In a paper posted on the arXiv pre-print server on Wednesday, physicist Stephen Hawking dashed the dreams of science fiction aficionados by declaring that black holes don’t exist.
Stephen Hawking claims that two of the properties most often identified with black holes — the singularity and the event horizon — don’t exist, at least not in the way that was previously thought. Therefore, black holes themselves can’t exist. At the moment, he hasn’t offered up a new name for the objects that look and act like the objects previously referred to as “black holes.”
In “Information preservation and weather forecasting for black holes,” Hawking argues that there is no event horizon, nor is there a singularity siphoning in all matter, light and information and destroying it. He claims that information about this material — which is communicated through “Hawking radiation” — would not be destroyed, merely reconfigured to such an extent that it would be impossible to reconstruct what the objects that fell into the hole originally were.
Physicist Don Page told Nature that it “would be worse than trying to reconstruct a book that you burned from its ashes,” which is why Hawking compared it to weather forecasting, which is possible in theory, but rarely accurate in practice.
The consequences of Hawking’s theory would be that information, however scrambled, could escape a black hole — and given that, according to Hawking, “there is no escape from a black hole in classical [quantum] theory,” that means that black holes as we know them cannot exist.
Hawking’s paper is an attempt to respond to what has been called “the firewall paradox,” an attempt to reconcile the relativistic physics of Einstein with quantum mechanics.
According to the theory of relativity, an astronaut passing through the event horizon of a black hole should observe the laws of physics behaving as they do in the rest of the universe, slowly feeling her feet being pulled more strongly than her head as she begins to undergo what physicists call “spaghettification.”
But a team led by theoretical physicist Joseph Polchinski demonstrated that according to the laws of quantum mechanics, an astronaut unlucky to dive into a black hole would slam into a highly energetic region of space they dubbed a “firewall,” which would instantly cause her to explode from the subatomic level up.
Hawking’s solution is that the laws of both general relativity and quantum mechanics still abide, but that the conception of the “event horizon” is mistaken: it simply doesn’t exist in a manner that would cause the astronaut to combust: “[t]he absence of event horizons means that there are no black holes — in the sense of regimes from which light can’t escape to infinity,” he writes.
In its place, he posits there is an “apparent horizon,” an area in which space-time fluctuates too wildly for a sharp boundary to exist, alleviating the need for either an event horizon or a firewall.
If this is true, however, it means that there is also no singularity at the core of the black hole. Gravity would pull matter and light into the black hole — and the more material it collected, the stronger that pull would be — but it would never truly be destroyed.
It would merely be incomprehensible, leaking out of the black hole via Hawking radiation, but as inadequate a means of understanding larger cosmic processes as a shifting breeze in upstate New York would be to predicting the 2056 hurricane season.
[Image via AFP]