As experimental proposals go, this one certainly doesn’t lack ambition. First, take a black hole. Now make a second black hole that is quantum-entangled with it, which means that anything that happens to one of the black holes will seem to have an effect on the other, regardless of how far apart they are.
The rest sounds a bit easier, but a lot weirder. Feed some information into the first black hole, encoded in a quantum particle. As it falls beyond the event horizon—the point beyond which not even light can escape—the information is rapidly smeared throughout the black hole and scrambled seemingly beyond recall.
But have patience—if you’ve linked the two black holes in the right way, after a short wait the quantum information will pop out of the second one, fully refocused into readable form. To get there, it will have traveled through a shortcut in space-time that links the two objects—a wormhole.
That, at least, is what physicists have predicted. Now a group led by Sepehr Nezami of the California Institute of Technology has suggested how to actually perform this extraordinary experiment—and it is beginning to work with collaborators to put the idea to the test.
If the predictions are borne out, the work may offer clues about where to look for the most elusive theory in physics: one that unites quantum mechanics with the theory of general relativity that describes gravity. And for good measure, it would support the idea that space-time is not the fundamental backdrop against which the universe plays out but is itself woven from the interconnections among particles described by quantum entanglement.