I love science fiction, and have been reading and watching it in all it's forms for thirty years. I am mostly into hard sci-fi, as opposed to soft sci-fi. Hard sci-fi refers to science fiction that is based on scientific reality at the time of it's creation, whereas soft sci-fi does not need to have a basis in reality whatsoever. Soft sci-fi in my opinion can be called sci-fantasy, as there is no significant science behind it's ideas.
Writers like Arthur C. Clarke and Issac Asimov are hard sci-fi writers, while most modern sci-fi movies are soft sci-fi, more concerned with special effects and futuristic-looking ideas that any adherence to real science. Hard sci-fi typically has a social commentary element to it, like the old Twilight Zones, usually implemented as a form of allegory or metaphor. Social commentary in modern science fiction is sadly lacking.
I love shows like Fringe, as they attempt a level of hard sci-fi dedication, while embracing some newer ideas such as multiverse and parallel dimensions. But is multiverse sci-fi really hard science, or is is soft as can be? This fun and informative video gives a brief overview of the different theories around parallel universes. As you can see, they are all completely theoretical. I don't think anything that is pure theory can be called science. But, will say I think mathematical model #1 in this video is the most plausible.
This video comes via minutephysics.