Apparent Weight of Photons

Pound, R. V.; Rebka, G. A.

doi:10.1103/physrevlett.4.337

Cited by 708 publications

(388 citation statements)

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“…(18) to a precision of 5% [12]. Experiments carried out on the surface of the earth involving the comparison of photon frequencies at different heights have improved the accuracy of verification still further to a precision of 1% [13][14]. With the two ends of the experiment separated by a vertical height h, the first-order frequency shift is calculated with the aid of Eqns.…”

Section: Classical Experimental Tests Of General Relativity In the Pvmentioning

confidence: 99%

Polarizable-Vacuum Approach to General Relativity

Puthoff

2002

Gravitation and Cosmology: From the Hubble Radius to the Planck Scale

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Topics in general relativity (GR) are routinely treated in terms of tensor formulations in curved spacetime. An alternative approach is presented here, based on treating the vacuum as a polarizable medium. Beyond simply reproducing the standard weak-field predictions of GR, the polarizable vacuum (PV) approach provides additional insight into what is meant by a curved metric. For the strong field case, a divergence of predictions in the two formalisms (GR vs. PV) provides fertile ground for both laboratory and astrophysical tests. IntroductionThe principles of General Relativity (GR) are generally formulated in terms of tensor formulations in curved spacetime. Such an approach captures in a concise and elegant way the interaction between masses, and their consequent motion. "Matter tells space how to curve, and space tells matter how to move [1]." During the course of development of GR over the years, however, alternative approaches have emerged that provide convenient methodologies for investigating metric changes in other formalisms, and which yield heuristic insight into what is meant by a curved metric.One approach that has intuitive appeal is the polarizable-vacuum (PV) approach [2-3]. The PV approach treats metric changes in terms of equivalent changes in the permittivity and permeability constants of the vacuum, ε o and µ o , essentially along the lines of the so-called "THεµ" methodology used in comparative studies of gravitational theories [4][5][6].In brief, Maxwell's equations in curved space are treated in the isomorphism of a polarizable medium of variable refractive index in flat space [7]; the bending of a light ray near a massive body is modeled as due to an induced spatial variation in the refractive index of the vacuum near the body; the reduction in the velocity of light in a gravitational potential is represented by an effective increase in the refractive index of the vacuum, and so forth. As elaborated in Refs. [3][4][5][6][7], PV modeling can be carried out in a self-consistent way so as to reproduce to appropriate order both the equations of GR, and the match to the classical experimental tests of those equations. Under conditions of extreme metric perturbation, however, the PV approach predicts certain results at variance with the

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Section: Classical Experimental Tests Of General Relativity In the Pvmentioning

confidence: 99%

Polarizable-Vacuum Approach to General Relativity

Puthoff

2002

Gravitation and Cosmology: From the Hubble Radius to the Planck Scale

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“…The first term is the gravitational redshift, originally measured [2] by Pound and Rebka in 1960, while the second term is the time dilation due to the clocks' relative motion. The redshift term can be isolated from the time dilation if the clocks' trajectories are known.…”

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confidence: 99%

“…The Pound-Rebka experiment [2] measured the gravitational redshift of a 14.4 keV transition in stationary 57 Fe nuclei. With Z = 26, 57 Fe has an unpaired valence neutron that makes a transition between different orbital angular momentum states.…”

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confidence: 99%

“…This effect, known as the gravitational redshift, is the original test of the Einstein equivalence principle (EEP) [1] that underlies all of general relativity; its experimental verification [2][3][4][5][6] is fundamental to our confidence in the theory. Atom interferometer (AI) tests of the gravitational redshift [4,6] have a precision 10 000 times better than tests based on traditional clocks [3], but their status as redshift tests has been controversial [7].…”

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Equivalence Principle and Gravitational Redshift

et al. 2011

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We investigate leading order deviations from general relativity that violate the Einstein equivalence principle in the gravitational standard model extension. We show that redshift experiments based on matter waves and clock comparisons are equivalent to one another. Consideration of torsion balance tests, along with matter wave, microwave, optical, and Mössbauer clock tests, yields comprehensive limits on spin-independent Einstein equivalence principle-violating standard model extension terms at the 10 −6 level.Gravity makes time flow differently in different places. This effect, known as the gravitational redshift, is the original test of the Einstein equivalence principle (EEP) [1] that underlies all of general relativity; its experimental verification [2-6] is fundamental to our confidence in the theory. Atom interferometer (AI) tests of the gravitational redshift [4,6] have a precision 10 000 times better than tests based on traditional clocks [3], but their status as redshift tests has been controversial [7]. Here, we show that the phase accumulated between two atomic wave packets in any interferometer equals the phase between any two clocks running at the atom's Compton frequency following the same paths, proving that atoms are clocks. For a quantitative comparison between different redshift tests, we use the standard model extension (SME) [8][9][10][11], which provides the most general way to describe potential low energy Lorentz symmetry-violating (thus EEP-violating) signatures of new physics at high energy scales. We show that all EEP tests are sensitive to the same five terms in the minimal gravitational SME [9][10][11] and, for the first time, comprehensively rule out EEP violation in redshift tests greater than a few parts per million for neutral matter.If two clocks are located at different points in spacetime, they can appear to tick at different frequencies, despite having the same proper frequency ω 0 in their local Lorentz frames. For clocks moving with nonrelativistic velocities v 1 and v 2 in a weak gravitational potentialThe first term is the gravitational redshift, originally measured [2] by Pound and Rebka in 1960, while the second term is the time dilation due to the clocks' relative motion. The redshift term can be isolated from the time dilation if the clocks' trajectories are known.The state of each clock can be described by a timevarying phase. If two clocks 1 and 2 are synchronized to have identical phase ϕ 0 = 0 at time t = 0, then theirMach-Zehnder clock or atom interferometer. Two otherwise freely falling clocks (or halves of an atomic wavepacket) receive momentum impulses that change their velocity by ±vr. The dashed lines indicate trajectories without gravity.specializing to a homogenous gravitational field so that φ 1 −φ 2 = g· r 12 , with r 12 being the clocks' distance vector and g the local acceleration of free fall. If the clocks are freely falling, then their motion is an extremum of their respective actions [12]Thus δϕ f is proportional to the difference S 1 − S 2 in the...

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“…If it could be carried out, a neutrino analogue [13] of the Pound-Rebka experiment [14], applying the Mössbauer effect to recoilless resonant capture of antineutrinos [15,16], would demonstrate the blue shift of neutrinos falling in a gravitational field.…”

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confidence: 99%