Famous for his work in math, astronomy, nuclear engineering, and theoretical physics, Freeman Dyson has left his mark on almost every scientific discipline. He's won countless awards, and written numerous books on a wide range of topics both scientific and philosophical. One of his biggest contributions to science was the unification of the three versions of quantum electrodynamics invented by Feynman, Schwinger and Tomonaga. 10 years after moving to the U.S. he started working on the Orion Project, which sought to create a spacecraft with a nuclear propulsion system. STNG exposed the idea of a Dyson sphere to the masses, and his hypothetical plan for making a comet habitable with the help of genetically-engineered plants is a personal favorite. Mr. Dyson has graciously agreed give us a bit of his time in order to answer your questions. As usual, ask as many as you'd like, but please, one question per post.