Black holes are the source of
endless fascination and speculation. Do they hold the secrets of the
universe and perhaps even the key to time travel itself?
We may never know the answers to those questions because famed theoretical physicist Stephen Hawking says black holes don’t actually exist. At least not in the way we’ve been taught to think about them.
"The absence of event horizons mean that there are no black holes —
in the sense of regimes from which light can't escape to infinity,"
Hawking writes in a new paper entitled, "Information Preservation and Weather Forecasting for Black Holes."So, what does that mean exactly?
Well, what Hawking is saying is
that he doesn’t believe "event horizons," gravitational traps from which
even light cannot escape, actually exist.
It’s a “mind-bending theory
” as New Scientist puts it, which ensures the debate will continue 40
years after Hawking first brought the concept of black holes to the
public.
In his lecture “Into a Black Hole,” Hawking described how an event horizon works:
“Falling through the event
horizon, is a bit like going over Niagara Falls in a canoe. If you are
above the falls, you can get away if you paddle fast enough, but once
you are over the edge, you are lost.There's no way back. As you get
nearer the falls, the current gets faster. This means it pulls harder on
the front of the canoe, than the back. there's a danger that the canoe
will be pulled apart. It is the same with black holes.”
But now, Hawking says event
horizons don’t exist. However, he does say that “apparent horizons”
could exist, meaning that light technically could escape from the deep
gravitational pull of a black hole. Put simply, an apparent horizon
would only temporarily hold light and information, eventually releasing
them back into space.
Though, “eventually” is a pretty relative term when we’re discussing the nature of spacetime.
“The picture Hawking gives sounds
reasonable,” Don Page, a physicist and expert on black holes at the
University of Alberta in Edmonton, Canada told Nature.
“You could say that it is radical to propose there’s no event horizon.
But these are highly quantum conditions, and there’s ambiguity about
what space-time even is, let alone whether there is a definite region
that can be marked as an event horizon.”
Still, that doesn’t mean astronauts will be lining up to dive into a black hole anytime soon.
As Nature puts it, an apparent hoizon wouldn’t burn you to a crisp like
an Event Horizon would but it wouldn’t leave you in “good shape”
either. Any information or object escaping from a black hole in this
scenario would be “pretty scrambled” in Hawking’s own words.
