# Time traveler puzzle

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A time traveler travels exactly 3 seconds to into the past from where he was standing, however when he arrives in the past and waits 3 seconds, he sees himself, but he does not see himself traveling into the future. How is this possible?

He travels into the future 3 seconds later. Wait, didn't read the second part of the problem. Have no clue. I don't believe it is possible. Prove it to me and I still won't believe you.

Edited by Lightmeow
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(It's a paradox, which is why time travel doesn't exist,) but imagining time travel was true, he would see himself because that's where he was standing in the past at those 4-dimensional coordinates. But if that was the past, why doesn't he see the same exact thing happening again?

No, your traveller was not at those 4D coordinates.

She occupies space, that is occupies an interval along each of the 3 spacelike axes.

Why do you suggest that this might be different along the timelike axis?

But there is more. A good deal depends upon what you mean by 'time travel'.

You cannot travel in space without also travelling in time.

In your terms if you are at position A and move to position B this takes time.

So why do you suggest you can travel in time without also travelling in space?

Edited by studiot
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• 2 weeks later...

Questionposter,

I am afraid the only thing that makes sense is that the guy gets stuck in an infinite loop.

The first thing the guy would experience is himself arriving in whatever form that would be from three seconds later, and then in three seconds he would go back and arrive and three seconds later he would go back and arrive...

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Perhaps time travel is not possible, and if it is not, the puzzle is mute. And if it is, we would have to know the effect of time travel on the surroundings of the traveler. The effects on the surroundings as the traveler steps into the past, the effect of the traveler on his surroundings while he is traveling back, and the effect on the surroundings the arrival of traveler would make to what was his past, that is now his present.

For instance, does your unrevealed answer to the riddle hold, and fit together, if measured from a movie camera fixed on the scene, from before, during and after the event(s), and what would we see, if viewing the movie later, happening to the clock on the wall, during the supposed time traveling?

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Time traveling into the past is highly improbable. I would very much like to say it is impossible, but I do not like to use the term liberally. Time traveling in to the future on the other hand is possible, Einstein's theory of relativity justifies this.

Moving on to the topic of discussion, if such a thing as time traveling into the past existed, then I could speculate one answer. If you traveled in the past to see yourself traveling into the past, you will not see yourself traveling into the future but rather the past. I'm not sure if I have missed something in the statement, but it seemed perfectly clear and concise.

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• 2 weeks later...

Because at that time the person is in past. When does his time-travel, a paradox is created and hence, he is not able to see himself at an different instance, because at that moment, he was in past, thus sort of creating a sequence where a similar frame or sequence repeats itself.

And highly knowledgeable and esteemed critics (to this thread), it is an question. When Einstein created his theory of relativity, he himself was doubtful of its existence, and yes, people did question him, but today, he is a superstar. So who knows, when the above may be proved or be possible.

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• 5 weeks later...

cant this be possible that when i go 3 sec back in past then i will reach there where i was present 3 second before (like writing this post !!) and then both me concide . after that what will happen i dont know .

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Why is it a common assumption that if you "travel" to a different place and time, you'll still also be in another place and time? I guess you're figuring that things persist through time in such a way that "time" dictates what exists and where. When and where become properties of time, rather than properties of the object (ie. its worldline).

I don't think this idea has any basis in reality. I think it's only based on a common-sense interpretation of our experience of time.

Consider this alternative puzzle:

A traveler travels exactly three meters north of where he is standing. When he arrives, he sees himself three meters away, but he does not see himself traveling to where he is now. How is this possible?

Is this really any different from the original puzzle, and can it be reasoned through? Both describe a physically impossible jump or movement through spacetime (this one involving faster-than-light travel, and the original involving negative time or some arbitrary control of a time coordinate or whatever), and I don't think that anything meaningful can come from it unless it is reasoned in terms of a real physical process or a theoretical one. (For example if you consider something like wormholes as a way to make it possible, then the description of what is seen should come from what wormhole theory predicts. And still I doubt that anything physically meaningful would come from such reasoning.)

Edited by md65536
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A time traveler travels exactly 3 seconds to into the past from where he was standing, however when he arrives in the past and waits 3 seconds, he sees himself, but he does not see himself traveling into the future. How is this possible?

because he isnt trying to travel in future since he had already seen himself

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Why is it a common assumption that if you "travel" to a different place and time, you'll still also be in another place and time? I guess you're figuring that things persist through time in such a way that "time" dictates what exists and where. When and where become properties of time, rather than properties of the object (ie. its worldline).

I don't think this idea has any basis in reality. I think it's only based on a common-sense interpretation of our experience of time.

Consider this alternative puzzle:

A traveler travels exactly three meters north of where he is standing. When he arrives, he sees himself three meters away, but he does not see himself traveling to where he is now. How is this possible?

Is this really any different from the original puzzle, and can it be reasoned through? Both describe a physically impossible jump or movement through spacetime (this one involving faster-than-light travel, and the original involving negative time or some arbitrary control of a time coordinate or whatever), and I don't think that anything meaningful can come from it unless it is reasoned in terms of a real physical process or a theoretical one. (For example if you consider something like wormholes as a way to make it possible, then the description of what is seen should come from what wormhole theory predicts. And still I doubt that anything physically meaningful would come from such reasoning.)

Yes. Yes yes.

That is also my understanding.

When someone moves, he moves in spacetime.

When someone stays at rest, he still moves in spacetime but only in time.

I repeat:

When someone stays at rest, he "moves" in time.

He change coordinates.

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The 4D spacetime view brings serious and fatal continuity issues.

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• 1 month later...

A time traveler travels exactly 3 seconds to into the past from where he was standing, however when he arrives in the past and waits 3 seconds, he sees himself, but he does not see himself traveling into the future. How is this possible?

I wonder why you selected 3 seconds for the duration of the time-trip into the past? Presumably, because such a short passage of time enables the Time-Traveler to be alive in both temporal situations. And so allows for paradoxical considerations.

However, suppose you'd asked: "A time-traveler travels exactly 3 centuries into the past.... and waits 300 years.... but does not see himself traveling into the future.... how is this possible?"

Then isn't the answer plain - not seeing himself traveling into the future is not just possible, but inevitable. Because after waiting 300 years, he's long-dead. And in no position to threaten paradox.

Or is that too simplistic?

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he would be in an endless loop (a paradox) of traveling in time to look a himself traveling in time!

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• 11 months later...

No language could possibly explain this. I'll try though. It is a classic paradox, where you can "screw up" space and time. Imagine a timeline. He time travels back past 3 seconds, and as time moves on, the man (past) doesn't move. Why? Because another man from another time line would go into this timeline, and the process will keep on happening until there is no more space on earth. Classic time travel paradox.

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No language could possibly explain this. I'll try though. It is a classic paradox, where you can "screw up" space and time. Imagine a timeline. He time travels back past 3 seconds, and as time moves on, the man (past) doesn't move. Why? Because another man from another time line would go into this timeline, and the process will keep on happening until there is no more space on earth. Classic time travel paradox.

As soon as he looks away from his other the paradox will evaporate. Only the observer is retained from any FoR.

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• 3 weeks later...

If I travelled 3 seconds in time then I'd turn up roughly a hundred kilometres away because of the earth's orbital motion.

Well, I think it must depend upon the position (or relative motion) of device, used for time travelling...

If it is not so, then there is not just the orbital motion of the earth, but also our solar system is moving around, in milky way galaxy, at much greater speed, and even our galaxy is moving at much much higher speed (as galaxies are saperating)

So, it must depend upon relative motion, and not orbital motion.

A time traveler travels exactly 3 seconds to into the past from where he was standing, however when he arrives in the past and waits 3 seconds, he sees himself, but he does not see himself traveling into the future. How is this possible?

If the time traveler had taken a gun with himself, and kills his past version, existence of his future version cannot be explained.

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It all depends on :

How did he travel into the past ?

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He doesn't see himself traveling into the future because he see himself traveling into the pass.

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A time traveler travels exactly 3 seconds to into the past from where he was standing, however when he arrives in the past and waits 3 seconds, he sees himself, but he does not see himself traveling into the future. How is this possible?

He traveled to an identical parallel universe that split off from the main timeline the moment the time-traveler arrived.I believe that alternate version should have attempted to travel back in time, unless the time traveler somehow disrupted him within those 3 seconds. U can only do TT like I proposed, else too many paradoxes that can exist.

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• 3 months later...

Because he didn't travel into the future

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