The Fiction/Science Fiction Interface

"'They'll find the molecular basis of heredity, approximately ten years from now.'
"'What?' I sat bolt upright. 'This you've got to tell me more about!'"
-Poul Anderson, There Will Be Time (New York, 1973), V, p. 47.

In this dialogue, the first speaker, Jack Havig, knows what will happen ten years hence because he is a time traveler. That is science fiction. The molecular basis of heredity will be discovered. Is that science fiction? No, because the book was published in 1973. But exactly that same sentence:

"They'll find the molecular basis of heredity..."

- would have been sf if published fifty years earlier.

A contemporary novel by the same author could have featured a minor character called Jack Havig. The reader would have learned that that character was a time traveler by reading There Will Be Time. Also, ambiguity is possible: Jack tells fascinating stories about the future Maurai Federation that he claims to have visited. Is he really a time traveler or just a good story-teller?

I think that imaginative writers can probably do more creative work at this interface between genres. A historical novel, a contemporary novel and a futuristic novel could be linked by the reader's knowledge that one of the characters is an immortal or a time traveler.