Retrocausality, Space-Time, and Photon Entanglement

Retrocausality

Cause and effect is pretty easy to understand. I pick up a remote control, press the power button and my TV turns on. Me pressing the power button is the cause, the TV turning on is the effect. We all learned about it in grade school.

But what if that were reversed? What if my TV turned on, and that caused me in the past to press the power button on the remote control? It goes against everything we think we know about the way the universe works, but that is the essence of the theory of retrocausality. The effect creates the cause. It sounds like something straight out of the pages of science fiction, but many scientists today believe that retrocausality could be a real phenomenon.

Space-Time

In 1895 HG Wells published his classic science fiction novel The Time Machine. Although Wells provided little details in the actual functionality of his fictional machine, his main character, known to the reader only as the Time Traveller, provided a basic theoretical concept which made his time travel possible. He posited that time existed as a fourth dimension no different than height, width and depth, the three dimensions we are already familiar with. Just as I can walk forward or backward, move from side to side or climb up and down a ladder in these three dimensions, so can I move forward and backward through the dimension of time.

Albert Einstein, in his famous writings on relativity, somewhat validated this view of time. He referred to Space-Time, where time is included as a fourth dimension and is inseparable from the three dimensions of space. We cannot separate one from the other.

Does that mean Albert Einstein thought time travel was possible? Well, not exactly. However his revolutionizing of the way we view the universe, and perhaps even more the later development of quantum theory and quantum mechanics (much of which Einstein rejected), have made retrocausality seem theoretically possible, at least to some.

Photon Entanglement