Description: You travel back in time and kill your grandfather before he conceives one of your parents, which precludes your own conception and, therefore, you couldn't go back in time and kill your grandfather. The grandfather paradox is a proposed paradox of time travel which results in an inconsistency through changing the past. The paradox is described as follows: a time traveller goes back in time and kills his grandfather, eliminating the possibility of one of the time traveler's parents ever coming into existence. As a result, the time traveller is never born. But if the time traveller is never born, then he does not travel through time and kill his grandfather, which means the time traveller is born after all, and he kills his grandfather, and so on "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 concept termed the grandfather paradox of time travel first described by the science fiction writer Ren e Barjavel in his 1943 book Le Voyageur Imprudent.