By showing that gravitational waves propagate along light-like curves in the spacetime geometry, whose perturbations they define. This geometry needn't be flat, by the way.

First, recognize the "speed of gravity" is not instantaneous but is much faster than light. IMO Newton in his book "Opticks" had a Theory of Everything (TOE) in the queries (1). Using Newton's 3 types of mass that a body has (from Principia), I like van Flandern's approach: note the difference between the direction light (from the Sun, or moon) and direction of the gravitational mass waves.

The idea that measurements of the gravity using GR yields the speed of light is a misinterpretation of the GR field equation. That is, the left-hand side (LHS) is a math mapping - it's not real. So, any experiment using the LHS without the inverse transform to energy-momentum is flawed. (2)

(1) SUMMARY

https://www.researchgate.net/publication/344442808_Scalar_Theory_of_Everything_STOE_unites_the_big_the_small_and_the_four_forces_GUT_by_extending_Newton's_model?_tp=eyJjb250ZXh0Ijp7ImZpcnN0UGFnZSI6InF1ZXN0aW9uIiwicGFnZSI6InByb2ZpbGUiLCJwcmV2aW91c1BhZ2UiOiJwcm9maWxlIiwicG9zaXRpb24iOiJwYWdlQ29udGVudCJ9fQ

(2) https://www.youtube.com/watch?v=TxoUAlek_9Q&t=4s

Dear @Preston Guynn and Sydney Ernest Grimm

Thank you for your opinions and the extensive references provided. The links provided by Preston Guynn, including the last 3, can be opened. I don't think there should be a reason why they can't be opened. Unfortunately the address of the video links provided by Sydney Ernest Grimm is blocked for me, those videos must have been a much more visual and imaginative presentations. Hopefully I will have access to those videos in the future.

Best Regards, Chian Fan

The thread question

“【NO.41】Doubts about General Relativity (6) - How do we define the Instantaneous Speed of a Gravitational Wave and how do we Measure it directly?”

- looks as rather vague one. That gravitational waves as “ripple in the spacetime” propagate in 3D space with the speed of light is a tenet in mainstream physics, and that is used at simultaneous operating of at least 3 GW observatories LIGO Virgo, KAGRA,

- aimed at to measure solid angles of/direction to GW sources by measuring retardations of detections relating to a first in time detection in an observatory in other two distant ones.

That is another thing, that till now such events are rather, if too, rare; and, besides, the events besides one case, aren’t accompanied by detection of corresponding cosmological event by traditional astronomic instruments; and so till now the “GW astronomy” looks as is rather far from really useful applicability;

- but that GW really propagate with standard speed of light is, of course, quite correct. Gravity is fundamentally nothing else than some fundamental Nature force, which in a few traits is similar to the Electric Force; and so it would be nothing surprising if at accelerations of large gravitational charges “gravitational masses” essential coherent flows of particles “gravitons” would be radiated,

- which would be detected as GW waves – as coherent flows of particles “photons” are radiated by accelerated electric charges, and are detected as EM waves.

At that both – gravitons and photons – are fundamentally – as everything in Matter – some disturbances in Matter’s ultimate base – the (at least) [4+4+1]4D dense lattice of primary elementary logical structures – (at least) [4+4+1]4D binary reversible fundamental logical elements [FLE], which is placed in the Matter’s fundamentally absolute, fundamentally flat, fundamentally continuous, and fundamentally “Cartesian”, (at least) [4+4+1]4D spacetime with metrics (at least) (cτ,X,Y,Z, g,w,e,s,ct), FLE “size” and “FLE binary flip time” are Planck length, lP, and Planck time, tP,

- and everything in Matter so constantly moves with 4D velocities in the utmost universal “kinematical” 4D space with metrics (cτ,X,Y,Z); the velocities have identical absolute values c,, what is determined by the lattice FLE parameters, c= lP/tP.

Since gravitons and photons move only in 3DXYZ space, they move in this space with c.

More about what are Gravity and Electric Forces, photons and gravitons, etc., see the Shevchenko-Tokarevsky’s 2007 these Forces Planck scale informational physical models in

https://www.researchgate.net/publication/365437307_The_informational_model_-_Gravity_and_Electric_Forces

Moreover, not only these Forces are similar, Nuclear Force that binds nucleons in nuclei act by the same scheme, more see the [recently a bit edited version] 2023 SS&VT Planck scale informational physical model in

https://www.researchgate.net/publication/369357747_The_informational_model_-Nuclear_Force/comments

Cheers

I would like to introduce my Question or argument(It may not be correct) on Special Relativity theory, posted Researchgate below including the file. I wish to have any comment on it. It may be also related with General Relativity, spacetime and universe. I am sorry for any disturbance. Thank you very much.

https://www.researchgate.net/post/Discussion_on_the_velocity_of_light_with_an_argument_different_from_Special_Relativity_theory

Special relativity is not scene for our era.

Article Universe's Rotation and Its Benefit

Dear Sydney Ernest Grimm

Thank you very much for providing the Specific Addresses. These organisations are new to me. I have viewed some of them. I know what's involved, although some videos are still unable to show.

I sincerely appreciate your generosity!

Best Regards, Chian Fan

Gravitational waves do not cause gravity, which is the curvature of the structure of space-time, but gravitational waves mediate the field changes of that structure and there is no need for them other than to be causal, i.e. they act at speed c. Gravitational waves are gravity, i.e. curvature in the structure. When the local energy density moves harmonically by oscillating, the gravitational curvature spreads quadrupole alternately, strengthening and weakening, which is what the waves are made of - so when they pass, they restore the situation to almost the same geometry, but some memory traces in the curvature structure have time to form. The Moon's rotation around the Earth is so slow that the "memory traces" are significant.

Dear Sydney Ernest Grimm,

Thank you very much for the comments and explanation. I am not sure I understood all of your explanation. I would like to reply with some explanation as follows.

I am a nuclear enginner, not physicist and have worked for over 30 years on utilizing nuclear energy to generate electricity and radiation(electromagnetic wave) detection for imaging, with interest on movement of energy. Engineer tends to start first based on the confirmed or self-assured facts.

EMW is generated and emitted by acceleration or vibration of a charged particle. Radiowave by electrons in wire, light by vibration of electrons in atoms in matter where the extent of vibrations depends on the temperature of the matter, gamma ray by vibration of elemenary particles in a nucleus of atom. The direction of emiited EMW is understood to be determined by the vibration direction of charged particles.

After EMW or light is emitted from its source, it is understood that it travels in straight direction at constant speed under vacumm with no obstacle(and possibly no electromanetic field and no gravity field).

Around 1905, it seems to me that there be a consensus in Physics community that light in vacuum or universe travel at constant speed in a hypothetical medium, called ether of universe, regadrless of movement of light source. I guess that around 1905, it was not clearly known that how light or EMW is generated and emitted, and structure of atom was not known enough at that time. Then, there was the famous Michelson-Morley experiment. To match these two, Special Relativity theory with a Lorentz transformation was derived.

My argument is that results of M-M experiment does not necessarily lead to Special relativity. It rather clearly showed that movement of light depends on movement of light emitter or source.

As an evidences to support Special Relativity theory, there is time dilation of atomic clock of Cesium in Earth orbits, which utilizes the deexcitation time. There is found no evidence of length contraction which is actually so much difficult. Considering excitation and deexcitation processes of electrons in a atom of cesium, there might be possibility of effects of others such as electromagnetic fields to slow down the deexcitation process in cesium atom in earth orbit to result in time dilation.

There is Doppler effect of light wich shows the wave characterisitc of light. When light emItter or light receives is moving, it would be simple that just assuming that light receiver is moving at relative velocity of emitter and receiver, which will results in same results of Doppler effect.

Thank you very much.

Best regards,

Chan Bock Lee

The most natural structure of space is a uniform field that conserves momentum and all quantum states as "non-local" correlations in its geometric structure. The Higgs field may well have antipodal symmetry, where each electric charge rotates as both negative and positive, but since the rhythm is common, the illusion is created that there are only one-sign conserved charges. In fact, it may be that only the conservation of state opposites is the fundament and is related to the Higgs scalar as parity. Those antipodes of the 4-dimensional field can easily be interpreted as magnetic monopoles, if that is necessarily desired. Electric monopolies are also relativistic emergences, time-like, while magnetic monopolies are space-like.

The only absolute fundamental entity is the 4-dimensional field structure. The first derivative for any proper time is an intrinsic property of the field, but the second and higher time derivatives are absolute evolutions between which light-like signals are needed.

What are the physical quanta of a 4-dimensional field? My guess is free flavor spectrum neutrino type standing waves. The flavors of the three leptons rarely show up in matter contexts. A double neutrino structure of light is not ruled out, but there is no need to be limited to three flavors; the directional coherence is enough and the energy difference between the antipodal neutrino waves determines the direction of action and the electromagnetic energy.

Dear Sydney Ernest Grimm,

Thank you very much for the reply. I am glad to hear that you agree with my conclusion on Special Relativity. I would like to mention that if theory of Special Relativity is not foundational, then General Relativity is not also, and subsequent effects would be enormous in the Modern physics including high energy particle accelerator physics, and many others which physicist will know better.

Best regards,

Chan Bock Lee

Dear Sydney Ernest Grimm,

Thank you very much for the encouragement. I have high respect for your straightforwardness to agree my opinion. As a nuclear engineer, I highly repect the great achievements of Einstein such as mass-energy equivalence, photoelectric effects and much more. For the relativity theory, I have tried to understand it since my college period more than 40 years and I failed to grasp it with some doubt. Then, since last year, stimulated by the amazing images of James Webb telescopes, I have tried to review old works in around 1850-1920 and found what I proposed in my manuscript.

Best regards,

Chan Bock Lee

The last post, where the thread question is really scientifically clarified, is the SS post on page 1, 6 days ago now.

Cheers