TELESCOPE TECHNOLOGY HELPING SOLVE MYSTERIES.

Byline: Robert S. Boyd Knight-Ridder Tribune News Wire

Thanks to spectacular recent advances in telescope technology, astronomers now believe they can see almost to the outer edge of the universe and nearly to the beginning of time.

They are finding a universe that is expanding, cooling, dimming and, according to some theories, may be only one of a multitude of universes - a ``multiverse.''

Their latest discoveries are enabling scientists to construct a history of the cosmos and to begin answering questions that used to be the province of priests and philosophers - the origin, history and ultimate fate of the world.

For example, the Hubble Space Telescope has taken pictures of four extremely faint galaxies that apparently were in the process of being formed when the universe was less than a billion years old - only one-twentieth of its present age.

``This is the deepest view of the universe by far,'' said Amos Yahil, an astronomer at the State University of New York. ``We may be witnessing the first star formation . . . at epochs reaching back 95 percent of the time to the Big Bang.'' Earlier findings reached back no more than 90 percent of the way.

(The ``Big Bang'' is the cataclysmic explosion of energy that most scientists believe marked the simultaneous creation of space and time some 13 billion to 15 billion years ago. To astronomers, looking ``out'' in space is the same as looking ``back'' in time.)

The sighting of what probably are primeval galaxies was one of many topics debated by 66 of the world's leading cosmologists at a conference at Princeton University late last month.

The cosmologists - the theoreticians of the universe - also swapped their latest opinions on such out-of-this-world questions as the age of the universe, the geography of space, the creation of atoms, stars and galaxies, and the elusive ``dark matter'' that makes up most of the universe's mass.

``It's embarrassing that 90 percent of the universe remains unaccounted for,'' said Sir Martin Rees of the Institute of Astronomy in Cambridge, England.

Sober scientists at the Princeton conference speculated that our universe could be surrounded by an infinite number of other universes, which are multiplying like soap bubbles.

``Our universe may be just one bubble among many,'' Rees said, ``just one element of a grander ensemble.''

Despite its science-fiction flavor, the concept of possible multiple universes flows logically from the theory of cosmic ``inflation.'' This is the belief, now widely accepted among cosmologists, that a fraction of a second after the Big Bang, one tiny patch of newborn space suddenly inflated at enormous speed, creating our particular universe. Other patches, no longer connected with ours, could have done the same.

Alexey Vilenkin, a cosmologist at Tufts University in Boston, explained: ``We used to think of the universe as an expanding ball. Now it seems it may be more like a balloon that produces a new balloon that produces a new balloon and so on ad infinitum.''

Unfortunately, scientists cannot prove or disprove the existence of other universes, because anything beyond the limits of this one is inherently unknowable.

As new data pour in, some mysteries of the universe are being cleared up, but many questions remain unanswered and some fresh puzzles arise. Some highlights from the Princeton conference:

The rate of star formation is slowing down, as most of the gas created in the Big Bang already has condensed into stars. As a result, the universe is gradually getting dimmer as stars burn out and galaxies disappear into black holes, hidden from sight forever.

``Things are running down,'' said James Peebles, a Princeton astronomer.

Cosmologists are not sure yet whether we live in an ``open'' universe that will continue to expand forever, or a ``closed'' universe that will cease expanding and, billions of years from now, collapse. They hope new measurements will settle the fate of the universe within the next decade.

The recent ``crisis'' over the age of the universe is diminishing, the cosmologists agreed. Two years ago, a group of astronomers offered evidence from the Hubble telescope that the universe was 8 billion to 10 billion years old - younger than the oldest stars - an obvious impossibility. Another group, using ground-based telescopes, insisted the universe was twice that old.

Later measurements have narrowed the gap between the two camps. They are converging on an age of 13 billion years - give or take 2 billion - old enough to accommodate the birth of ancient stars.

New observations have shed some light on the location and nature of dark matter, the invisible substance that fills most of the universe, but most of it remains unidentified.

Much, if not all, dark matter is concentrated in ``halos'' trillions of miles in diameter that surround galaxies and clusters of galaxies, cosmologists believe. Visualized on a computer screen, the halos look like a collection of pingpong balls, rather than the beautiful spirals and ellipses of the galaxies hidden within them.

About 20 percent of dark matter is believed to consist of ordinary material - protons, neutrons and electrons - contained in ``white dwarfs,'' the corpses of burned out stars, or ``brown dwarfs,'' balls of gas bigger than Jupiter but too small and cool to burn like a star.

``The best guess is white dwarfs,'' said David Bennett, an astrophysicist at Lawrence Livermore National Laboratories near Oakland, Calif., who has watched their shadows pass in front of distant stars.

The rest of dark matter probably consists of exotic particles with strange sounding names like axions, wimps and neutrinos.

Bernard Sadoulet, an astrophysicist at the University of California at Berkeley, said ``an urgent search'' for these particles is under way. ``This is a very hot topic in particle physics,'' he said.

A common theme of the Princeton conference was how much scientists still have to learn about the universe.

``We know almost nothing about star formation in the very early universe,'' said Joseph Silk, a University of California astronomer.

``We've come a long way in 30 years,'' added Princeton astronomer James Gunn, ``but there are still a very large number of unsolved problems.''