Do black holes pose a big problem for the basic laws of our universe? That was the topic up for debate all week in Stockholm, where some of the first people to work on black hole theory did their best to come to some new solutions to a question they posed decades ago.
They were focusing on something called the information paradox. Based on the incredible density of black holes, physicists believe the bodies must swallow anything that comes too close to them -- including the stars that they're initially formed from. But based on the work of Stephen Hawking, they also believe that black holes give off so-called "Hawking Radiation" and degrade over time, slowly disappearing.
The paradox is this: If a black hole swallows up all the things that make a star a star, and then the black hole disappears, does the information about that star disappear too? Information isn't supposed to disappear, and (according to some researchers, Hawking included) such a phenomenon could turn the basic laws of our universe upside-down.
On Saturday, the gathered researchers summarized their conclusions -- or lack thereof.
"It's been quite an exhausting week," Arizona State University physicist Paul Davies told the gathered crowd of students and media.
Davies went through a series of complex theories that had been debated over the week, painting a picture of a field that has a lot more thinking to do before it reaches consensus. But the hope is that this week's discussions will provide new tools for the next generation of physicists.
The conference, which was primarily funded by the Nordic Institute for Theoretical Physics (Nordita), is the brainchild of physicist Laura Mersini-Houghton of the University of North Carolina at Chapel Hill. Mersini-Houghton is a member of the next generation of scientists tackling these questions, and her work on black holes has drawn the "founding fathers" of the field into fierce (albeit good-natured) debate -- mostly via phone.
"On the one hand, we loved spending so much time on the phone talking about physics," Mersini-Houghton told The Post. "But we were getting nowhere in terms of convincing each other."
Mersini-Houghton started to think of the whole field as being a bit stuck. On the one hand, there were the men who had done the first work on black holes in the 1970s. On the other hand, there was a new generation of physicists -- Mersini-Houghton included -- who were doing exciting new work of their own.
But there seemed to be a communication divide. People coming to the field today, she explained, armed with new ideas and with access to new technology, weren't really diving back into the theories presented 40 years back.
"The younger generation, mainly due to this relatively new pressure to keep publishing new things, to keep pushing out new publications, most of what's transferred from the '70s is kind of cut-and-paste," she said. "Whatever was in those papers, it's just cut and paste without question. And there's so much confusion."
If the next generation had more unified, newly debated versions of these concepts to work with, she thought, they'd be more successful in pursuing new ideas.
"I thought, if we had these people, had them all in one room and locked them in for a week, we'd at least understand exactly what was going on, and what they agreed on," she said. "And everybody said yes. It must have been the right time for it."
Sitting in the aforementioned locked room -- a former chapel at the KTH Royal Institute of Technology, its image of Christ now hidden behind a gilded curtain -- it's hard not to feel that the meeting is a fairly historic one. During his conclusion summary, Davies joked that they'd debated the topic so exhaustively that he had no desire to think about it again for another 40 years. But with all due respect to the brilliant physicists who helped form our first theories about black holes, most of them won't be around for another powwow by then.
Hawking, in particular, is clearly fragile. At age 73 and more than half a century after being diagnosed with amyotrophic lateral sclerosis (ALS), the famed physicist was spirited in and out of conference sessions by his entourage, who firmly denied any requests for one-on-one chats with the media.
So it's not surprising that the public and press were rather breathless over Hawking's latest theories, which he presented Tuesday. But in watching the physicists in attendance, it was clear that Hawking's latest thoughts were just adding to a mix of many exciting new ideas. No one present expected to convince their colleagues that they had solved the whole mess -- they just hoped to spark some lively new debates.
As late as Saturday morning, in fact, the researchers were still debating whether or not the information paradox is even a paradox.
But that doesn't mean the gathering was useless.
"It has been a pleasure for me to participate … and to spend a week of intense discussion with old friends and colleagues," Hawking said Saturday. "It is many years since we experienced similar excitement on this topic."
And it's the right time to be reveling in that excitement: In the next few years, researchers will use a giant array of radio telescopes to get our first ever direct observation of a black hole — the one sitting at the center of our galaxy.
It could well be another 40 years before we have a real, working knowledge of how black holes work. But until then, theoretical physicists will just have to keep on arguing — whether or not they're physically stuck in the same place again anytime soon.
Correction: A previous version of this post incorrectly stated Paul Davies' affiliation as University of Arizona, when he is in fact a professor at Arizona State University.