The Billiard Ball

"The Billiard Ball" is a science fiction short story by American author Isaac Asimov, written in September 1966 and first published in the March 1967 issue of If. It appeared in Asimov's 1968 collection Asimov's Mysteries, in his 1973 collection The Best of Isaac Asimov, in his 1986 collection Robot Dreams and in The Complete Stories, Vol. 2.