If you travel back in time and kill your grandfather...?

This is the famous "grandfather paradox" of time travel. It is the bread-and-butter of time-travel science fiction.

The paradox doesn't require you to actually kill your grandfather. Anything that would prevent your own existence ... or even your entry into the time machine ... will do as well. For example in 'Back to the Future', Marty found that by traveling back in time he accidentally prevented his parents from getting together, and this was enough to trigger the paradox.

There are many solutions to the paradox. The most famous solution is the "many-worlds" (a.k.a. "parallel universes") theory of time. Basically, every event causes a fork or a *branching* of time into two timelines. For example, on the day your parents met, maybe there was some minor incident that caused them to meet (e.g., your mom got a flat tire and your dad stopped to help). At the instant of the flat tire, the universe splits into two timelines ... one with the flat tire (in which your parents meet and you are born) and one with no flat tire (in which your parents don't meet and you are never born).

If you were to sneak back and fix her tires that morning so that no flat occurred, then as your mom drove on that day with no flat tire, you (the time traveller) would just now be on the no-flat-tire timeline. No paradox.

This is a more philosophical question. There is a causal dependency of your existence based on your grandfather's existence. I believe that the most probable thing would be that you killed your grandfather and then you disapper immediately. This is the most probable answer I've come up with after talking to research scientists and watching South Park (the episode in which Cartman is waiting for Nintendo Wii).

This could create a paradox. If you killed your grandfather before your parents were born then you they would not be conceived therefore you would not be conceived. In theory, you would not exist from the moment your grandfather died. The paradox would be that if you "disappeared" after your grandfather died then would your grandfather return because the person who came back in time no longer existed. This, in theory, could cause a continual loop.

If you travel back in time and kill your grandfather that doesnt mean u disappear. Youve already bent the rules by traveling thru time! If you kill him it only changes the stories that your parents tell you about how great he was and how he died.

So basically you would still be able to kill him. Cuz u already "cheated" by time travel.

this is suggested as the anomaly theory. You defined the hypothesis nicely. In time commute theory it is likewise pronounced many times that a individual ought to no longer commute returned in time to a factor the place the time gadget have been made and initially started. Say you invented a time gadget immediately, Dec 5, 2007 and released a visit, you should purely bypass forward in time. the following day nevertheless, you should return to immediately. yet you should on no account bypass returned to 1297 and forestall the signing of the Magna Carta.

the case is impossible since you cannot travel back in time. the possible thing is seeing what happened before (by using the special theory of relativity). however, people still cannot do this today.

well if u travel back in time to kill ur grand father then ur grand fathr will surely die but since ur in past ur exsistence will be dere for a while but in the present u wud not be dere so if u travel back to ur present u will find urself unkown to the people u had known earlier.or maybe it can happen ur granfathr has bcum d fathr of ur fath so dis means if u kill ur grand fathr it wud not effect ur exsistence.but he will be modified from ur memory in the present.

it is impossible to go back in time

Good question. How about you try it and see, and we'll watch.