On Monday, Dr. Guth’s starship came in. Radio astronomers reported that they had seen the beginning of the Big Bang, and that his hypothesis, known undramatically as inflation, looked right.

Reaching back across 13.8 billion years to the first sliver of cosmic time with telescopes at the South Pole, a team of astronomers led by John M. Kovac of the Harvard-Smithsonian Center for Astrophysics detected ripples in the fabric of space-time — so-called gravitational waves — the signature of a universe being wrenched violently apart when it was roughly a trillionth of a trillionth of a trillionth of a second old. They are the long-sought smoking-gun evidence of inflation, proof, Dr. Kovac and his colleagues say, that Dr. Guth was correct.

Inflation has been the workhorse of cosmology for 35 years, though many, including Dr. Guth, wondered whether it could ever be proved.

If corroborated, Dr. Kovac’s work will stand as a landmark in science comparable to the recent discovery of dark energy pushing the universe apart, or of the Big Bang itself. It would open vast realms of time and space and energy to science and speculation.

THE UNIVERSE is just under 14 billion years old. From our position in the Milky Way galaxy, we can observe a sphere that is now about 92 billion light-years across. But there's a mystery. Wherever we look, the universe has an even temperature.

NOT ENOUGH TIME The universe is not old enough for light to have traveled the vast distance from one side of the universe to the other, and there has not been enough time for scattered patches of hot and cold to mix into an even temperature.

DISTANT COFFEE At a smaller scale, imagine using a telescope to look a mile in one direction. You see a coffee cup, and from the amount of steam, you can estimate its temperature and how much it has cooled.

COFFEE EVERYWHERE Now turn around and look a mile in the other direction. You see a similar coffee cup, at exactly the same temperature. Coincidence? Maybe. But if you see a similar cup in every direction, you might want to look for

STILL NOT ENOUGH TIME There has not been enough time to carry coffee cups from place to place before they get cold. But if all the coffee cups were somehow filled from a single coffee pot, all at the same time, that might explain their even temperature.

INFLATION solves this problem. The theory proposes that, less than a trillionth of a second after the Big Bang, the universe expanded faster than the speed of light. Tiny ripples in the violently expanding energy field eventually grew into the large-scale structures of the universe.

FLUCTUATION Astronomers have now detected evidence of these ancient fluctuations in swirls of polarized light in the cosmic background radiation, which is energy left over from the early universe. These are gravitational waves predicted by Einstein.

EXPANSION Returning to our coffee, imagine a single, central pot expanding faster than light and cooling to an even temperature as it expands. That is something like inflation. And the structure of the universe mirrors the froth and foam of the orig

Dr. Kovac said the chance that the results were a fluke was only one in 10 million.

Dr. Guth, now 67, pronounced himself “bowled over,” saying he had not expected such a definite confirmation in his lifetime.

“With nature, you have to be lucky,” he said. “Apparently we have been lucky.”

The results are the closely guarded distillation of three years’ worth of observations and analysis.

Eschewing email for fear of a leak, Dr. Kovac personally delivered drafts of his work to a select few, meeting with Dr. Guth, who is now a professor at Massachusetts Institute of Technology (as is his son, Larry, who was sleeping that night in 1979), in his office last week.

“It was a very special moment, and one we took very seriously as scientists,” said Dr. Kovac, who chose his words as carefully as he tended his radio telescopes.

Andrei Linde of Stanford, a prolific theorist who first described the most popular variant of inflation, known as chaotic inflation, in 1983, was about to go on vacation in the Caribbean last week when Chao-Lin Kuo, a Stanford colleague and a member of Dr. Kovac’s team, knocked on his door with a bottle of Champagne to tell him the news.

Confused, Dr. Linde called out to his wife, asking if she had ordered anything.

“And then I told him that in the beginning we thought that this was a delivery but we did not think that we ordered anything, but I simply forgot that actually I did order it, 30 years ago,” Dr. Linde wrote in an email.

Calling from Bonaire, the Dutch Caribbean island, Dr. Linde said he was still hyperventilating. “Having news like this is the best way of spoiling a vacation,” he said.

By last weekend, as social media was buzzing with rumors that inflation had been seen and news spread, astrophysicists responded with a mixture of jubilation and caution.

Max Tegmark, a cosmologist at M.I.T., wrote in an email, “I think that if this stays true, it will go down as one of the greatest discoveries in the history of science.”

John E. Carlstrom of the University of Chicago, Dr. Kovac’s mentor and head of a competing project called the South Pole Telescope, pronounced himself deeply impressed. “I think the results are beautiful and very convincing,” he said.