Poul William Anderson ( November 25 , 1926 â `` July 31 , 2001 ) was an American science fiction author . He began his career during the Golden Age of the genre and continued to write and remain popular into the 21st century . Poul William Anderson ( November 25 , 1926 â `` July 31 , 2001 ) was an American science fiction author who began his career during one of the Golden Ages of the genre and continued to write and remain popular into the 21st century .