AskDefine | Define wormhole

The Collaborative Dictionary

Wormhole \Worm"hole`\, n. A burrow made by a worm. [1913 Webster]

Word Net

wormhole n : hole made by a burrowing worm

English

Alternative spellings

Etymology

worm + hole

Noun

  1. a hole burrowed by a worm
  2. A hypothetical shortcut between distant parts of space, permitting faster-than-light travel and time travel.

Synonyms

Translations

a hole burrowed by a worm
a shortcut between distant parts of space
...
Lorentzian wormholes known as Schwarzschild wormholes or Einstein-Rosen bridges are bridges between areas of space that can be modeled as vacuum solutions to the Einstein field equations by combining models of a black hole and a white hole. This solution was discovered by Albert Einstein and his colleague Nathan Rosen, who first published the result in 1935. However, in 1962 John A. Wheeler and Robert W. Fuller published a paper showing that this type of wormhole is unstable, and that it will pinch off instantly as soon as it forms, preventing even light from making it through.
Before the stability problems of Schwarzschild wormholes were apparent, it was proposed that quasars were white holes forming the ends of wormholes of this type.
While Schwarzschild wormholes are not traversable, their existence inspired Kip Thorne to imagine traversable wormholes created by holding the 'throat' of a Schwarzschild wormhole open with exotic matter (material that has negative mass/energy).

Traversable wormholes

Lorentzian traversable wormholes would allow travel from one part of the universe to another part of that same universe very quickly or would allow travel from one universe to another. The possibility of traversable wormholes in general relativity was first demonstrated by Kip Thorne and his graduate student Mike Morris in a 1988 paper; for this reason, the type of traversable wormhole they proposed, held open by a spherical shell of exotic matter, is referred to as a Morris-Thorne wormhole. Later, other types of traversable wormholes were discovered as allowable solutions to the equations of general relativity, including a variety analyzed in a 1989 paper by Matt Visser, in which a path through the wormhole can be made in which the traversing path does not pass through a region of exotic matter. However in the pure Gauss-Bonnet theory exotic matter is not needed in order for wormholes to exist- they can exist even with no matter A type held open by negative mass cosmic strings was put forth by Visser in collaboration with Cramer et al.,, in which it was proposed that such wormholes could have been naturally created in the early universe.
Wormholes connect two points in spacetime, which means that they would in principle allow travel in time as well as in space. In a 1988 paper, Morris, Thorne and Yurtsever worked out explicitly how to convert a wormhole traversing space into one traversing time.

Wormholes and faster-than-light travel

Special relativity only applies locally. Wormholes allow superluminal (faster-than-light) travel by ensuring that the speed of light is not exceeded locally at any time. While traveling through a wormhole, subluminal (slower-than-light) speeds are used. If two points are connected by a wormhole, the time taken to traverse it would be less than the time it would take a light beam to make the journey if it took a path through the space outside the wormhole. However, a light beam traveling through the wormhole would always beat the traveler. As an analogy, running around to the opposite side of a mountain at maximum speed may take longer than walking through a tunnel crossing it. You can walk slowly while reaching your destination more quickly because the length of your path is shorter.

Wormholes and time travel

A wormhole could allow time travel. This could be accomplished by accelerating one end of the wormhole to a high velocity relative to the other, and then sometime later bringing it back; relativistic time dilation would result in the accelerated wormhole mouth aging less than the stationary one as seen by an external observer, similar to what is seen in the twin paradox. However, time connects differently through the wormhole than outside it, so that synchronized clocks at each mouth will remain synchronized to someone traveling through the wormhole itself, no matter how the mouths move around. This means that anything which entered the accelerated wormhole mouth would exit the stationary one at a point in time prior to its entry. For example, if clocks at both mouths both showed the date as 2000 before one mouth was accelerated, and after being taken on a trip at relativistic velocities the accelerated mouth was brought back to the same region as the stationary mouth with the accelerated mouth's clock reading 2005 while the stationary mouth's clock read 2010, then a traveler who entered the accelerated mouth at this moment would exit the stationary mouth when its clock also read 2005, in the same region but now five years in the past. Such a configuration of wormholes would allow for a particle's world line to form a closed loop in spacetime, known as a closed timelike curve.
It is thought that it may not be possible to convert a wormhole into a time machine in this manner: some analyses using the semiclassical approach to incorporating quantum effects into general relativity indicate that a feedback loop of virtual particles would circulate through the wormhole with ever-increasing intensity, destroying it before any information could be passed through it, in keeping with the chronology protection conjecture. This has been called into question by the suggestion that radiation would disperse after traveling through the wormhole, therefore preventing infinite accumulation. The debate on this matter is described by Kip S. Thorne in the book Black Holes and Time Warps. There is also the Roman ring, which is a configuration of more than one wormhole. This ring seems to allow a closed time loop with stable wormholes when analyzed using semiclassical gravity, although without a full theory of quantum gravity it is uncertain whether the semiclassical approach is reliable in this case.

Wormhole metrics

Theories of wormhole metrics describe the spacetime geometry of a wormhole and serve as theoretical models for time travel. An example of a (traversable) wormhole metric is the following:
ds^2= - c^2 dt^2 + dl^2 + (k^2 + l^2)(d \theta^2 + \sin^2 \theta \, d\phi^2)
One type of non-traversable wormhole metric is the Schwarzschild solution:
ds^2= - c^2 \left(1 - \frac\right)dt^2 + \frac + r^2(d \theta^2 + \sin^2 \theta \, d\phi^2)

Wormholes in fiction

Wormholes are a popular feature of science fiction as they allow interstellar (and sometimes interuniversal) travel within human timescales. It is common for the creators of a fictional universe to decide that faster-than-light travel is either impossible or that the technology does not yet exist, but to use wormholes as a means of allowing humans to travel long distances in short periods. Military science fiction (such as the Wing Commander games) often use a "jump drive" to propel a spacecraft between two fixed "jump points" connecting stellar systems. Connecting systems in a network like this results in a fixed "terrain" with choke points that can be useful for constructing plots related to military campaigns. The Alderson points used by Larry Niven and Jerry Pournelle in The Mote in God's Eye and related novels are an example, although the mechanism does not seem to describe actual wormhole physics. David Weber has also used the device in the Honorverse and other books such as those based upon the Starfire universe. Naturally occurring wormholes form the basis for interstellar travel in Lois McMaster Bujold's Vorkosigan Saga. They are also used to create an Interstellar Commonwealth in Peter F. Hamilton's Commonwealth Saga.
Concept of wormholes is used in The Wild Blue Yonder, a science fiction film by Werner Herzog
Wormholes also play pivotal roles in science fiction where faster-than-light travel is possible though limited, allowing connections between regions that would be otherwise unreachable within conventional timelines. Several examples appear in the Star Trek franchise, including the Bajoran wormhole in the Deep Space Nine series. In Star Trek: The Motion Picture in 1979 the USS Enterprise (NCC-1701) was trapped in a wormhole caused by an imbalance in the calibration of the ship's warp engines when it first achieved warp speed.
In Carl Sagan's novel Contact and subsequent 1997 film starring Jodie Foster and Matthew McConaughey, Foster's character Ellie travels 26 light years through a series of wormholes to the star Vega. The round trip, which to Ellie lasts 18 hours, passes by in a fraction of a second on Earth, making it seem that she didn't go anywhere. In her defense, Foster mentions an Einstein-Rosen bridge and tells how she was able to travel faster than light and time. Analysis of the situation by Kip Thorne, on the request of Sagan, is quoted by Thorne as being his original impetus for analyzing the physics of wormholes.
Wormholes play major roles in the television series Farscape, where they are the cause of John Crichton's presence in the alien universe, and in the Stargate series, where stargates create a stable artificial wormhole where matter is disintegrated, converted into energy, and is sent through to be reintegrated at the other side. In the science fiction series Sliders, a wormhole (or vortex, as it is usually called in the show) is used to travel between parallel worlds, and one is seen at least once or twice in every episode. In the pilot episode it was referred to as an "Einstein-Rosen-Podolsky bridge". Wormholes are part of the main back-story in the MMORPG EVE Online.
The central theme in the movie Donnie Darko revolves around Einstein-Rosen bridges.

References

External links

wormhole in Arabic: ثقب دودي
wormhole in Catalan: Forat de cuc
wormhole in Czech: Červí díra
wormhole in Danish: Ormehul
wormhole in German: Wurmloch
wormhole in Spanish: Agujero de gusano
wormhole in Persian: کرمچاله
wormhole in French: Trou de ver
wormhole in Galician: Burato de verme
wormhole in Italian: Wormhole
wormhole in Hebrew: חור תולעת
wormhole in Latvian: Tārpeja
wormhole in Lithuanian: Slieko tunelis
wormhole in Dutch: Wormgat
wormhole in Japanese: ワームホール
wormhole in Norwegian: Ormehull
wormhole in Polish: Tunel czasoprzestrzenny
wormhole in Portuguese: Buraco-de-minhoca
wormhole in Romanian: Gaură de vierme
wormhole in Russian: Кротовина
wormhole in Simple English: Wormhole
wormhole in Slovak: Červia diera
wormhole in Slovenian: Črvina
wormhole in Serbian: Црвоточина
wormhole in Finnish: Madonreikä
wormhole in Swedish: Maskhål
wormhole in Vietnamese: Hố giun
wormhole in Turkish: Solucandeliği
wormhole in Urdu: ثقب کرم
wormhole in Chinese: 虫洞
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