== Gravitation i den generelle relativitetsteori ==
{{Uddybende|Generel relativitetsteori}}
[[Albert Einstein|Einsteins]] [[relativitetsteori]] forudsiger, at gravitationens udbredelseshastighed skal være mindre end [[lysets hastighed]] i [[vakuum]].<ref>[http://www.sciencedaily.com/releases/2003/06/030619075759.htm June 19, 2003, sciencedaily.com: Berkeley Lab Physicist Challenges Speed Of Gravity Claim] Citat: "...According to Einstein's General Theory of Relativity, light and gravity travel at the same speed, about 186,000 miles (300,000 kilometers) per second. Most scientists believe this is true but the assumption was that it could only be proven through the detection of gravity waves..."</ref> 
<ref>[https://web.archive.org/web/20160730212313/http://www.astronomycafe.net:80/qadir/q2226.html Ask the Astronomer: If nothing can travel faster than light, why does gravity take affect instantly?] Citat: "...There is no observation that justifies this 'Newtonian' statement, and lots of evidence from special and general relativity that gravity obeys the speed limit set by the speed of light..."</ref> 
<ref>[https://web.archive.org/web/20160730212747/http://www.astronomycafe.net:80/qadir/q1399.html Ask the Astronomer: Are we gravitationally affected by where an object is now, or where it was when the light we see started its journey to us? ] Citat: "...Because all indications are that gravity travels at the speed of light, we can only be affected by where a body is at the SAME time we see the light from it..."</ref> 
Gravitationel interaktion kan altså ikke være øjeblikkelig.
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