Charles A. Sheffield was an English-born mathematician, physicist and science fiction author, whose words are collected here in one of his most iconic short story collections ever published, Hidden Variables. Known for his ability to incorporate real science into his fiction, Sheffield's stories exposed the potential flaws and triumphs of the human mind, by showing us that even if we've evolved enough to gain mastery of technology and advanced science, we can still fall prey to our selfish and emotional natures-but on a scale that can affect the rest of humanity. In "The Man who Stole the Moon" Sheffield tells of the depths one man will descend to overcome the bureaucratic stifling of initiative that happens when those in power aren't willing to grant someone's visions for the future. Will simple red tape prevent Man from leaving Earth to make the greatest leap for all of humanity? In "Forefather Figure," can the wish for us to know more about the Cro-Magnon's, our ancestors of an era long gone, justify creating the technology to help a man cheat death, only for the scientist to then use that life to achieve his own ends? And in "Hidden Variables," the story this collection was named after, can the mere potential for one man's greatest scientific achievement to have wide-ranging adverse consequences mean his murder is something that can be sanctioned? Whether it's a short story on one man's atonement after a murder in "From Natural Causes," or the discovery of a child prodigy on a generational asteroid ship, bound for a new colony in "All the Colors of the Vacuum," or the breathtaking tale of loss and redemption in "Summertide", the variations in the stories Sheffield wrote can be quite profound, but his talent was by no means hidden.