Either can occur.

nEither can occur because photons(light) have massless particles.

For example, In night, if there is a electric bulb in open space near to your home, see the scattering of light. Light travels everywhere equally(up and down) around the electric bulb.

it is written also here that there is no loss or gain of energy

Article Gravitation, photons, clocks

Yes, a photon has no mass, but the pressure of light exists. And the black hole does not emit light. Light is electromagnetic vibrations, and photons are particles with a certain energy. Then, according to the law E =mc2, the effective mass of the photon m= E\c2.

Rustam Khakimovich Rakhimov. Thanks for your answer.

The Velocity of a massless particle is equal to the velocity of light, but Einstein's mass-energy equation (E = mc^2) is not applicable for light/photon.

Einstein's mass-energy equivalence denotes the relativistic energy.

Yes, a photon has no mass, but light pressure exists and a black hole does not allow light to escape. Based on this, gravity can influence the energy of a photon. There is no prohibition at the quantum level. Of course, it is still impossible to say definitely. The future will show

“…It is written also here that there is no loss or gain of energy Article Gravitation, photons, clocks … …..”

- yeah, the authors of this article completely in framework of the GR explain to some physicists, who don’t know what is the GR enough, that photons, since in the GR haven’t “mass”, don’t change their energy at propagating in the “curved [by some GR “mass”] spacetime”, including between points with different “curvature”, i.e. points with different Gravity field potentials;

- and so though at experiments, say, Pound-Rebka-Snyder experiments where “red/blue shifts” of gamma-photons of Fe-57 decay observed, really there was no shifts, whereas this “shifts illusion” was caused by that radiating/receiving the photons Fe-57 nuclei were in points with different “gravitational time dilation in the curved by Earth spacetime”.

This article was rather popular in late 1990s and first 2000s years; including was free accessible on the RG.

Really, as that yet Newton understood, there exist two fundamentally different masses of particles, bodies, etc. “inertial mass” , and “gravitational mass”, while really – as that is rigorously shown in the Shevchenko-Tokarevsky’s informational physical model, in this case see

https://www.researchgate.net/publication/355361749_The_informational_physical_model_and_fundamental_problems_in_physics , more concretely Shevchenko-Tokarevsky’s 2007 initial model of Gravity and Electric Forces in

https://www.researchgate.net/publication/366536729_The_informational_model_-Gravity_and_Electric_Forces_Version_2 ,

- Matter’s spacetime is the fundamentally absolute, fundamentally flat, and fundamentally “Cartesian”, [4+4+1]4D spacetime with metrics (cτ,X,Y,Z,g,w,e,s,ct), which fundamentally cannot be impacted, i.e. “contracted”, “dilated” , “curved”, etc., by anything in Matter and anything in Matter fundamentally cannot impact on the spacetime.

So really there fundamentally cannot be the postulated in the GR interactions in systems “mass-spacetime-mass”, the observed gravitational effects in systems of gravitationally coupled bodies are caused by action of the fundamentally nothing else than the fundamental Nature Gravity force, which is in a few traits similar to the fundamental Nature Electric force, where electric charges interact in flat spacetime, and the gravitational charges “gravitational masses” quite analogously interact in flat spacetime above.

At that all particles, including photons, fundamentally have both masses – the inertial mass and gravitational mass, and so photons gain and lose energy when, say, move down and up in Earth gravity field.

That is another thing that really, because of that [more see the Gravity model above] an accelerated motion of a particle under Gravity Force happens at spending own intrinsic energy of the particle – particle moves in a Gravity field as, say, a human moves in water spending his energy,

- correspondingly intrinsic processes in particles [nuclei, bodies, etc.] at that really slow down [and remains be slowed at statics in the PRS experiments], what is observed as quite real “gravitational mass defect”,

- correspondingly in PRS experiments the sum of these effects, i.e. the photons’ gaining/losing of energy/frequency, and difference of intrinsic processes rates in Fe-57 on different heights, was observed, while the experiments results were in whole accordance with the GR predictions.

So to test really the GR it is necessary to make experiments where only one effect is, such experiment is quite easy, and can be made in a couple of weeks, see https://www.researchgate.net/publication/277710038_The_informational_model_-_gravity_a_next_experiment.

The result of the experiment, if would be in accordance with the GR, would be much more convincing confirmation of the GR than PRS experiments,

- or, as that is shown in the SS&VT Gravity model above, the difference of clocks showings will be twice lesser than the GR predicts.

Again, the experiment is quite easy now and can cost not more ~$200 000, but it wasn’t made officially till now; though it looks as that it was made, but didn’t confirm the GR…

Cheers

Chinnaraji Annamalai , Do photons gain or lose energy due to a gravitational field?

No, the gravitational redshift occurs because the clock runs slower at points of strong gravity than on the ground (i.e., the oscillation frequency is low). A propagating photon increases in wavelength and speed of light, but its energy remains the same. The Shapiro delay effect is similar.

https://einstein.stanford.edu/Media/ShapiroDelay-Flash.html