This week it's two short stories --A Sound of Thunder: “A Sound of Thunder” is a science fiction short story by Ray Bradbury, first published in Collier's magazine in the June 28, 1952 issue. As of 1984 it was the most re-published science fiction story up to the present time. It is based on the idea of the butterfly effect (though the story predates that phrase).Nightfall: “Nightfall" is a 1941 science fiction short story by Isaac Asimov about the coming of darkness to the people of a planet ordinarily illuminated at all times on all sides.