[Spaceships] Your preferences regarding plausible/playable Reactionless Drives

[teviet]

Originally Posted by sir_pudding

This a problem with any model of gravity that requires particles. I think it's becoming increasingly clear that "gravitons" probably don't exist.

"Gravitons", like "photons", are just a way to describe the quantization of energy and angular momentum in a field. We don't yet have a full theory of quantum gravity, but such a theory most likely will include gravitons. From "semiclassical" models of gravitational waves on a nearly-flat nearly-static background, it's predicted that gravitons are "spin-2 tensor bosons"; that is, they carry twice as much angular momentum as a photon.

Regarding the tractor/pressor beam, this will violate local energy/momentum conservation unless the beam itself has significant rest mass in the frame of whatever you're pushing against. (That is, it's more like the "beam" of a building than the "beam" of a laser.)

Otherwise what you have is a gravitational rocket, which has the same performance characteristics as a photon or a neutrino drive, except that the exhaust stream consists of gravitons. For a given wattage, a graviton beam is even less detectable than a neutrino beam, so a graviton rocket is actually an ideal "reactionless" thruster, if you want something whose exhaust passes intangibly through the interior of your ship, planet, or star.

TeV