Editing Gravitational time dilation (section)

==Experimental confirmation==
{{see also|Gravitational redshift#Experimental confirmation|Tests of general relativity}}

[[File:Orbit times.svg|thumb|right|upright=1.2|Satellite clocks are slowed by their orbital speed, but accelerated by their distance out of Earth's gravitational well.]]

Gravitational time dilation has been experimentally measured using atomic clocks on airplanes, such as the [[Hafele–Keating experiment]]. The clocks aboard the airplanes were slightly faster than clocks on the ground. The effect is significant enough that the [[Global Positioning System|Global Positioning System's]] [[satellite|artificial satellites]] had their atomic clocks permanently corrected.<ref name= Wolfson>{{cite book |author= Richard Wolfson |title=Simply Einstein |url=https://archive.org/details/simplyeinsteinre0000wolf/page/216/mode/1up?view=theater |page=216 |isbn=978-0-393-05154-4 |publisher=W W Norton & Co. |year=2003 }}</ref>

Additionally, time dilations due to height differences of less than one metre have been experimentally verified in the laboratory.<ref>C. W. Chou, D. B. Hume, T. Rosenband, D. J. Wineland (24 September 2010), "Optical clocks and relativity", ''Science'', 329(5999): 1630–1633; [https://dx.doi.org/10.1126/science.1192720]</ref>

Gravitational time dilation in the form of [[gravitational redshift]] has also been confirmed by the [[Pound–Rebka experiment]] and observations of the spectra of the [[white dwarf]] [[Sirius B]].

Gravitational time dilation has been measured in experiments with time signals sent to and from the [[Viking 1]] Mars lander.<ref>{{cite journal |last1=Shapiro |first1=I. I. |last2=Reasenberg |first2=R. D. |date=30 September 1977 |title=The Viking Relativity Experiment |url=https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/JS082i028p04329 |journal=Journal of Geophysical Research |publisher=AGU |volume=82 |issue=28 |pages=4329–4334 |bibcode= 1977JGR....82.4329S|doi=10.1029/JS082i028p04329 |access-date=6 February 2021|url-access=subscription }}</ref><ref>{{cite book |title=Modern Physics for Scientists and Engineers |edition=3rd, illustrated |first1=Stephen T. |last1=Thornton |first2=Andrew |last2=Rex |publisher=Thomson, Brooks/Cole |year=2006 |isbn=978-0-534-41781-9 |page=552 |url=https://books.google.com/books?id=g74rAAAAYAAJ}}</ref>