The brightest minds in our field have been trying to find a definition of science fiction for these past seventy years. The short answer is, science fiction stories are given as possible, not necessarily here and now, but somewhere, sometime.
Larry NivenThere had been a popular joke on Freedom, started by a man named Calder. Looking down from space, he had said, the dominant life forms on Earth were obviously the cereals and other grasses. They occupied all the most desirable and fertile land; and they had tamed insects and animals to care for them. In particular, they had domesticated the bipeds to nurture and cultivate them and to save and plant their seed. Now, watching the farmers, Alex could easily imagine that they were worshiping and genuflecting before their masters.
Larry Niven