<i>So I&#x27;m expecting any successful civilisation to start colonising the spaces between the stars, rather than the star systems themselves.</i><p>Before you start writing your book, you might want to familiarize yourself with the prior art in the field: start with the short story &quot;Swarm&quot; by Bruce Sterling, then the novel &quot;Permanence&quot; by Karl Schroeder, &quot;Blindsight&quot; by Peter Watts, and maybe &quot;Diaspora&quot; by Greg Egan. That&#x27;s assuming that by &quot;planning a book&quot; you&#x27;re thinking in terms of fiction rather than SETI-oriented non-fic, but even if you&#x27;re writing non-fic it&#x27;s worth noting that we SF authors have been all over the topic for decades. (As for non-fic, the prior art goes all the way back to J. D. Bernal&#x27;s &quot;The World, The Flesh, and The Devil&quot;, if not further: I don&#x27;t read Russian but I gather Nikolai Federov wrote on the subject, as did Konstantin Tsiolkovsky.)