Acknowledgment is made for permission to reprint the following material:
"Fermi and Frost," by Frederik Pohl. Copyright © 1984 by Davis Publications, Inc. First published in Isaac Asimov's Science Fiction Magazine, January 1985. Reprinted by permission of the author.
"A Desperate Calculus," by Gregory Benford. Copyright © 1995 by Abbenford Associates. First published (as by "Sterling Blake") in New Legends (Tor). Reprinted by permission of the author.
"Evolution," by Nancy Kress. Copyright © 1998 by Nancy Kress. First published in Asimov's Science Fiction, October 1995. Reprinted by permission of the author.
"A Message to the King of Brobdingnag," by Richard Cowper. Copyright © 1984 by Colin Murry. First published in The Magazine of Fantasy and Science Fiction, May 1984. Reprinted by permission of the author and the author's agent, Georges Borchardt, Inc.
". . . The World, as We Know't," by Howard Waldrop. Copyright © 1982 by Flight Unlimited, Inc. First published in Shayol #6, Winter 1982. Reprinted by permission of the author.
"The Peacemaker," by Gardner Dozois. Copyright © 1983 by Gardner Dozois. First published in Isaac Asimov's Science Fiction Magazine, August 1983. Reprinted by permission of the author.
"The Screwfly Solution," by Raccoona Sheldon. Copyright © 1977 by Alice B. Sheldon. First published in Analog Science Fact/Science Fiction, June 1977. Reprinted by permission of the author's estate and the agents for the estate, Virginia Kidd.
"A Pail of Air," by Fritz Leiber. Copyright © 1951 by Galaxy Publishing Corporation. First published in Galaxy, December 1951. Reprinted by permission of the author's estate and the agents for that estate.
"The Great Nebraska Sea," by Allan Danzig. Copyright © 1963 by Galaxy Publishing Corporation. First published in Galaxy, August 1963. Grateful acknowledgment is made for this story.
"Inconstant Moon," by Larry Niven. Copyright © 1971 by Larry Niven. First published in All the Myriad Ways (Ballantine). Reprinted by permission of the author and the author's agent, Eleanor Wood, Spectrum Literary Agency.
"The Last Sunset," by Geoffrey A. Landis. Copyright © 1996 by Dell Magazines, Inc. First published in Asimov's Science Fiction, February 1996. Reprinted by permission of the author.
"Down in the Dark," by William Barton. Copyright © 1998 by Dell Magazines. First published in Asimov's Science Fiction, December 1998. Reprinted by permission of the author.