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A look way, way back

New technique offers researchers clues to the universe's dark age

You wouldn't want to bounce them on your knee, but scientists believe they have located babies near the far edge of time and space: baby stars, infant galaxies, possibly the first-born of the countless trillions that today gambol across the heavens.

Astronomers at the California Institute of Technology, using a pioneering technique called gravitational lensing, say they have spotted the most distant galaxies ever seen -- stars bursting into existence 13.2 billion years ago, when the universe was only 500 million years old and just starting to take its present form. The six clusters of stars, the researchers theorize, were among billions of galaxies forming as the universe emerged from its Dark Age.

The Caltech announcement, made in a presentation last week before the venerable Geological Society in London, sent a ripple of surprise and skepticism through the small world of astrophysics.

"These six star-forming clusters lie at unprecedented distances, occurring at a time when the universe was less than 4 percent of its present age," said Richard Ellis, a noted Caltech astronomer. Ellis and graduate student Dan Stark pinpointed the faint clusters they believe to be early galaxies during three years of painstaking observations from the Keck II telescope atop Mauna Kea in Hawaii.

Scientists armed with ever more powerful telescopes and innovative techniques for collecting light and radio waves are pushing back time and closing fast on the Dark Age, regarded by many scientists as the universe's most mysterious era. For astronomers, the term Dark Age refers to a missing gap of hundreds of millions of years lying between the last flash of microwave light from the Big Bang and the emergence of the first sun like stars and galaxies like our own Milky Way.

"We think we may be detecting traces of the magic moment when the earliest generation of stars switched on," Ellis said in an interview.

Other scientists aren't so sure. While few astronomers failed to be intrigued by the Caltech findings, many reacted with caution.

Paul Schechter, a leading astronomer at the Massachusetts Institute of Technology, wryly noted that science is littered with lurid claims and learned articles that have been refuted after closer scrutiny.

"This sounds cool, a really big deal -- if true," he said. "There's a long history of people claiming high [distances], only to have their claims proved wrong."

Ellis and Stark, however, have faith in their findings.

"We're working at the far frontiers, and there are doubters who will demand further proof that the objects we've found are really so distant," said Ellis.

But few dispute that both distance and time are shrinking as scientists intensify efforts to pierce the great darkness near the dawn of the cosmos.

"There's this huge chunk of time that we really know nothing about," said Jacqueline Hewitt, director of MIT's Kavli Institute for Astrophysics and Space Research. "Something very important was going on, but we can't see it -- yet."

In the beginning was a white-hot blizzard of subatomic particles forged in the cosmos-creating eruption called the Big Bang.

Some 400,000 years later, this nascent universe started to cool, and electrons and protons joined to form huge swirls of hydrogen.

The formation of these first atoms allowed for an immense release of microwave energy -- rays of almost incomprehensible antiquity that still suffuse the galaxies, hissing with radio static.

"Most light we see in the night sky is the glow from the beginning of the universe." Schechter said.

But then the universe went black as a pervasive light-absorbing fog filled space. This was the Dark Age, and all attempts to fathom its secrets have so far failed.

Scientists have almost no grasp of what occurred during that era, except that it seems to have served as a sort of womb for galaxies.

"We know the universe underwent a wrenching transition during this time," said Avi Loeb, a theoretical physicist at the Harvard- Smithsonian Center for Astrophysics and a leading authority on early stars and black holes. "In went this primordial gaseous mist. Out came blazing celestial bodies, including stars creating carbon, oxygen, the stuff that made you and me.

"We're getting closer and closer to 'seeing' into this incredibly distant part of the past," he said.

Indeed, it's possible that the faint galaxies detected by Ellis and Stark are among the earliest entities to emerge from the pregalactic mists. "We don't know if we've seen the first generation of stars, but we're confident we've seen star-forming galaxies at an age earlier than anyone else has seen," Ellis said. "These small galaxies were forming stars at prodigious rates. Something very special and unusual was going on."

Last year, astronomer Masanori Iye of Japan located galaxies that existed 12.9 billion years ago. The Caltech team says it has gone an additional 250 million years further back in time. Because the universe is expanding and because some light must travel extraordinary distances before it can be perceived on earth, scientists, like all night gazers, actually study starlight shed hundreds of millions or billions of years ago.

To locate the six faint galaxies, the Caltech researchers boosted the power of the Keck II telescope by using other, nearer galaxies to magnify and focus the light from the distant formations.

"It all goes back to Einstein, as so many things do," said Steve Maran, spokesman for the American Astronomical Society. "His general theory [of relativity] said that a massive object would bend a light ray. You don't get much more massive than a galaxy."

The gravity of stars and black holes warps the light from more distant galaxies and concentrates it in a way that makes it easier to detect by astronomers peering into space from land-based observatories or space telescopes. The Caltech researchers used the gravitational- lensing effect to achieve a 20-fold magnification of the light from the distant galaxies.

Because galaxies moving away from earth give a different red-shift light signature according to their distance -- the farther out a star, the higher it's red shift -- astronomers can determine which light is coming from which star cluster across billions of light years.

Still, it was tough to find the distant clusters in the first place. "At those distances, it's like scanning space through a hypodermic needle," Ellis said.

New radio and optical telescopes are coming on line. Much of their mission will be to pierce the shroud of the Dark Age.

In western Australia, MIT, Harvard, and other research institutions are building the Mileura Widefield Array, a supersophisticated radio telescope that will consist of hundreds of antennas planted on a remote cattle station. The telescope, which should be in operation by early next year, is intended to look right into the middle of the Dark Age, when the force of gravity probably caused hydrogen clouds to collapse into fierier stuff.

"This will give us an opportunity to witness the formation of the first stars, galaxies, and galaxy clusters," said MIT's Hewitt.

Meanwhile, stargazers are looking to bigger, more powerful telescopes for future discoveries, including the Giant Magellan Telescope, a ground-based structure expected to be completed In Chile in 2016, and the James Webb Space Telescope, scheduled to be launched in 2013. Both telescopes are expected to use the gravitational- lensing effect .

"My prediction is that when we turn on the James Webb, we'll see a sky ablaze with the tiny, distant systems we are just beginning to see now," Ellis said. "We'll be witnessing our own origins and the origin of everything around us."

(Correction: Because of a reporting error, a graphic in yesterday's Health/Science section about looking into the earliest days of the universe contained incorrect time references. California scientists claim to have observed galaxies that came into existence 500 million years after the Big Bang. Last year, Japanese scientists observed galaxies that formed some 750 million years after the Big Bang. Also, the so-called Dark Age of the early universe began about 13.6 billion years ago.)

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