Edges

This novel is set millennia later in the author's Nanotech Succession universe; I read it without having read the previous books, and it worked great for me -- but it made me go back and read the original series, which is also highly enjoyable. However, that series is not required reading for Edges, which stands on its own.

The series is called The Inverted Frontier because it takes place many eons after humans' exodus from Earth; in the intervening time, the explorers and their descendants, looking back, saw many planets become occluded by Dyson structures, and later only partially-occluded by fragments of those structures. It seems that civilization became greatly-advanced, but that something went wrong. So a number of the descendents, with stasis and advanced drive technology, decide to go back inward to find out what happened to the very advanced civilizations which rose and then fell after their ancestors' departure.

This is a big adventure full of big ideas and the authors' usual excellent extrapolations of science. Highly recommended.