Lets suppose that, a few centuries from now, humanity has a need or desire to send a significant number of craft to other stars. Unfortunately warp drive and other FTL concepts are either still beyond our technology or have been proven to be outright impossible. In this scenario, what kind of propulsion technology would you use and what kind of craft would you build? I would imagine that at that point we might have many giant solar arrays orbiting the sun and beaming power back to Earth. Howeve