BERKELEY, Calif. -- On the first day back in his office at the Lawrence Berkeley Laboratory after his own professional "big bang," Dr. George F. Smoot tasted the celebratory cake and submitted to a shower of confetti, all the while casting a twinkling eye this way and that on the fame now engulfing him.
He was living through what his fellow physicists might call a phase transition in the long process of a scientific discovery. He had slogged through all the early steps: the definition of the question and the development of a way to answer it, with a set of instruments to be flown on a satellite.
When the data piled up, he and his colleagues had examined the results minutely, checked for errors and cautiously accepted the import of their findings.
Finally, on April 23, Dr. Smoot electrified the world of physics, and the world, with the news that his team had detected faint density fluctuations in the afterglow of radiation from the birth of the cosmos, the "Big Bang" explosion scientists theorize was the beginning of time and space.
These ripples in space were presumably the seeds that gave rise to the stars and planets and people -- the structure of today's universe.
Nothing in the laws of physics or the two decades he had invested in the research prepared the 47-year-old Dr. Smoot for what has happened since. In this phased transition, the discovery had emerged from the recondite confines of science, converged with philosophy and religion and struck a reverberating chord with its intimations of cosmic origins.
"It is a mystical experience, like a religious experience," Dr. Smoot said, reflecting the unscientific thoughts he had allowed himself in recent days, after the rigorous analysis of data was well behind him. "It really is like finding the driving mechanism for the universe, and isn't that what God is?"
For the moment, though, Dr. Smoot was more bemused than awed by his sudden celebrity.
Although he has the proper credentials -- a doctorate from the Massachusetts Institute of Technology -- his youthful shock of brown hair, trimmed beard, gold-rimmed glasses and neat dress do not fit the image of a creative scientist.
Since the early 1970s, he has been a respected research physicist, but by no means a star, at the Lawrence Berkeley Laboratory and also at the University of California campus down the hill.
But now Dr. Smoot is in demand day and night for radio and television interviews and could not even mow the lawn without being interrupted by a magazine photographer.
His desktop computer's memory was saturated with electronic messages of congratulation, requests for more details of the discovery, perhaps some critical comments.
As he sat in his cluttered office late last week, an assistant brought in a letter from a literary agent wanting him to write a book. A graduate student handed him a sheath of news clippings from all over the world and more interview requests.
Dr. Smoot, given to wisecracks himself, grinned at the attention, though he sometimes interrupted himself to turn conversation back to others on his research team and to the science behind the tumult.
Dr. Smoot had not reckoned with the discovery's philosophical ramifications, the reason for much of the interest among the nonscientific public. In the course of their research, he explained, scientists rarely let themselves think beyond purely scientific interpretations.
"It wasn't until we went public and started telling people, not other scientists, about the research that I began to really feel the excitement of what we had done and something of the bigger meaning," he said.
On the day of the announcement, Dr. Smoot had remarked, "If you're religious, it's like looking at God."
Reminded of this, Dr. Smoot grew uncomfortable. "What matters is the science," he said. "I want to leave the religious implications to theologians and to each person, and let them see how the findings fit into their idea of the universe."
According to the Big Bang theory, the prevailing idea among cosmologists, the universe began as a speck smaller than an atom, but of infinite density and temperature, and then exploded and has been expanding, thinning and cooling ever since. All particles in the universe have been moving away from one another, carried along by the expansion of space itself.
Evidence has mounted since the 1960s that the Big Bang model provides the best explanation for the observed expansion and age of the universe, which is estimated to range from 10 billion to 20 billion years.
The theory also accounts for the observed proportion of ordinary matter in the universe, which is composed of approximately 75 percent hydrogen and 25 percent helium. The heavier elements constitute a mere fraction of existence.
Strong confirmation came in 1964 when Dr. Arno Penzias and Dr. Robert W. Wilson of Bell Telephone Laboratories in Holmdel, N.J., detected strange radio noise in their antenna.
It was coming from all directions in space. This turned out to be the cosmic microwave background, invisible electromagnetic radiation left over from the explosive dawn of the universe.
The uniformity of the radiation in all directions, a condition known as isotropy, was a predicted consequence of the Big Bang. But isotropy posed a troubling problem. Today's universe is lumpy, not smooth, with matter clumped into galaxies and clusters of galaxies.