Here's a scary thought: a creepy, parasitic alien race like the Flood could be out there, waiting for us to stumble upon them. How would we theoretically build one of the gigantic, Flood-killing Halo arrays from the Xbox series of the same name? With super-science, of course.

Larry Niven is best known as author of Ringworld novels and creator of the Known Space universe — but did you know he also helped to reinvent the Green Lantern Corps and their masters, the Guardians?