Phase Space, subtitle: Stories from the Manifold and Elsewhere (published by Voyager an imprint of HarperCollins, ISBN 0-00-651185-6) is a 2003 science fiction collection by Stephen Baxter containing twenty-three thematically linked stories, in which the human relationship with the universe is explored: whether we are truly alone, if there are other intelligent species, if these have turned their backs on us, or if expansion itself is destined to fail. Maybe the reality we know is nothing but an elaborate hoax, protecting us from something far more sinister.

Written in the same style as most of Stephen Baxter's work, Phase Space is a collection of more or less scientifically based stories, in the tradition of Arthur C. Clarke.

The book contains the following short-stories:

• Prologue
• Dreams (I)
  • Moon-Calf
• Earths
  • Open Loops
  • Glass Earth, Inc.
  • Poyekhali 3201
  • Dante Dreams
  • War Birds
• Worlds
  • Sun-Drenched
  • Martian Autumn
  • Sun God
  • Sun Cloud
• Manifold
  • Sheena 5
  • The Fubar Suit
  • Grey Earth
  • Huddle
• Paradox
  • Refugium
  • Lost Content
  • Tracks
  • Lines of Longitude
  • Barrier
  • Marginalia
  • The We Who Sing
  • The Gravity Mine
  • Spindrift
  • Touching Centauri
• Dreams (II)
  • The Twelfth Album
• Afterword
• Acknowledgements