Source: National Post
Author: Lawrence Krauss
Black holes? Singularities? Unitarity? Some might wonder why the public should care about the esoteric, abstract work of Stephen Hawking. None of it will build a better toaster, after all. But Hawking’s work continues to drive physics at the very forefront — and ultimately may push us toward a theory that describes the very origin of our universe.
Hawking’s interest in black holes — which changed his life, and the future of physics — started in 1970, five years after he was diagnosed with ALS. He was collaborating with another noted mathematical physicist, Roger Penrose, to show that the universe had to begin in an infinitely dense “singularity,” much like the final stages of black hole collapse.
Black holes are objects that are so dense that even light cannot escape them. Hawking’s work helped support the claim that only the mass, charge and spin of a black hole could be discerned from the outside, and that no other information about what previously had fallen inside it could ever be discerned.
However, when Hawking began to apply ideas from quantum mechanics to processes associated with black holes in 1974, he discovered something completely unexpected. Black holes can actually radiate particles. And that radiation causes the black hole to shrink, potentially to the point of disappearance.
“Hawking Radiation,” as it came to be known, was a stunning revelation in and of itself. But it also suggested something of larger consequence: If the black hole eventually radiated away all of its energy and disappeared in a final flash, it would violate one of the central tenets of quantum mechanics, that the information associated with material that had collapsed to form the black hole would disappear as well. This violates a principle at the heart of quantum mechanics, called “Unitarity.”
It is hard to overstate the impact of this realization. The effort to solve the “Black Hole Information Paradox” has helped drive much of the current thinking about fundamental physics — including the development of String Theory, an idea which attempted to unify Einstein’s General Relativity (which, prior to Hawking, was largely decoupled from the rest of physics) with Quantum Mechanics.
Attempting to reconcile Quantum Mechanics with General Relativity may suggest — as both Hawking and I agree — that all the space and time of our universe might have arisen from Nothing as a spontaneous quantum fluctuation, without the need for any supernatural shenanigans. This, in turn, could help us grapple with questions that have been around since the dawn of human perception: How did the Universe begin? How might it end? What is our place in the cosmos?
So, no improved toaster. But addressing these, and other fundamental questions about our existence — like art, music and literature — forms the very essence of what it means to be human. And Hawking’s intellectual bravery, his refusal to give up his quest for knowledge in the face of a debilitating illness, provides a remarkable tribute to the power of human will.
Lawrence M. Krauss, a Canadian theoretical physicist and cosmologist, is Foundation Professor and Director of the Origins Project at Arizona State University. He is also the author of bestselling books including The Physics of Star Trek (with a foreword by Stephen Hawking) and A Universe from Nothing (with afterword by Richard Dawkins).