A Closer Look at the Big Bang

By John Langone

For astronomers, remote galaxies are cosmic Rosetta stones. Because their faint glimmers of light take billions of years to reach earth, these galaxies -- conglomerations of stars, dust, gas and, perhaps, planets -- offer a unique glimpse far back into time and provide clues to the age of the universe. As Physicist Stephen Hawking has observed: "When we look at the universe, we are seeing it as it was in the past." In those galactic outer reaches, too, lies hidden the answer to a tantalizing mystery: How soon after the cataclysmic fireball of the big bang, from which the universe presumably emerged, did the galaxies form?

A team of scientists attending last week's meeting of the International Astronomical Union in Baltimore may have unearthed an important clue to answering that question with the announcement that it has discovered the most distant galaxy yet seen by man. Designated 4C41.17, the galaxy is located some 15 billion light-years away (a single light-year is equal to approximately 6 trillion miles) -- about 90% of the distance from the earth to the visible limits of the universe.

But the discovery is not simply a mileage record. The galaxy is being seen only a few billion years after the big-bang explosion, which suggests that at least some galaxies were being formed while the universe was still in its infancy. This could very well challenge the cold dark matter theory of galaxy formation, which holds that galaxies required billions of years to grow around very dense clumps of invisible particles. Yet 4C41.17, which appears to be mature, is probably no older than 1 billion to 2 billion years. Says Team Member Wil van Breugel of the University of California, Berkeley: "If you are the universe and are ten years old, this galaxy is one year old."

The new galaxy was first located by its radio waves, then confirmed visually at the Kitt Peak National Observatory near Tucson, appearing as a faint, fuzzy object. A computer-enhanced photograph shows the galaxy as a brightly colored, amoeba-shaped mass. Next, the scientists determined the distance of the galaxy by taking an optical spectrum that revealed what one team member, Kenneth Chambers of Johns Hopkins University, calls cosmic fingerprints -- emission lines with sharp features characteristic of hydrogen and carbon. In distant galaxies, these lines occur at much redder wavelengths than those emitted by the same elements on earth; this so-called red shift, believed to be caused by the expansion of the universe, is what astronomers use to measure distance.

The scientists who found galaxy 4C41.17 -- the other discoverer is George Miley of Leiden University in the Netherlands -- say they are confident of its existence and distance. But they are, nonetheless, circumspect about the implications of their findings. "If every galaxy in our universe was formed at this time," says Chambers, "there are some serious problems with current theory." But, he adds judiciously, 4C41.17 has some peculiarities that cannot be ignored: it is more lumpy, elongated and turbulent than most other galaxies. Chambers speculates that "it may also be atypical in its time of formation, which would make current theory hold."

With reporting by Dennis Wyss/San Francisco