Can there be a civilisation that knows future?

             In a short span of 315,000 years of our stay on this planet as humans, we have evolved to predict the future to some extent with some accuracy. For example, we can predict when the sun will rise, how far will that ball go if I throw it, when is the next eclipse, and many small daily life predictions. We may speculate that given few more years, we will gain more scientific knowledge and maybe then we will be able to predict the exact future to an infinite extent in time (although chaos and Quantum uncertainty will trouble us), still lets logically try to see without a lot of technicalities if that's possible.

                  Say there is a civilization with people who can look into the future. Now two scenarios arise, first is, they know the future but they can't change it, and the second is they know the future and can change it.

                Let's take an example to illustrate. Say a guy from that civilization named Mantu knows that tomorrow he will die in an accident on the road. In the first case, he won't be able to change his future and will die the exact way he predicted. In that case, he is no different from a character in a movie recorded on a tape. Even if each character knows what's gonna happen they can't change anything i.e, no response based on the data they have. We don't call a movie character represented by a set of pixels on a TV screen conscious and hence we won't call Mantu, a conscious being. He is just a recorded character. Hence the first case rules out the existence of a conscious civilization that knows the future.

             Now let's look at the second case where the civilization knows the future and can change it. That is, Mantu can evade death by not leaving his home tomorrow and hence not meeting the accident. But in that case, how can they be certain about their knowledge of the future is true? What if all that they had is an illusion that led them to act in a way to result in the real future. Also because what they knew, that didn't happen, contradicts the fact that they knew the future. Hence we can't say that they knew the future. So even in the second scenario, the existence of future knowing civilization is ruled out.

             From the above two cases, we can be certain that there will never be a civilization that knows the future exactly. I rest my case here.