STOCKHOLM (AP) - The Royal Swedish Academy of Sciences says American Saul Perlmutter, U.S.-Australian citizen Brian Schmidt and U.S. scientist Adam Riess share the 2011 Nobel Prize in physics.
The trio were honored Tuesday "for the discovery of the acclerating expansion of the universe through observations of distant supernovae."
The physics prize is the second Nobel Prize to be announced this year.
The medicine prize, announced Monday, went to American Bruce Beutler and French scientist Jules Hoffmann who shared it with Canadian-born Ralph Steinman for their discoveries about the immune system. Their research has opened up new avenues for the treatment and prevention of infectious illnesses and cancer.
Steinman died of pancreatic cancer three days before the announcement. The Nobel committee said it was unaware that then cell biologist had already died when it awarded the prize to him. The committee is only supposed to consider living scientists, but after an emergency meeting Monday, the Nobel Foundation said the decision on the prize to Steinman will remain unchanged.
The prestigious Nobel Prizes were established in the will of Swedish industrialist Alfred Nobel, and have been handed out since 1901.
Last year's physics award went to Russian-born scientists Andre Geim and Konstantin Novoselov for groundbreaking experiments with graphene, the strongest and thinnest material known to mankind.
The prizes are handed out every year on Dec. 10, on the anniversary of Nobel's death in 1896.