Oh, and Dark Universe by Daniel F. Galouye - excellent book that I would
highly recommend to a younger reader in hopes of getting them hooked on
hard sci-fi.
And here is a great blog post by David Brin filled with great
recommendations:
http://davidbrin.blogspot.com/2011/1...ng-adults.html
He has some great suggestions there, including “Dinosaur Summer” by
Greg Bear, “Ender’s Game” by Orson Scott Card, “The Door into Summer” &
“Have Spacesuit, Will Travel” by Heinlein, “Brave New World”, of course,
& Walter Miller’s “Canticle for Leibowitz”.