Probes and people will travel across the stars as femtobyte electro-magnetic waves (cosmic rays) ala Rudy Rucker. It's the only way to travel.
That reminds me of an idea I had once...I envisioned a
magnetic propulsion system, utilizing gyroscopes or whatever (I am NOT well versed in physics), in which a strong magnetic field is created which "attracts" the craft from the front and "repels" the ship from the rear.
Thus the poles for the magnetic field have to be "projected" to a point outside the ship by some sort of field amplifier. The poles have to be reversible to stop.
Also, humans would have to be shielded or isolated from a magnetic field of that strength.
I'm sure this is impossible or someone would have thought of it...but it seems more likely than the other crazy propulsion systems I've read about.