Is it possible to build a space drive that doesn't expel reaction mass?

Erm…relativity is quite mute on the subject of whether or not artificial gravity is possible or not. Quite simply we do not know.

One way to propel a ship to a good fraction of the speed of light that is doable with today’s knowledge is with a microwave laser generated from a solar power station in orbit. The beam would shine on a microwave reflective carbon mesh and accelerate it to high speeds. The ship doesn’t have to carry any fuel, and thus is far easier to accelerate. There’s a rather good article on it in the Jan/Feb issue of the Planetary Report. Not having to carry around reaction mass makes the mission much easier.

I’m surprised nobody’s mentioned this yet, but legendary author/editor John Campbell was a firm believer in The Dean Drive, a supposedly reactionless drive system that didn’t require you to throw reaction mass out the back. Campbell was a truly fascinating person – he knew and anticipated some of the great scientific inventions and events of the 20th century, yet he believed in the Dean Drive, the Hieronymous Machine, ESP, Psionics, Dianetics/Scientology, and “critical action time” physics. A weird mixture of up-to-daye science and pseudoscience.

Rats! :stuck_out_tongue: