Copernicus, Galileo, Hubble, and Now...Guth

Alan Guth had an idea that fundamentally altered humankind's understanding of the universe. Ever heard of him?

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First published in our 1999 Genius Issue, this is the story of Alan Guth, a physicist whose theory of inflation — which attempted to explain how the universe expanded so quickly after the Big Bang — was supported today by the discovery of waves in the fabric of space-time. Essentially, if inflation can be proven, it would reveal our tiny speck of dirt to be even tinier. This man came up with the idea 35 years ago.

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LATE ONE DECEMBER NIGHT IN 1979, A YOUNG academic with a foundering career had an idea, which he committed to his notebook. Twenty years later, that idea--that notebook--rests under Plexiglas in a museum.

This happens in science. Not always; not often; not even occasionally. Rarely at best. But it does happen: the classic eureka moment that transforms a career, changes a discipline, and, if the idea behind it endures long enough, takes up residence in the halls of popular science.Even so, it doesn't often do what this idea does. If the theory is correct, everything we've ever seen in the universe, out to the farthest galaxies at the deepest reaches accessible by the most powerful telescopes in history, is only the merest fraction of what's actually out there. How mere? This mere: one ten-septillionth--or 1/10,000,000,000,000,000,000,000,000--of our universe alone, and quite possibly a lot, lot, lot (lot, lot, lot, lot) less. And that's just our universe. As for all the other universes, their number, according to the best estimates that have arisen out of this theory, is infinite.But that's not the unusual part, as scientific ideas go. Science is full of wild ideas that would seriously rattle our sense of reality if only we heard about them, which nonscientists usually don't. Usually we hear about only the ones that make the cut, a process that often lasts until long after the originator of the idea is dead. In this case, however, the vast majority of cosmologists agreed so quickly that this idea is in fact it--the real thing, the way the universe actually is, the only way to make sense of how everything we see came to be--that it became gospel before its creator entered middle age.

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But that's not the unusual part, either--or not the really unusual part, anyway. Yes, the theory is wild, and yes, it's already a given, but what's really unusual is that it's going to change the world in the same way that--well, take the tour of the "From the Night Sky to the Big Bang" exhibition at the Adler Planetarium & Astronomy Museum in Chicago and you'll get the idea. There's Copernicus, there's Galileo, there's Edwin Hubble, and then turn the last corner, and there's Alan Guth.



BICEP2 Collaboration (March 2014)

TO GET TO ALAN GUTH, YOU GO TO THE END OF THE Infinite Corridor, and then you keep on going. Up the stairs, take a left, several doors down, and there's his office, on the second floor of Building 6 on the Massachusetts Institute of Technology campus in Cambridge.

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It's a big office, with the approximate dimensions of a loft living room. The navigable area, however, consists of a single path that runs from the door past a set of standard college-issue chairs and a couch, wooden-framed and nubby-textured, to a pair of desks at the far end of the room. The rest of the floor is ankle-deep in several years' worth of magazines and journals and mail and empty cans and bottles and abandoned computer keyboards. There's the requisite blackboard covered with arcane equations, file cabinets bulging with drafts of journal articles, and bookshelves lined with the aquamarine spines of back issues of Physical Review, but the true position of honor in the office--occupying the narrow path from door to desks--belongs to the bicycle Guth uses to commute from his home in nearby Brookline.

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In other words, he's a cliche: the single-minded, if slightly idiosyncratic, professor. Still, cliches don't come from nothing. Ask Guth if there's anything in particular he'd like to do today, something exquisitely nonessential, like, oh, go to a Red Sox game, and he laughs. "I'm a cosmologist," he says. "All I do is cosmology."

Well, yes and no. As The Inflationary Universe, his 1997 chronicle of his discovery, made abundantly clear, there's more to cosmology than science. His book distinguished itself, in part, by how much it focused on the nonscientific details of postdoctoral survival: negotiating an offer of moving expenses up from one-way to round-trip; renting a house that was "more expensive than we could really afford" because it had an enclosed yard for his infant son to play in; trying to meet a grant-proposal deadline and pack for an important conference while installing two air conditioners and fixing his son's scooter. The cumulative effect was of someone who can't quite believe he's escaped economic ruin and doesn't quite believe it won't still befall him.

It would be difficult to miss Guth's boyish qualities: his easy enthusiasm, his eager laughter, and the ample bowl of hair that appears not to have changed styles in decades. But he's also boyish in a literal sense; he still thinks like the child who grew up in Highland Park, New Jersey, wondering when, or if, his grocer-turned-dry-cleaner father would make a go of it. Ask Guth what it's like to be enshrined in a museum as someone who has changed the course of human intellectual history and he has this to say: "I was rather gratified, to say the least. And also, I'm still trying to sell my book, so I figure all things like that are helpful."

More than anyone, Guth knows how fortunate he's been. "From the time I was a student, I think I was very confident in my raw abilities," Guth says. "I would think that, given a problem, I was as likely to solve it as anybody. But that's not enough in science to succeed, really." So what is? "Luck," he says--specifically, the luck of being in the right place at the right time.

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In November 1978, while a postdoctoral fellow at Cornell, Guth attended a lecture on a topic that didn't interest him--the big bang, the event at the beginning of the universe. "I was battling a case of bronchitis at the time," Guth wrote in the opening pages of his book, "so I would have missed the lecture if my doctor had scheduled an appointment for Monday afternoon instead of Tuesday morning. If my wife Susan had stubbed her toe that afternoon instead of the week before, I might have taken her to the Tompkins County Hospital for X rays at the time of the talk. Indeed, if the week had been a bit more hectic, I might very well have decided to skip this lecture. But it wasn't, and I didn't."

And that's how Alan Guth first came to hear that the universe had a flatness problem.

IF YOU GO TO GUTH, STOP when you get to the end of the Infinite Corridor. Before heading up the stairs to his office on the second floor, take a moment to turn around and gaze down the length of the hallway. You'll be looking back at a stretch of real estate that reaches, if not quite to the infinity promised by the nickname that students long ago bestowed upon it, then at least a couple of city blocks, all the way to Massachusetts Avenue. The corridor, you'll notice, is flat. Earth, however, is round. And there it is at a glance: the flatness problem.

The universe, of course, is more than a couple of blocks long. Still, according to Einstein, space on the whole should exhibit a curve in the same way that our home globe does. Yet the most sophisticated observations and calculations had yet to reveal the least such curvature. This suggested that the universe, throughout the thirteen billion or so years of expansion that it's undergone since its birth in the big bang, has somehow remained poised precisely between curving either inward or outward--a statistical improbability akin to a pencil standing on its point forever. Now, it may not necessarily be impossible for a pencil to do that, or for a universe, for that matter. But according to every law of physics we know, it's far too unlikely a scenario to take seriously.

So what was a physicist to do? This, in essence, was the question that Princeton University's Robert Dicke, one of the architects of the big-bang model of the universe, had asked the crowd at Cornell back in November 1978. For some time, a colleague of Guth's at Cornell named Henry Tye had been urging Guth to give cosmology, the study of the structure and evolution of the universe, a try.

"My career at that point was . . ." Guth stops, considers. When he's thinking in conversation, his almost perpetual smile wavers, and his eyes wander forlornly off to the side and down to the floor. "It was not by any means a failure, but it was also not a roaring success." His career, in fact, had consisted of a string of postdoctoral fellowships, a coveted form of research residency--in his case at Princeton, Columbia, and Cornell--that endows young minds with one to three years of intellectual freedom, at the end of which they need to move on. Unless, of course, a young mind should arrive at a breakthrough worthy of a job offer. "They were all at excellent places; that's a plus," Guth says of his appointments. "But being a postdoc for nine years was actually unusual, then and now."

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Even so, Dicke's lecture hadn't persuaded Guth that cosmology had anything to offer beyond an intriguing question: Why is the universe flat? It wasn't until physicist Steven Weinberg came to Cornell to deliver several lectures the following spring that Guth began to reconsider cosmology. This time, Guth's attendance was less a matter of luck; during Guth's student days at MIT, he'd been influenced by Weinberg's teachings. To Guth's surprise, what Weinberg was touting now was the same idea his friend Tye had been championing: grand unified theories, or GUTs, attempts to unify three of the four fundamental forces of nature. According to Weinberg, such a unification was theoretically possible--at 100 octillion (that's a 1 with twenty-nine zeros after it) degrees centigrade. This temperature, unfortunately, was something that physicists couldn't reproduce in a particle accelerator. In fact, it was a temperature so extreme that it had been present in the history of the universe only once: during the big bang that started it all.

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Guth, it turned out, had been in the cosmology business all along. Trace the expansion of the universe back to an infinitely dense, infinitely energetic primal grenade and you wind up with the kinds of mathematical conditions that Guth actually knew and loved. Guth told Tye he was beginning to suspect there might be something to GUTs after all. That fall, when Weinberg won the Nobel Prize in Physics, Guth told Tye he was beginning to suspect there was definitely something to GUTs.

By then, Guth had moved on to his fourth postdoc, a one-year position at the Stanford Linear Accelerator Center. Guth offered to do some GUT-level number crunching while Tye pursued his own work back at Cornell. On the night of December 6, 1979, Guth sat down at his desk in the study of the house he and his wife were renting--the one with the big yard that cost more than they could afford and that increasingly was calling into question the whole wisdom of his nomadic postdoc existence--and started calculating.

What emerged was evidence of a period of exponential expansion in the first fraction of a second of the universe's existence--literally, the first trillionth of a trillionth of a trillionth of a second--that put to shame everything to come in terms of sheer volume. Guth recalled the lecture by Dicke the previous year, and sure enough, here it was--the solution to the flatness problem.

Like the immediate landscape surrounding us on Earth that looks flat even though the planet is round, the space in the universe that astronomers study appears not to curve because it occupies only a relatively minuscule part of the universe as a whole. Einstein (as usual) was right; space does curve--only so far out there that we can't see it. According to Guth's preliminary numbers, what lies beyond the visible universe is a gulf that proportionally bears about the same relation to it as, say, everything else on Earth does to the two city blocks of corridor that stretch from Massachusetts Avenue to the stairs leading to Guth's office.

The following morning, he bicycled to SLAC (in the process establishing a new personal best of nine minutes and thirty-two seconds) and immediately sat down with his notebook to summarize his long night's work. "SPECTACULAR REALIZATION," he wrote near the top of a right-hand page, and then he did something to a notebook entry that he'd never done before and he's never done since. He drew two boxes around it.

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AT THE END OF THE INFINITE CORRIDOR, ALAN GUTH hangs a right, hits the doors, and enters another universe. This one has a street to cross, parking lots to shortcut through, a ringing and blinking railroad gate to duck under, and finally, around a couple more corners, an Italian restaurant at which to dine. ("I don't know how authentically Italian," Guth says, but hey--who's quantifying?) Waiting out front is his son, Larry, twenty-one and a math major at Yale. The same Larry whose yard play and scooter mechanics figured so prominently in the logistics of Guth's early career?

"He was a lot littler then," Guth says, laughing. "Kids get bigger."

So does the universe.

"But the universe hasn't increased by the same percentage over the same period of time." Then father and son head inside. "Probably because we feed kids a lot more."

In his book Lonely Hearts of the Cosmos, Dennis Overbye depicted Guth and two fellow cosmologists sitting around after a lecture and talking about nothing--not in the Seinfeld sense but in the where-the-universe-came-from sense. They talked about no time and no space and how quantum physics could account for time and space fluctuating into existence out of the absolute nothingness of no time and no space, like some kind of cosmic hiccup, and how, as another physicist once put it, "our Universe is simply one of those things which happen from time to time."

"Then, as good physicists did," Overbye wrote, "they repaired to a Chinese restaurant."

It was a funny moment for a couple of reasons. It illustrated the way spinners of theoretical universes effortlessly negotiate the transition between the infinite and the temporal, the cos-mic and the mundane. And it offered anecdotal evidence that at the end of the day, they're only human.

But the fact is, they're not--not at the very end of the day, anyway, and not entirely human. The end of the day, when the house is quiet and the phone's not ringing and his students are safely distant, is when Guth does his best thinking. And let's face it: The universe that cosmologists inhabit often isn't recognizably our own.

"To a theoretical physicist," Guth wrote, "there is no greater joy than to see that this curious activity we call calculation--the depositing of ink on paper, followed by throwing away the paper and depositing new ink on more paper--can actually tell us something about reality."

Near the end of January 1980, just a

month after his eureka night, Guth presented a seminar at SLAC on inflation, as he'd come to call his idea, with his reflexive invocation of household finances. The following day, he received seven calls from academic institutions around the country either inviting him to give seminars or asking if he'd consider a faculty position. "When I went to bed that night," he wrote, "I knew that my career in physics had entered a new world."

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Just how new, however, he didn't fully appreciate for another two years, when he attended a major cosmology conference at Cambridge University, organized in part by Stephen Hawking. "There, really for the first time in my own experience," he says now, "everybody was talking about inflation. It was being mentioned in almost every talk, and that knocked me off my feet. After this time, I felt if I had a question about something, I could call up whoever I thought knew the most about it and expect them to know who I was. The amount of time I spent on the phone went up. And," he adds, "my phone bills went up."

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Still, the revolutionary effects of inflation on the career of Guth and on the discipline of cosmology didn't necessarily mean that the idea was sound. Indeed, in the two years since Guth had unveiled inflation, a crucial, though not fatal, flaw had emerged: His model contained no mechanism for shutting off inflation--and clearly inflation had stopped, or we wouldn't be here. In the end, the solution to the problem posited an even wilder version of existence, one in which universes are coming into being out of nothing all the time and will be for all time.

But was any of this looking-glass speculation true? In the spring of 1992, a radio-satellite survey measured the faintest echo of the big bang and by extension that initial trillionth of a trillionth of a trillionth of a second that Guth rendered mathematically in 1979. The data matched the predictions of Guth's theory with such startling accuracy that the project leader proclaimed that the time had come for "everyone" to believe in inflation.

Of course, not everyone does. Cosmologists do; scientists do; but virtually nobody else, aside from the most ardent of science aficionados, has even heard of it yet, let alone begun to understand its implications. But they--we, you--will hear of it, because the implications, as the exhibit at the Adler Planetarium suggests, are these: Just as Copernicus and Galileo removed us from the center of the solar system and set us loose among planets orbiting a star, just as William Herschel set that star loose among the billions of stars of the galaxy, and just as Edwin Hubble set that galaxy loose among the billions of galaxies of the universe, so Alan Guth has set that universe loose not only into a much vaster and inaccessible universe, but also among the billions of universes.

The difference between Guth and all those other cosmologists, however, is that they're famous and dead, and he's neither. So he's as good a person as any to ask two questions that extraordinarily few people in history could answer. First: How does he live with the knowledge that what he's discovered about the world will change it forever?

His answer, not surprisingly, is that he was lucky to be in the right place at the right time--in this case, not a particular lecture hall on a particular day but a field of study that was still so fresh that nobody had yet had the opportunity to work through the fundamental problems. "The idea of combining the physics of modern particle theory with cosmology was very young when I started working on cosmology," Guth says. "It was that exact combination that made it possible to come up with very plausible theories to explain these properties of the universe."

The discovery of inflation, then, was only a matter of time. "I think it very definitely would have been invented very soon after 1979 or 1980 if I hadn't been there," he says. Indeed, when he wasn't there--during a cancer scare in the early 1980s that resulted in the removal of his colon--other theorists stepped in and salvaged inflation by fine-tuning it, an experience that for Guth only reinforces his relative unimportance. "It probably prevents one from being overly egotistical about it," he says, nodding his head and laughing. "It certainly points in that direction."

Which raises the second question that only he can answer: How does he live with the knowledge of what he's discovered about the world, period?

"One thing that was driven home long before inflation is that the world is really just a teeny, tiny part of what's around us, and that would be true if we only knew about the galaxy. But I guess my feeling is that it already goes so far that another factor of 1025"--or 1075 or 101,000, as other theorists have proposed--"doesn't really cause anybody to change his philosophy, I don't think. We have to convince ourselves that we're important just because we're here; it doesn't matter how much other stuff there is. We're here, and this is our life, and it's our job to make something worthwhile of it."

Even if we come from nothing?

"Even if we come from nothing. Right. Maybe especially if we come from nothing."

And that's it, then. Guth shrugs, as if to ask, What else is there to say? And he's (as usual) right. Because what he does now instead is lean into a plate of antipasto and ask his son how his day went. Pretty soon they're talking about cosmic strings, theoretical subatomic spaghetti-like building blocks of the universe. The topic is outside Guth's specific expertise; he's still working at refining inflation. But it's a fun and furious talk, nonetheless, the two of them tossing ideas around, back and forth, faster and harder, until they collapse in laughter.

This happens in families. Not always; not often; maybe only rarely. But it does happen: a eureka moment of another kind, one that you can't put into words or capture in an equation. For Alan Guth, what all the money woes and meditations on nothing and numbers with a thousand zeros add up to turns out to be what comes not quite at the end of the day, when he's only human after all: a father and son playing their own peculiar brand of catch.

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