The Present Can Effect The Past. The Future Can Effect The Present.
Photo via flickr by kwerfeldein
Retrocausality is the idea that the present can affect the past, and the future can affect the present. Strange as it sounds, retrocausality is perfectly permissible within the known laws of nature. It has been debated for decades, mostly in the realm of philosophy and quantum physics.
Researchers experiments may initially hold retrocausality’s feet to the fire. But, 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.
If retrocausality does exist, it says something profound about how the universe works. “It has the potential to solve what is one of the biggest problems in modern physics,” says Huw Price, head of Sydney’s Centre for Time. It goes back to quantum entanglement and “nonlocality”—one particle instantaneously affecting another, even from the other side of the galaxy.
If we measure one entangled particle that sends a wave backward through time to the moment at which the pair was created, the signal would not need to move faster than light; it could simply retrace the first particle’s path through space-time, arriving back at the spot where the two particles were emitted. There, the wave can interact with the second particle without violating relativity.
“I’m going with my gut here,” says Avshalom Elitzur, a physicist and philosopher at Bar-Ilan University in Israel, “but I believe that when we finally find the theory we’re all looking for, a theory that unifies quantum mechanics and relativity, it will involve retrocausality.”