Assume that mankind could create a computer-like device that would simulate the life and path of every particle in our universe and show us everything that has happened and everything that will happen. You could enter time and coordinates and the device would show you a picture.
Since we don't have free will, we could do nothing to alter the future that this device would illustrate.
What would happen?
Just looking at an image of yourself in the future could have some fairly detrimental consequences and the illusion of free will probably wouldn't last very long?
Is there some paradox related to this?