What Classifies as Science Fiction?

Today we touched on the subject of what actually can be classified as science fiction? Is it something that is impossible in the present but plausible at some point in the future? Is it something far removed from our realm of reality and the world as we understand it? While I was home last month my mother dvr'ed "Joan of Arcadia". I found it fascinating that the reruns were playing on scifi...or I guess "syfy" now (a name change which I find ridiculous but that's beside the point). I talked to my mother about this and she said "yeah, it's weird; talking to God is not science fiction--if so, the Bible is a sci fi text written by a bunch of crazies". I had to keep my mouth shut so as not to laugh or offend but it was at that point I realized science fiction is all about perception. To me, and to the powers that be on the sci fi network, the plot of "Joan of Arcadia" is impossible and can be classified as science fiction. To my mother it was just very plausible fiction. Basic point of this babble: Sci fi is in the eye of the beholder.