Tests of General Relativity with Light  

Gravitational Redshift > s.a. doppler [redshift].
* Idea: A photon's energy/frequency decreases as it climbs out of a gravitational potential well.
* Tests: Pound & Rebka (1960) used the Mössbauer effect, 1%; Vessot et al used H masers launched by rocket.
* Plan: Put a stable clock around the Sun, to give () = 10–6, () = 10–7.
@ General references: Pound & Rebka PRL(60); Vessot & Levine GRG(79); Okun MPLA(00), MPLA(00)hp [thought experiment]; Teyssandier et al a0711 [using Synge's world function].
@ Specific situations: DeDeo & Psaltis PRL(03)ap [atomic lines from neutron stars]; Kopeikin et al PLA(07)gq/06 [Cassini and radio waves near the Sun]; Müller AN(07)ap/06 [from disk around black hole].

Light Deflection > s.a. lensing; phenomenology of gravity; Runge-Lenz Vector; tests of general relativity [and other theories].
* Prediction: For a light ray grazing the Sun, = 1.75".
* Results: Consistent with = 1; 1989, Analysis of radio waves using VLBI in progress, estimate () = 0.002.
* Remark: In general relativity, although particle paths depend on orientation of spin, there is no optical birefringence (> see polarization).
* LATOR: A proposed mission that would send two laser-transmitter spacecraft behind the Sun to measure the relative gravitational light bending of their signals using a hundred-meter-baseline optical interferometer, to be constructed on the ISS; Should allow a simultaneous determination of the orbit parameters of the spacecraft and of with an uncertainty of 2.4 10–9, a 6 × 10–9 determination of the solar quadrupole moment J2, and the first measurement of the second-order post-PPN parameter to an accuracy of about 10–3.
@ General references: Dyson et al PTRS(20); Dyson Nat(21)feb; Fomalont & Sramek PRL(76); Richter & Matzner ASS(81); Richter & Matzner PRD(82), PRD(82); Bruckman & Esteban AJP(93)aug; Lebach et al PRL(95) [radio waves by Sun]; Lerner AJP(97)dec [in Schwarzschild]; Dodelson & Wiegert ap/97 [by vector perturbations]; Gerard & Pireaux gq/99; Bodenner & Will AJP(03)aug [to second order]; Díaz-Miguel PRD(04) [fall in uniform g field]; Brügmann PRD(05)gq [post-linear order]; Iyer & Petters GRG(07) [Schwarzschild spacetime, analytical perturbation framework]; Magnan a0712 [complete derivation]; Díaz-Miguel a0809 [and principle of equivalence]; Hioe PLA(09) [exact expression].
@ With cosmological constant: Islam PLA(83); Freire et al GRG(01)gq/02 [+ conical defect]; Rindler & Ishak PRD(07)-a0709 [non-vanishing effect]; Gibbons et al CQG(08)-a0808 [Schwarzschild-de Sitter]; Miraghaei & Nouri-Zonoz a0810 [Newtonian limit of Schwarzschild-de Sitter].
@ LATOR mission: Turyshev et al CQG(04)gq/03-in, NPPS(04)gq-in, gq/04-in, IJMPD(04)gq-in, gq/05-in, gq/06-in; Plowman & Hellings CQG(06)gq/05; Turyshev & Shao IJMPD(07)gq-in.
@ By planets: Kopeikin ap/03 [Jupiter]; Crosta & Mignard CQG(06)ap/05 [and Gaia mission]; Kopeikin & Makarov PRD(07)gq/06 [planetary multipoles]; Malkin et al SSR(09)-a0907 [radio sources].
@ Kerr metric: Iorio NCB(03)gq/02; Kraniotis CQG(05)gq [and Kerr-AdS]; Edery & Godin GRG(06) [second-order, equatorial].
@ Other metrics: Lake PRD(02) [Kottler]; Ruggiero et al IJMPD(06) [rotating sources, and quadrupole moments].
@ Related topics: Durrer PRL(94) [in perturbed FRW spacetime]; Mohanty & Prasanna ap/95 [no birefringence]; Ferraro AJP(03)feb-gq/02 [and equivalence principle]; > s.a. history [1919 eclipse expedition].

Signal Retardation (Shapiro time delay) > s.a. gamma-ray astronomy; neutron stars.
* Idea: The light travel time between planets is longer than the corresponding flat spacetime value.
* Remark: It is always a delay, not an advance, as follows from the energy conditions [@ Visser et al NPPS(00)gq/98].
* Results: Consistent with = 1, with () = 0.002, from Viking landers; 2003, 1.5 order of magnitude improvement with Cassini.
@ General references: Shapiro PRL(64); Reasenberg et al ApJL(79); Richter & Matzner PRD(83); in Wald 84, 146–148; Bruckman & Esteban AJP(93)aug; Teyssandier et al a0711-in [using Synge's world function].
@ In binary systems: Laguna & Wolszczan ap/97 [pulsar-black hole]; van Straten et al Nat(01)jul [pulsar-black hole]; Tartaglia et al PRD(05)gq.
@ Related topics: Kopeikin ApJL(01)gq [quasars, extra term from speed of gravity]; Iorio NCB(03)gq/02 [in Kerr]; Ciufolini et al PLA(03)gq/02 [rotating masses]; Bertotti et al Nat(03)sep + pw(03)sep [Cassini]; Ruggiero & Tartaglia PRD(05)gq [binary pulsars, gravitomagnetic corrections]; Bertotti et al CQG(08)-a0709, comment Kopeikin a0901 [effect of Sun's motion]; Kutschera & Zajiczek a0906 [for relativistic particles]; Ballmer et al a0905 [on Advanced LIGO laboratory distance scales].
@ In other theories: Asada PLB(08)-a0710; Schucker & Zaimen a0801 [effect of cosmological constant]; Bailey PRD-a0906 [Lorentz-violating SME]; > s.a. brans-dicke theory; Non-Symmetric Gravity.

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