Research Points to Younger Universe, New Value for Astronomical Constant

The universe is significantly younger and smaller than previously believed, unpublished research conducted by a Harvard astronomer and two other scientists indicates.

Those conclusions, among others, stem from several years of investigation into Hubble's constant, one of the most important figures used to determine the properties and dimensions of the universe.

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The results give nine billion years as the approximate age of the universe. Most previously accepted estimates of the universe's age ranged from 15 to 18 billion years. (The Earth and the solar system are about 4.6 billion years old.)

The observations also limit the distance to the edge of the universe to nine billion light years.

John P. Huchra, lecturer in Astornomy and a staff member at the Harvard-Smithsonian Center for Astrophysics (CFA), along with Marc Aaronson of the University of Arizona and Jeremy Mould of the Kitt Peak (Ariz.) National observatory, conducted the research that led to these conclusions. Aaronson attended graduate school at Harvard from 1972 to 1977.

Hubble's Constant, named after the late astronomer Edwin P. Hubble, sets the ratio of the velocity of objects to their distance. Equations for determining the size, age and density of the universe depend critically on plugging in Hubble's Constant.

Huchra and his colleagues conclude that astronomers came up with an incorrect value for Hubble's Constant because they limited their observations to relatively nearby clusters of galaxies--those less than 70 million light years away.

When Huchra, Aaronson and Mould calculated Hubble's Constant for these relatively nearby clusters, they also found a value comparable to old determinations.

But for clusters outside our supercluster--as far as 200 million light years away--Huchra determined a value for Hubble's Constant twice as large as the old one.

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"The simplest explanation of the discrepancy is to postulate a motion of our galaxy in the direction of Virgo," Huchra said Saturday.

Virgo is a cluster of galaxies located near the center of the Milky Way's supercluster.

In other words, our galaxy is speeding toward Virgo at about 200 million kilometers per hour. This previously undetected motion was not taken into account in earlier calculations of Hubble's Constant.

Huchra's conclusion that our galaxy is moving at a rate different from the "Hubble Flow," the average speed of matter in the universe, is corroborated by other research.

Astronomers at Harvard and elsewhere reacted to Huchra's research with approval and cautious acceptance. George B. Field, Paine Professor of Practical Astronomy and director of the CFA, said it represents the "sharpest indication yet" of Hubble's Constant's true value.