How To Travel To The Stars

A few weeks back we chatted to Chris Wanjek about human spacefaring and he briefly talked about hollowing out an asteroid to use as an interstellar spacecraft. 
This got us thinking about the idea of interstellar travel so we decided to find ourselves a scientist who was working on that precise thing.
Our regular listeners will probably be unsurprised to hear that there is not just one scientist engaged in this research but numerous organisations
Andreas Hein is the Executive Director of one such organisation;  The Initiative for Interstellar Studies