Okay, this one makes my head hurt a little. There’s nothing in the known laws of physics to preclude the idea that the present can influence the past (or the future the present), and now there may be a way to see if it’s possible.
Researchers are on the verge of experiments that will finally hold retrocausality’s feet to the fire by attempting to send a signal to the past. What’s more, they need not invoke black holes, wormholes, extra dimensions or other exotic implements of time travel. It should all be doable with the help of a state-of-the-art optics workbench and the bizarre yet familiar tricks of quantum particles. If retrocausality is confirmed — and that is a huge if — it would overturn our most cherished notions about the nature of cause and effect and how the universe works.