Time travel within the same universe is not possible
Not exactly true. Technically, paradox free time travel would theoretically be possible.
As long as the time travel follows the Novikov self-consistency principle, there’s no need for parallel universes.
Essentially the type of time travel employed in Harry Potter and the Prisoner of Azkaban. So you wouldn’t be able to change anything, even if you did do things — as if you did something, it had always already been done previously (before you travelled back).
3volver@lemmy.world 7 months ago
It is true, don’t waste my time.
Dasus@lemmy.world 7 months ago
“it’s a fun fiction which is always contradictory in some way” <-- that is not true.
General relativity allows for closed time-like curves and the existence of those means time travel isn’t necessarily impossible, and if that is the case, it has to abide by the Novikov self-consistency principle.
Willfull ignorance wastes only your own time.
3volver@lemmy.world 7 months ago
In that case time travel would be meaningless regardless, impossible to prove, and doesn’t matter.
Dasus@lemmy.world 7 months ago
Dumbledore disagrees. The type of timetravel that happens in HP: Prisoner of Azkaban is self-consistent. Same as with Rick’s timetravel in the snake episode of Rick & Morty (specifically excluding the snake time travel, which is an example of non-consistency, leading to endless paradoxes).
Now ofc having a timeturner and/or a timemachine would be the impossible part there, but again, CTC’s are technically allowed by GR.