American physicist Saul Perlmutter said the Nobel Prize Committee must have had the wrong number because he did not hear the news from them yesterday that he was a winner of the 2011 prize for physics.

Instead he learned it from a member of the Swedish media.

“It was a quarter to three in the morning our time in California. Actually, I got a call from a reporter first from Sweden. He said ‘Congratulations,’ and I said, ‘Congratulations about what?’”

The winner, a professor of physics at the University of California, Berkeley, said that about 10 more calls from media followed in the first hour after the announcement was made in Stockholm, Sweden.

Meanwhile, his wife dashed to the computer.

“My wife checked online... to make sure it was not a hoax,” Prof. Perlmutter said.

He got a call about an hour later from the Nobel Foundation itself.

“The problem was that the Nobel committee had the wrong phone number,” he said.

Prof. Perlmutter, 52, said they had asked a Swedish collaborator on his project for his contact information and had received a mobile number he had not used in five years.

Prof. Perlmutter shared the Nobel Physics Prize for discovering that the expansion of the Universe is accelerating with Adam Riess of the United States and US-Australian Brian Schmidt.