Astronomers at the University of California at Berkeley yesterday reported they have found three new galaxies more than halfway across the universe, the most distant ever detected and dramatic proof the universe began with a "Big Bang" almost 18 billion years ago.

"Evidence from these farthest galaxies strongly supports a theory suggesting that a primordial explosion occurred about 18 billion years ago," the university said yesterday, "and was followed by the formation of stars and galaxies from the expanding gases within about 2 billion years."

University of California astronomer Hyron Spinrad reported in the March 2 issue of the Astrophysical Journal that he and associates had found three new galazies 10 billion light years from Earth, meaning that the light from the galaxies started out 10 billion years ago. If the universe came into being 18 billion years ago as most astronomers believe, these new galaxies are more than halfway to the edge of the universe.

The discovery was made at the university's Lick Observatory using a new electronic scanning device that stores the light of the faintiest star, building up the image night after night until a photograph can be made. The light from the distant galaxies is so faint it "is only about 2 percent as bright as the background glow of the night sky," the report in the Astrophysical Journal said.

To photograph just one of three new galaxies, Spinrad said he had to make 23 visual observations of the galaxy spread over three years. The observations took 40 hours of telescope viewing time.

Spinrad said the three new galaxies were first hinted at from observations of radio telescopes, which heard whispers of their radio noise a number of years ago.The size of the three galaxies is thought to be much larger than our Milky Way, which contains 100 billion stars.

"It would require 1,000 billion stars like our sun," Spinrad said in the article, to create the light each of these three distant galaxies generated early in time.

The discovery strengthens the theory that a "big bang" took place long ago and drove primordial matter outward in every direction. Indirectly, the new galaxies suggest the universe is open and will continue to expand forever, a view that is heatedly debated among astronomers.

The current view of creation is that it happened 17 billion to 18 billion years ago. The expansion of the universe began anywhere from 1 billion to 2 billion years later, when galaxies began to form from the hydrogen and helium that condensed out of the original fireball when it cooled down. The temperature of the original fireball is felt to have been 100,000 million degrees.

Astronomers hope that with the orbiting of the Large Space Telescope later in the decade that they will see almost to the edge of the universe, at least 15 billion light years away. The four tons of optics that will make up the telescope are expected to reveal as much as 1,000 times more information about the heavens than all the telescopes before it produced.