Bootstrap Paradox

So I've been thinking about time travel recently, and I'm not so interested in the Grandfather paradox, because that seems to be easily solvable through self-consistency in the timeline, or in other words you will never go back and kill your grandfather because the proof that you have not done so in the future is that you exist. The things you you will do when going to the past have already happened, and you will do then later. However, the one paradox I find really weird that isn't solved by this self-consistent timeline is the bootstrap paradox, where you go back in time and give yourself some piece of  information, which your past self will then later do the same, essentially creating a piece of information in a loop with no origin. For example, let's say some mathematician sees a beautiful proof in a book, which she then proceeds to take back in time and show to someone. The second mathematician is equally impressed, so he includes it in his book, which is the same book the first mathematician got the proof from originally. The timeline is self-consistent, but where did this proof come from? Nowhere, apparently. Another example would be to go back in time and have sex with your grandmother, Futurama style. Now the same problem exists with the 25% of DNA that you got from your grandfather, who is apparently you. Where did that 25% come from?

So yeah, this is bothering me.

I'm going to hi-jack your thread and push it on a step as my thought of the day.
Lets make the assumption that time travel is possible. That's not important how, its just accepted.
The theory is that nature somehow always avoids getting itself into a position of paradox - I saw this on TV some months ago with a wise science maths guy. That creating a paradox is impossible as nature will always choose the alternative path.
Now to make this simplistic lets say I toss a coin, but that I make it so as heads is fine and tails would cause a paradox. Maybe because I tell myself the result using time travel. The coin will always be heads.
So now I don't need to travel to the future to find the result. I need only travel to the past to tell myself the result. If the coin is wrong, I would know in future to travel to the future and not just guess. If I am right, travelling to the future is unnecessary and my coin tossing self never knows any better. So I guess heads, it must be heads. I cannot be wrong.

Ok, so what? Well armed with the knowledge that nature can't have a paradox is there anything I can do to exploit this? Example, death and taxes are inevitable. But in order for me to be dead I have to die. This is obvious. But can I use things I know will be a dead cert in the future, to predict things that aren't, in order to know what the future holds. Can I extrapolate this back to bet on a horse or get the lottery numbers? By knowing the dead certs and forcing choices between paradox and viability, could I see into the future and exploit it? Be able to use paradox to accurately guess anything, just by making paradoxes against things I know must happen and therefore knowing the future and using it? Can paradox become a useful tool?

Trekkie:
The bootstrap paradox is only a paradox if you see time as one way. It isn't. Events of the future can create objects in the past. So long as you don't keep creating objects you're fine.
Ex: I got a baseball card from my dad. I go back in time to give him mine so now he has two copies. He then gives both to me in the present and I go back in time to give him both making the total 3. Repeat until you have infinite cards.
As long as this doesn't happen then I don't see why things can't exist soely in a fixed time frame.

Trekkie:
The bootstrap paradox is only a paradox if you see time as one way. It isn't. Events of the future can create objects in the past. So long as you don't keep creating objects you're fine.
Ex: I got a baseball card from my dad. I go back in time to give him mine so now he has two copies. He then gives both to me in the present and I go back in time to give him both making the total 3. Repeat until you have infinite cards.
As long as this doesn't happen then I don't see why things can't exist soely in a fixed time frame.

Yes, but this doesn't work with the self-consistent timeline I'm fond of. Here, your actions in the past can change future outcomes, creating Grandfather paradoxes that don't occur in the self-consistent solution. Here, even by merely going back to give the first card, you could change the future in a butterfly effect fashion, maybe changing which sperm fertilizes the egg that becomes you, erasing you from existence, etc.

Quote from: Lorddave on August 08, 2011, 09:11:55 AM

Trekkie:
The bootstrap paradox is only a paradox if you see time as one way. It isn't. Events of the future can create objects in the past. So long as you don't keep creating objects you're fine.
Ex: I got a baseball card from my dad. I go back in time to give him mine so now he has two copies. He then gives both to me in the present and I go back in time to give him both making the total 3. Repeat until you have infinite cards.
As long as this doesn't happen then I don't see why things can't exist solely in a fixed time frame.

Yes, but this doesn't work with the self-consistent timeline I'm fond of. Here, your actions in the past can change future outcomes, creating Grandfather paradoxes that don't occur in the self-consistent solution. Here, even by merely going back to give the first card, you could change the future in a butterfly effect fashion, maybe changing which sperm fertilizes the egg that becomes you, erasing you from existence, etc.

Your assuming that your actions in the past don't create the future you currently live in and inaction would erase it.

I don't think time works that way, you can't go backwards. Create impossible circumstances, and you create unsolvable problems.

If you were to go back in time and erase yourself, who is to say you would actually be erased? How are you linked to your original time line anymore?

If you were to go back in time and erase yourself, who is to say you would actually be erased? How are you linked to your original time line anymore?

Exactly.
Or maybe the act of going backwards in time causes you to be forced outside of the space-time continuum so any changes you make don't affect you personally but they can affect your timeline.

Reminds me a little of the key in Timesplitters: Future Perfect. Cortez is given the key to the castle by his future self, he fights his way through the castle and finds a time vortex which takes him back to give his past self the same key.

The key had no origin.

Or the later brilliant scene where Cortez enters a room with 2 computers and an army of robots. A time portal opens and a future cortez drops through to give you the password to the computer while he fights the robots, then another Cortez drops through with the password to the other computer and another drops through to deal with the robotic reinforcements. You end up playing the same 5 minutes of the game through 4 times from a slightly different perspective.

Dr. Who explains it all.

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Berny
Going back to XP theme

How is a discussion like this meaningful at all? We can't time travel, so we don't know how it would work in reality. You have to have a firm set of rules before you can talk about violations of those rules.

Time travel is a sort of misleading term, as anyone can travel through time, at least forwards.

http://www.physorg.com/news/2011-03-grandfather-paradox.html

This sounds interesting.

http://www.physorg.com/news/2011-03-grandfather-paradox.html

This sounds interesting.

Translation: you can't change history, only help create what you already knew.

I believe in the many-worlds interpretation of Shrodinger's Cat, which would follow into this.

Unless someone can produce and interpretation of Time that can accept these kind of time manipulations, I do not think that time travel could be possible. But this is a belief.

About the time travel itself; I am going to quote Sheldon Cooper when he is defining the room mate agreement with Leonard. They agree that if any of them discover time travel, the first stop they will make would be this specific time point. Nothing happens, and therefore is concluded that they do not make a time traveling machine.

You could say that this is pre-arranged, and it causes no real havoc / paradox or anything. But I think that it is the only way to remain consistent.

Furthermore time travel may face some engineering problems, and I really do not think it can be possible short of using wormholes, black holes or the like.... which in most cases would prove to be...uncomfortable for the traveler.

HOWEVER; if you admit the infinite universe theory ( multiverse/multidimensional etc.. ) and you make an inter-dimension travel machine. THEN, maybe, you can choose what moment of the time line of this other universe you pop out from ours. Then, you are affecting this other universe, not "your own"