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The Theory of Everything - Esquire
EIGHTEEN MONTHS TO GO. And now some nights Nima Arkani-Hamed can’t sleep. Because in eighteen months someone will flip a switch in something called the Large Hadron Collider in Switzerland. And when that switch is flipped, billions of protons will fly around a seventeen-mile loop at nearly the speed of light until they smash together hard, harder than any subatomic particles have ever been smashed together on earth. It’s the greatest, most anticipated, most expensive experiment in the history of mankind. And if Arkani-Hamed is right, it could help prove that the laws that govern the universe at every scale—from the smallest quarks to the largest black holes—are one and the same. Or else, of course, it could prove that Arkani-Hamed is full of shit.
IT’S A FOOL’S ERRAND, this quest for a theory of everything. And Arkani-Hamed is only the most recent of thousands of theoretical physicists to embark on it. The idea seemed logical enough when Einstein first set out on it in the 1920s. If general relativity explains the universe from afar—why gravity pulls the earth around the sun—and quantum mechanics explains the world up close—how atoms, protons, and neutrons react to electromagnetism and the strong and weak forces—surely there must be a way to put the two theories together. After all, whether cosmic in size or minuscule, the particles and forces that govern our universe were all born at the same primordial moment. Yet Einstein failed. And in the interim, armies of physicists, equipped with similarly well-intentioned yet ultimately faulty or unprovable ideas, have followed him to the same well-trod dead end.
Since the mid-1980s, the leading contender for a grand unifying theory has been string theory. The idea is deceptively simple: At the core of every particle in the universe is a tiny thread of energy. Each of these filaments vibrates like a violin string, and its rate of vibration determines its vital characteristics, or tone. There are neutrino strings and electron strings, photon strings and graviton strings. When played together, they compose the symphony of the universe. Or at least, that’s the theory.
There’s a problem, though. The strings have too much range. So much, in fact, that for string theory to agree with the established laws of physics and mathematics, there must be not three but at least ten dimensions (including time) that are curled up and tucked away. And because each of these multidimensional landscapes requires a different string tuning, there are potentially billions and billions of different versions of string theory relating to billions and billions of different universes.
Then there’s the problem of testing string theory. That’s how science works. We hypothesize, then we test. And if a hypothesis passes muster, it becomes law. But the strings that supposedly make up our universe are so infinitesimal—one string is to an atom as a single atom is to the entire solar system—that critics argue that we may never be able to build a collider powerful enough to find them, even the collider that Arkani-Hamed stays up all night thinking about.
So here’s the latest tally: Number of years since string theory became dominant: 20. Number of potential string-theory solutions: 10500 (the number of atoms in the galaxy squared and then squared again). Number of testable theories: 0. In other words, Arkani-Hamed better be at least partially right, because the natives are getting restless.
IF THE PROBLEM WITH STRING THEORY, as some critics claim, is that it’s a closed-minded boys club whose lifetime members hopelessly shuffle and redeal the same deck of equations ad nauseum, then the solution may be found at the Jane Bond, a bar in the staid Canadian college town of Waterloo. The Jane Bond has a decidedly grungy 1970s flair. Tattooed hipsters talk with awed reverence of Brooklyn while DJs spin eclectic and esoteric music next to the bathroom, near the disco ball. And then there are the physicists from the Perimeter Institute for Theoretical Physics who have made the Jane Bond their watering hole. They talk theory sometimes. But mostly they just bullshit.
“You want to know the true story?” goads a young postdoctoral researcher at that magical hour in any bar when only bad things can happen. “It’s the post-9/11 theocons.” Just like the rest of America, he continues, the science establishment is afraid of anything new. It doesn’t want to consider any alternatives. “The string theorists just masturbate to their same ideas.” At this, the rest of the table—a mixed group of young cosmologists, quantum-information theorists, and quantum-gravity buffs—breaks into nervous laughter. Yes, their friend is drunk. But he’s right in a general sense, they concede. There is a growing fissure in the physics world between the haves (string theorists) and the have-nots (everyone else). But not at Perimeter, they caution. Perimeter is different.
The first thing you notice when walking through the concrete-and-glass hallways of PI are the lounges with blackboards. They are ubiquitous. And at each one there are usually two or three young physicists—mostly men, most in their late twenties or thirties—arguing over equations. The feeling is more dorm-room TA session than serious discussion about the origins of the universe. Sneakers and jeans rule. The researchers come and go as they please, and they work as they please. And when they grow too tired of drilling through equations and erasing equations and drilling through them some more, they might take a break. There’s a squash court near the billiard table, a few floors below the bistro and bar. But don’t get the wrong idea. Foosball aside, the physicists at PI are doing serious work.
Perimeter was founded by Mike Lazaridis, founder and co-CEO of Research in Motion, maker of the BlackBerry. As the story goes, Lazaridis, who went to college in Waterloo, thought the scientific world was much too focused on areas of research that promised immediate results and fast returns on investment. Nobody was willing to fund basic research into arcane fields, like the foundations of quantum mechanics. So in 2000 he cut a check for $66 million and convinced two partners and the Canadian government to chip in tens of millions more. His plan was to build a physics institute that was different, a place where physicists would have the freedom to probe more foundational physical questions. Along with executive director Howard Burton, he envisioned a true community of scholars, where physicists from disparate disciplines would cross-pollinate in a noncompetitive environment. It now has sixty-four resident researchers, including ten faculty members.
Taking up residence here is a bit like joining the priesthood. You’re segregated from the rest of the world, and your job is to get into God’s head and figure out how the big damn machine works. And though you can work with others, often you’re alone, stuck with only the equations and pictures in your head. It’s like exploring a forest, says Andrei Starinets, a postdoctoral researcher from the former Soviet Union who studies string theory and black-hole physics. You can see the forest ahead, he says; it’s tall and lush and filled with swamps. The task is to figure out how to enter, which path will have the least sinkholes and booby traps. So that’s what he and his colleagues do all day. They gather in PI as if it were a fort, planning a means of attack, looking for the paths of least resistance. This means twisting and retwisting equations as if the search for a unified theory were the world’s biggest game of sudoku.
Here’s how Laurent Freidel, a faculty member in quantum gravity and particle theory, describes the search: “You feel that there is a beast running in the woods. And you don’t let it go, you don’t stop. And sometimes if you need to, you don’t stop at all for two or three days in a row. But that’s the fun part, when you’re on track and when you know something’s out there. There are no rules. You need intuition to make a connection. And then you have to gather evidence; the more evidence you gather, the more you know you’re on the right track. The key for me is not to let go, to continue until I reach it. And there’s always a way.”
Last year, when Freidel discovered a possible rigorous mathematical solution for the strong force—which acts as the glue between protons, neutrons, and nuclei, and which to that point had been studied only by approximation—he didn’t sleep for two weeks straight. “His wife ran into me,” recalls a colleague, “and she said, ‘Can you do something? He’s going insane.’ “
On the third floor of Perimeter, at the far end of the hall, is a small office with a small sofa wedged next to an overflowing bookshelf. And on that couch, dressed more like a New York artist than a theoretical physicist—black, black, and more black—is Lee Smolin. One of PI’s initial faculty hires, Smolin, fifty-one, began his career in string theory before becoming fed up with the lack of progress and turning instead to loop quantum gravity, an alternate possible unified theory. Unlike string theory, which critics describe as background dependent—i.e., space and time are constant and unexplained—LQG posits that space, time, and even people are all formed from the same network of interconnected loops and nodes, which take on electrical charges when twisted. If the tension between string and antistring theorist was once a family argument, Smolin, the author recently of The Trouble with Physics, is the person who decided to air the dirty laundry.
“This is an experiment,” says Smolin of PI. “Like any experiment, it’s a risk and it could fail. The most important question is, Will important science get done here? And I think there are already examples of things that happened here that would not have happened elsewhere, because the people would not have been in touch with each other.”
Things like safer cryptography, recent advances in loop quantum gravity, and a possible refutation of special relativity, the law that nothing can move faster than the speed of light.
But what about the big questions? Was it really necessary to blow up the model of how a science institute should function in order to break the stalemate in theoretical physics and eventually discover a theory of everything? “I think that the pragmatic, antiphilosophical thing played itself out,” says Smolin, referring to results-oriented physics.
“I think what’s going to succeed in the big-open-questions part of gravity unification and so forth are going to be approaches that take the foundations and the fundamental questions more seriously than they have been. And why do I believe that? Because if these problems could have been solved by this very pragmatic approach, they would have been. Because a lot of really smart, motivated people have been working on these problems for three decades in that frame of mind, and if it were possible to solve these problems, they would have done it. I should say, we would have done it. Because it was my generation.”
FAR AWAY FROM WATERLOO and Perimeter, both in geography and state of mind, stands an old clock tower surrounded by vast fields of overgrown grass and hickory trees. It was here that Albert Einstein first began pondering a grand unified theory in earnest. And it is here at the Institute for Advanced Study, in Princeton, New Jersey, that some of the world’s most prominent string theorists—including their master guru of sorts, Edward Witten—now gather in their own fort. If PI is a model of the theoretical-physics think tank of the future, then IAS—like the storied Ivy League university next door—is a reminder of the well-mannered past. You won’t find a bar or a foosball table here. But tea is served daily at 3:00 P.M.
At six two, Witten is big both in size and presence. He began focusing on string theory in the mid-1980s, soon after the first string revolution suggested that it was a viable theory of everything. Ten years, a MacArthur grant, and a Fields Medal in mathematics later, he ushered in the second revolution by postulating that the five main competing string models of the time were all part of a bigger, more complex model, which he termed “M-theory.” His synthesis—the name of which is still a matter of fierce debate in the physics world. Mother? Membrane? Magic? Masturbation?—broke a logjam that had snared progress in string theory for nearly a decade and added to his mystique as perhaps the true heir to Einstein.
But now string is at another logjam, in which there are literally billions of possible string-theory solutions and perhaps no means of testing any of them. “Well, you can’t have your best year every year,” he says of the frustration in the field, weighing every word very carefully in a voice that is just a few decibels above a whisper. “I’ve lived through two periods, the mid-eighties and the mid-nineties, where for about six or seven years, roughly, there were a lot of really interesting results that were also relatively easy. And I’ve also lived through several periods by now where you have to work a little harder to get something interesting.”
To Witten, the game is far from over for string, and he hopes the something interesting will be found in Geneva. When it begins tests about a hundred yards below the border of Switzerland and France in spring 2008, the Large Hadron Collider and its 1,232 thirty-nine-ton superconductor magnets will propel billions of protons with seven times the strength of the current strongest particle collider in Illinois, and will mimic the conditions of the universe a millionth of a millionth of a second after the big bang.
At the very least, Witten believes, the LHC should be able to explain the lack of symmetry between electromagnetism, which shapes many of the phenomena of daily life, and “weak interactions,” which affect the decay of subatomic particles and are related to radiation. “There’s something deeply, deeply wrong if the LHC doesn’t discover that,” says Witten. Both interactions appear nearly identical at the atomic level (they are grouped together as “electroweak interactions” in the standard model) yet behave very differently in the real world.
One possible explanation is the Higgs boson, or “God particle,” which has never been seen or measured but which theorists speculate could be responsible for giving all particles mass. According to Witten, its discovery would be a simple, long-theorized solution to the problem of electroweak “breaking,” yet carries numerous pitfalls of its own. For example, the value of the Higgs mass has only been estimated so far; an actual measurement may well require adjustment of that value, which could carry huge implications for how the whole machine—our universe—is put together and whether other universes tuned with different Higgs bosons might exist.
A different, even more extreme explanation for the symmetry breakdown is known as supersymmetry, which theorizes a set of counterparts to our known subatomic particles that are embedded in the architecture of space-time. Besides explaining electroweak interactions, the discovery of supersymmetric particles, with cool names such as squarks, sleptons, and selectrons, would be a huge boon to string theorists, whose model of the universe depends upon them.
Finally, there are the wild-card explanations, such as very large dimensions or low-scale string theories, or perhaps solutions that physicists have not yet even dreamed of. Each of these would vastly change our entire outlook of the universe and our place in it. Luckily for us all, perhaps, the chance of discovering them any time soon is rather unlikely.
JUST DOWN THE HALL from Witten is another leading theoretical physicist who also speaks in hushed tones. Like his mentor, Witten, twenty years ago, Juan Maldacena, a thirty-eight-year-old Argentine, is regarded as one of the great young thinkers of his time. Need proof? Well, here’s the song:
You start with the brane
and the brane is B.P.S.
Then you go near the brane
and the space is A.D.S.
Who knows what it means?
I don’t, I confess
Sung to the tune of “Macarena,” those words were used to serenade Maldacena at the 1998 string-theory conference in Santa Barbara. The occasion was Maldacena’s newly published work on black holes, which became known as the Maldacena conjecture. It’s complicated stuff, but by demonstrating a relationship between quarks and black holes, Maldacena showed that quantum field theory could be used to solve string equations. This was huge, a method of inquiry that might finally bridge the gap between the forces that govern the cosmos and the forces that govern particles. Nearly overnight, thousands of string theorists got to work on Maldacena’s work. And at the conference, it was an occasion to sing and dance.
But there’s more. The way Maldacena solved his conjecture—by converting complicated five-dimensional equations into four-dimensional equations, then back again—was a discovery in and of itself, leading to an even more jarring conclusion: Gravity and time could be an illusion. Just like the shimmering holograms we grew up with—say, Michael Jordan jumping out of a shiny silver sticker for a slam dunk—our universe could be a giant hologram: a massive two-dimensional plane encoded with quantum information at the edges that makes it appear three-dimensional. It’s a mind fuck, for sure, but the payoff could be huge. Holograms could provide an explanation of how a theory of everything might relate to the whole universe and beyond.
Think of our universe, or dimensional landscape, as a giant DVD floating among an infinite number of other DVDs. Each two-dimensional DVD was built in the same factory according to the same theory of everything, yet each one is embedded with a different movie. While our DVD shows a three-dimensional universe ruled by the standard model, the DVD landscape next door could be embedded with a five-dimensional movie and a separate, slightly different standard model. If we could view all of these separate landscapes in four dimensions—perhaps the equivalent of a universal HD-DVD player—we might be able to glimpse the underlying architecture that they all share.
If Maldacena is right, the holographic principle could reveal the order behind everything; there might be an infinite number of universes, but they’d all be ruled by the same laws, just experienced slightly differently.
Still a mind fuck, but not crazy.
FOR CRAZY, YOU HAVE TO GO about 250 miles north. At thirty-four, Nima Arkani-Hamed, born in Houston to Iranian physicists, is in the sweet spot of his career: young enough to still have fresh, insubordinate ideas; old enough to have the wherewithal and grounding to push fresh and insubordinate ideas. His office at Harvard is clean and minimal, all polished wood offset by a floor-to-ceiling, wall-to-wall blackboard. He’s made a career of producing models of the universe that are staggeringly elegant. And so it figures that when he speaks—and he speaks a lot—it is with authority and simplicity. Plus there is his overwhelming sense of urgency, excitement, and swagger—forget the antistring polemicists! They’re just reactionaries! This could be the greatest discovery of our time!
Nima, as everyone calls him, first stunned the physics community in 1998 by postulating—along with Savas Dimopoulos and Gia Dvali—that unknown extra dimensions could be far larger than anyone ever thought possible, perhaps even nearly a millimeter wide. This was counter to everything physicists had theorized about hidden dimensions, which were believed to be only one hundredth of a thousandth of a trillionth of a centimeter wide. In an insular community where hidden universes, parallel realities, and black holes are discussed with the nonchalance of the weather, this was crazy talk. But nobody could find any mathematical or theoretical evidence to disprove it.
Much of Nima’s work relates to the theory of the multiverse to which Maldacena’s work on holograms alludes. In this model, as described by Nima’s colleague Lisa Randall, our universe is just one of a nearly infinite number of universes floating through the soup of space-time like the bubbles in a glass of champagne. Each universe is a completely self-contained habitat—no particles or forces can go in or out—with one big exception: Gravity can travel freely, slipping from one membrane of strings, or universe, to another.
This is a big deal, because it offers a possible solution to what is called the hierarchical problem—why gravity is far, far weaker than the current theories might predict. (When compared with the electromagnetic and strong and weak nuclear forces, gravity appears to be ten million billion times weaker than it should be.) Nima’s answer is as simple as it is astounding: The gravity that affects us has been deflected and diffused by other universes, like a bottle of whiskey that has been passed around the galaxy a few too many times. By the time the bottle reaches us, all that’s left is a few fingers of backwash.
But here’s the exciting part: Because Nima’s proposed extra dimensions are so large, we may actually be able to see this cosmic shell game between universes in real time with the LHC—gravity from one dimension disappearing into the next. While a long shot by all accounts—including Nima’s—this would be near irrefutable experimental evidence of string theory. The world, in fact, would be on a string.
And yet there’s more. Because the most
controversial ideas Nima hopes to test with the LHC don’t deal with gravity but with the question of why there are 10500 possible string-theory solutions rather than just one. Unlike Maldacena and Witten, who believe that the near-infinite number of string theories may one day be reconciled into a single solution, Nima thinks each string solution could randomly apply to a different universe, and he hopes to prove it. It just happens that humans live in a universe tuned precisely to support life as we recognize it.
The idea is that each possible string theory, when coupled with a cosmological constant that varies randomly, corresponds to a different universe in the multiverse. The reason humans and all life exist in our universe is chance—the conditions just happened to be finely tuned in a way that allowed it. Termed the anthropic principle, it’s a theory that drives many physicists insane, both because humans recapture their role at the center of our galaxy from Copernicus and because it seems utterly untestable: How could we ever test or even perceive the conditions in other universes if we’re stuck in our own?
Nima may be in the minority, but he is undeterred. In fact, he’s convinced that just as Maldacena showed how quantum mechanics could be used to show what happens in the formation and decay of black holes, quantum mechanics could help describe the contours of the multiverse we can’t otherwise see. And just like many of the other aspects of string theory, the answer could stem from the LHC’s experiments. It’s a possible outcome that Witten acknowledges but despairs over. It would mean that science has finally jumped a barrier from being fully experimental to mostly theoretical.
Yet Nima is steadfast. “The mantra of string theory ten years ago was that the theory was smarter than you,” he says. “So people would work on it, and there would always be more things coming out than went in. Well, exactly that—just follow the theory where it leads you, and it leads to this precipice. And now we have to decide what to do. So now a number of people are deciding to jump. … And I think that those of us that decided to take the plunge are staring at the true nature of the beast for the first time.
“I think this is the correct answer, and we are going to have to come to terms with it. And coming to terms with it is going to require a revolution of comparable magnitude to the revolution going from classical mechanics to quantum mechanics. So I think something similar is at stake. And the struggles we are having right now feel a lot like the sort of birthing pains in the twenty-five years from 1900 to 1925, when quantum mechanics started off as a twinkle in the eye of Planck and ended up as a full-fledged theory. I think we are sort of in the 1908, 1909 part of that period right now.”
Which is to say, he thinks this moment is comparable to the most potent and revolutionary period in the history of physics, when Max Planck, Niels Bohr, and Einstein entirely changed the way we look at the atoms that make up our universe and our place in it.
SO THAT IS WHY Nima can’t sleep. Much will be at stake when the LHC powers up. Supersymmetry, with those dreamed-about shadow particles string theorists have bet their careers on, could be a no-show, accelerating the end of string theory and giving renewed life to different ideas, like loop quantum gravity. Perimeter’s unorthodox approach to research would be celebrated as prescient, Smolin and other vociferous critics of string theory remembered as visionaries with the guts to shout that the emperor has no clothes. Or else, of course, the pendulum and the Higgs boson could swing the way string theorists predict—and hope against all galactic hope—that it must. With a single selectron or graviton, M-theory and the holographic principle could begin their slow shift from the category of conjecture to principle; the theory of everything would be tantalizingly closer than ever before, our lonely place in the cosmos, trapped in an obscure two-dimensional universe within a sea of other two-dimensional universes, glimpsed for the first time.
Like Nima, we are all overlooking a steep precipice.
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