Strictly speaking, every science fiction tale presents its own version of future and therefore there are as many science fiction universes as there are science fiction stories. Many SF tales follow dictates of a particular subgenre like Cyberpunk or Space Opera of which, see the separate entry.
... then there are two different solutions x, both of which are real. (Geometrically, this means that the parabola intersects the x-axis in two points.)
If the discriminant ...