Time Travel -- The Flash or Avengers:Endgame?

[FireAP]

Summary:: Which form of time travel would be considered more close to reality: The Flash or Avengers:Endgame?

Which form of time travel would be considered more close to reality: The Flash or Avengers:Endgame?

 

[member 656954]

Neither. There is no scientific basis for these comic book universes with regards time travel - or pretty much anything else that goes on.

There have been multiple Flash characters in DC lineage, and none of them accord to any physics we know. The original, Jay Garrick, did not time travel. Three others did: one by by changing the vibrations of his body to traverse dimensions (as far as we know, there are no other dimensions), and two did this by running faster than the speed of light to break the 'time barrier' (Einstein showed that this is not possible in our universe).

MCU characters have generally been suggested to reside in a multiverse and the Infinity Stones (or Gems, the name was changed in the movies for some reason) supposedly anchor one thread of this, but there is no consistency across the different comics with their multiverse concept so it's essentially used as the writers need for their plot at the time. We may be living in a multiverse, but so far no theory makes it anywhere near as exciting as Avengers.

 

[FireAP]

So basically what you're saying is that changing the past would create n number of alternate timelines branching out from the original one where the number of changes ∝ n, rather than just taking effect on the present timeline?

 

[member 656954]

So basically what you're saying is...

Umm, no, I'm not saying that

There are speculative GR space time geometries that allow for directed time travel, including into the past, but none of them appear to be congruent with how our universe is configured. It is not entirely confirmed because reconciling GR with QM may allow for that, but while I'd love for it to be possible, I'd not bet money on it being practical and no less than led Stephen Hawking suggested a chronology protection conjecture that bakes explicit time travel prevention into the laws of the universe.

A multiverse is a different beast entirely, but you have to keep in mind that the concept is fully-fledged speculation. So, yes, it is possible that an event now would trigger branching alternative timelines in the fashion you describe. There is a Many Worlds Interpretation (MWI) of quantum mechanics that is (somewhat) along these lines. PF has some fun discussions about MWI in the QM section, but it's not clear to me that this branching creates any opportunity for time travel. Perhaps, if there is an infinite number of branches and you can figure out a method to travel between the branches, then you could conceivably 'kind of ' travel in time by selecting a branch that matches the past you want to reach, though how you would find that specific past in an infinite number of branches is a vexing question.

 

[some bloke]

I find the idea that an event creating any number of timelines is a very narcissistic outlook on the universe. The decisions of a human are vastly insignificant compare with the number of chemical reactions, nuclear reactions and all number of random events which would, in theory, be creating multiverses. whether you stop someone from crashing their car would create so many less options than whether the carbon-16 (or is it 14) isotopes in their bodies choose that moment to randomly decay. multiply that by the entire universe and you're up to infinite timelines before you even start to think about any meaningful differences.

I prefer the idea that timetravel will either already have happened, or that it simply overwrites the future.

example of number one: The theory that the titanic actually sank through the weight of time travellers who went back to see it.

Example 2, the strange affair of spring-heeled jack, where he jumps back in time to change something, and then can't go back forward to his time because it simply will never happen.

The idea of each action creating infinite alternative timelines which we cannot travel to or interact with would also imply infinite energy within the universes, and "infinite" is not a good thing to be adding to physics.

 

[mfb]

MWI doesn't give rise to any time travel method, and it is questionable how time travel would work in MWI. More questionable than in other interpretations I think.

If you travel back, you want to land in some well-defined state that we consider "our past". How do you pick that one? You don't want to end up in all together, because most will look nothing like our world. In interpretations with a single history this isn't an issue.

You can have a self-consistent universe: The effect of the time travelers is already part of our history.

MCU characters have generally been suggested to reside in a multiverse and the Infinity Stones (or Gems, the name was changed in the movies for some reason) supposedly anchor one thread of this, but there is no consistency across the different comics with their multiverse concept so it's essentially used as the writers need for their plot at the time.

There is inconsistency even within the single movie.

Spoiler

You can't alter the past of the timeline you are in? But Cap, after going back in time, aged in the past of the main timeline we follow.

Oh, and why didn't they recover Black Widow and Ironman from an earlier time? It worked with Gamora.

 

[OCR]

... the titanic actually sank through the weight of time travellers who went back to see it.

Well, I said there were too many. . . nobody would listen, though. . .

.

 

[member 656954]

There is inconsistency even within the single movie.

Adhering to consistent physics, it seems, is too dull for a billion-dollar-revenue action movie, even if it's your own physics you are (not) adhering to!

I find the idea that an event creating any number of timelines is a very narcissistic outlook on the universe.

A man said to the universe:​

“Sir, I exist!”​

“However,” replied the universe,​

“The fact has not created in me​

A sense of obligation.”​

​

― Stephen Crane, War Is Kind and Other Poems​

Your sense of narcissism, @some bloke, reminds me the conversations going on in another thread about physics and philosophy. Whatever our feelings, the universe is what it is, though the energy required to spawn the multiverse is a good thread to unpick because apparently there is no need for extra energy. I find QM brain-bending stuff on the best of days, but MWI is particularly tricky for me to consider.

 

[Whipley Snidelash]

Time traveling to the future is easy, we are all time travelers in that respect. Just don’t expect to skip the intervening time into the future because that won’t happen. Take any classic time travel story to the future. Say it happens right in front of you and the person going to the future disappears. You’re still here where are they in the intervening time?

Time travel into the past is impossible unless you believe an infinity of infinities is possible. In order to travel into the past there Has to be a record existing somewhere of the position and state of every single particle in the whole universe for every single Plank moment of time back to the beginning of time, an infinity of infinities of information. Does that sound reasonable? And that doesn’t even take into account changing the past like you would inevitably do

 

[mfb]

Does that sound reasonable?

No, what you wrote sounds purely made up.

This thread is almost one year old, by the way.

 

[Whipley Snidelash]

I know. I was reading it a year ago and while I was replying I accidentally traveled to the future and now I’m stuck here. Are you accusing me of not being an expert on the physics of time travel? I guess I’ll have to cancel making the time machine I had planned