If judged by their speed alone, photons are Newtonian particles. The speed of light VARIES, both in the presence and in the absence of gravity, just as does the speed of ordinary projectiles (e.g. bullets):

"Emission theory, also called Emitter theory or ballistic theory of light, was a competing theory for the special theory of relativity, explaining the results of the Michelson–Morley experiment of 1887. [...] The name most often associated with emission theory is Isaac Newton. In his corpuscular theory Newton visualized light "corpuscles" being thrown off from hot bodies at a nominal speed of c with respect to the emitting object, and obeying the usual laws of Newtonian mechanics, and we then expect light to be moving towards us with a speed that is offset by the speed of the distant emitter (c ± v)." https://en.wikipedia.org/wiki/Emission_theory

"To see why a deflection of light would be expected, consider Figure 2-17, which shows a beam of light entering an accelerating compartment. Successive positions of the compartment are shown at equal time intervals. Because the compartment is accelerating, the distance it moves in each time interval increases with time. The path of the beam of light, as observed from inside the compartment, is therefore a parabola. But according to the equivalence principle, there is no way to distinguish between an accelerating compartment and one with uniform velocity in a uniform gravitational field. We conclude, therefore, that A BEAM OF LIGHT WILL ACCELERATE IN A GRAVITATIONAL FIELD AS DO OBJECTS WITH REST MASS. For example, near the surface of Earth light will fall with acceleration 9.8 m/s^2." http://web.pdx.edu/~pmoeck/books/Tipler_Llewellyn.pdf

Logical biconditional:

The speed of light is variable as per Newton

if and only if

the wavelength of light is constant for a given emitter.

The second statement, "the wavelength of light is constant for a given emitter", will become the fundamental axiom of future, Einstein-free physics. Important corollaries:

Corollary 1: Any frequency shift entails (is caused by) a proportional speed-of-light shift.

Corollary 2: If the emitter and the observer (receiver) travel towards each other with relative speed v, the speed of light as measured by the observer is c' = c+v, as per Newton's theory.

Corollary 3: Spacetime and gravitational waves (ripples in spacetime) don't exist. LIGO's "discoveries" are fakes.

Corollary 4: Light falls in a gravitational field with the same acceleration as ordinary falling bodies - near Earth's surface the accelerations of falling photons is g = 9.8 m/s^2. Accordingly, there is no gravitational time dilation - Einstein's general relativity is nonsense.

Corollary 5: The Hubble redshift is due to light slowing down as it travels through vacuum. The universe is static, not expanding.

See more he https://twitter.com/pentcho_valev

Pentcho Valev