[iansales]

I don't think that's true. Sf doesn't have to be set in the future, or space, or feature time travel or space travel. Would a post-holocaust novel set next year be science fiction? Would a novel set next year in Iraq after the troops have finally withdrawn be sf?

To me, a story is science fiction is it is involves some invented object or process which is either defines the setting or plot or creates the setting or plot.