Both Gregory Benford and Larry Niven are some of the finest minds in current hard-sci-fi, and this latest collaborative novel is demonstrative of all that makes them fine writers and scientists, as well as what drags them down in a narrative and plotting sense.
Shipstar is the second book in a planned series, one that began with The Bowl of Heaven (2012). In this world, mankind is on its way to colonies the universe when their spaceship collides with a strange spiral world, where they are drawn in and subjugated by a mysterious alien race. The first novel did a great deal to set the scene, and the second one now continues by exploring the odd and fantastic and yet scientifically grounded world that has been created. Aside from the physics discussions, there are also explorations into biology, as a range of odd and fantastic alien species are introduced.
To be perfectly honest however, Shipstar is not my favourite work by either author. Niven particularly seems to be riffing on old material, as his classic Ringworld series just comes across as far too similar, making this one a pale copy by reflection. Both authors also indulge their worst habit, which is to pontificate to a boring extent about the details of their world, without anything actually happening. In fact, very little at all happens in the novel as a whole.
The science is well thought out, and fans of speculative sci fi and hard sci fi might well enjoy this novel, however, I have seen better from both collaborators, which makes this harder for me to digest. Perhaps the series will improve and I will return to it, but the third book will really have to blow my mind at this stage. In the world of fantastic sci-fi, these authors have somehow managed to make it a little boring. Which is a disappointment.