Does anyone know the "Grandfather paradox" in time travel?

Hi. It states that if you could travel back in time you could kill your grandfather ( a horrid thought) and prevent your birth, so how could you go back in time if you were never born?

You're incorrect about the reasoning behind the paradox. It is not a paradox merely because of a spatial dependency, but rather because the time traveler is permitted to enter a period that severely impacts his future. If our traveler begins her journey in anyplace on Earth, and returns to the past where her grandfather is, then their mere interaction may have enough consequence to alter the course of the grandfather's decision that prevents the grandmother from being in the location where she was supposed to be at the moment their lives crossed. Consequently, this leads to a series of events that effectively prevents the children from being conceived and subsequently the grandchildren. Naturally, this can be extended to the more fatal version. As you can see, space and wormholes have little to do with the development of what is considered the actual paradox; that is, the interruption of the children having a beginning. Now, certain Quantum Mechanical properties allow these strange type of histories to continue. For example, even though the traveler returned to a period that would alter the grandparent's history, it is now a different grandfather (looks and acts the same) with a different future than the one that will lead to the birth of the traveler. Stated differently, the histories of two separate events have crossed, but without any paradoxical impact. Whether the second case is true or not is a matter of personal belief, since there is no device being built in the foreseeable future that will allow one to find which theory is correct.

The most famous paradox is the grandfather paradox: you travel back in time and kill your grandfather, thereby preventing your own existence. To avoid inconsistency some circumstance will have to occur which makes you fail in this attempt to kill your grandfather.

The "Grandfather Paradox" is the theory that if you go back in time and kill your grandfather, then you cause yourself to not exist in the present.

However, while time travel does exist, because of the certain paramaters regarding time travel, you can't kill any of your relatives.

OK you know how everyone like to think time travel is real? well some people say that it isn't real, because if you go back in time and kill your grandfather (grandmother is the version I heard) then how are you supposed to be born? you would cause yourself to not exist, meaning you couldn't go back in time to stop yourself being born, meaning you would go back adn killy our grandfather, meaning you couldn't be born... and it just continues like that.

there are a few theories here. the first is that if you tried to kill your grandfather, as soon as you killed him, you would keep yourself from being born, and that's it. it's like that's what really happened, and some scary man from another dimension just made something happen. you would then live in that time, probably in jail, and in a lot of trouble, seeing as you probably didn't bring your social security card, which wouldn't even have a valid number on it, seeign as you came form the future.. and yea you know how that goes.

second theory: time travel isn't possible. the only known way to travel into the past would be to exceed the speed of light, which with present theories and technology, is indeed impossible. darn, so much for me getting a second chance at that history test... (just kidding, I'm really good at history)

theory number 3: there would be 2 different dimensions here. like how they say that until an experiment is observed, all possibilities are true at the same time? then once its observed, one of them becomes true? well this theory is that you go back in time and kill your grandfather. it would be like theory number one, except it would be like hopping into a parallel universe, where you alter one thing, making the universes take two different paths. like, in the universe you came from, no one killed your grandfather, because when you went back in time, you ceased to exist. in universe number 2, you just appeared out of nothing.

theory number 4, aka, the no free will theory: when you go back in time, you are forced by all things on earth to not kill your grandfather. in other words, you are really in the past, but you just made time continue on its destined course. maybe you didn't get to kill your grandfather in time, so he impregnated your grandmother before you could kill him. this would have been 100% true, and you would have been told that as a child.

those are the different theories, none of which are correct or wrong, because all different possibilities are possible at the same time, until the experiment is observed =)

u go back in time and kill ur grandfather but since u kill ur grandfather ,u wont exist so u never really went back in time

to kill him.so u would still exist and can go kill ur grandfather.

I do