Henry Beam Piper was an engineer as well as a mystery and science-fiction writer. He was born in Altoona, Pennsylvania, and lived most of his life around Williamsport, where he served on the engineering staff of the Pennsylvania Railroad. On 11 November 1964 he committed suicide, possibly because of family problems.

Piper began his career as a writer a few years after World War II, "the Golden Age" of science fiction and a boom period for science-fiction journals. His first short story, "Time and Time Again," appeared in the April 1947 issue of the leading magazine of the day, Astounding Science-Fiction . Between 1947 and 1964 Piper contributed sixteen stories to Astounding Science-Fiction and seven stories to other important science-fiction periodicals. In about half of these short stories Piper develops the "paratime" concept with special emphasis placed on the necessity of policing across alternate worlds. Piper's paratime idea is based on the imaginative conception...