[FreedomPoster]

I may be giving away an important plot element, but Project Orion appears as an important plot element in Niven and Pournelle’s Footfall.

http://www.amazon.com/Footfall-Larry-Niven/dp/0345323440

Good stuff, as are most if not all of their collaborations.

[TChad]

Project Orion appears as an important plot element in Niven and Pournelle’s Footfall.

I first heard of Dyson spheres in a Larry Niven's "Ringworld."

That's a sun in the middle of a gigantic (artificial) Dyson sphere.