.

In addition to this metaphysical sticking point, the big bang picture runs into some practical problems when physicists try to calculate how the universe has evolved. One is explaining why the universe looks smooth and homogeneous in every direction, when a violent explosion should have left different regions with vast discrepancies in such properties as density. One proposed solution stipulates that the universe initially expanded extremely rapidly, doubling 100,000 times in a billionth of a billionth of a trillionth of a second — a smoothing procedure known as “inflation,” put forward in 1981 by mit professor Alan Guth. Complicating matters was the discovery during the 1990s of a mysterious substance called dark energy, which forced physicists to conclude that expansion must have sped up once again, nine billion years after the big bang, and that it will continue to accelerate until the universe has been diluted into a nearly perfect vacuum.

What set out as an appealingly simple picture of our origins — the one most of us take for granted — thereby started to look more like a Rube Goldberg machine, with multiple additional parts grafted on to keep theory consistent with observed reality. “What’s good is that there’s a growing body of experimental checks,” Smolin says. In April, for example, the European Space Agency will launch the Planck satellite, which will measure minuscule variations in the cosmic microwave background, checking for features predicted by competing models. “It would be very hard for Planck to rule out inflation completely,” says Ghazal Geshnizjani, a post-doctoral cosmologist from Iran who came to Perimeter in 2007. “But it could definitely rule out the simplest version.” Even that correction would be significant, though, because the more you have to patch a model, the more you start to wonder whether there’s something wrong with its core.

This is the line of thought that brought Turok and Steinhardt to propose a radical departure from the inflationary model. The cyclic universe theory, described in their 2007 book, Endless Universe: Beyond the Big Bang, presents the big bang as just one in an endless series of collisions between our universe and a parallel one situated a tiny distance away along a hidden dimension. These collisions happen once every trillion or so years, each time sparking the evolution of planets, stars, and galaxies, in a way that doesn’t require patching in an arbitrary period of ultra-rapid expansion. In the cyclic model, our current universe will continue to expand until it is nearly featureless. Then tiny quantum ripples in spacetime will amplify during the buildup to the next big bang, forming the seeds of the next cycle’s galaxies. This, Turok and Steinhardt argue, is the answer to the question “What banged?”

The elements of the hypothesis that would seem most implausible to a layperson — parallel universes, extra dimensions — are garden-variety constructs in string theory. Still, the cyclic theory is at odds with the prevailing view among physicists. Indeed, after Turok had presented his model at a conference of the National Academy of Sciences in the United States a few years ago, Guth began his own talk with an attack on his colleague’s theory, complete with a slide showing a caricature of Turok as a monkey. The incident ruffled feathers, though Turok downplays it as an anomaly. “I was sorry that it came out in the press, because it was misleading — we actually get on very well,” he says. “But it is true it happened, and it is true that the audience was quite shocked.”

Turok’s willingness to pursue ideas outside the mainstream made him a good fit, scientifically, to lead the institute. His theory has since moved in from the margins, to the point that many observers consider it one of several credible alternatives to the still-dominant inflationary picture. Resolving the debate will likely fall to the new generation of theorists. “Younger people vote with their feet, and they work on what they think is exciting,” Turok says. “So in a way, the older people’s opinions don’t matter so much. I’m getting into that class.”

In his study of what motivates and guides physicists over the course of their careers, sociologist Joseph C. Hermanowicz recognized the central role played by past heroes. “The scientist, like the artist or the athlete, follows a pantheon of immortals,” he wrote. Most start with the general goal of joining that pantheon, perhaps by having an effect or a theory named after them, but their ambitions adapt over time, according to circumstance and ability.