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It’s another shot in the black hole wars. The edge of a black hole might be a brick wall, says Nobel laureate Gerard ’t Hooft, against which information about in-falling stuff bounces back like a tennis ball.

’t Hooft was responding to Stephen Hawking’s 25 August announcement of a new solution to the information paradox – a problem that has plagued scientists for 40 years.

The paradox is this: if any object, be it an iPhone or an elephant, ventures into a black hole, it stays there. From the outside, we will never be able to learn about any of its characteristics, information about it disappears behind the black curtain.

But in 1974, Hawking discovered that quantum weirdness at their edges causes black holes to leak radiation in the form of photons. This radiation, dubbed Hawking radiation, makes black holes slowly lose mass and evaporate.

Eventually, they pop completely out of existence, snuffing out all the details that lived inside. But quantum mechanics says information can neither be created nor destroyed, so the information has to go somewhere. Where?

“The answer is that matter going into the hole has an effect on outgoing Hawking particles,” says ’t Hooft. “Hawking did not believe that at first, but gradually he is revising that opinion.”

Hawking’s new claim is that if, say, an elephant passes over the edge of a black hole, the information about its elephant-ness stays on the edge as a holographic imprint. When the Hawking radiation seeps out, it carries that imprint with it. But questions remained: how does the in-falling matter make a mark? And how does that mark tattoo itself onto the outgoing radiation?

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