DESPITE BEING SET mostly on earth and in this century, David Brin’s Existence is science fiction on a grand scale. Brin has long been one of the leading American writers of hard SF, his work informed by his own strong scientific background, which includes a PhD in astrophysics from UC San Diego. While one of his novels, The Postman, was developed into a major Hollywood film in 1997 (with somewhat unfortunate results), he is best known as the author of the imaginative “Uplift” series, set in a universe in which advanced races use their knowledge to “uplift” less developed species to the fulfillment of their potential as intelligent spacefaring beings. Brin’s latest novel, Existence, is in many ways less optimistic about the future of galactic civilization, though it is perhaps the most ambitious of all his novels in a literary sense. Those ambitions are largely fulfilled, and, as a result, Existence may be Brin’s masterwork.

Set mostly in the mid-twenty-first century (though the plot extends for several decades), Existence is, among other things, a veritable encyclopedia of SF concepts and subgenres. An inventive alien-contact story lies at the heart of the novel, while much of its science-fictional technology derives from the legacy of cyberpunk but moves beyond most cyberpunk to contemplate the potential of a genuinely posthuman future. Along the way, Brin also injects elements of political intrigue, space opera, media satire, class warfare, and post-disaster (economic, environmental, and nuclear) recovery efforts. Existence even includes one plot strand related to the Uplift series, though this novel appears to take place in a different universe in which human efforts to uplift dolphins have hit a snag due to lack of funding and in which interstellar species mostly strive to destroy, rather than uplift, each other.

All of this thematic and generic complexity is conveyed by means of an intricate narrative: each of the major characters is involved in his or her own subplot, which is often only loosely and incidentally related to the others. Perhaps the central character is one Hamish Brookeman, a science-fiction writer who might in some ways be taken as a stand-in for Brin himself, though in this future world different media have thoroughly converged so that Brookeman creates not just novels but also films and video-games, without much sense of a distinction between these different forms. Meanwhile, most of Brookeman’s works are (unlike Brin’s) cautionary tales of technology gone wrong, and the author himself is, through much of the book, in league with a conspiracy of trillionaire oligarchs to seize power and establish a feudal political system in which technological progress is disavowed in the name of greater stability, with themselves serving as the aristocratic rulers. It is not clear how the economy would work under such a set-up, while this emphasis on wealthy neo-aristocratic individuals seems to underestimate actually existing corporate power. Nevertheless, Brin’s portrayal of the super-rich is surely one of the book’s strengths, and his satirical treatment of their feelings of entitlement is not only effective but timely.

Another particularly important character is Tor Povlov, an online journalist whose body is virtually destroyed in a would-be terrorist attack but who is able to live on encased in a “survival capsule” while her mind continues to roam free in the virtu...