# Time travel into the past, why does there have to be an original timeline? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [February 24, 2012, 8:56am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821 "2012-02-24T08:56:06Z")\ **Posts on this page:** 17\ **Page:** 2
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [February 26, 2012, 1:53am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/21 "2012-02-26T01:53:24Z")
As for something like the grandfather paradox I still stick to my theory that you’d enter a time loop. You’re born; You get older; You build a time machine; You go back and kill your grandfather. You’re not born; You don’t build a time machine; You don’t go back and kill your grandfather. So, your grandfather doesn’t die. You’re born; You get older; You build a time machine… As for introducing an object into your past and then wondering where it came from or if you’ve created a paradox, I made this silly drawing for another time-travel thread a few months ago to show how there is no mystery or paradox. And yeah, I’m a nerd. [Drawing](http://imageshack.us/photo/my-images/831/timetravel.png/) ---
**Author:** ![cmyk](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmyk/32/3353_2.png) [@cmyk](https://boards.straightdope.com/u/cmyk)\ **Post date:** [February 26, 2012, 2:19am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/22 "2012-02-26T02:19:09Z")
> [@Nobody](#): > > As for something like the grandfather paradox I still stick to my theory that you’d enter a time loop. > > You’re born; You get older; You build a time machine; You go back and kill your grandfather. > You’re not born; You don’t build a time machine; You don’t go back and kill your grandfather. > So, your grandfather doesn’t die. You’re born; You get older; You build a time machine… > > As for introducing an object into your past and then wondering where it came from or if you’ve created a paradox, I made this silly drawing for another time-travel thread a few months ago to show how there is no mystery or paradox. And yeah, I’m a nerd. > [Drawing](http://imageshack.us/photo/my-images/831/timetravel.png/) The diagram is sound as you depict, but the question is, how do we know there’s nothing preventing you, at timeframe #4, from not bothering to go to the store to buy the an item you already have? Let’s replace the stapler with a one-of-a-kind object: You spend a fortune and lose an eye due to an accident building a time machine. Yet, you steal the Mona Lisa, and travel back 10 years to give it to yourself. There is now a genuine Mona Lisa at the Louvre, and one hanging over the toilet in your bathroom. 10 years go by. Do you still bother to build the time machine? And if you do, do you still steal the Mona Lisa? And if you do, when you bring it back 10 years, is there now three Mona Lisas? Or are you saying, all you ever knew was that a 10 year older version of you traveled in time to give you a priceless painting, then left. And you’d have no choice but to build the machine and steal the art because what happened, happened — in that, despite the fact it’ll cost you your life savings, can’t sell the painting for your lost fortune (because the “original” is still at the Louvre), and will end up losing an eye, you still go through with it? It’s like the idea of a black box with a red button, and a green light. When you press the button, the green light turns on — but 5 seconds _before_ you pressed the button. So, if you see the green light turn on, it means in 5 seconds, you’ll be pressing that button. It makes my head asplode if I think about toying with such a thing, seeing the light turn on, then trying to _resist_ pressing the button. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [February 26, 2012, 2:31am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/23 "2012-02-26T02:31:48Z")
You go back in time and kill your grandfather. You are then stuck and can’t get back because you have unwritten history and it only writes itself back at 1 sec/sec. There is no paradox-you’ve only given the Novel of Life a different beginning, and what follows then is still a mystery. Your choice is to try to blend in, or get committed. Time travel to the future just isn’t possible, even back to your own. ---
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [February 26, 2012, 4:22am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/24 "2012-02-26T04:22:44Z")
> [@cmyk](#): > > The diagram is sound as you depict, but the question is, how do we know there’s nothing preventing you, at timeframe #4, from not bothering to go to the store to buy the an item you already have? > > Let’s replace the stapler with a one-of-a-kind object: You spend a fortune and lose an eye due to an accident building a time machine. Yet, you steal the Mona Lisa, and travel back 10 years to give it to yourself. There is now a genuine Mona Lisa at the Louvre, and one hanging over the toilet in your bathroom. > > 10 years go by. Do you still bother to build the time machine? And if you do, do you still steal the Mona Lisa? And if you do, when you bring it back 10 years, is there now three Mona Lisas? > > Or are you saying, all you ever knew was that a 10 year older version of you traveled in time to give you a priceless painting, then left. And you’d have no choice but to build the machine and steal the art because what happened, happened — in that, despite the fact it’ll cost you your life savings, can’t sell the painting for your lost fortune (because the “original” is still at the Louvre), and will end up losing an eye, you still go through with it? I’m not sure it is possible to deviate from the chain of events. But if you can, then yes, you will have a paradox. > [@](#): > > It’s like the idea of a black box with a red button, and a green light. When you press the button, the green light turns on — but 5 seconds _before_ you pressed the button. So, if you see the green light turn on, it means in 5 seconds, you’ll be pressing that button. It makes my head asplode if I think about toying with such a thing, seeing the light turn on, then trying to _resist_ pressing the button. If the light turned on, then it means that you pressed the button. If you choose not to, then you won’t see the light turn on first. You can’t deviate because the light going on means you already made the choice. Yeah, the light going on first seems to mess with causality, but in my non educated opinion, I think there still is causality. You press the button and a signal goes back in time to turn on the light. Cause and effect. The signal can only be sent if the button is pushed. IMHO. ---
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [February 26, 2012, 4:32am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/25 "2012-02-26T04:32:52Z")
> [@Czarcasm](#): > > You go back in time and kill your grandfather. You are then stuck and can’t get back because you have unwritten history and it only writes itself back at 1 sec/sec. There is no paradox-you’ve only given the Novel of Life a different beginning, and what follows then is still a mystery. Your choice is to try to blend in, or get committed. Time travel to the future just isn’t possible, even back to your own. IMHO traveling into the future is difficult to think about. I believe that time is real and not an illusion, and I think it probably is constantly being created. Kind of like how space is continually expanding. So, with that, let’s say time is currently at 2/25/2012. The future doesn’t exist yet so we shouldn’t be able to go any further. But yet, someone in 1980 should be able to come to 2012. So far, so good. But yet, in a year someone from 2012 should be able to time travel to 2013. So at some point out limitation to going beyond the present will be gone. But when and how that happens… I don’t know. Again, this is assuming that time travel is possible at all. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [February 26, 2012, 4:46am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/26 "2012-02-26T04:46:06Z")
> [@Nobody](#): > > IMHO traveling into the future is difficult to think about. > > I believe that time is real and not an illusion, and I think it probably is constantly being created. Kind of like how space is continually expanding. > > So, with that, let’s say time is currently at 2/25/2012. The future doesn’t exist yet so we shouldn’t be able to go any further. But yet, someone in 1980 should be able to come to 2012. > > So far, so good. But yet, in a year someone from 2012 should be able to time travel to 2013. So at some point out limitation to going beyond the present will be gone. But when and how that happens… I don’t know. > > Again, this is assuming that time travel is possible at all. Here’s the deal: the guy from 2012 can travel back to 1980, but as he travels back he unwrites the time stream, and there is nothing to travel back to because the future has yet to be re-written. ---
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [February 26, 2012, 4:55am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/27 "2012-02-26T04:55:26Z")
I see what you’re saying. That’s an interesting theory. Just out of curiosity, how did you come up with that? Also, something I’ve wondered about is that sci-fi that I’m familiar with usually has a concept of of a “correct” timeline. For example it’s been mentioned in Doctor Who (fixed points in time), various Star Trek time travel episodes, Fringe (the Observers not only observe time, but make sure things happen the way they’re supposed to). But why is any one timeline more or less valid than another? I mean, you can have timelines that are better or worse than the one you know, but I don’t see what that has to do with the validity of any of them. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [February 26, 2012, 5:16am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/28 "2012-02-26T05:16:28Z")
> [@Nobody](#): > > I see what you’re saying. That’s an interesting theory. Just out of curiosity, how did you come up with that? It the simplest theory that takes all factors into account, and it eliminates the paradoxes. Killing your grandfather doesn’t eliminate your future because you _already_ did that by traveling back in time. New start-new story. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [February 26, 2012, 5:32am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/29 "2012-02-26T05:32:20Z")
BTW, if you happen across someone who you think is on the brink of inventing time travel, you might want to do her/him in and burn the notes, because if that person is successful _you_(and everyone and everything else) will be unwritten. There is only the one timeline, and the person that unravels it by going back unravels it for everyone. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [February 26, 2012, 6:05am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/30 "2012-02-26T06:05:52Z")
> [@Czarcasm](#): > > BTW, if you happen across someone who you think is on the brink of inventing time travel, you might want to do her/him in and burn the notes, because if that person is successful _you_(and everyone and everything else) will be unwritten. There is only the one timeline, and the person that unravels it by going back unravels it for everyone. The problem isn’t unraveling our pasts, if such a thing could happen. The problem is removing any future. We stop \*being \*in the situation you describe. Not like we’d care much what happens to our past after that. ---
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [February 26, 2012, 6:16am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/31 "2012-02-26T06:16:33Z")
> [@Czarcasm](#): > > It the simplest theory that takes all factors into account, and it eliminates the paradoxes. Killing your grandfather doesn’t eliminate your future because you _already_ did that by traveling back in time. New start-new story. But if going back undoes the past then you can’t go any further than your conception because if you weren’t conceived then you never were born and never grew up to create a time machine in the first place. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [February 26, 2012, 7:08am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/32 "2012-02-26T07:08:35Z")
> [@Nobody](#): > > But if going back undoes the past then you can’t go any further than your conception because if you weren’t conceived then you never were born and never grew up to create a time machine in the first place. No such thing as a “personal timeline”, just _the_ timeline.-it unravels as far back as you go, even if you go back farther then your own birth. You will be an anomaly, but you won’t be a paradox. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [February 26, 2012, 7:27am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/33 "2012-02-26T07:27:41Z")
> [@TriPolar](#): > > The problem isn’t unraveling our pasts, if such a thing could happen. The problem is removing any future. We stop \*being \*in the situation you describe. Not like we’d care much what happens to our past after that. There is never any future to unravel. There is past, present , and an infinite number of possibilities. It’s like a trillion-pin pachinko machine-move any pin and the game changes in ways you cannot predict. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [February 26, 2012, 7:56am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/34 "2012-02-26T07:56:50Z")
It’s not a future to unravel. There is no future at all. When the time traveler starts his journey backwards, we end. Zippo, nada, nothing. Our time has ceased to move forward. The unraveling of pasts is irrelevant when you cease to be. ---
**Author:** ![Nobody](https://avatars.discourse-cdn.com/v4/letter/n/94ad74/32.png) [@Nobody](https://boards.straightdope.com/u/Nobody)\ **Post date:** [February 26, 2012, 8:04am UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/35 "2012-02-26T08:04:48Z")
> [@Czarcasm](#): > > No such thing as a “personal timeline”, just _the_ timeline.-it unravels as far back as you go, even if you go back farther then your own birth. You will be an anomaly, but you won’t be a paradox. Right, and you exist in _the_ timeline so if you erase it before you came into being, then you stop yourself from coming into being. Of course then time would just rebuild itself the same way as before so you then you would come into being and then… Oh oh, time loop again. ---
**Author:** ![Scumpup](https://avatars.discourse-cdn.com/v4/letter/s/ce73a5/32.png) [@Scumpup](https://boards.straightdope.com/u/Scumpup)\ **Post date:** [February 26, 2012, 1:43pm UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/36 "2012-02-26T13:43:13Z")
There is no original timeline that is “more valid” than any others. Stop thinking of a line that splits. Think instead of a tangled web that extends infinitely in all directions. You can jump from string to string, perhaps, but you don’t make any new strings or break any old ones. They have all always been there. They will all always be there. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [February 26, 2012, 2:23pm UTC](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821/37 "2012-02-26T14:23:50Z")
> [@Nobody](#): > > Right, and you exist in _the_ timeline so if you erase it before you came into being, then you stop yourself from coming into being. > > Of course then time would just rebuild itself the same way as before so you then you would come into being and then… Oh oh, time loop again. The paradox doesn’t happen. You become an artifact from a story that has been deleted. [Previous page](https://boards.straightdope.com/t/time-travel-into-the-past-why-does-there-have-to-be-an-original-timeline/613821.md?page=1)