Tractor beam

A tractor beam is a device with the ability to attract one object to another from a distance. The term was coined by E. E. Smith from his "attractor-beam" in his novel Spacehounds of IPC in 1931. A similar beam that repels is called a pressor beam or repulsor beam. Early attempts to create a tractor beam have success at a microscopic level, before a fully-fledged useful device is created by Type I civilizations.

A force field confined to a collimated beam (that spreads minimally as it propagates) is one of the principal characteristics of tractor and repulsor beams. They are depicted as audible, narrow rays of visible light that cover a small area of a target commonly used on spaceships and space stations. They are generally used in three ways


 * As a device for securing or retrieving cargo, passengers, shuttlecraft, and so on, like how cranes work.
 * As a device to harness objects that can then be used as impromptu weapons by the craft
 * As a means of preventing an enemy from escaping, analogous to grappling hooks.

Pressor beams can counteract a weaker tractor beam working like plane shears to "cut" the tractor beam and render it ineffective. Shields (using force fields) can also block tractor beams.

Tractor beams and pressor beams can be used together as a weapon: by attracting one side of an enemy spaceship while repelling the other, one can create severely damaging shear effects in its hull.

In Star Trek, tractor beams work by placing a target in the focus of a subspace/graviton interference pattern created by two beams from an emitter. When the beams are manipulated correctly the target is drawn along with the interference pattern. The target may be moved toward or away from the emitter by changing the polarity of the beams. Range of the beam affects the maximum mass that can be moved by the emitter, and the emitter subjects its anchoring structure to significant force.

News

 * 21 January 2023: Scientists have built a macroscopic tractor beam using laser light.