Stephen Hawking, the British physicist whose body was chained to a wheelchair by the ravages of a degenerative neuromuscular disease, but whose mind soared to the boundaries of the universe and beyond, died Wednesday morning in Cambridge, England, The Associated Press confirmed. He was 76.
His death came from complications of amyotrophic lateral sclerosis, more commonly known as Lou Gehrig's disease, from which he had suffered since he was 20.
Hawking, whose contributions to theoretical physics are frequently compared to those of Albert Einstein, was the Lucasian Professor of Mathematics at Cambridge University, occupying the same seat once held by Sir Isaac Newton. From that venerated position, he changed the way the universe is viewed by physicists and laymen alike -- the former through his seminal theories about the nature of black holes and the origin of the universe, the latter with a best-selling book, "A Brief History of Time," that fulfilled his ambition by appearing on the shelves of airport newsstands throughout the world.
Carrying out complex mathematical calculations in his head because of his physical inability to use pencils -- a feat once compared to Mozart scoring an entire symphony in his head -- and speaking only with a computer-controlled speech synthesizer, Hawking reshaped basic ideas about the universe not once but twice. He first helped to promote the theory that the universe originated in a "big bang" about 15 billion years ago, then reversed field and postulated a universe without beginning or end.
Hawking's field was cosmology, the branch of physics that deals with the origin, structure and evolution of the universe. "My goal is simple," Hawking once told Science magazine. "It is complete understanding of the universe, why it is as it is and why it exists at all."
Hawking made his reputation with his study of "singularities," unimaginable objects predicted by Einstein's theory of general relativity. When a star with several times the mass of our sun exhausts its nuclear fuel, it collapses, its matter crushing together with such force that it forms a singularity, an infinitely dense point with no dimensions and infinitely large gravity.
The region around the singularity is a black hole, whose immense gravity prevents anything, including light, from escaping.
Although a variety of evidence confirmed the existence of black holes, physicists in the 1960s were less sure about singularities, questioning whether a real object could be so small as to be dimensionless and nonetheless be infinitely dense.
As a Cambridge graduate student working with mathematician Roger Penrose of Birkbeck College in London, Hawking was able to prove mathematically that, if Einstein's general relativity is correct, then singularities must exist precisely as described. He subsequently showed, also if general relativity is correct, that the universe must have begun as a singularity, which exploded in the tremendous burst of the big bang.
Later, he also demonstrated that the big bang must have created huge numbers of mini-black holes, each with the mass of a mountain condensed into a space the size of a proton. He reached the then startling conclusion that these mini-black holes would evaporate, shedding particles in spite of their massive gravity.