Quasars, distant and mysterious objects that have intrigued astronomers for 30 years, can be used to calculate the age of the earliest galaxies and, thus, of the universe, according to European astronomers. They report in Nature that they have finally solved the puzzle of whether the most distant quasars really are the most distant--or whether there are some more hiding behind dust. There aren't.
"This means we can pinpoint the beginning phase of the universe as we know it," said cosmologist Jasper Wall of Cambridge University. Wall and his colleagues studied radio signals from quasars to determine that no more quasars are hidden behind cosmic dust.