Tests of General Relativity  

In General > s.a. gravitational constant; gravitomagnetism [including brane]; modified general relativity; modified newtonian gravity [PPN].
* Status: 1989, Experimental gravitation is now becoming a major part of general relativity, which is finally recovering a balance between theory and observation; This pushes the theory to justify better its approximations; Also, new tests are being devised, gravitational lensing being one of the most rigorous.
* Types: Weak-field, low-velocity (Solar System tests); Strong-field, low-velocity (binary compact object inspiral); Strong-field, high-speed (binary compact object coalescence); Radiation.
* Solar-system tests: 2014, The two types of tests that have mainly been done so far are weak-field tests in the PPN framework and searches for a fifth force, although spacecraft tracking has been used for tests of the MOND idea and other proposals, and one can constrain Standard Model Extension parameters using Solar System data.
* Bounds on PN parameters: For the non-linearity parameter, β < × 10–3; For the curvature parameter, γ –1 < 10–3 (VLBI and quasars), = (4.8 ± 5.7) × (2.1 ± 2.3) × 10–5 (2003, Cassini spacecraft) [below, η:= 4βγ – 3, and σ = standard error].
* Strong-gravity regime: Two approaches use observations of compact objects and detection of gravitational waves.
@ General references: Møller ed-62; Bertotti ed-74; Will PRP(84); Cook RPP(88); Will Sci(90)nov; Berezin TMP(92); Will IJMPD(92), 93; Karim & Qadir ed-CQG(94); Nordtvedt PT(96)may; Esposito-Farèse in(00)gq/99; Iorio IJMPD(11)-a0908 [bias in some tests]; Morales-Técotl et al ed-10; Tartaglia PoS-a1503; Yunes REF-a1510; Peebles EPJH-a1603 [history, role of Robert Dicke].
@ Reviews: Brill in(73); Damour gq/94, gq/94, in(95), gq/96-proc, gq/97-proc, NPPS(00)gq/99; Will gq/98-ln, LRR(01)gq; Turyshev et al LNP-gq/03; Will pw(05)jan; Ni IJMPD(05)gq; Will LRR(06)gq/05, AdP(06); Bertolami et al gq/06-proc; Turyshev et al IJMPD(07)-a0711, Maleki GRG(08) [space-based research]; Turyshev EPJST(08)-a0804-conf [in space], ARNPS(08)-a0806, PU(09)-a0809; Turyshev in(10)-a0906; Will AJP(10)dec-a1008 [precision tests, RL]; Ni a1204-conf; Bertolami & Páramos a1212 [status]; Hu et al PRD(13)-a1307 [constraints after Planck]; Will LRR(14)-a1403, a1409-in; Baker et al ApJ(15)-a1412 [comparing tests of gravity on all scales]; Asmodelle a1705-BS.
@ Satellite ranging: Giampieri ap/95-proc; Iorio ASR(07)gq/02-conf; Williams et al IJMPD(04), Penanen & Chui NPPS(04)gq [precision].
@ Other solar system tests: Allemandi & Ruggiero GRG(07)ap/06; Iorio PSS(07)gq [effect of Kuiper Belt objects and asteroids]; Wolf et al EA(09)-a0711 [SAGAS project]; Iess & Asmar IJMPD(07) [cosmology-motivated]; Reynaud & Jaekel a0801-ln; Turyshev et al IJMPD(09)-a0805 [BEACON mission]; Jaekel & Reynaud in(07)a0806; Turyshev a0902-rp [opportunities]; Reynaud et al SSR(09)-a0903 [ACES and SAGAS space projects]; Iorio JCAP(11)-a1012, Carloni et al PRD(11)-a1103, Iorio MNRAS(12)-a1108 [and Rindler-type acceleration]; Lenoir et al a1107-conf [Odyssey 2, proposed mission to Neptune and Triton]; Exirifard a1206 [micron-range, near the gravitational saddle point of the Sun-Jupiter system]; Fienga a1209-proc [rev]; Iorio MNRAS(14)-a1307 [tests of gravitational Local Position Invariance]; Hees et al a1403-proc; Iorio IJMPD(15)-a1412 [gravitational anomalies in the Solar System, rev]; Hees a1509-proc [Gaia observations]; Ni a1611-in [rev].
@ Post-Einsteinian framework: Jaekel & Reynaud CQG(05)gq, CQG(06)gq/05; Cornish et al PRD(11)-a1105 [gravitational-wave tests]; Sampson et al PRD(13)-a1307 [connections between the parameterized post-Newtonian, parameterized post-Keplerian, and parameterized post-Einsteinian frameworks]; > s.a. gravitational-wave detection.
@ Clock experiments: Will gq/95; Damour gq/97-proc, gq/99-proc [stringy motivation]; Lichtenegger et al gq/98-conf; Tartaglia CQG(00)gq/99; Schiller et al NPPS(07)gq/06 [in space]; Le Poncin-Lafitte & Lambert ap/06-proc; Bondarescu et al a1412-proc [and interferometers]; > s.a. clocks.
@ Lab experiments: Chen & Cook 93; Barrett gq/97; Zhang et al MPLA(01)gq/00, Iorio CQG(03)gq/02 [rotating bodies]; Dimopoulos et al PRL(07)gq/06 [atom interferometry]; Bimonte et al PRD(08)-a0707 [gravity of magnetic energy and stresses].

blue bullet Main types of tests: see astrophysical and cosmological tests; light deflection; redshift and signal retardation; tests with orbits and spinning bodies.
blue bullet Aspects of gravitational phenomenology: see phenomenology of gravity / equivalence principle; gravitational radiation; gravitomagnetism; lensing.

Effects and Applications > s.a. Aberration; de Sitter-Fokker Precession; gravitational constant.
@ Gravitational time dilation: Hafele & Keating Sci(72)jul, Sci(72)jul; Alley in(79); Alberici gq/04, gq/05 [uniform gravitational field]; > s.a. gravitational redshift.
@ Measuring curvature by interferometry: Audretsch & Marzlin PRA(94)gq/93; Snadden et al PRL(98) + news pn(98)jul.
@ Speed of gravity: Novello et al AP(97) [theory with different speed]; Van Flandern PLA(98), comment Marsh & Nissim-Sabat PLA(99), reply PLA(99); Kopeikin PLA(03)gq/02, CQG(04)gq/03; news pw(03)jan; Samuel PRL(03); Will ApJ(03)ap; Fomalont & Kopeikin ApJ(03)ap [Jupiter]; Faber ap/03/ApJL; Asada ap/03-proc; Musser SA(03)apr; Kopeikin & Fomalont PLA(06)gq/03, FP(06)ap/03; Carlip CQG(04)gq [model-dependence]; Samuel IJMPD(04)ap, comment Kopeikin IJMPD(06)gq/05, Asada IJMPD(06), Carlip IJMPD(06); Kopeikin & Fomalont GRG(07) + sr(07)oct [gravitomagnetism and aberration of gravity]; Krasnikov G&C(11)-a1009; Paranjape a1208 [proposed lab experiment]; Finn & Romano PRD(13) [Rømer time-delay determination]; Collett & Bacon a1602/ApJL [test with strong gravitational lensing]; > s.a. bimetric theory; propagation of gravitational waves.
@ Other topics: Wex IAU-gq/00 [dipole radiation, Stark effect]; Unnikrishnan & Gillies PRD(06), IJMPD(08) [gravity of quantum Fermi pressure].
> On particles and light: see graviton; neutrino; photon; quantum states.

Macroscopic Systems > s.a. neutron stars; phenomenology of gravity.
* GPS: 24 satellites at 12,000 mi + 5 ground stations, operational since 1994; Use two different frequencies, for corrections; Civilian accuracy ≈ 25 m, ≈ 1 m for differential GPS (about $200 by 1995), but ≈ 1 cm is possible.
@ GPS: Kleppner PT(93)apr; Misner gq/95; Herring SA(96)feb; Bahder gq/98 [model-clock behavior in Minkowski], PRD(03)gq; Ashby PT(02)may, LRR(03); Pascual-Sánchez AdP(07)gq/05-conf.
@ Space-based tests: Will Nat(90)oct; Alexeev et al G&C(99)gq/00; Iorio RNC(02)gq/01 [β, γ], JGSJ(02)gq/01 [LAGEOS, Ajisai]; Ni IJMPD(02), et al IJMPD(02) [ASTROD]; Anderson et al gq/03-wd [Cassini]; Lämmerzahl gq/04-MGX; Iorio JCAP(05)gq/04 [of brane-world, comment]; in NPPS(07)166; Appourchaux et al EA(09)-a0802 [ASTROD 1]; Kopeikin PLA(09) [Cassini]; > s.a. tests with orbits [lunar ranging].
@ Other: Longuski et al PRL(01), PRD(04) [spacecraft deflection]; Pascual-Sánchez LNP(03)gq/02 [Earth's gravitomagnetism].

Tests of Other Theories > s.a. gravitational radiation; gravity theories; tests with light [Weyl gravity, light deflection].
@ Fifth force, Yukawa potential: Iorio PLA(02)gq [and LAGEOS]; Bertolami & Páramos IJMPD(11)-a1006 [Galileo satellite constellation].
@ Higher-derivative theories: Accioly & Blas PRD(01)gq [quadratic, light dispersion]; Smith et al PRD(08)-a0708 [Gauss-Bonnet term]; Huang et al a1303 [f(R) gravity, light deflection]; > s.a. higher-order gravity.
@ Brane-world gravity: Ghosh & Raychaudhuri PLB(00), Iorio AdP(12)-a1112 [Randall-Sundrum]; Jalalzadeh et al CQG(09)-a0906, Böhmer et al CQG(10)-a0910 [classical tests].
@ Higher-dimensional theories: Wesson et al MPLA(97), Liu & Overduin ApJ(00)gq [5D, Kaluza-Klein theory]; de Aragão et al gq/05 [and preferred frames]; Rahaman et al IJTP(09)-a0707 [mostly incompatible]; Eingorn & Zhuk a0912, CQG(10)-a1003 [negative result]; > s.a. higher-dimensional gravity; tests with orbits.
@ Other theories: Bailey PRD(09) [Lorentz-violating]; Frye & Efthimiou a1306 [string theory].
> Other theories: see einstein-cartan theory; Gauge Theory of Gravity; Gravity's Rainbow; scalar-tensor theories; torsion.

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