New evidence of early cosmic architecture.

Forming a cosmic web, galaxies in relatively nearby parts of the universe arrange themselves as spidery filaments or as giant walls separated by huge voids. That's what telescope surveys began to reveal in the 1980s, when astronomers charted the cosmos a few hundred million light-years from Earth.

A team of astronomers reported last May that they had seen hints of the same large galactic structures in a patch of sky 20 to 30 times more distant (SN: 4/27/96, p. 260). Although researchers cautioned that the pattern of galaxies in this single region of the sky might not be representative of the cosmos as a whole, the observations suggested that the smooth, primordial universe developed lumps-networks of galaxies- earlier than some theorists have asserted.

Now, the same team has examined the distribution of distant galaxies in a different patch of sky and found indications of a similar structural pattern.

Study coauthor Judith G. Cohen of the California Institute of Technology in Pasadena emphasizes that neither sky survey is large enough to do more than suggest the existence of galactic walls and filaments at large distances.

Nonetheless, the new work validates the earlier findings, she says.

"We were worried that [our earlier findings] could be a statistical fluke," she says. "It's nice to know that they have been confirmed."

As in their previous study, Cohen and her collaborators used the 10-meter W.M.

Keck Telescope atop Hawaii's Mauna Kea to measure the redshifts, or recession velocities, of a group of galaxies first identified by the Hubble Space Telescope. Cosmic expansion makes distant galaxies recede faster than nearby ones and shifts the light they emit to correspondingly redder wavelengths.

Thus, redshift indicates a galaxy's distance from Earth.

In the Nov. 1 Astrophysical Journal Letters, Cohen and her colleagues report that slightly more than half of the 140 galaxies in their survey, some of which lie halfway to the edge of the visible universe, aren't distributed evenly. Instead, they cluster together in six main groupings. In a separate study, other astronomers have reported evidence of clustering among 18 galaxies that lie at far greater distances (SN: 9/7/96, p. 149).

The new observations suggest that the universe may have evolved more rapidly than standard cosmological theories would allow, Cohen says.

Theorist Simon D.M. White of the Max Planck Institute for Astrophysics in Garching, Germany, disagrees, noting that observers haven't compiled enough data for a showdown with any theory. He adds, however, that the studies "hint that a confrontation may be coming."