THREE HUNDRED and fifty years after the trial of Galileo, at a little symposium in a small auditorium at Catholic University, that same fissure between faith and knowledge that troubled Galileo Galilei opened up briefly.

In the process of clearing away some of the myths surrounding the famous trial, one of the most important political events in the history of science and a singular case of conflict between faith and knowledge, the scholars themselves fell into a dispute about the meaning of believing.

All present stared for a moment into the dark uncertainty.

Owen Gingerich, a small gray-haired astronomer from Harvard, was speaking toward the end of the symposium about Galileo's trouble as a man of faith who had found some evidence that his church and scripture were wrong.

Today in science, Gingerich said in a rather offhand way, there is no "belief" as such, only probability.

A man in the audience, visibly emotional, stood up.

"I cannot credit it. I cannot believe you would say" that scientists do not really "believe" in the objects they study, and that it is possible astronomical science is wrong about what stars are and how they move. "Do you really think it's possible that it's all wrong?" he demanded.

"Yes," said Gingerich. It is possible.

As an example, physicists if pressed will say that atoms, as real objects in the form we imagine them, cannot be proved absolutely. The most you can say, Gingerich explained, "is that the universe acts as if it is made of atoms." With the stars too, the distinguished astronomer said, we know stars only as grains of light exposed on photographic plates. Absolute proof of what they are is absent.

But, intoned a tall, gray-haired Dominican priest, Rev. William Wallace of Catholic University, "Do you take astronomical knowledge as only highly probable? Or do you really believe it as something that is true?"

For the most part, scientists don't think about it, Gingerich said.

But when pressed, scientists now cannot fail to remember that absolute reality collapsed just after the turn of the century, with Einstein, Gingerich said. Time itself was proved to be elastic, a matter of perception. Matter proved to be fluid and quirky. It became apparent that no measurement of any kind is absolute.

"So much of the absolute reality of space and time had to be abandoned," Gingerich said. Since then, one simply cannot speak of certainties, of what is real and what is not.

"I can't believe it," muttered the man in the audience as he sat down.

The symposium, called "Reinterpreting Galileo," was held last week at Catholic University and the Smithsonian to review new evidence uncovered in recent years about the life and trial of Galileo.

The talk at the symposium, from the speaker's platform and in the hallways, was about the new bits of evidence about Galileo and, even more, about the decision of the Catholic Church to reopen Galileo's case.

The facts of the case were fairly simple. In 1616, a commission of theologians declared two propositions to be contrary to the literal word of the Bible--that the sun stands still, and that the Earth moves, both spinning on its axis and revolving around the sun. In 1632, Galileo published a book, "Dialogue on the Two Chief World Systems," in which he taught and defended the two outlawed principles.

Hence the trial, in 1633, and the verdict of guilty. Afterward, Galileo was asked to recant, to state explicitly that he did not hold that the Earth moves and the sun stands still. Galileo complied.

But at the symposium -- from the evidence of Catholic U.'s Wallace, Harvard's Gingerich and Polish scholar Joseph Zycinski--a number of misconceptions about Galileo and the trial were buried.

The scholars said that, contrary to popular belief:

Galileo was neither charged with, nor convicted of heresy. Galileo was not tortured, nor was he shown the instruments of torture.

The issue at the trial was not strictly one of religious ignorance versus scientific truth; the scientific evidence itself at the time was quite unclear and equivocal.

And, after Galileo agreed to say he did not believe in a moving Earth and a steadfast sun, he probably did not, as legend now has it, utter the defiant words, "it still moves."

One of those at the symposium who has a direct link to the Vatican's reopening of Galileo's trial is Wallace, who said that in reopening the case, the church is not seeking a new verdict of "not guilty."

In fact, said Gingerich with a smile, it would be difficult for the church to find Galileo not guilty. He was only charged with disobeying a church order, and clearly, did disobey.

The real reason for reopening the case, Wallace said, is to give the church a forum to show that science and religion are really not in conflict. They apply to two different worlds, the world of faith and the world of what man can know by sense and reason.

Wallace said that reopening the case will thus help "to counteract the wave of religious fundamentalist fanatacism that seems to be sweeping the world, from our own United States to the Middle East." He said that fundamentalism and creationism try to show science and religion in conflict, and the church needs to counteract these impressions.

The legend of the conflict between religious belief and scientific knowledge was in great part formed by the legend of Galileo and his trial. But as one speaker after another came to the podium at last week's meeting, it became clear that the feeling is now a consensus--Galileo's scientific evidence was simply wrong.

According to Wallace, early in life Galileo thought his great proof would be in the tides, if only he could show a direct connection between the Earth's spinning and revolutions around the sun and rise and fall of the seas.

But of course Galileo was wrong. The tides are not caused by the Earth's movement, but by lunar gravity.

Worse, there was simply no evidence to show Galileo's and Copernicus' sun-centered model any better than the popular Earth-centered model of the day that was set out by Tycho Brahe. And Brahe's system had the advantage of not challenging scripture or church doctrine.

So, by the lights of the time, the scholars said at the symposium, there was some justification for the trial, for finding that Galileo disobeyed the church orders and for believing that Galileo hadn't the necessary proof to demonstrate a sun-centered cosmos.

But on the final dramatic moment of Galileo's trial, his confession, the scholars disagreed.

Using new documents on Galileo's science, Wallace said that Galileo believed through much of his life that he would eventually get strong proof for the sun-centered cosmos. But by the time of the trial, when Galileo was in his fifties, he realized he had no "necessary demonstration" to prove his view.

And so, Wallace said, his confession was genuine, and not forced by the pressure of the inquisition. Galileo knew he hadn't the proof necessary to overturn current belief, Wallace said, "and he was honest enough, as a believer, to acquiesce to the church's interpretation of the scriptures when he lacked" the proof.

Wallace said this way of thinking may be alien to modern minds, but made sense in the 17th century, when an old doctrine of Thomas Aquinas still held up--that a man cannot hold a truth by faith and by reason at the same time. If he believes by faith, it is because reason has failed to show him the way. If he believes by reason, he has no need for faith.

Since Galileo could not prove by reason that the cosmos was sun-centered, then as a true son of the church he would let the question remain open to be decided by faith.

But Gingerich openly disagreed with the notion. "I don't believe things are so simple as Father Wallace said."

The motives were more complex, Gingerich said. Galileo had been for some time in a battle of wits with the church over what he might say and not say. Then, when the final summons to trial came, Galileo was simply stunned. He had tried all along to comprise and now had no choice but to confess, no matter what he believed.

Gingerich said he is unwilling to accept that Galileo confessed willingly. But, he told Wallace from the podium, their disagreement may never be resolved. It is a question about what was in the mind and mood of Galileo at one moment 350 years ago.