Phew: Einstein right about black holes after all

Posted by Kate Taylor

Scientists at the University of York say they've dispelled the so-called firewall paradox which suggests that anything falling into a black hole would be burned up as it crossed the event horizon.

The conclusion contradicted Einstein's theory of general relativity - not something anyone would want to do lightly - which suggests that aging black holes must hoard information about everything they swallow.

The solution, say Professor Sam Braunstein and Dr Stefano Pirandola,  may lie in quantum information theory, involving the existence of `spooky' quantum entanglement across a black hole's event horizon.

Quantum mechanics shows that entanglement can exist across the event horizon, between particles inside and outside the black hole.

"But should this entanglement ever vanish, a barrier of energetic particles would be created: an energetic curtain (or firewall) would descend around the horizon of the black hole," says Braunstein.

"We are the first to show the necessity of entanglement across all black hole event horizons and to consider what happens as black holes age. The greater the entanglement, the later the curtain descends. But if the entanglement is maximal, the firewall never occurs."

The finding supports the theory that entanglement  exists for some types of black holes, and comes up with exactly the same maximum value.

"When quantum mechanics, and in particular entanglement, are included in the story, Hawking's prediction holds for the longest time possible," says Braunstein.

"Our results not only back up Einstein's theory of gravity, but also point to quantum information theory as a powerful tool for disentangling the deep mysteries of the universe."