Larry Niven is at the top of his form in this collection of short stories, most of which take place in the futuristic realm of his "Known Space" series. Hard science is probably Niven's biggest strength, and his most effective strategy involves assuming some distinct technological breakthrough, then working out all the physical limitations and social ramifications that said breakthrough implies. For example in "Rammer," the design of the ramjet is interesting, but the clever way it's used to escape a global tyranny is even more fascinating. Still more attractive is the idea of the "displacement booths" which allow instant transportation from one booth to another. Niven discusses the exciting possibilities of this technology, particularly its application to criminal activities.