I'd note that another critical, showstopping problem is shielding against the interstellar medium when moving at relativistic speeds. http://en.wikipedia.org/w

I'd note that another critical, showstopping problem is shielding against the interstellar medium when moving at relativistic speeds. http://en.wikipedia.org/wiki/Interstellar_travel#Interstellar_medium http://en.wikipedia.org/wiki/Interstellar_travel#Interstella... http://www.academia.edu/4692178/Speed_kills_Highly_relativistic_spaceflight_would_be_fatal_for_passengers_and_instruments http://www.academia.edu/4692178/Speed_kills_Highly_relativis... http://arxiv.org/ftp/physics/papers/0610/0610030.pdf http://arxiv.org/ftp/physics/papers/0610/0610030.pdf