According to Newton's theory, in a gravitational field light particles fall with the same acceleration as ordinary falling bodies - on the Earth, the acceleration of falling photons is g. This is an obvious consequence of the equivalence principle and many Einsteinians teach it, not knowing that in this case "g" is fatal for Einstein's relativity:

"If we accept the principle of equivalence, we must also accept that light falls in a gravitational field with the same acceleration as material bodies." http://sethi.lamar.edu/bahrim-cristian/ ... ns_PPT.pdf

The variation of the speed of light in a gravitational field predicted by Newton's emission theory has been confirmed experimentally:

University of Illinois at Urbana-Champaign: "Consider a falling object. ITS SPEED INCREASES AS IT IS FALLING. Hence, if we were to associate a frequency with that object the frequency should increase accordingly as it falls to earth. Because of the equivalence between gravitational and inertial mass, WE SHOULD OBSERVE THE SAME EFFECT FOR LIGHT. So lets shine a light beam from the top of a very tall building. If we can measure the frequency shift as the light beam descends the building, we should be able to discern how gravity affects a falling light beam. This was done by Pound and Rebka in 1960. They shone a light from the top of the Jefferson tower at Harvard and measured the frequency shift. The frequency shift was tiny but in agreement with the theoretical prediction. Consider a light beam that is travelling away from a gravitational field. Its frequency should shift to lower values. This is known as the gravitational red shift of light." https://courses.physics.illinois.edu/ph ... /L13r.html

Albert Einstein Institute: "One of the three classical tests for general relativity is the gravitational redshift of light or other forms of electromagnetic radiation. However, in contrast to the other two tests - the gravitational deflection of light and the relativistic perihelion shift -, you do not need general relativity to derive the correct prediction for the gravitational redshift. A combination of Newtonian gravity, a particle theory of light, and the weak equivalence principle (gravitating mass equals inertial mass) suffices. [...] The gravitational redshift was first measured on earth in 1960-65 by Pound, Rebka, and Snider at Harvard University..." http://www.einstein-online.info/spotlig ... ite_dwarfs

As the quotation below suggests, Pound, Rebka and Snider knew that their experiments had confirmed the variation of the speed of light predicted by Newton's emission theory of light, not the gravitational time dilation predicted by Einstein's relativity:

R. V. Pound and G. A. Rebka, Jr, APPARENT WEIGHT OF PHOTONS http://journals.aps.org/prl/pdf/10.1103 ... Lett.4.337

R. V. Pound and J. L. Snider, Effect of Gravity on Gamma Radiation: "It is not our purpose here to enter into the many-sided discussion of the relationship between the effect under study and general relativity or energy conservation. It is to be noted that no strictly relativistic concepts are involved and the description of the effect as an "apparent weight" of photons is suggestive. The velocity difference predicted is identical to that which a material object would acquire in free fall for a time equal to the time of flight." http://virgo.lal.in2p3.fr/NPAC/relativi ... /pound.pdf

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Michael Fowler, University of Virginia: "One might conclude from the brief discussion above that a light beam in a gravitational field follows the same path a Newtonian particle would if it moved at the speed of light. This is true in the limit of small deviations from a straight line in a constant field, but is not true even for small deviations for a spatially varying field, such as the field near the sun the starlight travels through in the eclipse experiment mentioned above." http://galileo.phys.virginia.edu/classe ... ivity.html

So for "small deviations from a straight line in a constant field", that is, in the framework of the freely-falling-elevator experiment, the speed of light varies as predicted by Newton's emission theory of light and in violation of Einstein's relativity. Given this, considering complicated situations involving "spatially varying field" is totally irrelevant.

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