OK, Physicist didn't like my theory, to say the least, so here is my humble follow up: All four of the fundamental forces involve the exchange of one or more wave-like particles.
Strong Force -> pion (and others)
Weak Force -> W and Z
Electromagnetic Force -> photon
Gravity -> graviton
Such exchange forces may be either attractive or repulsive. The maximum range of each exchange force is further dictated by the uncertainty principle. Since the particles involved are created and exist only in the exchange process, they are called "virtual" particles.
If a force involves the exchange of a virtual particle, then that particle has to "get back home before it is missed" in the sense that it must fit within the constraints of the uncertainty principle, and a particle of mass m and energy E=MC^2 can be exchanged if it does not go outside the bounds of the uncertainty principle.
The graviton is the exchange particle responsible for force of gravity. Although it has not been directly observed, a number of its properties can be implied from the nature of the force. Since gravity is an inverse square force of apparently infinite range, it can be implied that the rest mass of the graviton is zero.
The photon is the exchange particle responsible for the electromagnetic force. The infinite range of the electromagnetic force is due to the zero rest mass of the photon, but so long as the photon has a non-zero mass (i.e. not at rest), it is capable of deflection by gravity due to its ability to exchange gravitons.
Where it gets interesting, however, is that we know that photons (much less gravitons) are not normally at rest. Moreover, photons that are not at rest will always be affected by the gravity of a large object (and this is proven by observation). This would imply that photons not at rest have mass, except that we know that anything that travels at light speed can not have mass. Thus, one is left to conclude that photons not at rest gain an imaginary or "virtual" mass that can exchange gravitons.
This is experimentally verifiable. Recent experiments have demonstrated that as light slows to near-zero velocity, it is less and less affected by gravity.
Thus: Southack's Theory on the Speed of Gravity
Part Two:
(Virtual Mass of Graviton)
E=MC^2
All mass has energy
Gravity (G) is the energy of a mass, therefore
G=E/M
G=CGp (Southack's Theory on the Speed of Gravity)
Gravity and Light are inter-related due to the virtual mass of gravitons and photons at speed, therefore G=C^2
Gp=C
Gp = Virtual Mass of Graviton / Virtual Mass of Photon
Virtual Mass of Graviton = C * Virtual Mass of Photon
Part One
(Speed of Gravity)
1. Light has no real mass
2. Photons of light have no real mass at rest.
3. Photons of light not at rest have virtual mass.
4. Non-resting photons emit gravitons, giving light a virtual mass and a real gravity.
5. Gravity can appreciably bend light due to the emission by photons of gravitons.
6. Light does not appreciably bend gravity.
7. Gravity can appreciably bend light because gravitons have much more virtual mass than photons.
8. Gravitons have much more virtual mass than photons because gravitons travel much faster than photons.
Therefore, Gravity is much faster than the speed of Light. The Speed of Gravity (G) can hereby be represented as the speed of light (C) multiplied by the constant Gp. G=CGp. Gp represents the ratio of difference in virtual mass between photons and gravitons. The ratio of this difference in virtual masses is equal to C.
The Speed of Gravity is therefore the speed of light squared (G=C^2), 3.4703029E10 miles per second.
In contrast, Ralph Sansbury describes the near-instantaneous propagation speed of gravity and related phenomena as essentially equivalent to the computed necessary speed of a sub-electron particle. Sansbury says that the electron structure is really a number of charged particles (he calls subtrons) orbiting within the classical radius of an electron. His calculation gives the surprising result that these subtrons are moving at the much faster speed of 2.5 million light years per second (1.4686906E19 miles per second).