Hard Science and Tall Tales

I've always admired Isaac Asimov's Foundation series of novels for covering such a long span of human history -- as much as 10,000 years, as I recall. Stephen Baxter expands that number by two orders of magnitude, covering five million years of human history, or at least history after the beginning of humanity (hint -- humans may not necessarily be around forever, at least in this universe!). Using wormhole and, later, string theory to explain interstellar ship technology, Baxter tells the story of a humanity that accidentally discovers that its home sun, and its entire universe, is doomed to an early death just a few million years away. How the main characters manage to be there at the beginning and the end of this five million year adventure is difficult to explain. Let's just say that when you combine advanced alien technology, time travel, and hard-wired human determination, such things are possible. If, perhaps, a little creepy when you read about what 1,000-year-old humans look like.