Idea about time travel

[Quantum]

Basically, in an infinite amount of time, there are an infinite amount of
thing that could possibly happen. If someone were to travel in time, then wouldn't there be an infinite amount of time for an event to happen that cancels out what ever the time traveler may have accomplished? What I'm stating here is that manipulation of the dimension of time would be thus impossible, and stopped before it could begin, as any and all events of the sort would result in paradoxes abounding.


This, I believe, is why the world has never seen any sort of time traveler. Any events that would have happened in the individuals perspective would have been resolved before they could have affected the present timeline, as if there is a safeguard against people tampering with the safety and sanity of our reality..


So basically, wibbly wobbly, timey wimey stuff. Also, I apologize if this is confusing to read.. the idea just popped into my head a few weeks ago and I just wrote it all down in five minutes.

 

[Czech Yes or No]

I have also thought about those same things and have come up with much of the same conclusions, such are the observations of us. I often end up getting stuck with things like, "if someone kills them self in another time period, did they ever even exist at all to kill themselves in the first place?"
BTW, love the avatar.

 

[walfin]

No, what you're saying is like the "motion is impossible" paradox.

 

[Sensi Star]

You are assuming that when one time-travels, one travels within one time-line.

On a documentary about theoretical time travel, I remember Michio Kaku saying that if one were to travel backwards in time, that one would enter a new, parallel timeline/universe, and the original timeline would be unaffected. This solves the paradox.

But even still, I think, what happens to the time traveler? Does he just disappear from the original timeline, and appear in the parallel one? Or does he continue to exist on both timelines?

 

[Amagi82]

You are assuming that when one time-travels, one travels within one time-line.

On a documentary about theoretical time travel, I remember Michio Kaku saying that if one were to travel backwards in time, that one would enter a new, parallel timeline/universe, and the original timeline would be unaffected. This solves the paradox.

But even still, I think, what happens to the time traveler? Does he just disappear from the original timeline, and appear in the parallel one? Or does he continue to exist on both timelines?

This is correct (according to our best theories at the moment). As for what happens to the time traveler, he only ends up in one worldline. There may be another nearly identical time traveler from another worldline that ends up in his original one. From a local observer's perspective, he'd simply assume the same guy just came back, which is not necessarily true, but the worlds and people could be so similar that nobody would know the difference. There is also the unlikely possibility that two identical individuals end up in one worldline, or the person vanishes from another.

There are no "safeguards" against time travel- there don't need to be.

 

[physchem]

It seems to me logically that if we were to visit some given point in time, that it would mean that there is an infinite number of points in time coexisting at the same time in order for us to visit them. And besides that, there is an infinite number of possibilities of what we could do in one point in time, thus effecting our future. For example if I type this message at 4:35, there will be a universe for the consequence of that action, or if I don't type it at all, there is again a different universe with different consequences, so cool But probably rubbish

 

[Vrecknidj]

Basically, in an infinite amount of time, there are an infinite amount of thing that could possibly happen.

Two problems: 1) there's no clear demonstration that there is an infinite amount of time, 2) even if there were an infinite amount of time, it doesn't follow that an infinite number of things would happen. (Just because there are an infinite number of positive integers, it doesn't follow that there's an infinite number of even primes. There's just one even prime, no matter how many numbers there are.)

...
This, I believe, is why the world has never seen any sort of time traveler. Any events that would have happened in the individuals perspective would have been resolved before they could have affected the present timeline, as if there is a safeguard against people tampering with the safety and sanity of our reality..

I think there haven't been any time travelers because...
1) No one will develop the ability to control the movement of sufficient mass at the necessary speeds,
2) As everything in the entire universe is in motion, arriving at the right place when traveling through time would be astronomically difficult,
3) Time's dimensions aren't like space's dimensions and there isn't a "forward and back" like there is along each of space's three dimensions,
4) Even if we get outside the four-dimensional space-time continuum and accept the consequences of both general relativity and quantum mechanics, the issues in (3) above don't get resolved, they get made worse.

So basically, wibbly wobbly, timey wimey stuff. Also, I apologize if this is confusing to read.. the idea just popped into my head a few weeks ago and I just wrote it all down in five minutes.

Yep, I do the same thing from time to time. No problem.

Dave

 

[walfin]

If you think about closed timelike curves, I think you'd find that you could only ever be a time traveller if you were meant to be a time traveller. You'd have no future since you're perpetually stuck in the time loop which goes on and on and on. Or the whole universe might be like that.

 

[Cognisant]

When we say "time traveller" we mean this person is leaving their time/space and that's why you can't affect you present by doing something in your past because when you "travel through time" you're traveling through time/space, put simply it's just the traveller that's moving, the universe around them isn't a clock winding back, it continues forward, so by traveling through time you're leaving your time/space continuity of origin.

A different form of time travel whereby you are wound back like a clock going in reverse would mean that you get physically and mentally younger the further back you go, but of course then you wouldn't remember that you've travelled back, and theoretically causality would play out just as it did before, so you wouldn't have the chance to change your past.

 

[Jennywocky]

2) As everything in the entire universe is in motion, arriving at the right place when traveling through time would be astronomically difficult,

That seems to be a biggie that is overlooked.

I mean, if you just "stopped moving in space" altogether for a second in relationship to the planet/solar system/galaxy, you'd be tens/hundreds of thousands of mile off of your original location. Or to travel into the future and land in the exact same spot on the planet, you'd have to travel astronomically a very very far distance to hit your mark, compounded by how far you were traveling.

So traveling in time isn't just time travel, it also involves nearly impossible issues with space travel as well.

 

[Amagi82]

We don't know if it's possible to lock a time-traveling device to a specific geographic location on a moving body. It's a bit presumptuous to claim that is an impossible hurdle (it may be, or it may not be... we do not know).

Another note about why we don't have time travelers: how would we know? If you claim to be a time-traveler, people will think you're nutty. They'll expect you to have sports statistics memorized, or knowledge of exactly what happens when, but how much do you know about the exact events of, say, 1997? Nobody would believe you. If you had a time travel device, you couldn't show anyone, for fear the government would find out and steal the technology from you, leaving you stranded, or worse, in a holding cell for "questioning". There could be thousands of time travelers wandering about today and we'd never know.


A rather interesting incident of someone claiming to be a time traveler (and providing some fairly impressive documentation and evidence if it was a hoax) is here: http://www.johntitor.com/ (website is shitty, but basically, a guy claiming to be a time traveler hung out on a web forum and convinced a lot of people he was from the future)

 

[corn]

Basically, in an infinite amount of time, there are an infinite amount of
thing that could possibly happen.

No. If the infinite amount of time goes by in circumstances governed by some physical laws, the quantity of possible things is not infinite.

If someone were to travel in time, then wouldn't there be an infinite amount of time for an event to happen that cancels out what ever the time traveler may have accomplished? What I'm stating here is that manipulation of the dimension of time would be thus impossible, and stopped before it could begin, as any and all events of the sort would result in paradoxes abounding.

I don't know enough about physics to assert if such a situation is possible or not, but your argument in this quote is not sound as you can see from the first paragraph of this post.

 

[walfin]

When we say "time traveller" we mean this person is leaving their time/space and that's why you can't affect you present by doing something in your past because when you "travel through time" you're traveling through time/space, put simply it's just the traveller that's moving, the universe around them isn't a clock winding back, it continues forward, so by traveling through time you're leaving your time/space continuity of origin.

According to relativity it doesn't matter if you are travelling to the past or if the universe is travelling in the opposite direction (i.e. the future).

I mean, if you just "stopped moving in space" altogether for a second in relationship to the planet/solar system/galaxy, you'd be tens/hundreds of thousands of mile off of your original location. Or to travel into the future and land in the exact same spot on the planet, you'd have to travel astronomically a very very far distance to hit your mark, compounded by how far you were traveling.

But this presupposes that if you travel in time, you'd hit the same location in space (i.e. probably empty space and you'd die from asphyxiation).

Wouldn't that depend on the curvature of spacetime and how the wormhole (the whole universe, for that matter) was shaped?

We always think of time as moving forward forever, what if the universe was torus shaped on the time/some space dimensions (eternal cycles of creation/destruction), or mobius strip like (at the "end of time" everyone gets turned upside down inside out etc and life goes on in reverse)?

 

[MissQuote]

I think a big (incorrect) assumption a lot of people make when pondering time travel and such is the idea that everything going on right now is actually going on right now. That the perception of what one is experiencing as any given point in time is in fact actually true at that point in time, rather than what it is, which is a perception and not the actual fact of the point in time that is actually occurring.

I'm talking infinitesimal points of time (repeating "point in time" now has me thinking of time in terms like light particles), if I watch a leaf fall from my tree in my from yard by the time my optic nerves have fired up over the movement and sent a message to my visual cortex to be interpreted the event has already occurred but I think I am seeing it in live time!

If I look at starlight I am not only looking at an event that occurred millions, or billions perhaps, of years ago and is nothing more than an echo (I know that isn't the perfect word I am looking for, it works well enough for what I mean) just reaching me, add on top the fact that my brain doesn't register the echo of that light until after the time I looked at it (just like with the leaf from the tree). If looking at more than one star then it is more than one event.

I'm just making things more complicated, even, perhaps (and I only read half of the responses up there so far) It seems trying to pin down the math of exactly what "point" in time one is leaving or entering in the first place would be a least a little tricky, seeing as our own brains are deluding us to what point we are already in every moment.

 

[DetachedRetina]

That is a really cool trippy insight but I don't think it poses any problems in terms of if time travel is even conceptually possible. This whole thread has made a lot of points about things to be considered in order to build a successful time machine.

I will continue in this vein. In light of time travel being space travel, how would one travel to the future? You could, theoretically, I suppose know where the earth was at a specific when in the past. But if you wish to travel to earth in the future, how can you be sure it's still in the place you expect it will be? What if a meteor knocked it off its orbit or if it doesn't exist anymore at all?

Could you ever accurately enter spacetime coordinates into a time machine that could travel to the future? You'd be taking a gamble, unless you could forsee the future, at which point traveling to the future doesn't seem very fun.

It would be hard enough to calculate correct coordinates for backwards traveling time machines, working only with the information of what apparent time and location you currently occupy.

 

[walfin]

Not to mention that travelling to the future might affect the past, depending on what time is like.

We always think of causality as being one way; perhaps it is not?

I'm talking infinitesimal points of time (repeating "point in time" now has me thinking of time in terms like light particles)

This has gotten me wondering about the quantisation of time.

Perhaps time is a fractal? Weierstrass function or something?

 

[DetachedRetina]

Not to mention that travelling to the future might affect the past, depending on what time is like.

We always think of causality as being one way; perhaps it is not?



This has gotten me wondering about the quantisation of time.

Perhaps time is a fractal? Weierstrass function or something?

Like if event x happens in the future it becomes destiny and forces the past to alter itself such that it leads to event x in the future?

huh.

Fractal would be way cooler than it being linear.

 

[MissQuote]

Time as a fractal, now there is an interesting concept that makes so much more sense.

If the universe is indeed some sort of spiral expanding and contracting all at once then time as a fractal it is caught in is very explanatory and interesting.