When Stephen Hawking talks, people listen
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“SHOCK FOR SCIENCE BUFFS!” shouted an all-capitals headline in the Malaysia Chronicle. “There are no black holes.” Stephen Hawking’s latest paper, submitted to arXiv on 22 January, has generated interest around the world, with news reports appearing, for example, at the Times of India, News Tonight Africa, The Australian, and Al-Arabiya.
No doubt the news will boost viewership for PBS’s 29 January documentary profile of Hawking (for which Parade has posted a 31-second video teaser clip).
Most physicists foolhardy enough to write a paper claiming that “there are no black holes”—at least not in the sense we usually imagine—would probably be dismissed as cranks. But when the call to redefine these cosmic crunchers comes from Stephen Hawking, it’s worth taking notice. In a paper posted online, the physicist, based at the University of Cambridge, UK, and one of the creators of modern black-hole theory, does away with the notion of an event horizon, the invisible boundary thought to shroud every black hole, beyond which nothing, not even light, can escape.
In its stead, Hawking’s radical proposal is a much more benign “apparent horizon,” which only temporarily holds matter and energy prisoner before eventually releasing them, albeit in a more garbled form.
Often the coverage involves headlines like Nature’s, reporting that Hawking says there are no black holes, but with quick clarification in the subhead or article text echoing Nature’s stipulation “at least not in the sense we usually imagine.”
In the US, the widespread interest has led to coverage, for example, by the business website Forbes.com, by Fox News, and by the Atlanta Journal-Constitution, where an online article includes a three-minute explanatory video clip.
Even the New Yorker’s satirist Andy Borowitz has joined in, using the news to make fun of a politician. “Dr. Stephen Hawking’s recent statement that the black holes he famously described do not actually exist,” Borowitz began, “underscores ‘the danger inherent in listening to scientists,’ Rep. Michele Bachmann (R-Minnesota) said today.”
Last August at the New York Times, Dennis Overbye published a long Science Times piece under the headline “A black hole mystery wrapped in a firewall paradox.” He reported that a “high-octane debate [had] 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.” A summarizing passage said:
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.
Overbye sought to dramatize for the public the proposition that “some of the basic tenets of modern science and of Einstein’s theory are at stake.” Much of the coverage of Hawking’s new paper shows that people appreciate that.
Here’s a copy of Hawking’s abstract, complete with the paper title that Nature calls “whimsical”:
Information Preservation and Weather Forecasting for Black Holes
It has been suggested that the resolution of the information paradox for evaporating black holes is that the holes are surrounded by firewalls, bolts of outgoing radiation that would destroy any infalling observer. Such firewalls would break the CPT invariance of quantum gravity and seem to be ruled out on other grounds. A different resolution of the paradox is proposed, namely that gravitational collapse produces apparent horizons but no event horizons behind which information is lost. This proposal is supported by ADS-CFT and is the only resolution of the paradox compatible with CPT. The collapse to form a black hole will in general be chaotic and the dual CFT on the boundary of ADS will be turbulent. Thus, like weather forecasting on Earth, information will effectively be lost, although there would be no loss of unitarity.
Steven T. Corneliussen, a media analyst for the American Institute of Physics, monitors three national newspapers, the weeklies Nature and Science, and occasionally other publications. He has published op-eds in the Washington Post and other newspapers, has written for NASA's history program, and is a science writer at a particle-accelerator laboratory.