Editing Gravity (section)

===Speed of gravity===
{{Main|Speed of gravity}}
In December 2012, a research team in China announced that it had produced measurements of the phase lag of [[Earth tide]]s during full and new moons which seem to prove that the speed of gravity is equal to the speed of light.<ref>[http://www.astrowatch.net/2012/12/chinese-scientists-find-evidence-for.html Chinese scientists find evidence for speed of gravity] {{Webarchive|url=https://web.archive.org/web/20130108083729/http://www.astrowatch.net/2012/12/chinese-scientists-find-evidence-for.html |date=8 January 2013 }}, astrowatch.com, 12/28/12.</ref> This means that if the Sun suddenly disappeared, the Earth would keep orbiting the vacant point normally for 8 minutes, which is the time light takes to travel that distance. The team's findings were released in ''[[Science Bulletin]]'' in February 2013.<ref>{{cite journal|last=TANG|first=Ke Yun|author2=HUA ChangCai |author3=WEN Wu |author4=CHI ShunLiang |author5=YOU QingYu |author6=YU Dan |title=Observational evidences for the speed of the gravity based on the Earth tide|journal=Chinese Science Bulletin|date=February 2013|volume=58|issue=4–5|pages=474–477|doi=10.1007/s11434-012-5603-3|bibcode=2013ChSBu..58..474T|doi-access=free}}</ref>

In October 2017, the [[LIGO]] and Virgo detectors received gravitational wave signals within 2 seconds of gamma ray satellites and optical telescopes seeing signals from the same direction. This confirmed that the speed of gravitational waves was the same as the speed of light.<ref>{{cite web|url=https://www.ligo.caltech.edu/page/press-release-gw170817|title=GW170817 Press Release|website=LIGO Lab – Caltech|access-date=24 October 2017|archive-date=17 October 2017|archive-url=https://web.archive.org/web/20171017010137/https://www.ligo.caltech.edu/page/press-release-gw170817|url-status=live}}</ref>