Australian Nobel laureate, Brian Schmidt first thought when he received the call that would change his professional career was that it was nothing but an elaborate joke.

"My first thought was 'Geez my students have done a pretty good job on this accent'," the Australian-American astronomer told AFP, Wednesday.

"She asked me to confirm that I was Brian Schmidt and told me I had a very important call, and then the members of the panel went out and read the citation to me and congratulated me."

"I feel like when my first child was born. I'm kind of weak in the knees and a little, you know, I guess a little -- hard to describe -- almost speechless at this point."

Professor Schmidt was named joint winner of the Nobel Physics Prize for his work in discovering that dark energy was steadily expanding the universe. He is Australia's 12th Nobel laureate and the first to receive the physics prize since 1915. Schmidt shares the prize with American researchers Adam Riess, of Johns Hopkins University and Saul Perlmutter of the University of California. The three men will split the 10 million Swedish kroner prize money.

Prime Minister Julia Gillard joined in congratulating the new Nobel laureate and said the Nobel prize was a testament to Schmidt's "rigor and determination".

"This discovery turned some of our most stable notions of the universe on its head and challenges our understanding of its very composition," said Gillard.

"They stuck with their observations and made the theory fit the facts, however revolutionary and inconvenient."

Professor Schmidt formed an international research team in 1994 to study the universe's rate of expansion by observing distant exploding stars. The team discovered that the universe was actually speeding apart and that the cosmos will end with the stars too far apart. The discovery was named the scientific breakthrough of the year in 1998 by the journal Science.

Born in the US, Professor Schmidt has joint American and Australian citizenship. After completing his PhD at Harvard University, he joined the staff of the Australian National University in 1995, and was made a Federation Fellow in 2005.

He has won many accolades, including the inaugural federal government Malcolm McIntosh award for achievement in the physical sciences in 2000 and the Australian Academy of Science's Pawsey Medal in 2001.

Professor Schmidt says he plans to use his share of the prize money towards "some sort of public good" after consulting his 20-person team.

"I like my life as it is, so I'm hoping that it doesn't change too much," he said.