"Science fiction is any idea that occurs in the head and doesn't exist yet, but soon will, and will change everything for everybody, and nothing will ever be the same again. As soon as you have an idea that changes some small part of the world you are writing science fiction. It is always the art of the possible, never the impossible." - Ray Bradbury
Travel to distant planets, discover intergalactical life, multiple dimensions or alternate realities. Read the thought experiments in which authors describe how different our world could be if you would change one or two things about it. In our science fiction section, everything is not only possible, but also often plausible.