Diaspora Is the Chewiest Hard Sci-Fi I've Finished This Year

Grabbed this off a recommendation thread that warned me not to even attempt it unless I was solidly into hard sci-fi with some actual physics background, and honestly the warning undersold how chewy this book gets. Diaspora opens with a character being born as pure software inside a polis, one of several digital city-states humanity has splintered into by the thirtieth century, alongside gleisner robots and the fleshers who stayed behind in actual bodies, and from there Egan just does not slow down for you.

The concepts are the whole draw here, running personalities on substrates other than gray matter, what it means when there can be multiple copies of the same person existing at once, distances and timescales stretching out to genuinely cosmic proportions once the plot leaves Earth behind. Somebody compared the vertigo of it to Arthur C Clarke and Olaf Stapledon at their most cognitively overwhelming, and that’s about right, there’s a specific kind of dizzy feeling reading a chapter where the scale of what’s being described outpaces what you can actually picture.

Where it lost me a little was the human side of things, the characters are so far removed from anything resembling ordinary human concerns by the second act that I had trouble caring what happened to any specific one of them, which is a real tradeoff for a book this committed to following its ideas wherever they lead. The middle stretch also gets noticeably angrier in tone than the rest, enough that I know at least one other reader almost put the book down there, though I pushed through and the payoff in the final section was worth it.

Not a book I’d hand to someone looking for an easy entry into science fiction. If you already like your sci-fi hard enough to require actual physics vocabulary, this delivers more genuinely new ideas per chapter than almost anything else on my shelf.