A Black Hole Mystery Wrapped in a Firewall Paradox


Dennis Overbye in the New York Times:

A high-octane debate has broken out among the world’s physicists about what would happen if you jumped into a black hole, a fearsome gravitational monster that can swallow matter, energy and even light. You would die, of course, but how? Crushed smaller than a dust mote by monstrous gravity, as astronomers and science fiction writers have been telling us for decades? Or flash-fried by a firewall of energy, as an alarming new calculation seems to indicate?

This dire-sounding debate has spawned a profusion of papers, blog posts and workshops over the last year. At stake is not Einstein’s reputation, which is after all secure, or even the efficacy of our iPhones, but perhaps the basis of his general theory of relativity, the theory of gravity, on which our understanding of the universe is based. Or some other fundamental long-established principle of nature might have to be abandoned, but physicists don’t agree on which one, and they have been flip-flopping and changing positions almost weekly, with no resolution in sight.

“I was a yo-yo on this,” said one of the more prolific authors in the field, Leonard Susskind of Stanford. He paused and added, “I haven’t changed my mind in a few months now.”

Raphael Bousso, a theorist at the University of California, Berkeley, said, “I’ve never been so surprised. I don’t know what to expect.”

You might wonder who cares, especially if encountering a black hole is not on your calendar. But some of the basic tenets of modern science and of Einstein’s theory are at stake in the “firewall paradox,” as it is known.