If there were a time paradox, would current world destruction be immediate or gradual?

The future as you know it would not be destroyed. It would just never happen.

I don’t think anything would be destroyed.

At most it would create an alternate timeline, but more likely it wouldn’t change anything. There are no paradoxes with time travel. You have to understand that the past has already happened. If you went back 20 years to go kill someone, that has already happened now, 20 years ago. If that person is alive today, then you know you failed or decided against it. Whatever you went back to do, you already did, and this world is the result including your hand in the timeline.

If it happened a certain way at a certain speed the first time around, it would happen that way again in the throes of the paradox. I can’t contemplate a reason for change.

The inherent flaw in someone going back in time (or the future, for that matter) is to do so one would have to take the whole universe back with them. If one follows the science that all matter is constant, there is no more or less than the alleged Bib Bang, then one cannot take part of this matter back through time and overlay it on matter of the past. To do that would take more power than humans could muster. Furthermore, if it is all connected, it has to be seen like the human body. You cannot take the heart of a person and send it back to the Civil War battle of Shiloh and have it survive, less have the body in present time without a heart survive. To go back n time means you have to take everything. To say you can take the present Earth back in time would leave the present solar system Earth-less, that would cause major problems. About the best anyone could do, is to go back themselves but then they would be in a latent overlapping universe where even if they could see and hear what was going on, they could not interact with it because they would not share the exact same time and space (because they can’t take absolutely everything with them). Maybe those of the past Earth, if they saw anyone at all, would see them as ghost or specters. But for giggles let’s run wild with this a moment, IF, and that is a big “if”, someone could go back and train and arm the Native Americans against the settlers, for example, the change would seem instantaneous if you jumped in your way back machine and came back to the present. To the world the change would be very subtle if noticed at all (how could they tell because the previous past their future, would have been erased and rewritten). The most logical conclusion would be the latent overlap which cannot be affected by time travelers. If I got wind of an inventor of time travel but did not want time travel released upon the world so I use his/her invention and go back in time to where they were in high school and assassinate them, how could I? If I were successful I would never have the time machine I used to go back and kill them because they would never have been able to invent it because they would have mysteriously died (by their present) before they could graduate from MIT with any notion of time travel as to invent the very machine I used to go back and wipe them out. If I were able to go back using their machine I would just be a mere observer watching things as in a extreme 3D movie.

Physicist Sean Carroll has a nice article on time travel. In particular, check out point 9 about the multiple universe interpretation of quantum mechanics. It removes many apparent paradoxes, because the universe that you would be traveling to is not the one that you are currently inl

@Hypocrisy_Central There’s an interesting short story by Fredric Brown you might like.
I can summarize the concept.. But, in the event you want to check it out, I don’t wanna spoil it for you right away.

If you wanna read, it’s here: http://americanliterature.com/author/frederic-brown/short-story/hall-of-mirrors

Or if you’d prefer to listen, it’s here: https://www.youtube.com/watch?v=xbNufmyeFIA

Or I can just summarize.