Stephen Baxter's Vacuum Diagrams is a collection of short stories set in the universe of his Xeelee sequence, spanning a timeline from the 3500s to several million years in the future - at the time our Universe (in the form we know it) is ending. It's a good example of a single, self-contained, well-developed future history serving as a backdrop for many stories - much like Cordwainer Smith's Instrumentality universe, Alastair Reynolds' Revelation Space universe, Paul McAuley's Quiet War universe or Asimov's Robot/Foundation universe. I generally like the future history approach to sf world-building a lot - it tends to lead to large, interesting universes in which many interesting stories can take place. The Xeelee universe is no exception, and Vacuum Diagrams gives an excellent little collection of stories that happened at various points of that universe's future history.
The short stories recount various events and anecdotes that happen in various eras of human history - the expansion of human culture into the rest of our solar system (and discovery of various kinds of extremely alien lifeforms here), the two epochs where humanity was conquered and enslaved by aliens (the ﬁshlike Squeem and the amorphous Qax, respectively), humanity's domination and assimilation of most of the other lifeforms in the galaxy, the massive species imperative-level military campaign against the Xeelee, the defeat of humanity by the Xeelee, and the defeat of the Xeelee by the dark matter-based photino birds. The protagonists are usually human or posthuman, with a few alien protagonists (and a few humans so far removed from modern humanity that they might as well have been aliens).
As is common for Baxter, Vacuum Diagrams is hard sf. Faster-than-light travel is possible - but so is time travel (this is in fact one of the main points about the history of the Xeelee species itself). There are a number of phenomena that aren't consistent with modern science - but they all have well-explored implications. The result is a consistent universe for Baxter to play with a variety of scientific what-ifs. His math and physics background clearly shows.
I generally have mixed feelings about Baxter's novels, because they tend to have two major failings - both of which are fortunately absent from his short stories. First, his characters tend to show very little character development. This is generally less of a problem in short stories, because the characters typically don't have the time to develop meaningfully anyway. Second, he tends to write very unsatisfying endings for his novel-length outings – however, the stories in Vacuum Diagrams didn't suffer from this. I generally ﬁnd his short stories consistently enjoyable - in fact, the same applies to Traces (another Baxter short story collection; I should probably review it here at some point).
Highly recommended. If you're not well-versed in the Xeelee universe, it's a good place to start.