Light At The End of the Cosmos

By Michael D. Lemonick/Austin

When University of Arizona Astronomer Richard Elston first aimed a newly assembled infrared-light detector at the heavens last spring, he was hoping to find objects so faint that they had never been seen by human eyes. Almost at once, his specially equipped telescope picked up something astronomers have been seeking for years. Last week Elston and two colleagues announced at an American Astronomical Society conference in Austin that they had found what appeared to be primeval galaxies some 17 billion light-years from earth -- so far away in both space and time that they seemed to be poised at the edge of the universe.

If the discovery is confirmed, it will be one of the most important in the history of astronomy. These galaxies will provide a missing evolutionary step between the big bang, when the universe began, and the mature cosmos that is observable today. Though there is no final proof yet, many astronomers find Elston's circumstantial evidence convincing. Says Patrick McCarthy, an astronomer at the University of California, Berkeley: "This is a very good bet. If they can prove it, it will wipe out a number of theories on the formation of large-scale structure in the universe." Declared Hyron Spinrad, another Berkeley astronomer, more simply: "If true, it's spectacular."

The find would have been impossible without a new generation of infrared detector chips developed by Rockwell International for the military. "Other astronomers have similar setups," says Elston, "but we got ours going first. The rest are undoubtedly going out to find these objects now."

Primeval galaxies resembling the objects Elston found have been postulated by astronomers since the late 1960s. Most scientists regard the fact that he stumbled over the reddish sources of light within a randomly chosen tiny section of sky as evidence that the galaxies actually exist. Reason: similar bodies "should be all over the place," as Elston puts it, in our galaxy- filled universe. Moreover, Elston and his team took a second look at the suspected galaxies without the aid of the infrared device and found them about 20 times fainter in ordinary, visible light. The difference in brightness and the location of that difference on the electromagnetic spectrum make sense to astronomers: a newly formed galaxy would give off just such a light signature as it rushed away from earth in the general expansion of the universe.

If the distant objects are really galaxies, their number and distribution across the sky should help solve fundamental astronomical mysteries. How, for example, did the big bang, by all estimates a very smooth, if violent, explosion, evolve into the universe of galaxies and clusters of galaxies that exists today? Were stars created before galaxies or vice versa? And perhaps most intriguing, are these galaxies poised at the edge of the observable universe? Astronomers believe most galaxies formed at the same time, shortly after the big bang. If these galaxies come from that epoch, their light began its journey to earth 17 billion years ago, and they are likely to be the most distant objects in the cosmos. There is a chance, of course, that the objects are something other than what Elston suspects, and astronomers are racking their brains for a convincing alternative explanation. So far, they are stumped.