Age of universe is now settled, astronomer says

17 Jun 2002

Astronomers working with new measurements by the Hubble Space Telescope believe that they have finally settled a long-standing controversy over the age of the universe. Dr. Allan Sandbag of the Carnegie Observatories in Pasadena, Calif., and his colleagues calculate that the universe is at least 15 billion years old, and they say that recent challenges to the standard theory of how the universe began and evolved stand refuted.

Other astronomers do not agree that the debate is over, but they acknowledge that Sandage's results, to be reported in a forthcoming issue of The Astrophysical Journal, represent a major development for cosmological theory. The new report, the seventh in a series by the same team, was published by Sandage and colleagues from the University of Basel, Switzerland, and the European Space Agency, who analyzed data from the space telescope and various ground-based observatories.

Sandage's investigation has concluded that observed globular star clusters are on the order of 13 billion years old, while their parent universe is at least 15 billion years old-- a comfortable margin, consistent with the Big Bang theory. The conclusion resolves a discrepancy between physical observations of the universe and theoretical models that estimate its age.

A critic who has frequently challenged Sandage's estimates of the Hubble constant over the years, Dr. Wendy L. Freedman, who is also a Carnegie Observatories astrophysicist, remains skeptical of Sandage's latest estimate. Sandage and his partisans have long maintained that the Hubble constant-- a measure of the rate at which the universe is expanding-- is somewhere between 42 and 56, while Freedman and many other astrophysicists have argued for a value of about 80, which would imply a much younger universe, perhaps as young as eight billion years old.