What the heck has "science fiction" to do with belief or non-belief in ghosts?? (or God, for that matter -- ?)

It's a literary genre of fiction "that often involves speculations based on current or future science or technology". No specification or exclusion of exploration of spiritual topics in that...

Maybe you really meant to refer to the fiction genre of Fantasy, as in the sort that involves, magic, etc?

At any rate, they call it "fiction" for a reason -- you don't have to believe it's true to enjoy a story...

~ Becky in Tucson