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[[Fil:spacetime curvature.png|thumb|right|300px|Todimensionel analogi af rumtid.]]
I [[Albert Einstein|Einsteins]] specielle og [[almen relativitetsteori|almene relativitetsteori]] er [[tid]] og det tredimensionelle [[rum]] slået sammen til en enkel firedimensionel [[Mangfoldighed (matematik)|mangfoldighed]] kaldet '''rumtid'''. Et punkt i rumtiden bliver benævnt en hændelse. Enhver hændelse har fire koordinater: (t, x, y, z). ▼I [[Fysik|fysikken]] er '''rumtid''' defineret som en matematisk model, som kombinerer vores tredimensionale syn på [[universet]] med [[tid]]. Rumtid er sædvanligvis tolket som firedimensionale objekter hvor objektet har de tre ''kendte'' rumdimensionene, i tillæg til tid som en fjerde dimension.
Begrebet rumtid er i nyere tid blevet en fællesbetegnelse på teorier som går udover de tre dimensioner. Hvor mange dimensioner man faktisk må tage i brug for at beskrive universet, er stadig et åbent spørgsmål. [[Strengteori]]en tilsiger, at vi har fra 10 til 26 dimensioner.
▲I [[Albert Einstein|Einsteins]] specielle og [[almen relativitetsteori|almene relativitetsteori]] er [[tid]] og det tredimensionelle [[rum]] slået sammen til en enkel firedimensionel [[Mangfoldighed (matematik)|mangfoldighed]] kaldet '''rumtid '''. Et punkt i rumtiden bliver benævnt en hændelse. Enhver hændelse har fire koordinater: (t, x, y, z).
== Relaterede artikler ==
* [[Warp drive]]
== Eksterne henvisninger ==
* Webarchive backup: [http://web.archive.org/web/20040128015658/www.natnet.dk/udfordringer/naturbyggesten/naturkraefter/ NatNet: Hvordan virker naturkræfterne?]
* Google: [http://directory.google.com/Top/Science/Physics/Relativity/ Relativity], [http://directory.google.com/Top/Science/Physics/Relativity/Special_Relativity/ Special Relativity]
* [http://home.att.net/~bob.rutkiewicz/force.htm Robert Rutkiewicz: Explaining Particle Force] Citat: "...[[subatomar partikel|Particles]] move together not because there is something pulling them together, they all are traveling in the straightest line possible, its just that space is curved..."
* [http://archive.ncsa.uiuc.edu/Cyberia/NumRel/NumRelHome.html University of Illinois: Spacetime Wrinkles] (med video).
* [http://www.theory.caltech.edu/people/patricia/st101.html Caltech: Spacetime 101]
* [http://www.astro.ku.dk/~cramer/RelViz/ KU.dk, Michael Cramer Andersen: Geometry Around Black Holes] A WWW Exhibition in Relativistic Computer Dynamics and Visualization.
* [http://math.ucr.edu/home/baez/physics/Relativity/GR/gravity.html Physics FAQ, By Martin Hogbin, 11 February 1998, What causes Gravity?] Citat: "...[Dette bud indeholder ikke [[kvantemekanik]]kens teori!] The world we live in consists of four dimensions, the three space dimensions and one that is not exactly time but is related to time (it is in fact time multiplied by the square root of -1 [i, j, det imaginære 'fortegn']). This is not at all easy to understand but it means that space-time as we call it has some rather weird properties. In particular, when you move through one of the space dimensions you also travel, unwittingly, through time...."
* [http://einstein.stanford.edu/content/story_of_gpb/gpbsty1.html Stanford: What is Gravity Probe B?] Physicists and engineers at Stanford University have created a wide range of exotic technologies to perform a satellite experiment that will probe the very foundations of space time.
* [http://einstein.stanford.edu/content/story_of_gpb/gpbsty3.html Stanford: The Geodetic Effect: Measuring the Curvature of Space-time] Citat: "... Third, most important, Gravity Probe B investigates the gravitational action of moving matter. Matter moving through space-time can be thought of as creating a new force -- gravitomagnetism -- which John Wheeler..."
** [http://www.sciencedaily.com/releases/2004/09/040908091101.htm 2004-09-09, Sciencedaily: NASA Gravity Probe B Mission Enters Science Phase, Ready To Test Einstein's Theory]
* Stanford, Dr. Sten Odenwald, [http://einstein.stanford.edu/content/relativity/qanda.html Special & General Relativity Questions and Answers]:
** [http://einstein.stanford.edu/content/relativity/q1347.html How are electromagnetism and space-time related, and can electromagnetic fields exert a force on space-time?]
** [http://einstein.stanford.edu/content/relativity/a11277.html What happens in the space between gravitating bodies?]
** [http://einstein.stanford.edu/content/relativity/a11134.html If space exists, what is it?]
** [http://einstein.stanford.edu/content/relativity/a10743.html What is the relationship between space and time?]
** [http://einstein.stanford.edu/content/relativity/a10591.html Does space have more than 3 dimensions?]
** [http://einstein.stanford.edu/content/relativity/q2916.html What is the simplest evidence that there are more than 4 dimensions?]
** [http://einstein.stanford.edu/content/relativity/q2850.html How do you explain Einstein's relativity theory to a 12 year old?]
** [http://einstein.stanford.edu/content/relativity/q1669.html Is gravity the exchange of gravitons, or the curvature of space-time?]
** [http://einstein.stanford.edu/content/relativity/q909.html What happens to the fabric of space-time when an object moves through it near the speed of light?]
** [http://einstein.stanford.edu/content/relativity/q710.html Does 'now' have a size instead of being a point in spacetime?]
* [http://www.aip.org/enews/physnews/2003/split/660-2.html Number 660 #2, November 4, 2003, Physics News Update: Acceleration Disrupts Quantum Teleportation] Citat: "...While this effect is small for typical accelerations in Earthly labs the result shows an interesting relationship between the effects of space-time motion and the [[kvantemekanik|quantum world]]..."
* [http://www.aip.org/enews/physnews/2001/split/562-1.html Number 562 #1, October 23, 2001 Physics News Update: Loop Quantum Gravity] Citat: "...Loop Quantum Gravity (LQG), rival of string theory in the quest to unite quantum mechanics with general relativity...In loop theory, the merger is attempted by imagining that space itself consists of moveable tiny loops..."
* [http://www.reciprocalsystem.com/spu/spums2.htm Dewey B. Larson: ] Citat: "...Time is the reciprocal of space... Instead of space and time we have have space-time..."
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