I think you heard about gravitational redshift and blueshift which was confirmed by Pound–Rebka experiment. Pls read regarding these topics. It is available in all standard GR book or simple online materials.

Gravity is not as Einstein or Newton thought...

Article Earth Gravity is not Newtonian

regards

General relativity (GR) predicted gravitational frequency shift of light while travelling from the surface of the sun to earth. This was verified with a terrestrial experiment by Pound and Rebka, but the actual mechanism of how this frequency shift occurs within the electromagnetic wave is not known to physicists. On top of this general relativists have abandoned a key parameter called relativistic mass from their theory which is essential to understanding this mechanism. Another major point is how the force is defined in GR. It is defined as rate of change of momentum. This further prevents understanding the effect of gravity on light wave. Another key factor is how the time is defined at a quantum level. Linear time of GR does not work here. It has to be periodic time of wave and the wavelengths. I considered all these factors in my research and found out the mechanism of gravitational frequency shift. This research lead to the conclusion that the electromagnetic wave is held together by gravitational forces. This is described in sec 2.1 of the following article and the references there in. This result cannot be derived in GR.

https://www.researchgate.net/publication/350061711_ADVAITIC_COSMOLOGY

@Vikram, you are correctly said the mechanism behind this effect is not known in GR. But the concept relativistic mass is already contained in GR. Also, the force we defined in Newtonian case can't apply in GR (unless weak gravity is assumed) because the gravity force is not due to changed in momentum but by the deformation of spacetime. And since the EM wave is purely quantum in nature hence one can't understand using GR how the EM waves stretched or compressed to get the corresponding phenomena. So i think this discussion is meaningless unless we consider Quantum Gravity.

“How does gravity affect light as a wave?”

- practically as Gravity affect on anything other in Matter, besides the difference that Gravity affect on any – fixed and moved in a Gravity field particles, bodies, etc., whereas light – i.e. really photons – always move.

That is because of Gravity is, of course, the “fourth” fundamental Nature force, which in a number of traits is similar to the Electric Force, but differs, including, in that, whereas only some particles have electric charges, all/every particles have gravitational charges - gravitational masses – there cannot be fundamentally “neutral gravitationally” particles, etc..

Though in the GR it is postulated that the gravitational mass of photon is equal to zero, and so photons don’t change their energy/frequency/wave length at propagating in Gravity fields, really that is incorrect – as the GR postulate that there is no some fundamental Force “Gravity”, and gravitational phenomena are interactions in systems “a mass-spacetime-a mass”, where “bended spacetime” forces masses to move along “curved geodesics” is fundamentally wrong.

So at propagating in space between points with different Gravity field potentials photons are red/blue shifted. However that

“…I think you heard about gravitational redshift and blueshift which was confirmed by Pound–Rebka experiment. …..”

- is rather questionable claim in the GR. Again – in the GR photons principally aren’t red/blue shifted, and in the Pound–Rebka experiments, according to the GR, not red/blue shifted photons were observed - in the experiments the result of predicted in the GR “gravitational time dilation” affect was observed,

- and, after Pound–Rebka in their first publications wrote about the observed photons’ red/blue shifts, they were corrected by Wheeler, etc., that really effect is caused by that intrinsic processes in nuclei of Fe-57 on the up and down positions are affected by different “gravitational time dilations”, and so, say, photons that are radiated in lower source have lesser frequency that are radiated by upper source, and, when radiated, say, by the lower source’s nuclei photons hit in the nuclei in upper source, that to compensate the difference in frequencies of internal processes in nuclei it is necessary to use Mossbauer effect red/blue shift motion.

Really, again, Gravity is fundamentally only Force, and so, whereas intrinsic processes in particles, bodies, etc., are indeed slowed in bodies, which compose some gravitational systems – because of the negative mass defect [more see the Shevchenko-Tokarevsky’s 2007 initial models of Gravity and Electricity Forces in https://www.researchgate.net/publication/273777630_The_Informational_Conception_and_Basic_PhysicsDOI 10.5281/zenodo.16494, section 2.2.8 “Mediation of the forces in complex systems” and 3 “Some consequences from the model – gravity, electricity, etc.”],

- however this effect is, at least for weak Gravity, two times lesser than that GR predicts, and in Pound–Rebka experiments the sum of two effects was measured, which is in accordance with the GR.

That above can be really tested only if one effect is measured, and that is rather easy now – see the paper “The informational model – gravity; a next experiment” Jun 2015

https://www.researchgate.net/publication/277710038_The_informational_model_-_gravity_a_next_experiment DOI: 10.13140/RG.2.1.4502.800; the experiment is so simple, that practically for sure was made, however the result wasn’t in accordance with the GR.

Cheers

• Matter attenuates the omnidirectional flow of fast netrino-like ether-particles.
• Fewer particles are leaving a body, and the difference in flow is the cause of gravity. So, gravity is caused by a radial ether wind in negative direction.
• Light moves down faster than up.
• Therefore, 2-way light speed is increasing with distance to the Sun.
• This increase causes an illusion of decreasing speed is a space station.
• This explains the Pioneer anomaly.

I agree with the comments of Ksh. Newton Singh . Anyway, there are a lot of discussions about gravity at Researchgate. But the discussions have not resulted in (accepted) new concepts.

With kind regards, Sydney

Massive bodies such as the Sun curve spacetime around them and this is gravity. As a consequence, light either as electromagnetic waves or particles bends as it passes near them even though light or photons are massless.This is due to the fact that waves carry momentum or energy allowing the coupling between the physical gravitational metric and photons. It is worthy of note that photons or any other massless particles such as gravitons or gluons have equivalent masses derived from the mass-energy equivalenve relation discovered by Albert Einstein.

More details can be enjoyably read in the book "General Relativity " by Hobson et al. and https://royalsocietypublishing.org/doi/10.1098/rsta.2014.0287

Light is neither waves or particles like objects we see, but has properties of both. Having energy means it has mass gravity acts on all mass, transferring energy to and from masses. All models of gravity must do that to be valid.