Old sci-fi book where a tunnel with varying values of pi leads to alien civilization
94948
Book about time portals inside an asteroid in Earth orbit
28892
Time Travel Book featuring dinosaurs, cave people, and children
75047
Scifi novel where humans defeat an ancient AI enemy by firing a wave of "slowness", preventing hyperdive space travel
43429
Scifi novel from 90's with AI, robots, and a holodeck-like room
154417
help remembering book title - multiverses/bladerunner-ish future. "sphere of influence. 2150"?
99076
Short story (maybe two in the same collection) about Alien education versus Earth
20264
SciFi book where scientists learn to peek through time (possibly controlled miniature wormhole?). Computer screens were carried like a handkerchief
108699
Book: AI controls what is left of humanity, forces people to live in cave
95235
Story about a sentient star system, in a 50s or early 60s anthology
60657
Title of a book telling about people teleported to a hostile planet while in deep meditation
62073
Wormhole-like tunnels used to look back in time
93979
Help Identifying a Sci-Fi Book: Humans transported to alien world and given tasks to escape
128624
Trying to remember the name of a grade-school book about an alien in a cereal box
89070
Unknown Science Fiction Space Book
111401
Short sci-fi story about Earth blockaded by other human colonies
17179
80's (or earlier) book about a role-playing group getting sucked into a new realm
62827
90s-2000s sci-fi book: detective that travels to an alternate world that is first viewed from an airplane