From the back cover:

"In The Peace War Vernor Vinge introduced the technology of bobbles, creating spheres where time stands still while minutes, years, or eons pass by outside. Originally used to counter the nucler threat, then to enforce an oppressive government, they don't really come into their own until the century after the Peace War. What better means for one-way time travel? With the bobble plus longevity treatments, human achievements would seem to have no limits... You can hardly turn the pages fast enough... (Marooned in Realtime) is a winner." -- Locus