If Price is right (ha!), it could be the solution to something that has puzzled physicists all the way back to Albert Einstein: quantum entanglement, which Einstein ridiculed as “spooky action at a distance.” The idea is that you can link the states of two particles so that even when they’re separated over an infinite distance, the state of one affects the state of the other. The problem with this is that it seems to require information to be sent faster than the speed of light, which is impossible. That’s what’s so “spooky” about it.
In 2017, Matthew Leifer and Matthew Pusey applied Price’s idea to the puzzle of quantum entanglement. If the current state of a particle can affect its state in the past, then maybe quantum entanglement isn’t action at a distance but action back in time. That is, if time can run backwards, a particle can take the action of its measurement — the event that makes it “choose” a state — back in time to when it was linked with its partner. Trading faster-than-light travel for time travel doesn’t sound like much of an improvement, but when it comes to the rules of quantum physics, it solves a lot of problems.
Of course, there are huge caveats. First, this doesn’t mean that a physicist could send a message to her younger self, or that you could go back in time to kill Hitler. We still live in the macroscopic world of classical physics, where entropy is still a thing. Second, this is a very fringe idea in the physics world. “There is not, to my knowledge, a generally agreed upon interpretation of quantum theory that recovers the whole theory and exploits this idea,” Leifer told Phys.org. “It is more of an idea for an interpretation at the moment, so I think that other physicists are rightly skeptical, and the onus is on us to flesh out the idea.”