Isaac Asimov has some free short stories as well. 'Nightfall' is a very famous one. It explores the idea of a planet where night comes very rarely and what happens when it does. The story is full of scientific and philosophical ideas. Another Asimov story is 'The Last Question', which delves into the concept of entropy and the ultimate fate of the universe. These stories can be found for free on various classic sci - fi literature websites and in some public domain collections.
Well, 'A Sound of Thunder' by Ray Bradbury is a great free sci - fi short story. It deals with the concept of time travel and how small changes in the past can have huge consequences in the future. Then there's 'The Veldt' also by Bradbury. It's about a family living in a high - tech house and the problems that arise when the children become too attached to a virtual reality room that starts to take on a life of its own. Bradbury's stories are often freely available due to their popularity and influence on the sci - fi genre.
One popular free sci - fi short story is 'The Cold Equations' by Tom Godwin. It's a thought - provoking story about a spaceship's pilot facing a difficult moral dilemma. Another is 'Flowers for Algernon' by Daniel Keyes, which, while often considered in the realm of science - fiction related to intelligence, is freely available in short - story form in many places and is quite well - known.