Galaxy May Be Less Dense, Study Says

Cosmologists studying the big-bang theory of the galaxy’s formation reported Thursday that the universe may be far less dense than believed, a finding that may cause scientists to rethink how the universe was created and how it may end.

If confirmed by further research, the finding “may require us to abandon at least one of the basic tenets of current theories for the formation of structure in the universe,” researchers at Britain’s University of Durham said in the British scientific journal Nature.

It also could cause scientists to rethink the universe’s future. If far less dense than believed, the universe would continue expanding forever. Current theories suggest that the universe is so dense its gravity will someday arrest its expansion, or perhaps cause it to collapse in on itself.

The researchers reached their conclusion after finding evidence that baryonic matter--ordinary atomic protons and neutrons--may make up as much as 20% of galaxy clusters, or vast groupings of billions of stars. Their finding would doom theories that only about 5% of the universe is composed of baryonic matter.