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| A '''tractor beam''' is a hypothetical device with the ability to | |||
| A '''tractor beam''' is a hypothetical device (such as by the ] in the ] movies) used at certain lengths with a field intensity beam that "locks" on to an object and can attract that object. On the ] ] on the ] ], it is part of the deflector dish and employs ] particles, the theoretical particles that cause ]. The Enterprise's beam can also be used to repel objects. | |||
| attract one object to another from a distance. Tractor beams are | |||
| frequently used in ] ]s and ]s. They | |||
| have not been demonstrated in real life. | |||
| Tractor beams can be compared to the ] | |||
| An obvious problem to be overcome if a tractor beam is to be viable: Mass-Mass interaction between the source and target objects. If the object emitting the beam (source object) is significantly more massive (e.g. a planet v.s. a ship) than the targeted object, then the tractor beam will draw the target toward it. | |||
| attraction between two masses, or the attraction between two | |||
| ]s. 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 ] ], for example, the tractor beam | |||
| is explained as using ]s, the elementary particles | |||
| speculated to cause ]. 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 | |||
| However, if the two objects are of similar ], then the laws of momentum conservation state that both objects will move toward their mutual center of gravity, with the more massive object moving a smaller distance. Center-of-Gravity and ] concepts are explained in most ] 101 textbooks within the first ten chapters. | |||
| 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 | |||
| Final note: In the case of a planet-ship interaction, the planet is so much more massive than the ship that its motion may be disregarded, as it essentially doesn't move (with respect to the center-of-gravity). A similar case is when dealing with star-planet interactions (the star is way more massive than a planet). | |||
| on ]s and ]s. | |||
| They are generally used in two ways: | |||
| # As a device for securing or retrieving cargo, passengers, shuttlecraft, etc. This is analogous to ] on modern ]s. | |||
| # As a means of preventing an enemy from escaping, analogous to ]s. | |||
| In the latter case, there are usually countermeasures that can be | |||
| employed against tractor beams. These countermeasures may include | |||
| pressor beams (a stronger pressor beam will counteract a weaker | |||
| tractor beam) or ''plane shears'' (a device to "cut" the tractor beam | |||
| and render it ineffective). | |||
| Two objects being brought together by a tractor beam are usually | |||
| attracted toward their common center of gravity. This means that | |||
| if a small spaceship applies a tractor beam to a large object such | |||
| as a planet, the ship will be drawn towards the planet, rather than | |||
| vice versa. | |||
| Tractor beams appear in the following works: | |||
| *] (TV series, movies, books, games) | |||
| *] (movies, books, games) | |||
| *The '']'' books by ] | |||
| *The ''Sector General'' books by ] | |||
| <!-- and surely there are others! Please add them. --> | |||
Revision as of 03:54, 27 September 2003
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. They have not been demonstrated in real life.
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 grappling irons.
In the latter case, there are usually countermeasures that can be employed against tractor beams. These countermeasures may include pressor beams (a stronger pressor beam will counteract a weaker tractor beam) or plane shears (a device to "cut" the tractor beam and render it ineffective).
Two objects being brought together by a tractor beam are usually attracted toward their common center of gravity. This means that if a small spaceship applies a tractor beam to a large object such as a planet, the ship will be drawn towards the planet, rather than vice versa.
Tractor beams appear in the following works:
- Star Trek (TV series, movies, books, games)
- Star Wars (movies, books, games)
- The Lensman books by E. E. Smith
- The Sector General books by James White