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Chasing the Great Beyond

Adam Riess discovered that the universe was expanding faster and faster, thanks to a repulsive force dubbed "dark energy" — a breakthrough that has led scientists to reconsider the fundamentals of physics.

By Michael Anft
Photos by Steve Spartana

There are billions of galaxies, a zillion stars, swirling clouds of dust, and bulging pockets of gas. Cosmic radio waves fan out around something called "dark matter" — "dark" because no one really knows what it is — while remnants of energy that date back to the Big Bang 14 billion years ago swell and contract. Stars eat up other ones, then implode. Asteroids and comets wreak their usual havoc.

Don't let the perspective and calm of a clear night sky fool you: The universe is a mess.

Astrophysicists, cosmologists, theorists, and other Big Thinkers intimately understand this. It's a lot to clean up, intellectually speaking. They will tell you that the whole shebang is up for grabs, that theories of its vastness and mechanics are constantly in flux, falling in and out of fashion almost as rapidly as amateur television singers. And the conjecture is seemingly as infinite as space itself.

One pair of astrophysicists in England believes, for example, that the universe is part of a series of Big Bangs, the result of an extra cosmic dimension or two. Others contend that the universe is being pulled apart by the gravity from surrounding, er, universes. And one well-published physicist has thrown his epistemological hands into the air, arguing that scientists practice a belief system bordering on religion, an overzealous "faith" in the idea that the universe can be explained in rational terms.

You can see the dilemma. Stabs at making sense of the universe can jab out in a million directions and, sometimes, make people crazy. To carve a slice out of The Problem of the Universe, an astrophysicist would have to make an extraordinary claim, one that requires, as the late astronomer Carl Sagan would say, extraordinary evidence to make it believable.

So in 1998, when a group of 19 carbon-based life forms on a planet in the Milky Way galaxy discovered a new kind of force in the universe — one that pushes it outward in all directions at an ever-faster clip — the world of science stood up and took notice. At the group's center was a Harvard postdoc who boiled down a mass of hand-scrawled data and came up with the calculations that would reverse the orbit of astrophysical thinking.

Adam Riess found "dark energy," the anti-gravitational force that makes up nearly three-quarters of the universe and causes it to expand at an accelerated rate. His team had mathematically digested information from telescope images of distant exploding stars (supernovae) to measure the age and mass of the universe. His work on supernovae led Riess to conclude that the laws then believed to be governing the movement of the cosmos were dead wrong. He had just turned 28.

Now a professor of physics and astronomy at Johns Hopkins' Krieger School of Arts and Sciences, Riess compares dark energy to the effect one would observe as a raisin amid a baking loaf of raisin bread — a loaf made with all the yeast ever grown. "All the other raisins — other galaxies — rush away from us," he says. "You might expect it to keep expanding at a certain rate. But what we found was the loaf is getting bigger and bigger at an ever-greater speed."

The discovery fills a void in scientific thinking. "It's central," says Riess. "Dark energy is most of the universe and we don't understand it. It's like an auto mechanic who says he knows cars but hasn't worked on 75 percent of one."

Noted scientists with longer track records also marvel at the momentousness of the dark energy discovery, which they compare to astronomer Edwin Hubble's observation, made 80 years ago, that the universe was expanding. Riess' methods accounted for so-called nuisance factors having to do with the effect of dust particles on light from fading supernovae, allowing scientists to measure their distance from Earth accurately enough to conclude that the universe was speeding up.

Scientists had long been aware of dark matter — unseen particles that make up about 22 percent of the mass of the universe. But the rest of it had been a mystery. Dark energy is "the missing piece, the one that makes the rest of cosmology make sense," says Michael Turner, professor of physics, astronomy, and astrophysics at the University of Chicago. Turner is also the man who provided the admixture of public relations and science that coined the term "dark energy." (The moniker makes it easier for scientists to concisely reference it in their publications, he notes, plus the energy doesn't contain light or particles. "You have to have a catchy name, one that people will like," he adds.)

Dark energy could provide clues as to how the universe was formed or whether there is some kind of mixture of space and time that astrophysicists, caught without the benefit of a unifying "theory of everything," have overlooked or misunderstood. "We had considered other things, but they didn't add up," Turner adds. "Dark energy explained the 70 percent or so of the universe that we couldn't factor in when we added up all of its mass. This could be a clue that leads to a new theory of gravity, or the first detection of an extra dimension in space. It's a big, big, big deal."

The National Aeronautics and Space Administration agrees. At the urging of the National Academies, an association of scientists that helps set the agenda for future research, NASA has made dark energy its top research priority and plans to commit around $1 billion to develop space telescopes for investigations into its nature. Three laboratories, including one led by Charles L. Bennett, also a Krieger School professor of physics and astronomy, are competing for the cash and the glory of finding answers to the cosmos' most vital mystery. A "winner" will likely be named later this year. If Bennett's bid is successful, Riess will be part of his team, searching for 1,000 or more supernovae that could provide clues as to how dark energy works.

The project isn't all that's at stake for Riess, colleagues and observers whisper. He's been a winner or co-winner of a heaping handful of top-drawer international science awards since 1999, had his dark energy observations touted as one of the major discoveries of the 20th century, and seen some of the papers he has written since then become among the most-cited in his field.

But Riess isn't the only one claiming the dark energy discovery. Saul Perlmutter, a physics professor at University of California, Berkeley and head of the Supernova Acceleration Probe at its federally supported Lawrence Berkeley National Laboratory, is one of the project leaders competing with Bennett's telescope proposal. Media reports cited Perlmutter as heading a team that announced — a few weeks earlier than Riess' group did — its observations of conditions supporting the existence of dark energy. And academics from both sides have shaken the hive, all saying they want to set the record straight — but perhaps hoping as well to have an effect on who gets the highest accolade a scientist can receive, the Nobel.

"There's this prize that some committee gives out in Sweden each year that might have something to do with it,"says Turner, who has connections to both sides: He is a member of Perlmutter's team and has co-authored papers with Riess.

In the middle of it all is Riess, who prefers to paint himself as he is: a coin-collecting, football-loving family man who believes deeply in science and who has no time or interest in such foolishness. Turner says Riess has "admirably" stayed out of the skirmish, concentrating instead on the science and transcending the hubbub surrounding the discovery of dark energy, the credit for which he is more than willing to share. There's no room for egos in science, Riess offers.

"What's important is you have two different teams that got the same result. That's good for science and for everyone else," Riess adds.

But upon meeting a reporter one day for lunch, Riess pulsates with anger at another scribe in London who is writing a story that tilts definitively — and unfairly, he says — to the side of Perlmutter. Some awards committees have made the same mistake, other physicists point out.

Riess is a reasonable guy. He really doesn't want it to get to him. But it does.

The front door of Office 207 at Johns Hopkins' Bloomberg Center for Physics and Astronomy is adorned with a copied photo of Riess' 3-year-old daughter, Gabrielle, holding open a book featuring a famous image of Albert Einstein. Both have their tongues out. Inside, the walls hold little more than several framed awards and provide a leaning spot for a 10-foot-high bookshelf lined with hardback tomes as weighty in mass as they are in subject matter.

At the room's center is a simple wood desk topped by an Apple computer with a 30-inch monitor. This is the entirety of the Riess lab.

He is the ultimate low-maintenance researcher, say his colleagues. His surroundings mirror that, as does his nondescript, office-Joe uniform: a blue Oxford shirt, green pants, gumsoled brown leather shoes. His round face sports a simple square goatee. Atop the brain that figured out what nearly three-quarters of the universe is made of sits a bristle of brown hair encircling an emerging Friar Tuck's bald spot.

Playing against type comes naturally to Riess. Images of the lone astronomer shuddering against the cold as he searches the heavens via a mountaintop telescope don't apply. Riess admits he wouldn't know most constellations if the stars fell on him. His hands may tremble occasionally — not from the cold, but from energy and excitement, especially when he tells of something he's learned. His colleagues marvel at Riess' ability to convey rich and ponderous concepts to the laity. He'll pepper his explanations with analogies and references to Akira Kurosawa films, an ancient tale from India, or football. That talent isn't wasted at the Krieger School: Every other year, he teaches a course called Great Discoveries in Astronomy and Astrophysics to non-majors.

"It's something I really enjoy doing," he says. The text he uses includes a final chapter on his work and dark energy. "It kind of gives people the idea that there's more to this astrophysics stuff than old men and telescopes."

Instead of making observations with a ground-based telescope, his stargazing tool of choice is the computer, its oversized screen serving as his window to the universe. Using wide-angle images — or "tiles" — taken by the Hubble Space Telescope, Riess has spent one-third of his working time in recent years chasing the past, searching for stars that crashed and burned billions of years ago.

Riess traces the light of ancient and intact stars, but only as comparison points for supernovae. When a star explodes and dies, it creates an incredibly bright flash of light — equal to 4 billion suns. But unlike neighboring stars that shine all year, supernovae only remain prominent in the telescopic sky for a month before disintegrating, making rapid identification and calibration paramount.

It isn't easy. The tiles resemble a splattering of whiteout on black construction paper — random, melded together, seemingly impenetrable. Riess' mind penetrates them, sometimes with the help of a postdoc or the two graduate students in his charge. He analyzes these images for changes in a patch of sky, searching for a new exploding star. "It would look to the layperson exactly like a TV channel with pure static, except, once in a lucky while, there will be a collusion of a dozen white pixels that join together in a round blob," he explains.

Physicists since the 1930s have known that supernovae of a certain type could be useful for measuring the depths of the universe, but they lacked the technology to do it. They can calculate expanses in space using the speed of light, which will also peg the age of bodies in space and, ultimately, the universe. But telescopes with the strength necessary to track down the exploding stars took decades to develop.

During the 1990s, once technology started catching up with the desire to scan the most distant parts of the universe, supernovae became the yardstick of choice for astrophysicists. Riess latched on to the fleeting bodies partly by luck. Indeed, supernovae and serendipity have played the major roles in his (pardon the phrase) stellar career.

After graduating with a degree in physics from the Massachusetts Institute of Technology in 1992, Riess began working toward a PhD at Harvard. Early on, he was bewildered as to what his area of focus would be. He toyed with the idea of studying "SETI" — the search for extraterrestrial intelligence — a subject that resonated with a guy who wrote space-based sci-fi stories in his spare time. But his older sister and her husband talked him out of it. He'd be a student forever, they told him, because he wouldn't have any data to clinch his dissertation. He decided to survey the terrestrial intelligence at Harvard for answers.

"I asked a bunch of professors what I should do," Riess remembers. "I knew next to nothing about astronomy or astrophysics. But I was intrigued with ideas like, How will the universe end? and, How long has it been here? These were the big questions. What I was amazed to find was that this wasn't just a subject for speculation. You could go out with a telescope and answer them. It may be difficult, but there's a methodology."

He took up with Robert Kirshner, a Harvard physics professor who had developed an international reputation in supernovae research. Riess, always an excellent student in the sciences and everything else, had long been attracted to those bigger questions because of an innate discomfort with not understanding how things work. "I've always had to know what makes things go," he says.

The son of a psychologist mom and an engineer-turned-entrepreneur dad, Riess was raised by egalitarians who encouraged him to follow his insatiable inquisitiveness, but never pushed him. The youngest of three siblings, young Adam was a pleasant kid who was nonetheless daring and creative, his mother, Doris Riess, says.

Those who grew up with him remember a sports freak, one who wasn't satisfied with playing by the official rules. The family's white house on an exurban hill in Warren, New Jersey, often served as a backdrop for wild games that ended in injuries, if not mayhem. "We'd never play the game the way you were supposed to play it," says Chris Kratt, Riess' closest childhood friend. "It wasn't just about getting the most baskets. You had to dribble three times around his mom's car, then run up the street and back backwards. It was crazy stuff."

Adam played organized sports as well, especially soccer. His mother remembers him as the small kid who would erupt out of a pile of players with the ball and head toward the goal. "You got the feeling he understood the game more deeply than the other kids," says Doris Riess.

Adam also showed a deep and early understanding of science and history, from dinosaurs to the Civil War and beyond. His interest in the past would continue to drive his curiosity at college. He would minor in history at MIT, writing a final research paper on baseball's 1919 "Black Sox" scandal. He investigated whether the Chicago White Sox's effort to throw the World Series that year could be deduced from news reports and box score statistics. (The answer: It couldn't.)

Early on, he and his dad would look up at the sky to ponder a thunderstorm or a black blanket dotted with planets, stars, and the occasional comet. Michael Riess told his son that the light he was seeing from stars is millions of years old, and that a star or two he was viewing may no longer exist. Adam's mind was blown.

The rest of Riess' early life reads like yet another smart-kid-as-supergeek story: At 8, he and a sister built a tree-house and outfitted it with a basement and a working telegraph line; in second grade, he gave a talk to a fifth-grade class on the workings of the stock market; at 11, he was giving orders to his Radio Shack computer and, at 13, teaching an adult class in programming.

With his budding-scientist's bona fides piling up, young Adam could get away with being proud, but Riess mére et pére wouldn't stand for arrogance or entitlement. His parents valued education but tutted and tsk-ed discretely at neighbors who paid their children $100 for A's or forced them to take advanced courses. High intelligence and membership in an upper economic class didn't excuse their children from behaving with equanimity and compassion to other humans, or absolve them from tedium, the Riesses reasoned.

When the Riess kids were growing up, they worked at the New York-style deli run by their father. One day, Michael Riess asked his son to clean up after a customer had gotten sick in the bathroom. Adam didn't want to do it.

"He lit into me later about that," Riess says. "He told me, 'You have to do what you have to do. You think you're better than everyone else there?' He let me know that there were people who had to do that kind of work for a living. What I took from all that was that I had to really work hard to do the things I like. I was terrified of having to do something where I would just watch the clock."

At Harvard, Kirshner recognized that Riess was the kind of kid who was on his way to somewhere. He was imaginative. When he taught a class, Riess would stage a Jeopardy!-style game show to get his students thinking. "He had that self-starting quality you see in good graduate students — the ones who become successful scientists," Kirshner says.

At the time, supernovae were being found more rapidly than ever by Perlmutter's team at the Berkeley Lab. But Kirshner wanted to measure the distance of supernovae more precisely than they had. To do that, someone would need to come up with a mathematical model to determine which supernovae appeared dim because they were distant and which were dim because intervening dust particles made them look that way, making their distance difficult to quantify. That someone was Riess, who developed a method that would — eventually with a 99.7 percent level of certainty — account for dust and the variations in supernovae light caused by gravity-created curvatures.

Computations showed there wasn't enough mass or gravity to add up to deceleration. The universe had to be speeding up. "Your first reaction is, 'I screwed something up.'"
The technique earned Riess a PhD in 1996, after only four years instead of the usual five. More importantly, it would prove crucial for scientists who wanted to use supernovae as regularly reliable universe-calibrating tools. Within a year, Riess would turn down a fellowship offer from Perlmutter and take another one based at Berkeley. Eventually, he would sign on with the High-Z Supernova Search Team, the band of astrophysicists working in Australia, Chile, England, Germany, and elsewhere that Kirshner began to assemble around 1993. ("High-Z" refers to "redshift," the symbol of measurement named after the tint we see in very distant bodies in space.)

Brian Schmidt, the Australian elected as the team's principal investigator, needed someone to analyze data for a project called "Measuring the Cosmic Deceleration and Global Geometry of the Universe with Type Ia Supernovae" (italics added). Riess was drafted for the job. He was hardly ecstatic. The research team already knew what it was going to find — that universal expansion was slowing down — and the project was chock-full of mathematical tedium. Riess wasn't sure he wanted to waste his time.

"Here I was working on this prestigious fellowship where I could go totally in my own direction," he says. "I had three years to make my mark, to prove that I was worthy of a job in this field. And this would take one year. There was no glamour in this, I thought."

No matter, he hunkered down to work like a monk in a tiny office at Berkeley, 200 yards down the hill from Perlmutter's team. There, he and another postdoc locked into their computers while listening to rock on the radio, taking particular delight when a song title or band name, such as Semisonic, let them know that pop culture hadn't totally written off science geeks as irrelevant. They'd get particularly excited when they heard a song called "Champagne Supernova," by Oasis, a band that once haphazardly referenced Isaac Newton by naming a CD Standing on the Shoulder of Giants.

While a longtime fan and student of Einstein's work, Riess hadn't thought more than a day in his life about one of the more obscure concepts included in his theory of general relativity: the "cosmological constant," a mathematical construct that posited a vacuum energy working against gravity to keep the universe static. In fact, Einstein had shelved the cosmological constant a decade after inventing it — calling it a "blunder" — upon hearing of Hubble's findings that the universe was expanding and not static, as he had assumed. By the middle of 1997, when Perlmutter's team measured supernovae and found the universe to be decelerating, all signs pointed to a slowing universe — not to one speeding up under the influence of an obscure kind of energy.

But soon Riess and the High-Z team would stand on Einstein's shoulders. In fall of 1997, Riess began to notice that his measurements weren't adding up. He asked his computer to calculate the total mass of the universe. Totally unexpectedly, he got a number with a negative sign. The implications of that sign would contradict scientific orthodoxy. As time moves the universe further away from the violent outburst of the Big Bang, the conventional wisdom went, the soup of particles it created would decelerate, giving them a chance to form structures — moons, planets, stars, etc. — with the help of gravity. Theorists wondered whether the universe, tens of billions of years later, would end in a "Big Crunch," when all matter, drawn together by gravity, would implode.

But Riess' computations of supernovae distances showed that there wasn't enough mass or gravity to add up to deceleration. The universe had to be speeding up. All of which meant, Riess thought at the time, that his results were wrong. "Your first reaction is, 'I screwed something up,'" he says.

Only one other member of the High-Z team was on site, Berkeley astronomy professor Alex Filippenko, who had switched from Perlmutter's team, led by hierarchically minded particle physicists, for the High-Z team's group rule. Riess pumped him for help.

"We had an idea that the [Perlmutter] team was getting the same results as we were," Filippenko says. "Adam was always concerned with what might be going wrong and what might be fooling us. One of the reasons he joined the High-Z team was that we dealt with the subtleties, the nuisance factors involved."

The nuisance factors had themselves become a nuisance, Riess recalls. After spending nearly all of 1997 trying to mathematically deal with them, he summoned Schmidt, the principal investigator, for help at the end of the year. Schmidt added up the data and came to the same conclusion: The cosmological constant, or some variation on its theme, was back on the astrophysical table.

"This thing called science is somehow the fabric of the universe. It's the most egalitarian enterprise I know of. It speaks to everybody in the same way."
As Riess and Schmidt e-mailed back and forth to each other in early 1998, they were hardly confident in their findings. They signed their e-missives "Pons" and "Fleischmann" — tongue-in-cheek references to Stanley Pons and Martin Fleischmann, the two University of Utah electrochemists who made a big splash with the "discovery" of cold fusion in 1989, an idea soon refuted by others. "We didn't want dark energy to be the next cold fusion," says Riess.

Despite the self-doubt, Riess and Schmidt started talking about getting their ideas out to the public, possibly with a press release announcing their findings. That was right around the time when Perlmutter told a group of astronomers at a convention that the "universe would expand forever," but did not mention anything about cosmic acceleration.

Before Riess' team could reach a conclusion on what to do next, Riess took a break to marry Nancy Schondorf, whom he met when the two studied together at MIT. The wedding would end a four-year romantic, if geeky, courtship. The two had been physically separated when Riess left MIT for Harvard, so the couple communicated across the Charles River by blinking flashlights and their apartments' porch lamps.

After the wedding in Connecticut, the two returned to their Berkeley apartment to pack for their honeymoon at Big Sur. Riess got on the computer to let the rest of the High-Z team know what he had found and how big an idea they were sitting on.

"I thought that, after two days, my wife was going to divorce me," Riess says. "She thought I was this workaholic."

The scientist/history buff saved what he wrote that day — January 12, 1998 — four days after Perlmutter's announcement: "My God! A guy goes away for his wedding and when he comes back, the universe is expanding (forever) and out of control! A guy at the wedding said to me, 'I read in The New York Times that the universe will expand forever, did you know that?' I said, 'I'm familiar with that work.'"

The High-Z team then discussed online what to do with Riess' results. Filippenko believed that the group should release a short announcement to the public, but Riess argued against it. If the team was going to beat Perlmutter's to the publication punch, it would have to quickly write what he calls the "War and Peace version" — an exhaustive explication of their work. "Let's not waste our energy and reputation waving half-baked results around," Riess wrote. "Let's band together to work carefully and efficiently and maybe the tortoise can catch the hare." Eventually, the group agreed unanimously. The paper, published in May 1999, beat Perlmutter's by nine months.

Riess' life didn't really change after the news broke that his team's research had nixed the entrenched idea that the universe's expansion was slowing down. His local paper in Warren offered a down-to-earth headline: "Local Boy Does Well in Astrophysics." While Science, CNN, and others set up shop in the cramped hallway outside his office, he had the chance to hold court as the new authority on cosmic movement on The Jim Lehrer News Hour, his dad's favorite show.

He did confide to his mother, though, that he worried he'd "peaked too early."

Early on, the two research teams began to stake their claims. A terrestrial tug of war ensued between the Riess and Perlmutter teams. Investigating the cosmic tug of war, the Perlmutter team claimed the first announcement to the public while Riess argued that his team's detailed and lengthy publication in the Astronomical Journal was the definitive word.

Perlmutter says his team showed data in early January 1998 that cosmic acceleration existed. But some on the High-Z team argued that Perlmutter's findings six months earlier in favor of deceleration weren't strongly contradicted by what his team offered that January. "When we're being impolite, we say they were first, but they were wrong," says Kirshner, who has maintained a Web page devoted to extolling the High-Z team's role in the discovery of dark energy, and playing down Perlmutter's.

Perlmutter says it's all a matter of semantics. "We thought 'acceleration' was a bad term to use. It would confuse science and the public if the universe was once decelerating, but now accelerating. The fact that the universe would expand forever would make for a good headline, we thought. I guess we were wrong," he says.

Turner, the University of Chicago professor and a member of Perlmutter's current team of physicists, wondered at the time of Perlmutter's announcement why he de-emphasized cosmic acceleration. "I've given Saul a hard time over this. His team had the same data and diagrams" as the High-Z team, he says. "There's been some bad blood over this, but the majority of people in science say, 'Look, there were two teams on this at roughly the same time. Let's not be silly.' There's no precedence in science that publication is the only way to announce a discovery."

Others say that the intermittent square-off is par for the cosmic course. "In the last 100 years, it's been hard to find a major discovery that didn't involve more than one team," says David Gross, director of the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara, and the 2004 Nobel Prize winner in physics. "It's very normal for scientists to be involved in an episode like this."

Riess and some others on the High-Z team don't dispute Perlmutter's connection with the discovery. Perlmutter's team had found four times as many supernovae by 1998 as the High-Z team did, and had done a lot of work on software and optics that aided the discovery. But the High-Z team wonders if its work has been marginalized by people with an opposing agenda. At least one major international prize has been awarded to Perlmutter alone.

"The [Perlmutter team] hadn't significantly considered the possibility of dust dimming supernovae, but Adam understood the subtleties of the symptomatics," says Filippenko. "We did the work to account for other factors and went out on a limb regarding acceleration."

Some have kept the matter alive. With major scientific prizes, possibly including the Nobel, and the $1 billion-or-so Joint Dark Energy Mission (JDEM) project, run by NASA and the Department of Energy, in the wings, the matter is open for rehashing. "If there are people who want to make this a point of contention, [the JDEM money] would generally fan the flames," Perlmutter says.

All of which sometimes distresses the usually good-natured Riess, those close to him say. "The whole thing perplexes and angers him," says his mother. "He's very idealistic, so he can't understand why people make claims that are not true."

Riess won't point any fingers — he prefers to believe that major awards will follow the example of the one international committee that honored all members of both teams in 2005, or perhaps another that awarded him, Perlmutter, and Schmidt a major prize in 2006. He believes that dark energy was co-discovered, and that the two teams should both share in the glory.

Riess reacts with a smile and a "Good!" when he hears that Perlmutter feels the same way.

Since coming to Baltimore in 1999 to start work in a low-level job at the Space Telescope Science Institute (STSci), where he's now a senior member of the science staff, Riess has honed his supernovae studies and undertaken an intense investigation of the nature of dark energy. But he found a need to make some adjustments to his thinking. For up to a year after figuring out dark energy existed, he had to return to toiling anonymously, reminding himself, "All science is interesting" — even if it wasn't anywhere near as exciting as the months that led up to the finding of cosmic acceleration.

Despite being the guy who cracked a major code of the universe, his career options were limited back then. What's more, when a group wanted to hire a speaker on dark energy, they most often called Kirshner. "I didn't have many offers," he says. "I was still a junior guy, a largely unknown quantity. People might have been thinking: 'Is he a one-hit wonder?' I had to do other projects to stake my place out in the field."

So Riess began to plumb the depths of the universe, using the Hubble Space Telescope, which is outfitted with a camera designed by Holland C. Ford, a physics and astronomy professor at the Krieger School. Riess calls Hubble "a supernova search engine." Within two years, he had made a second momentous discovery: a supernova that dates back 9 billion years — the oldest ever found. Three years later, Riess found that the universe started speeding up 5 billion years ago. The paper garnered more citations than any other in astrophysics had for several years.

"These are important clues because dark energy could have been quite different over time," Riess says. "We could make a really solid measurement of what the universe was doing. The smart money says that it's Einstein's cosmological constant. Our data has supported that."

Although Riess was directed toward supernovae and the discovery of dark energy with the help of chance, those who watch him work say he has continued to be in the forefront of new research because he's incredibly driven — and because luck is the residue of design.

"I like to say that luck helps the well-prepared," says Mario Livio, Riess' friend and a theorist at STSci. "This is very characteristic of Adam. He has a good nose for things to look at and go after. It's an instinct. He's the type of observer who takes the care to learn about all the details surrounding the topic he is interested in. You can't surprise him."

Riess continues to ask the Hubble for clues. Since coming to Baltimore, he has used it for 5 percent of its total working time — more than any other scientist. Such diligence and attention to detail led to his appointment at Hopkins in 2005. Now, Riess and his team, with the help of Hopkins research money, will play a small part in a project directed by the Air Force to identify and target asteroids that could smash into the Earth. Riess' interest has little to do with that part of the mission. Instead, his team will develop a telescope filter that will make certain supernovae stand out in the sky. "It'll be like watching a hockey game on TV in which they light up the puck," he says.

Riess will also piggyback on Bennett's telescope project, called ADEPT — assuming it gets the nod from NASA and the Department of Energy. Bennett has successfully used another method — measuring cosmic sound waves and their oscillations dating back to the Big Bang — to peg the universe's age at 13.7 billion years old and to bear out the existence of dark energy. There are a small handful of other techniques in use now as well, but Riess will continue to study supernovae.

Technology now in the pipeline will provide the next step toward understanding what dark energy is. As for what that might be, Riess won't hazard a guess. "I don't really want to think about it because I don't want to have any preconceived notions," he says. All he knows is that he'll spend 10 hours a day working at it, before heading home to a suburb north of Baltimore to be with Nancy — a Web designer — and to play with Gabrielle, watch football, or study his coin collection. He won't be in the backyard with a telescope. "If we hear anything about a meteor shower, it's because my mother has called," says Nancy Riess.

Then, the next day, he'll be back at his computer, sifting out especially bright spots from a field of intergalactic ephemera, comforted by the idea that as little as astrophysicists might know, they know more of it today. All controversies aside, there may never have been a better time to practice the science, Riess says. "We're in a special time right now, a time some call The Era of Precision Cosmology. This used to be a more speculative science, but in the last decade we've come up with new ways to measure the universe," he adds.

Producing good science will remain his passion, he says. The world of scientific inquiry is a meritocracy, an idea with which he was raised. He is at home in that world. "Most of the things we talk about or know of are stories, or they're belief systems, or they're philosophies. This thing called science is somehow in the fabric of the universe. It's the most egalitarian enterprise I know of. It speaks to everybody in the same way," he says.

"Everybody" — all 5 billion of us — makes up part of the 4 percent of the universe that isn't dark energy or dark matter. We have the privilege of being made of atoms. Some physicists say this makes us irrelevant freaks. Others say this rareness of position in the universe makes us special.

This line of thinking, which leads not so neatly from physics to metaphysics and back, doesn't interest Riess. That the cosmos has begrudgingly — at least for now, and as far as we know — given up a secret about its movements means little more than that there is no meaning in it.

"I see it as a strong sign of how little regard the universe has for our existence. It doesn't send us special clues. It doesn't encode them in matter or energy. We're like the flea hiding on the back of a dog. We're hanging out there and the dog doesn't give a hoot about the fact we're there. The universe isn't malicious. It's not benevolent," Riess says. But, with a kick from dark energy, it's accelerating: "It's just not going to stop for us."

Michael Anft is a senior writer for Johns Hopkins Magazine.

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