Astronomers report a big contradiction: young universe and old stars

September 29, 1994|By Los Angeles Times

The universe is a far younger and smaller place than anyone suspected, two independent teams of distinguished astronomers announced yesterday. In fact, the universe may be only about half as old as the oldest stars and galaxies it contains.

That fundamental paradox -- sure to keep philosophers, theologians and astronomers awake at night -- is one byproduct of the newest and most accurate estimates of the size and age of the universe.

Taken together, the new findings promise to startle the astronomical world by challenging some long-held assumptions about the properties of the universe, which encompasses all known matter and space, since it evolved from a primeval fireball.

"It gives cosmologists and astronomers the marching orders to go and explain the discrepancy between the oldest stars and the age of the universe," said Stephen Maran, a senior astronomer at National Aeronautics and Space Administration's Goddard Space Center outside Washington and a spokesman for the American Astronomical Society. "There is something very profound going on."

In an often frustrating effort to solve one of nature's most fundamental puzzles, scientists have argued for decades over the age of the cosmos and how fast space itself has expanded since creation.

Astronomers believe the key to any scientific answer is Hubble's constant, which is a measure of the ratio of velocity to distance for remote, receding galaxies. Scientists have been constantly refining their calculation of the constant, based on new data. The right answer holds the key to whether the universe may one day reach the end of its outward rush, reverse, and slowly collapse in on itself in what some astronomers call the Big Crunch.

By radically different routes, the two international teams have arrived at what several experts say are surprisingly similar and unsettling answers.

One group, led by Indiana University astronomer Michael J. Pierce, developed a better yardstick for gauging the size, and hence the age, of the expanding universe by calculating the distance to the Virgo Cluster 50 million light years away with unprecedented precision.

Their calculations led them to believe the universe could be as little as 7 billion years old, compared with previous estimates of as much as 20 billion years old.

The other researchers, led by Harvard University astronomer Robert Kirshner, used five exploding supernovas as surveyor's marks to calculate the cosmic distance scale. That group found the universe to be between 9 billion and 14 billion years old, but still much younger than previously believed.

"Either we are missing something in our understanding of the evolution and the age of the oldest stars or we are missing something in our understanding of how the universe has been evolving since the Big Bang," Dr. Pierce said.

The Indiana study appears in today's issue of Nature, and the Harvard research is published in the current Astrophysical Journal.

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