Ok so you know the grandfather paradox. You try to kill him but something, no matter what, prevents you. What if when you go back in time you cant even interact with the past because its only light your witnessing. Like no matter, just the light. Kinda like re-watching something on TV. That would let you go back into time without altering the past or causing a paradox.
Wouldn't that cause changes in his upbringing in some manner possibly causing him to never go back in time in the first place? Or how about the idea that if he did that, this thread wouldn't of existed(even if he does it in the future) because it would've already been done in the past?
I'm gonna venture to say that it's going to be difficult to come up with a sound and plausible theory involving backward time travel. Best of luck anyway.
The problem is still there, by going back in time you are effectively changing everything into light. Time is a local event so traveling back through it shouldn't change the nature of everything else in the universe. I think the answer is that when you travel back in time you get "bumped" into another universe that is similar but at a "later" point in it's evolution. As in it's still at whatever time you wanted to travel back to. This would allow you to kill whoever you want and it not effect the time line you came from (i.e. the paradox in the first place). Also this prevents any other paradox's (by way of altering a time line) because in that universe the thing you are "changing" hasn't happened yet so there isn't anything really to be changed in the new universe.
It depends on which theory of time travel you look at to be honest. A lot believe that no matter what you change in the past, the present will stay the same. Or at least the present you are used to. As when you change one thing in the past, the "timeline" splits into two separate realities. One where you have done what you have done, and another where you haven't. So killing your grandpa, for us nothing will happen. But when you kill him and travel "back to the future" (lol I had to do it) you will be entering a different future than the rest of us (but our duplicates will be there). Hard to explain while baked, but I hope you get the general idea ***Edit: It's like the parallel universe theory***
Indyair, i think you're right. I never got into deep thought about time travel but this seems like the only good explanation. Because, let's be honest, matter can't disappear. I think that there are billions of possible outcomes each on their own time line. If you go into another one (into another time) you switch out of your own time line and invade another one. What you do here will not affect your original time.
Wouldn't that mean that those universes are going on simultaneously to our own? It would be like an infinite multiverse theory.... This would also mean that to travel time, you would have to cross a reality of sort.
Exactly. Keep in mind time isn't real, so your standard "time machine" isn't as cut and dry as the movies make it seem.
Ok, when you look at a star thats 5 LIght years away, Youre seeing what that star looked like 5 Light years ago. if you travel faster than the speed of light, you can go back and see this light that made the image of the star you saw once the light has come and passed your eyesight. get it?
You never know. Suppose time travel was even possible (I don't think it'll ever happen), you could have a life where you know your grandpa and shit, but travel back to kill him. I don't know why you would, but the only chance you'd have is getting him after your dad is born. It could change things, or only change the fact that you had a grandpa. Your dad could turn into some fucked up kid and still end up meeting your mom, fucking at the exact moment needed to make you, or it may not even affect your dad. When you try and come up with what the universe is, how would time travel work, if there is a God, things like that, the possibilities are endless. Reason being, we won't know the answer until it happens.