question about time travel

[Vault101]

I dont know if there are any geniouses out there but yeah here we go

so this is one element of the whole time travel thing that Ive been thinking of

the whole "changing" thing for example using Back to the future

when Marty goes back and changes somthing, eather intentionally or unintentionally its represtented as some kind of clean fading effect, like the photo, or the newspaper or even him at one point

or to put a more clear example, you go back in time find your past self and cut off his or her hand, now your hand isnt suposed to exist anymore (but youre still alive assuming getting your hand cut off didnt kill you ect..)

so does it "fade" away like in BTTF or does it simply instantly dissapear? or does your hand not disapear at all due to some paradox?

this question is probably impossible to answer

 

[Samwise137]

Probably impossible to answer, but it's fun to think about. I, personally, subscribe to the Doctor Who wibbly-wobbly-timey-wimey line of thinking in that certain events are fixed points in time that cannot be altered. That said, I feel that time itself would prevent you from being able to cut your own hand off thus leaving the progression of time unaltered. The universe is often much more powerful than we give it credit for. Now, I'm sure I didn't answer the question but you'll agree, there's much more to it than just simply disappearing or fading out.

 

[Strixvaliano]

Time travel becomes tricky, I've actually spent most of my time in college playing video games with friends and discussing time travel and it can get pretty out there.

My best guess is that it would create a loop between two points in time that would endlessly repeat.

IE:

- go back in time and cut your hand off
- since your hand isn't there you wouldn't go back in time to cut your hand off
- since you didn't go back in time, your hand would still be there
- go back in time and cut your hand off
- repeat Ad infinitum

Which would be a paradox

The next possibility would be circular causation which you could go back in time but you would never succeed in cutting your hand off, just the same as if you tried to go back in time to try and save somebody but they die no matter what you do.

Another possibility would be that you can succeed in cutting your hand off but you had altered another reality and there would be a divergence in the time line (providing that time is linear)

It has been years since I've discussed or went in depth into a lot of time travel talk so I might be missing something or be a bit inaccurate but hell, time travel is all theory anyway so does it really matter?

 

[Aeokirr]

time travel in itself is already impossible, but if we ignore that fact, then i would say that one would not be able to knowingly change the past with actions they commit, as then it would already have happened, and you would not know what the "real" future was supposed to be. Basically what im saying is that if you were to go back in time and cut off your own hand, the moment you did something different it would change the past, your memories, and you. so you would remember an older, one handed you cutting off your hand, and as far as you knew, that would be the actual past. no fading. fading is movie stuff.

 

[Wade-DeadPool]

(providing that time is linear)

That's true, there might be ahuge amount of different realities. One where Hitler was killed/ diden't existe. Another where he did win. Might be one where the bombs never fell over Hiroshima or Nagasaki.

But as Samwise137 also said, there might be a "force" that will come in and make sure that what ever should have happened will happen.

But I did hear from a scientist that travling back in time is much harder then travling in to the future. To travel in to the future you need a machine that can go 99.99999% of the speed of light you would reach the year 3000 in six months.

 

[2xDouble]

It happens exactly like this [http://www.vgcats.com/comics/?strip_id=271]. It's been researched and everything...

 

[Wapox]

I think (and these are my own speculations), that if it were possible to travel back in time, you would be unable to change anything. I think the Terminator movie-series showed it the best. What was sent back in time, to change what happened, was actually the things that made it happen, so nothing was changed, only made to be, as it was supposed, and already had.

A bit roundhousy and incoherent, but I'm tired and pumped on RedBull...

 

[AcacianLeaves]

I like time travel as a thought experiment, so I'll contribute to this discussion with my own views on how such a system would work. It will be a long, drawn out, overly theoretical post so bear with me.

I think your question is part of a larger question - if you could travel to the past and change something, how would it affect the future? This of course assumes that "The Universe" (or God if you prefer) would allow you to change anything. That kind of depends on how you believe the Universe is put together.

If you think that there is only one Universe, one reality, one existence - then obviously there is only one timeline that meddling in the past can change. So, using your example, if you traveled back in time and cut off your own hand your own hand would turn to a stump instantly, you will remember your entire life having lived with your hand as a stump, and you will remember that time when someone who looked exactly like you cut off your hand so many years ago.

That doesn't seem very likely to me. Using the BTTF example, what if you prevented your own birth? There wouldn't be a timer on this kind of thing, as if the natural laws that govern time and space give you 48 hours to fix your mistake. Once its done you would immediately cease to exist and everyone who ever knew you would forget all about you.

To me, if Time Travel is possible then it confirms the hypothesis that there are in fact many alternate Universes - perhaps an infinite number of alternate Universes. Or, perhaps, one alternate Universe per change caused by actual time travelling events. For example if you went back in time and murdered Hitler, when you return you may be in a world where England has taken over the entire world. That is now the Universe that you live in. You didn't change history in the original timeline - that timeline simply continued on with World War 2. What you did is create an alternate timeline, an alternate Universe where Germany was easily trounced by the English who continued on their Empirical journey eventually leading to world domination.

But what if you realize your mistake and go back in time AGAIN to the exact moment that you did before and prevented yourself from killing Hitler? Would you be back in your original timeline? Well, no I don't think so. No, you simply created a 3rd timeline where WW2 still happened as it originally did, but you still changed history and reality. Assuming you didn't kill your other self to prevent him from changing history - there are now two of you. You may have changed other things you didn't notice, or things that may seem small but would still alter reality - a footprint, your body heat, radiation, CO2 levels, etc. When you go back to your time, it would be on this 3rd timeline.

And so on and so forth...

 

[Keava]

Time travel within same strand of multiverse is most likely not possible since considering the butterfly effect your interference could cause you to never time travel in first place which would cause a paradox - If you never travelled back in time you couldn't have changed it.

Of course, we could argue that changes are happening constantly and since our perception is based on memory the memory itself could be altered every moment, so even if some time traveller would somehow stop WW2 you wouldn't be able to register it, you would live remembering that WW2 never happened and it would be obvious to you. Your perception of reality would adjust to those changes.

Now as for 'fading' effects. No, doubt it. It's just a nice plot device that gives protagonist time to react. If it would happen in reality the change would be with t=0, instant, impossible to register by any means.

 

[Gamblerjoe]

I dont know if there are any geniouses out there but yeah here we go

so this is one element of the whole time travel thing that Ive been thinking of

the whole "changing" thing for example using Back to the future

when Marty goes back and changes somthing, eather intentionally or unintentionally its represtented as some kind of clean fading effect, like the photo, or the newspaper or even him at one point

or to put a more clear example, you go back in time find your past self and cut off his or her hand, now your hand isnt suposed to exist anymore (but youre still alive assuming getting your hand cut off didnt kill you ect..)

so does it "fade" away like in BTTF or does it simply instantly dissapear? or does your hand not disapear at all due to some paradox?

this question is probably impossible to answer

The whole fading thing, its called "artistic license." In reality, odds are that whatever events where changed would have snowballed into a drastically different future, mainly for him and his family. In other words, the picture probably wouldn't have ever been taken.

Time travel within same strand of multiverse is most likely not possible since considering the butterfly effect your interference could cause you to never time travel in first place which would cause a paradox - If you never travelled back in time you couldn't have changed it.

Of course, we could argue that changes are happening constantly and since our perception is based on memory the memory itself could be altered every moment, so even if some time traveller would somehow stop WW2 you wouldn't be able to register it, you would live remembering that WW2 never happened and it would be obvious to you. Your perception of reality would adjust to those changes.

Now as for 'fading' effects. No, doubt it. It's just a nice plot device that gives protagonist time to react. If it would happen in reality the change would be with t=0, instant, impossible to register by any means.

this is similar to the "arrow of time" Steven Hawking explains in "A brief History of the Universe." That book is a short easy read, with some really neat concepts. It is designed to be understandable to people with no math or science skills, but is certainly geared toward the likely interests of those who do.

 

[Webb5432]

Depends on the theory.

My theory is that if you were to travel back in time, you would not be effected by anything you did. However, that would be because while you are in the same plane of existence (matter, time moves forward, gravity effects you, etc.) you are treated as nothing special, but just another piece of matter.

But, if you were to jump back into the future, that's when you would be in serious trouble. Your actions as a "second self" could butterfly effect and change the future you want to jump back to. You could be stuck with two of you for the rest of your natural life if your past self decides not to jump back in time.

So, cutting a hand off, in this case, would do rather little seeing as you are treated as seperate pieces of individual matter, with no connection whatsoever. You're perfect clones, not the "same being".

Now, that theory puts into effect an idea that, if time was changed, you would be creating an alternate universe rather than redirecting an existing one. That would probably be the safest option, too.

Now, if you tried to changed the past of the same universe, I'd say cutting off your past self's hand was result in an explosion of at least a megaton.


Just my idea, anyway.

 

[Aeokirr]

time travel in itself is already impossible, *snip*

Says who?

Physics. Relativity supports (the incredibly slim possibility of) time travel FORWARD through travel at the speed of light(which will probably never happen), but to go backwards you would have to go FASTER than the speed of light(which will definitely never happen).

Wormholes won't work unless negative mass not only exists, but can be used by us who only have access to things with positive mass.

 

[Bobbity]

I like Terry Pratchett's trousers of time theory. I won't elaborate, because you'll have pickeed it up if you've read his work, and if you haven't then you really need to

 

[thylasos]

The premise is based on no science whatsoever, so whatever makes sense visually for the fictional scene.

 

[AlkalineGamer]

Well if you did somehow end up back in time (which as far as we know is impossible)
And you did cut you past selves hand off, then i don't think anything would happen to you, i don't think you'd be the same person. he wouldn't be like you, he wouldn't have all your memories all your features etc.
The universe itself would be different, it would have one key difference, your existance.

 

[Jonluw]

It won't disappear at all, since if time travel is possible, it will probably be with the multiple timelines theory, so you can't change the past.

That's just my guess anyways.