Tractor beam
A tractor beam is a hypothetical device with the ability to
attract one object to another from a distance. Tractor beams are
frequently used in science-fiction books and movies.
Tractor beams can be compared to the gravitational
attraction between two masses, or the attraction between two
magnets. They differ from such natural attractive forces in that
they operate in a particular direction or on a particular object. The
theory of operation depends upon the story they are used in. In
the Star Trek television show, for example, the tractor beam
is explained as using gravitons, the elementary particles
speculated to cause gravity. In some cases, the theory is not
explained, and is left to the imagination of the reader or viewer.
Tractor beams are sometimes depicted as being reversible, so they
repel the other object rather than attracting it. When used in this
mode, they may be referred to as pressor or repulsor beams.
The most common place where tractor beams are used is
on spaceships and space stations.
They are generally used in two ways:
- As a device for securing or retrieving cargo, passengers, shuttlecraft, etc. This is analogous to cranes on modern ships.
- As a means of preventing an enemy from escaping, analogous to Star Trek (TV series, movies, books, games)
In the real world, scientists are able to manipulate objects at the atomic and molecular scale using lasers, but no technology capable of manipulating bulk matter with the level of precision envisiaged in science-fiction has yet been devised.
