An unabridged collection spotlighting the best hard science fiction stories and novellas published in 2023 by current and emerging masters of the genre, edited by Allan Kaster.

"The Last Cathedral of Earth, In Flight" by Tobias S. Buckell - The last of humanity flees, among the stars, from alien Prowlers. "The Unpastured Sea" by Gregory Feeley - A mission to the planet Neptune runs into many setbacks. "The Tinker and the Timestream" by Carolyn Ives Gilman - Colonists on a planet orbiting a decaying sun encounter interstellar time travelers. "Six Incidents of Evolution Using Time Travel" by Derek Kuensken - Time travel is found to be encoded in the DNA of some alien species. "Cloudskimmer" by Geoffrey A. Landis - Robots and humans team up to explore Venus. "Even if Such Ways Are Bad" by Rich Larson - A two-person crew goes on a deep space mission inside a living wormship. "The Enthnomusicology of the Last Dreadnaught by Yoon Ha Lee - The battle glory of an atrocious weapon of war is honored. "Exiled to Gravity" by Marissa Lingen - A mysterious ailment hampers an engineer's return to space. "Clockwork Melting by James Maxey - An immortal races against time to complete an ice sculpture on Venus. "The Elephant Maker" by Alec Nevala-Lee - Scientists clash with hunters and poachers for a rogue elephant needed to test a brain implant. "The Ghosts of Mars" by Dominica Phetteplace - A teenager struggles to survive on Mars amidst peculiar phenomena attributed to ghosts. "The Many Different Kinds of Love" by Geoff Ryman with David Jeffrey - After ten years of silence, an abiotic intelligence on Enceladus receives unauthorized messages from Earth. "Lemuria 7 Is Missing" by Allen M. Steele - The disappearance of a passenger moonship is scrutinized. "Defective" by Peter Watts - A zero-sum battle for survival rests on the ability of a scientist to communicate with an alien species. "OCASTA" by Daniel H. Wilson - An AI, with an algorithm that analyzes and learns, has a story to tell.