Somehow, I suspect Diaspora is unlikely to reach the best-seller charts. No reflection on the author, but the degree of intellectual commitment (read: serious skull-work) required of the reader may be off-putting. Egan seems to be consciously testing the limits of traditional fictional narrative as a medium for exploring arcane, outer-edge speculations in physics and computer science. Hard science? Any harder and he’d be writing it in tensor equations.

Consider: a novel in which flesh and blood humans make only a brief, doomed appearance. All the principals are sentient AIs: self-aware computer programs. Consider further: the mind-bending implications of a continuum with six spatial dimensions rather than the ‘usual’ three. Visualising, let alone understanding, 6D space is no easy task, and Egan allows no convenient shortcuts.

Yet, for those prepared to put in the effort, Diaspora is exhilarating; an achievement of the first order. Immense in scope of time and space; awesome science which truly reveals that (to paraphrase a famous quote) 'the universe is not only stranger than we imagine, it’s stranger than we can imagine'. They used to call it ‘sensawunda’. And last but not least, Diaspora is profoundly philosophical, setting serious questions on the nature of humanity itself, once liberated from the primitive wetware. What, in other words, defines ‘human’? In Egan’s work, form is irrelevant. His AIs, or the Gleisners – humanoid, almost Asimovian, robots – are entirely human in all that matters. Need I say, ideas which can only be expressed in SF, and this is sf at its most uncompromising.