Does shooting a laser from a laser generator not generate opposite force of the beam output? Do photons from a laser upon impact of a reflective surface cause an inertial reaction, no matter how infinitesimal? If lasers have no "kick" upon firing, and photons from a coherent laser do cause an inertial reaction, then lasers could be used as reactionless propulsion. It would be interesting to note simple reactionless propulsion from mirrors. "How is it done? Mirrors. "My initial design ideas would be a ring of lasers around a hole in a sphere pointing towards a parabolic mirror on the other side. The engine could be mounted on a gimbal or gyrodyne setup for directional reactionless propulsion. As a craft propelled by such moved along, it's trail would be a beam of coherent light flying at the speed of light away from the engine. If the force from firing a laser and its reaction upon impact cancel, then this would not work. If it does work, it is copyrighted by me. Fifth- or higher dimensional travel would still be preferable as it would eliminate any concerns of distance. Have a nice day,-- Ross Andrew Finlayson 202/387-8208 http://www.tomco.net/~raf/ "C is the speed of light."