To say something is completely impossible means that you know literally everything in the universe. To say that Time Travel is impossible means that you know literally everything about the subject, which is more than Einstein would know more than any theoretical scientist would know. We think that because we can fly in the air in planes and go 100mph in cars that we're so advanced. Bullshit, we know nothing in the grand scheme of things and that is where the heart of the science fiction writer lies believing that somewhere out there in the infinitesimal mass of space/time there are answers that prove us right or wrong.
EDIT: I gotta stop coming on here when I'm drunk! Anyway, the point stands.
EDIT: I gotta stop coming on here when I'm drunk! Anyway, the point stands.