Reactionless Drive: Difference between revisions

 

== Anime ==

 

 

== Comic Books ==

* Most super heroes who can [[Flight|fly]] under their own power in space have some form of reactionless drive, [[Required Secondary Power|even if the comic's authors don't call it this]]. [[Superman]], for example, can accelerate, decelerate, and turn in Earth orbit, with no (obvious) rocket exhaust coming out.

 

== Literature ==

* The [[Trope Namers]] is [[Larry Niven]]'s [[Known Space]] universe stories. The utility of this technology is made clear in the ''[[Ring World]]'' books as it allows the ships to remain stationary relative to the Ringworld for extended periods.

* ''Ender In Exile'' actually plays this one fairly straight as far as power goes. The starship engines work with a directional forcefield, dissolving space debris in front of the ship and propelling it out the back. Of course, it was the same dissolving technology that created the Little Doctor Device, a weapon that rips molecules apart, increasing by proximity of mass. Meaning that if someone drove the ship's engine into a sizable mass (say, a planet) the entire structure would unweave.

* The ''Cities in Flight'' series has the Dillon-Wagoner Graviton Polarity Generator or "spindizzy" which gets more efficiency when it moves greater amounts of mass.

* [[Isaac Asimov]] featured such a drive ''in The Gods Themselves''. It worked through the momentum being shunted into another dimension.

* The eponymous technology in [http://worldebookfair.org/eBooks/Baen_Library_Collection/038075357X.pdf Anti-Grav Unlimited] are rods that act like "gravity magnets". Through experimentation, he not only manages to create a perpetual motion engine for his van (by welding two rods perpendicular to each other so that they're always being pulled up on one side and down the other), but also manages to rig rods such that he can make the van fly.

* In ''Stone'' by [[Adam Roberts]], reactionless propulsion is achieved by extremely rapid teleportation in infinitesimal steps. This can even be applied to an individual, who can be wrapped in a protective shell, with life-support equipment and a teleportation device, and then sent off to their destination through interstellar space. The speed of this mechanism is affected by gravitational fields, where a stronger field requires more complex calculation (and thus less rapid steps). The reader may notice this sounds exactly like the Stutterdrive mentioned for ''[[Sword of the Stars]]'' under Video Games. As Stone was published in 2003, and the game in 2006, I can only assume it was half-inched.

** [[Larry Niven]] proposed more-or-less this design in his "The Theory and Practice of Teleportation", originally a speech at [[Fan Convention|Boskone]] in 1969.

 

 

** A sail is not a truly ''reactionless'' drive - indeed, such a thing may not actually be possible. In the case of a solar sail, for example, the ship doesn't carry fuel but it still has reaction mass, because it's still a Newtonian reaction generating the sail's thrust. In this case the reaction mass is ''photons'' from the sun.

*** Magnetic sails transfer momentum without transferring mass. And so far, no one has demonstrated that photons have mass.<ref>Under the Standard Model of particle physics, photons don't have mass, but they do have energy and momentum.</ref> Some people insist that reactionless drives violate conservation of momentum ''by definition''. This is not the definition used in this article (see above description). But this is why Dr Woodward prefers "impulse engine" for a Mach Effect drive.

** A photon drive fits our definition; photons do exert pressure, and they are massless. A photon drive only consumes power. Unfortunately, a photon drive is horribly inefficient.

** The Ambient Plasma Wave Drive would use ambient plasma as its reaction medium, generating waves in it to propel itself. Sort of like how a propeller uses ambient air (or water) to create thrust.