In short stories like “The Immortals” and novels like “The Listeners,” Mr. Gunn helped prepare readers for the future.In short stories like “The Immortals” and novels like “The Listeners,” Mr. Gunn helped prepare readers for the future.Read MoreGunn, James (1923-2020), Deaths (Obituaries), Science Fiction, Writing and Writers, Books and Literature, The Listeners (Book), The Immortals (Book), Isaac Asimov: The Foundations of Science Fiction (Book)