Stephen Hawking: Black holes offer a way to another universe
Stephen Hawking has laid out a theory that suggests black holes aren’t quite as black as previously thought.
Rather than destroying everything that goes near them, we might not need to be so afraid of black holes, he said in a paper published this week in Physical Review Letters, written with colleagues Andrew Strominger, a professor of physics at Harvard University, and Malcolm Perry, a professor of theoretical physics at Cambridge University.
If the work is correct – and the new paper means that the theory, only suggested, has now received approval from other experts – then it could solve a central paradox of black holes.
Professor Hawking’s paper addresses a fundamental assumption about black holes – that they have “no hair”. It has previously been assumed that anything that falls into a black hole would be destroyed and lost forever.
That caused problems because the information about the object has to be preserved, even if the object itself is entirely swallowed up – and it has remained unclear how those two things could both happen. The universe is meant to keep a kind of log of what it contains – even if it fell into a black hole and was destroyed – but until now the information in that log was thought to be lost along with the thing itself, swallowed up by the black hole.
But Professor Hawking has since last year been implying that anything that falls into a black hole shouldn’t give up hope of coming back out – somewhere. The paradox is solved because the information is stored on the boundary, or event horizon, of the hole, so it doesn’t come back out of the pit so much as stay away from its most terrifying part.
“Black holes are not the eternal prisons they were once thought,” Professor Hawking said in a speech last year. “If you feel you are trapped in a black hole, don’t give up. There is a way out.”
That way out wouldn’t take people back to where they’d come from, he has said. Instead, they would reappear, but somewhere else – perhaps even in an alternative universe.
“The existence of alternative histories with black holes suggests this might be possible,” Mr Hawking said in a speech last year. “The hole would need to be large and if it was rotating it might have a passage to another universe. But you couldn’t come back to our universe.
“So, although I’m keen on space flight, I’m not going to try that.”
Professor Hawking’s theory helps keep some of the most central parts of our assumptions about the universe intact.
If it is possible to destroy information, for instance, then it’s possible to speculate that the past might not exist at all. Black holes would be able to delete parts of the past – and, as Mr Hawking said: “It’s the past that tells us who we are. Without it we lose our identity."
Until now, scientists weren’t sure how exactly that information could be preserved when it dropped into the dark pit of the black hole. They do that through the “hair” that was previously rejected.
That means that if you were able to look at a black hole in the right way – essentially standing at a distance far ahead in time – you might indeed see those hairs hovering on the edge. The pattern that you would be able to see would be made up of the “soft hairs” that serve as a log of what has been lost inside the black hole.
Those hairs – the workings of which are laid out in the new paper – still don’t fully solve the information paradox about where exactly it could go. But they could provide some of the fundamental parts that are needed to try to help us understand exactly how they work.
Independent News Service