Luis W. Alvarez, a Nobel Prize-winning physicist who helped develop the atomic bomb and a controversial theory that asteroids wiped out the dinosaurs, died Wednesday of cancer at 77.

He was awarded the Nobel Prize in physics in 1968 for his development of the liquid-hydrogen bubble chamber and for the numerous elementary particles of matter that his team discovered using the device. But in the last decade, he was catapulted into headlines by the dinosaur-extinction theory.