How the Stars Were Born

Richard Ellis paces impatiently back and forth across a small room lined with computer terminals, trying to contain his mounting frustration. The British-born astronomer, now at Caltech, has been granted a single precious night to use one of the twin Keck telescopes, among the most powerful in the world. Last night he and his observing partner, a graduate student named Dan Stark, flew 3,000 miles, from Southern California to Hawaii, where the Kecks are located. And during most of the afternoon and early evening today, they've made their final plans for the "run," as astronomers call a night of peering into the heavens.

But things are not going right. It isn't the weather, which is what usually trips up stargazers. Here at Keck headquarters in the sleepy town of Waimea, nestled in the midst of cattle-ranching country on Hawaii's Big Island, thick clouds are scudding past, occasionally dipping low enough to send a driving mist across the grassy hills. But the telescopes are some 25 miles away and more than two miles up, in the thin, frigid air at the summit of the extinct volcano Mauna Kea. At an altitude of nearly 14,000 ft., the observatory sits well above the cloud deck. Live video-camera images piped down to the Waimea control room show white domes silhouetted against a fading but crystal-clear sky.

The problem is that Keck 2, the scope Ellis and Stark have been assigned for the night, stubbornly refuses to focus. Time and again, the professional telescope operator who sits in a control room up on the summit and actually runs the mammoth instrument has issued the command that tells it to focus. Time and again, the focusing routine has responded to his commands by crashing. For half an hour, engineers have been trying to figure out what is going on—while the first of the precious celestial objects on Ellis and Stark's observing schedule sinks inexorably toward the horizon. "This is pretty profound," says Ellis, bitterly. "If you can't focus the telescope, you're stuffed."

No astronomer likes to be cheated out of an observing night, whether the quarry is a mundane moon of Jupiter or an exotic quasar halfway across the cosmos. But Ellis has special cause for frustration: he's looking for something far more elusive than any quasar. Tonight he intended to bag something most astronomers consider next to impossible: the most distant galaxy ever seen—and not the farthest by just a little bit. The current record for distance, held by another giant Mauna Kea observatory, Japan's Subaru telescope, is for a galaxy whose light started its journey to Earth a billion years or so after the Big Bang. But Ellis and Stark suspect they have found not one but six galaxies from an astonishing half a billion years earlier still. Tonight's run could confirm it.

A discovery like that would give Ellis bragging rights at astronomy conferences for years to come, and it would let Stark finish his dissertation with a dramatic flourish. But far more important, it would give astrophysicists their first real glimpse into a crucial and mysterious era in the evolution of the cosmos. Known as the Dark Ages of the universe, it's the 200 million-year period (more or less) after the last flash of light from the Big Bang faded and the first blush of sun-like stars began to appear. What happened during the Dark Ages set the stage for the cosmos we see today, with its billions of magnificent galaxies and everything that they contain—the shimmering gas clouds, the fiery stars, the tiny planets, the mammoth black holes.

When the Dark Ages began, the cosmos was a formless sea of particles; by the time it ended, just a couple hundred million years later, the universe was alight with young stars gathered into nascent galaxies. It was during the Dark Ages that the chemical elements we know so well—carbon, oxygen, nitrogen and most of the rest—were first forged out of primordial hydrogen and helium. And it was during this time that the great structures of the modern universe—superclusters of thousands of galaxies stretching across millions of light-years—began to assemble.

UNRAVELING A MYSTERY

So far, however, even the mightiest telescopes haven't been able to penetrate into that murky era. "We have a photo album of the universe," says Avi Loeb, a theoretical astrophysicist at Harvard University, "but it's missing pages—as though you had pictures of a child as an infant and then as a teenager, with nothing in between." The full answer may have to wait for a new generation of telescopes expected to come on line within the next decade. In astronomy, size matters, especially for faraway objects. The bigger a telescope, the more of a distant galaxy's meager light it can gather—just as a swimming pool catches more rain than a bucket. So astronomers are looking forward to a ground-based monster with nearly 10 times the light-gathering area of the Keck, a space telescope more than 10 times as big as the Hubble and several radio telescopes with unprecedented sensitivity. Meanwhile, using the basic laws of physics, sophisticated computer simulations and tantalizing hints from existing telescopes, astronomers have put together a plausible scenario of what must have happened during the Dark Ages.

The first of those hints comes from the universe-wide flash of light that followed nearly half a million years after the Big Bang. Before that flash occurred, according to the widely accepted "standard model" of cosmology, our entire cosmos had swelled from a space smaller than an atom to something 100 billion miles across. It was then a seething maelstrom of matter so hot that subatomic particles trying to form into atoms would have been blasted apart instantly and so dense that light couldn't have traveled more than a short distance before being absorbed. If you could somehow live long enough to look around in such conditions, you would see nothing but brilliant light in all directions.

But as the universe expanded, it finally cooled down enough to allow atoms to form and light to shine out across open space. The accidental discovery of that light back in the 1960s convinced astronomers that the Big Bang was a real event, not just a theoretical construct.

That first detection of the remnants of the Big Bang was crude, but a series of increasingly sophisticated instruments, culminating in the Wilkinson Microwave Anisotropy Probe (wmap) satellite in 2003, have laid bare the structure of the 400,000-year-old cosmos—only a few hundred-thousandths of its present age—in surprising detail. This was the baby picture Loeb referred to. At that point, the universe was still a very simple place. "You can summarize the initial conditions," says Loeb, "on a single sheet of paper." Some regions were a tiny bit denser than average and some a little more sparse. Most of the stuff in it—then and still today—was the mysterious dark matter that nobody has yet identified, largely because it doesn't produce light of any sort. The rest was mostly hydrogen, with a bit of helium mixed in. So far, the universe hadn't done much of anything.

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