Spacecraft need so much fuel to travel interstellar distances that fuel becomes the only thing they can bring along. Are there any solutions to this problem? This article looks at two: interstellar ramjets and antimatter drives.
Astrophysicist Philip Lubin has said, “Chemistry will get you to Mars, but it won’t get you to the stars.” What did he mean by that? And, if chemistry won't get us to the stars, what will?