what is GRANDFATHER PARADOX and time machine?

Question

if there is such kind of possibility for e.g we r abel to kill hittler or other historical mass murder to save innocent lives

Answer 1

The Grandfather Paradox is a paradox that is used to illustrate the theoretical logical difficulties of time travel. If time travel were possible, it would be possible for someone to travel back in time and kill his own grandfather. But if he killed his own grandfather he'd never be born. And if he was never born he could never have built the time machine, gone back, and killed his grandfather. See the paradox?

There are two popular possible resolutions to the Grandfather Paradox (besides the obvious one that time travel is impossible).

One is predestination. When the time traveller built his time machine he had already tried to kill his grandfather in the past. So obviously he failed to kill his grandfather for some reason, since he exists. This theory makes some people uncomfortable because it can be interpreted as suggesting that there is no such thing as free will (since the time traveller cannot change events in the world's past but his future).

The other is the many worlds theory. According to many worlds theory when the time traveller kills his grandfather he actually creates a parallel universe where he never existed. He can continue to exist in this parallel universe without paradox, as a traveller from the old universe.

Either theory would indicate that it would not be possible to actually change world history by, say, assassinating Hitler. According to predestination theory the assassination attempt will fail, because it has already occured in the past and obviously has already failed. According to the many worlds theory we could, in fact, create a parallel universe where Hitler was assassinated, though of course this wouldn't technically be changing OUR history. Actually, whether or not this would save the lives of the people killed in the Holocaust is an interesting philosophical and metaphysical question (they would still die in our universe, but they'd live in the parallel universe).

I would also point out that even if we could in fact change the past a la Back to the Future it might not necessarily be prudent to do so. First of all, for better or worse, it would destroy the timeline we know, and many of the people who live in this timeline might never be born. For instance, in a universe with no WWII my mother would never have left Germany and would never have met my father, and I would not exist. So arguably changing the timeline could be considered mass murder. Also, the changes made to history could have unpredictable unintended consequences. What if one of the people Hitler gassed turned into an even worse evil dictator, for instance?

Anyway, why is this in Religion and Spirituality? Shouldn't it be in physics or something?

Answer 2

The paradox is: What would happen if you go back and kill your own Grandfather?

No possibility any time soon, but who's to say some future generation isn't coming back and making small beneficial changes?

Have you seen The Last Mimsy?

Answer 3

The "grandfather paradox" is this:
Suppose you had a time machine--and used it to go back in time to a point before your father was conceived.

Now, lets assume that you accidently kill your grandfather (we'll assume you're not a bad sort--it was an accident!)

But--if you did that, thenyour father would never have been born. So you would have never been born. Therefore, you coudn't go back in time and kill your grandfather.

But in that case, your father would have been born-and you as well. so thenyou could go back in time and kill your grandfather, But. . . .

And around and around it goes!

Answer 4

People never think about the consequences for those things.

If you go back and kill hitler, whats to say some OTHER guy wouldnt show up and WIN ww2 for germany that MIGHT be worse then hitler?

Hitler was a jerk that needed killing no doubts about it, but there coulda been someone worse. Theres always someone worse. And in this case, by worse i mean a racist mass murder that WASNT a insane junky.

Answer 5

if you went back & killed your grandfather then you would never have been born & couldnt go back & kill your grandfather