A Negation of the Grandfather Paradox

[jacirez]

I believe I found a solution (or a negation) to one of temporal mechanics most enduring paradox:
If you travel back in time, could you kill your own grandfather, thereby altering your future, even erasing yourself from existence?

The short answer is NO. You can't.

This is simply because the moment (present instant) you formulate the thought to travel back in time to do anything to alter your fate as you remember in that instant (past and present), the mere act of formulating the thought means that on fact you DID NOT travel back in time and altered your fate as you remember it in the first place.

This is because if you did in fact travel back in time and altered your fate (past and present), you would (in the present instant you formulate the thought) already have the memory that you did in fact travel back in time and altered your fate.

Since you do not have these memories (as you formulate the thought of traveling back in time in the first place), simply asking the question, rather than remembering past actions (remembering that you already traveled back in time and altered your future) , negates the paradox...

 

[UltrafastPED]

But the paradox is that you kill your grandfather prior to the birth of your father!

It has nothing to do with your memories; it has been explored mostly in science fiction. Makes for interesting stories! http://en.wikipedia.org/wiki/Grandfather_paradox

 

[jacirez]

@UltrafastPED,
I respectfully disagree. Please bear with me: If we agree that the basic definition of time is the interval between two events (i.e a complete revolution of a planet around its host star; a complete revolution of a planet around its own axis...the number of oscillation in a quartz crystal, etc.), then how do we know how much time has passed between two events? We count the number of intervals between the initial event and the moment we first formulate the idea (or remember) to measure it (for example).

This is why you know how much time has passed between the instant I first posted this reply and the instant you are reading it. But what happens if there are no records (or memories) of "the initial moment"? As far as any observer is concerned, the event did not take place between any intervals.
Conversely, if neither I nor any observer has any record (or memories) of me traveling back in time and killing my grandfather it must mean that such an event (as far as me or any observer is concerned) never took place (it did not occur between any intervals)...

 

[micromass]

This is too speculative. As far as I know, there has not been a conclusive physics experiment that has tested this issue. Therefore, all answers are purely hypothetical and philosophical. Hence, this discussion is better suited on some philosophy forum instead of PF.

Thread locked.

Do read this (section 4, 5 and 6): http://en.wikipedia.org/wiki/Time_travel#Time_travel_to_the_past_in_physics
Any question about this can be asked in our forum. Personal theories such as the OP cannot be allowed as such.