Editing Lunar Laser Ranging experiments (section)

=== Gravitational physics ===
*[[Albert Einstein|Einstein's]] theory of gravity (the [[General relativity|general theory of relativity]]) predicts the [[Orbit of the Moon|Moon's orbit]] to within the accuracy of the laser ranging measurements.{{r|jwjd1}}<ref name=":2" />
* [[Gauge fixing|Gauge freedom]] plays a major role in a correct physical interpretation of the relativistic effects in the Earth-Moon system observed with LLR technique.<ref>{{cite journal |last1=Kopeikin |first1=S. |last2=Xie |first2=Y. |year=2010 |title=Celestial reference frames and the gauge freedom in the post-Newtonian mechanics of the Earth–Moon system |journal=[[Celestial Mechanics and Dynamical Astronomy]] |volume=108 |issue=3 |pages=245–263 |bibcode=2010CeMDA.108..245K |doi=10.1007/s10569-010-9303-5|s2cid=122789819 }}</ref>
* The likelihood of any [[Nordtvedt effect]] (a hypothetical differential acceleration of the Moon and Earth towards the Sun caused by their different degrees of compactness) has been ruled out to high precision,<ref>{{cite journal|last1=Adelberger|first1=E. G.|last2=Heckel|first2=B. R.|last3=Smith|first3=G.|last4=Su|first4=Y.|last5=Swanson|first5=H. E.|year=1990|title=Eötvös experiments, lunar ranging and the strong equivalence principle|journal=[[Nature (journal)|Nature]]|volume=347|issue=6290|pages=261–263|bibcode=1990Natur.347..261A|doi=10.1038/347261a0|s2cid=4286881}}</ref><ref name=":2">{{cite journal|last1=Williams|first1=J. G.|last2=Newhall|first2=X. X.|last3=Dickey|first3=J. O.|year=1996|title=Relativity parameters determined from lunar laser ranging|journal=[[Physical Review D]]|volume=53|issue=12|pages=6730–6739|bibcode=1996PhRvD..53.6730W|doi=10.1103/PhysRevD.53.6730|pmid=10019959}}</ref><ref>{{cite journal|last1=Viswanathan|first1=V|last2=Fienga|first2=A|last3=Minazzoli|first3=O|last4=Bernus|first4=L|last5=Laskar|first5=J|last6=Gastineau|first6=M|date=May 2018|title=The new lunar ephemeris INPOP17a and its application to fundamental physics|journal=Monthly Notices of the Royal Astronomical Society|volume=476|issue=2|pages=1877–1888|arxiv=1710.09167|doi=10.1093/mnras/sty096|doi-access=free|bibcode=2018MNRAS.476.1877V}}</ref> strongly supporting the [[strong equivalence principle]].
* The universal force of [[gravity]] is very stable.  The experiments have constrained the change in [[Isaac Newton|Newton's]] [[gravitational constant]] ''G'' to a factor of {{val|2|7|e=-13}} per year.<ref>{{cite journal|last1=Müller|first1=J.|last2=Biskupek|first2=L.|year=2007|title=Variations of the gravitational constant from lunar laser ranging data|journal=[[Classical and Quantum Gravity]]|volume=24|issue=17|page=4533|doi=10.1088/0264-9381/24/17/017|s2cid=120195732 }}</ref>