Philadelphia, PA

Dear Decker,

The evidence from the LIGO detections support the idea that gravitational waves move with the speed of light. Given that point, it would seem to follow that in (any viable) theories postulating gravitons as carrier particles, in analogy to photons as carriers of electromagnetic energy, the gravitons would need to be massless, since in accordance with GR, no massive particle can attain the speed of light.

But, you ask, "Does the long range of gravity require massless gravitons? ; and that would seem to be a slightly different question. Neutrino emissions also have very long range effects, thought the best evidence is that they are not completely massless. It is not the long range but rather light-speed of gravitational emissions that would require massless gravitons.

H.G. Callaway

Philadelphia, PA

Dear Decker,

The evidence from the LIGO detections support the idea that gravitational waves move with the speed of light. Given that point, it would seem to follow that in (any viable) theories postulating gravitons as carrier particles, in analogy to photons as carriers of electromagnetic energy, the gravitons would need to be massless, since in accordance with GR, no massive particle can attain the speed of light.

But, you ask, "Does the long range of gravity require massless gravitons? ; and that would seem to be a slightly different question. Neutrino emissions also have very long range effects, thought the best evidence is that they are not completely massless. It is not the long range but rather light-speed of gravitational emissions that would require massless gravitons.

H.G. Callaway

In Newtonian physics, it's often claimed that gravity can't affect massless particles because the Newtonian gravitational force is proportional to the product of the masses. ... It's not curvature of spacetime that guarantees that massless particles are affected by gravitation just like massive particles.

“…Does The Long Range Of Gravity Require Any Graviton To Be Massless?…”

as that H.G. Callaway pointed above, the fact that Gravity is a log range force and the phenomenon “massless” have no direct relations. Moreover, there cannot be anything that would be “massless”, all/every particles, including very probably existent gravitons [the existence of gravitons seems can be discovered experimentally, some discussion see SS posts inhttps://www.researchgate.net/post/Why_are_scientists_trying_to_merge_gravity_and_quantum_physics_even_though_gravity_is_just_the_curvature_of_space-time?view=5acbb915b0366deaf33cffd9]

have both, i.e. the inertial mass and the gravitational mass, more see SS posts and linked Shevchenko and Tokarevsky papers that are linked in these posts in the thread https://www.researchgate.net/post/Is_gravity_a_dark_energy_effect

including, for example, photons have both these masses.

Thus, for example that

“…In Newtonian physics, it's often claimed that gravity can't affect massless particles because the Newtonian gravitational force is proportional to the product of the masses…”

is incorrect. Photons change their energy just in “Newtonian” gravity fields;

that in the GR it is postulated that (i) - there is no some Nature force “Gravity” at all, and (ii) - photons don’t change their energy in the “gravitationally curved spacetime” when move “along geodesics”. Both these [and not only these] GR postulates are incorrect, Gravity is the fundamental Nature force, as the EM, strong, and weak forces; and photons, as any other particle/body, change their energy if move in gravitational fields between points that have different gravitational potentials.

The last [gravitational impact on photons] can be easily checked and with rather large probability confirmed in rather simple experiment that was suggested a 3 years ago https://www.researchgate.net/publication/277710038_The_informational_model_-_gravity_a_next_experiment

And will cost no more then 1 $million, that is very small money for the fundamental result; but it isn’t made till now.

Besides as , for example, that

“…rest mass is created by the transfer of energy from the Higgs field to the electromagnetic field…”, etc.

seems is rather far from the objective reality [as the GR postulates above also], both, the “rest” and gravitational masses are the result of that all particles are closed-loop algorithms, what reveals in Matter as they are some 4D gyroscopes, which resist to attempts to change their 4D vector rotation rates [inertial mass], and because they radiate [“circular”] gravitons at every rotation; and make that without any necessity in some “Higgs fields”, etc.

relating to this point again more see SS posts in the thread “Is Gravity the dark energy effect?” linked above.

Cheers