Cosmic dark ages come into view.

• Position: Quasars

The most distant known quasars show that some supermassive black holes formed when the universe was merely six percent of its current age, or about 700,000,000 years after the big bang. How black holes of several billion solar masses formed so rapidly in the very early universe is one mystery raised by astronomers with the Sloan Digital Sky Survey. They have sited 13 of the oldest, most far off quasars yet found.

"We hope to at least double that number in the next three years," states Xiaohui Fan of the University of Arizona's Steward Observatory in Tucson. Fan discovered the distant quasars, which are compact but luminous objects thought to be powered by supermassive black holes. The farthest quasar, in the constellation Ursa Major, is roughly 13,000,000,000 light years away.

These ancient quasars raise tantalizing questions about the infant universe, which was comprised mainly of hydrogen and helium. "But we see a lot of other elements around those early quasars," Fan notes. "We see evidence of carbon, nitrogen, iron, and other elements, and it's not clear how these elements got there. There is as much iron, proportionate to the population of those early systems, as there is in mature galaxies nearby."

Astronomers estimate the...