Unfortunately those who have worked out the physics for Bussard ramjets in detail find that they don't really work as an energy source or a propulsion mechanism

Unfortunately those who have worked out the physics for Bussard ramjets in detail find that they don't really work as an energy source or a propulsion mechanism while cruising. Indeed - more useful as a brake. See http://www.centauri-dreams.org/?p=22115 http://www.centauri-dreams.org/?p=22115 for some pointers.