Timetraveller killing himself in the past

[Flustered]

To a person from the future, of course.

Yes so that would mean we have already lived our life. God knows are fate, my 10 year old self is still living in his 10 year old time frame.

 

[DaveC426913]

Yes so that would mean we have already lived our life. God knows are fate, my 10 year old self is still living in his 10 year old time frame.

Perhaps, but there are many ifs in the chain to that conclusion. Any if of them poor assumptions and the whole thing falls apart.

If time travel is possible.
If tt's visit their own past, and not an alternate.
If you believe in God and fate.

 

[Adel Makram]

the time travel is a logical result of a math consistent with speed > c. Remember the whole theory of relativity is created to make c invariant not to explain why it is so. The math foundation is based on the experiment of M&M which is liable to the experimental correction such as CERN experiment. Therefore, SR is not a true theory in physics, it is a math to fit for the invariance of c

 

[nitsuj]

not that I read more then the first few posts in this thread, but wow hows is this thread still open

 

[rbj]

i don't know why, but it appears to me that no one is mentioning the obvious. unless you spin this into something like separate time-lines (that somehow get crossed or generated when one time-travels to the past), when you step into the time machine, go back a half hour and kill your past self, then who steps into the time machine to go back in time to kill the person who steps into the time machine? the paradox could be expressed as the grandfather thing.

BTW, this is not a conceptual problem for time-traveling into the future. in fact, we're now time traveling into the future at the rate of one minute per minute. all you have to do is wait around and you'll find yourself in the future. pretty cheap and available to all.

if you don't like waiting around, it'll cost you a bit more; you'll need a spaceship and a nearby black hole to hurry it up a little (for you).

 

[nitsuj]

case & point

 

[DaveC426913]

case & point

Um. Did you mean case in point?

 

[DaveC426913]

i don't know why, but it appears to me that no one is mentioning the obvious. unless you spin this into something like separate time-lines (that somehow get crossed or generated when one time-travels to the past), when you step into the time machine, go back a half hour and kill your past self, then who steps into the time machine to go back in time to kill the person who steps into the time machine? the paradox could be expressed as the grandfather thing.

Because it is obvious. And it is known as the grandfather paradox.

Thing is, relativistic time travel (if it is possible) does not forbid this kind of paradox.

 

[ZapperZ]

Well, I'm surprised that, after 4 pages of discussion, no one mentioned the recent Seth Lloyd's idea on what could possibly save the grandfather paradox.

http://www.physorg.com/news198948917.html

Zz.

 

[PAllen]

Well, I'm surprised that, after 4 pages of discussion, no one mentioned the recent Seth Lloyd's idea on what could possibly save the grandfather paradox.

http://www.physorg.com/news198948917.html

Zz.

I took a quick look at this. I could be wrong, but it only provides QM rationale for Novikov consistency. Thus it would allow the case that I find actually more perverse than the grandfather paradox: that Beethoven's 9th symphony has no author. Someone from the future goes to the past and hands the score to Beethoven, who publishes it, allowing future person to receive it. This does not violate Novikov, or the P-ctc of this paper (at least as I understand it so far).

 

[rbj]

... it would allow the case that I find actually more perverse than the grandfather paradox: that Beethoven's 9th symphony has no author. Someone from the future goes to the past and hands the score to Beethoven, who publishes it, allowing future person to receive it.

how do you know that's not how it happened? something inspired Beethoven.

 

[torquil]

I go back to Shakespeare's time and discover he has some idea about the play Macbeth, but has writer's block and can't get it going. You give him a copy of Macbeth, he loves it and produces it (no plagiarism, since he wrote it). So who really wrote Macbeth?

That's quite easy to answer: Shakespeare. Just follow the "oriented" worldline of your Macbeth-book in the backwards direction, and it will eventually go towards a spacetime event whereby Shakespear writes it. This worldline will of course go back and forward in the time time dimension, since we are allowing time-travel in this example.

Cause and effect will always follow some allowed worldline. If time travel is allowed, then this "following the worldline backwards" method must be a valid form of causality. Macbeth will only appear "out of the blue" for those who are unable to examine the entire 4d worldline.

 

[PAllen]

That's quite easy to answer: Shakespeare. Just follow the "oriented" worldline of your Macbeth-book in the backwards direction, and it will eventually go towards a spacetime event whereby Shakespear writes it. This worldline will of course go back and forward in the time time dimension, since we are allowing time-travel in this example.

Cause and effect will always follow some allowed worldline. If time travel is allowed, then this "following the worldline backwards" method must be a valid form of causality. Macbeth will only appear "out of the blue" for those who are unable to examine the entire 4d worldline.

Your argument is not correct. The scenario I posited has only one (forward only) world line for Shakespeare. Your proposal does not follow from either the math of GR, nor from the Novikov assumption (in fact this situation being allowed is discussed in the literature on Novikov conjecture).

 

[torquil]

Your argument is not correct. The scenario I posited has only one (forward only) world line for Shakespeare. Your proposal does not follow from either the math of GR, nor from the Novikov assumption (in fact this situation being allowed is discussed in the literature on Novikov conjecture).

My proposal assumes that I'm allowed to draw a time-travelling worldline that turns backward in time (makes a U-turn in the time dimension), and perhaps that some sort of alternate future is generated each time the time-travelleler interacts with anything else, so as to render any paradoxes impossible. This may not be compatible with the assumptions that is made when discussing the Novikov self-consistency principle/CTCs/time-paradoxes.

I'll have a quick look at it then to educate myself a bit :-)

EDIT: That Gödel solution is far out!

 

[PAllen]

My proposal assumes that I'm allowed to draw a time-travelling worldline that turns backward in time (makes a U-turn in the time dimension), and perhaps that some sort of alternate future is generated each time the time-travelleler interacts with anything else, so as to render any paradoxes impossible. This may not be compatible with the assumptions that is made when discussing the Novikov problem.

I'll have a quick look at it then to educate myself a bit :-)

Your proposal about past interaction creating an alternate future has been made many times, and is a solution to causality problems. Unfortunately, it is not required by GR (purely classically, or with quantum corrections per ZapperZ's reference. Note that (as far as I can see), it cannot even be added as an additional conjecture, like Novikov. It requires that any forward pointing world line encountering a backward going world line, must split into two world lines. I am skeptical that such a solution is even mathematically possible in GR.

 

[torquil]

Your proposal about past interaction creating an alternate future has been made many times, and is a solution to causality problems. Unfortunately, it is not required by GR (purely classically, or with quantum corrections per ZapperZ's reference. Note that (as far as I can see), it cannot even be added as an additional conjecture, like Novikov. It requires that any forward pointing world line encountering a backward going world line, must split into two world lines. I am skeptical that such a solution is even mathematically possible in GR.

Agreed on all points.

 

[nitsuj]

Um. Did you mean case in point?

Ah ha, that one wasn't too bad for me. To maybe offer a laugh, up until I was about my early 20's I thought the term misdemeanor (small crime) was Mister Meaner lol. sorry for the side track all.