Ask Lemmy

Either 1 or 3. I tend to lean towards 3

Time travel to the future is possible if you travel fast enough. For example, traveling to the nearest galaxy at near-light speed wouldn’t take long for you, though it would take significantly longer for those observing you from Earth.

As for traveling to the past, I imagine it might involve the many-worlds interpretation of quantum physics, where every possible event that can happen does happen in a separate timeline. In this view, you wouldn’t be “changing” the past but rather experiencing an alternate version of it.

I don’t believe in free will, so I’m not concerned about the idea of altering the future by changing the past. If you traveled back in time and killed Hitler, it wouldn’t affect this timeline’s future; instead, you’d simply enter a timeline where that event occurred. The future of your original timeline would remain unchanged.

I'm definitely subscribing to the 3rd one, even if the 2nd one makes more sense to me...

Whichever is closest to science and physics.

It'd be a horrifying thought if the time travel theory you believed in was different to what you got, UGH just the thought gives me existential dread.

This also reminds me of:

I think technically idea 2 and 3 have the same end result. I can't see 3 working without 2 already being true.

• something else

3 dimensions of space + 2 dimensions of time

Probably "read only"/neighboring dimensions. Can't change the timeline you came from. If you could there's just no way there wouldn't be evidence of people doing it.

But otherwise I guess "all changes due to time travel have already happened" as incompatible with free will as it is.

One timeline, actions can have an effect. But once you time travel you unmoor yourself from normal causality, so you could do things that should negate your existence and nothing will happen to you.

Indeed, if you time travel again you can't affect your own actions anymore. Like, you travel back 20 minutes, do things for an hour, then jump back 5 minutes, when you go back the second time you can't alter yourself. You could go later the you from before you ever time traveled though.

Each has Pros and Cons.

I liked what the show Dark did with the first idea. Having a constant move of time, and a fixed "jump distance"is really cool. Each new timelone also has those points, but some just happen to be created or destroyed in your lifetime.

The second seems kinda boring in real life (except for visiting the past) and can get really tricky fast if it would be usable in real life, but in movies it mostly rocks.

Having actions matter is very cool, but sounds dangerous and paradox-y. If not done like in Looper its still fun though (for real, don't watch that movie) and maybe it even has a fixed flow of time (like the tomorrow war).

What I would want the most and what prevents a lot of paradoxes though is the trope of "getting sent back into your younger body" like in butterfly effect (which got real stupid in the second half with the Jesus hands). But I would still really like that and in the best case with the possibility of going back in time after my death.

Wormholes. Travel some place faster than light and see light from the past from your source of travel when you arrive, travel again back to your original spot and theoretically you travel backwards in time to before the light from the past that you just saw was even produced yet. Might work the same for just seeing the future if you glimpse through a wormhole that leads to someplace in the future by doing an Allie oop to further into the future someplace far away, then back to someplace in your future but your destinations past. Speed and gravity both impact time. A wormhole fits that description to a T.

Whatever it is, I don't believe paradoxes are possible (other than language ones that basically just confuse any attempts to resolve a statement or set of statements to true or false without breaking any physical laws or causality).

That said, I don't think an unstable time loop would necessarily be impossible. Eg, you go back in time and kill your grandfather before your father is conceived, which results in you never existing in the timeline, which then means no one is there to go back in time and kill your grandfather, which means the loop disappears and the timeline snaps back to the version where you do go back, and it continually alternates from there.

Not sure if any future outside of the unstable loop would exist, I think that would depend on if there's a higher dimension of time that these loops could play out over.

Or, if everything experiences the same present at the same time, it's also possible that after the first loop, it wouldn't go back to resolve the whole "killer pops out of literally nowhere" because it was in the past and no time traveler is bringing the timeline back to there, so it's all in the past. Though I think in that case, you wouldn't disappear after killing your grandfather. You'd just be an enigma that would require going outside of time to understand the origin of.

Tbh though I'm 99% sure time travel just isn't possible (paradoxes or not), just a fun thing to think about. And no, I don't consider quantum effects being symmetrical in time to be time travel, they are just cases where you can reverse cause and effect and still have a valid cause and effect sequence.

1

Time travel will never have any effect on anything.