I don’t think there ever could be observable evidence of a changed timeline. Especially nothing stupid like Marty slowly fading out of existence in Back to the Future.
But tbh, I’m not sure going into the past to change something is actually possible in most cases without creating some sort of time paradox. Interacting with the future shouldn’t cause any problems, but the past is probably set in stone. After all, if I went back in time to assassinate hitler, there is no reason for future me to go back in time to kill hitler since he was already killed, causing hitler to never get assassinated. And on and on it loops.
Ignoring space for a moment, it depends whether you see time as a single - linear - dimension, or as a set of n dimensions.
If time can only exist as a single dimension, then yes, we’d have a paradox.
If time is two-(or more)-dimensional, then you’d just step into a parallel timeline/dimension for every change made, forsaking the old timeline Steins’ Gate-style.
Obviously, 2+ dimensional time cannot be proven, so it’s just a fun thought experiment. It’s not entirely unlike the hypothetical 4th dimension of space - which would leave space-time with 4 dimensions of space and one of time.
I don’t think there ever could be observable evidence of a changed timeline. Especially nothing stupid like Marty slowly fading out of existence in Back to the Future.
But tbh, I’m not sure going into the past to change something is actually possible in most cases without creating some sort of time paradox. Interacting with the future shouldn’t cause any problems, but the past is probably set in stone. After all, if I went back in time to assassinate hitler, there is no reason for future me to go back in time to kill hitler since he was already killed, causing hitler to never get assassinated. And on and on it loops.
Ignoring space for a moment, it depends whether you see time as a single - linear - dimension, or as a set of n dimensions.
If time can only exist as a single dimension, then yes, we’d have a paradox.
If time is two-(or more)-dimensional, then you’d just step into a parallel timeline/dimension for every change made, forsaking the old timeline Steins’ Gate-style.
Obviously, 2+ dimensional time cannot be proven, so it’s just a fun thought experiment. It’s not entirely unlike the hypothetical 4th dimension of space - which would leave space-time with 4 dimensions of space and one of time.