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Rival Scientists Headed Toward Agreement on Age of the Universe

By Kathy Sawyer
The Washington Post

Rival scientific teams attempting to measure the age of the universe reported Thursday that they are in greater agreement on the contentious issue than ever before, and are headed toward "convergence."

Two years ago, one team created a stir with controversial findings from the Hubble Space Telescope that suggested the universe is only 8 to 10 billion years old and therefore younger than the oldest stars - an impossible contradiction.

Thursday, Wendy Freedman of the Carnegie Observatories, representing the "young universe" camp, reported that those startling findings are holding up, buttressed by distance-scale observations of more than five hundred stars in a dozen galaxies. But the age range has gone up slightly, to 9 to 12 billion years.

At the same time, Abhijit Saha of the Space Telescope Science Institute in Baltimore, a representative of the "old universe" team, said the age range on his side has inched downward, to 11 to 15 billion years.

The age estimates depend on extremely difficult calculations of the rate at which the universe is expanding outward. After decades of debate in which estimates by rival teams ranged from less than 10 billion years old to more than 20 billion years old, astronomers believe they have now narrowed their differences to within a measly two or three billion years.

"There is now a convergence," said Freedman, leader of the Hubble Space Telescope Key Project team, an international group of more than 20 astronomers. She presented her interim results at a meeting at the Space Telescope Science Institute in Baltimore Wednesday. She and Saha, along with other scientists, discussed their narrowing differences at a NASA headquarters briefing Thursday.

There was one notable holdout, however. Allan Sandage, leader of the "old universe" group, disputed not only Freedman's conclusions but the interpretation of his own team's work as presented Thursday. His numbers have not budged, he said in a telephone interview from his office at the Carnegie Observatories in Pasadena. "We are where we've been since 1974. The Hubble wars continue."

Theoretical cosmologist/astrophysicist David Spergel of Princeton, who is not on either team, said each side, using different methods, has moved toward the other by about 10 percent, and the convergence is toward the low end of the age range. Considered with all their theoretical baggage, he said, one side's findings imply an age of nine billion years, the other an age of 12 billion years.

Although the upper end of the age range (15 billion years) could accommodate the oldest stars, many scientists said the findings point with increasing weight to the conclusion that something is wrong with some element of leading cosmological theory.