(7 of 9)
Until someone finds better evidence to the contrary, it's safe to assume that the very tiny galaxies filled with second-generation stars were by far the dominant type in the early cosmos. It would also have been safe to assume that nobody could spot them in their earliest incarnation without giant new telescopes--if not for Ellis. "He does like to push the frontiers," says theorist Norman with mixed amusement and respect. "It's always great fun to go to a meeting and see the latest Ellis most-distant-object sweepstakes entry."
EINSTEIN'S GIANT LENS
Ordinarily, Ellis explains, you could never see small galaxies a mere 500 million years after the Big Bang; they're just too faint for any telescope now in existence. But the universe itself has supplied a way of boosting a telescope's magnifying power. The theory of relativity says massive objects warp the space around them, diverting light rays from their original path. In the 1930s Albert Einstein realized this meant a star, say, could act as a lens, distorting and amplifying the light from something behind it. In practice, he said, it probably happens so rarely that we will never see it.
Einstein was wrong. So-called gravitational lenses have become a major factor in modern astronomy. They have revealed, among other things, the existence of tiny planets around stars thousands of light-years away and have created weird optical effects, including multiple images of faraway quasars. If you look at a massive cluster of galaxies, Ellis figured, you might see amplified images of more distant galaxies, too faint to be seen otherwise. So a year or two ago, he started aiming the Keck at galactic clusters, and along with Stark, he identified six candidate objects. To make certain that these were truly far away, the pair has come back to the Keck for a second, more intensive look. "We want to be absolutely sure we aren't fooling ourselves," says Ellis. "Before we claim we've really found them."
For an hour or so, it looked as though they wouldn't get the chance. They had just this one night at the Keck; the telescope is so overbooked that even an eminent astronomer like Ellis has to wait his turn, and his next observing run isn't until January 2007. But the engineers this night have figured out the problem. When Stark entered his user name in the online telescope log, he made a typo. Every time the focusing routine came upon it, the program froze. The typo has now been corrected. The Keck can focus again, and to their delight, Stark and Ellis are able to confirm that at least three of their faint galaxies do seem to lie hundreds of millions of light-years farther awayand hundreds of millions of years closer to the Big Bangthan anything ever seen before.
"It's regrettable that we couldn't check the other three," Ellis says a few days later, "but we're now very confident and very excited. If we've found this many in such a tiny area of the sky, there could be enough of these small galaxies to supply a substantial fraction of the energy that reionized the universe. I'm very confident that we have an important result."