> “You have to be very careful in a retrocausal model because the fact of the matter is, we can't send signals back in time,” Adlam explained. “It's important that we can't, because if we could, then we could produce all sorts of vehicles or paradoxes. You have to make sure your model doesn't allow that.”
This rings false to my scifi-trained brain. Paradoxes emerge when information about the future allows you to change it in some way. But if the future is truly immutable, there's no reason why you can't learn what it will be. Any attempts you make to alter it will only result in the exact thing that you already knew would happen.
Maybe I'm misunderstanding the author. Maybe what they MEANT to say is if you didn't already receive an email from your future self 5 years ago, then you can't send one today that your past self will receive at that time. Just as the future is immutable, so is the past. But if we had some sort of quantum email that allowed for such a thing, it WOULD be possible to go check it today and find a message from yourself 5 years in the future.
I'm guessing it's in terms of quantum information. Quantum entanglement and tunneling can happen faster than the speed of light, which causes similar time paradoxes with special relativity. This is avoided by the impossibility of sending observable classical information. Two entangled objects can affect each other, but you can't get actual information about it, because it is destroyed upon observation.
This rings false to my scifi-trained brain. Paradoxes emerge when information about the future allows you to change it in some way. But if the future is truly immutable, there's no reason why you can't learn what it will be. Any attempts you make to alter it will only result in the exact thing that you already knew would happen.
Maybe I'm misunderstanding the author. Maybe what they MEANT to say is if you didn't already receive an email from your future self 5 years ago, then you can't send one today that your past self will receive at that time. Just as the future is immutable, so is the past. But if we had some sort of quantum email that allowed for such a thing, it WOULD be possible to go check it today and find a message from yourself 5 years in the future.