Variable lightspeed by gravity direction dependent lightspeed frame dragging. According to Quantum FFF Model
Einstein did already suggest a possible variable lightspeed.
Einstein wrote in 1912 :
The principle of the constancy of the speed of light can be kept only when one restricts oneself to space-time regions of constant gravitational potential.
see:
https://en.wikipedia.org/wiki/Variable_speed_of_light
Einstein "did not need the ether" mathematically, so he stopped thinking to make it more complex.
However in Quantum FFF Model, the gravitational potential is subject to gravitational linearity from the source. (earth). So I suggest a cigar shaped gravitational potential around the earth. called LASOF.
See: The CHAMP-GPS outliers.
Local Anti-Symmetrical Oscillating vacuum Frame (LASOF).
Cigar shaped LASOF bubble structure around the earth, with 2 proposals with future experiment. A: a two-way triangle satellite (balloon) signal interference experiment and B: a two way lightspeed interference laboratory experiment with a vast rotating mirror drum.
See CHAMPs-GPS outliers in:
Experiments to determine the mass related Lightspeed extinction volume
around the Earth and around spinning objects in the Lab.
http://vixra.org/pdf/1102.0056v2.pdf
an example: Comparison of the absolute kinematic orbit solution w.r.t. RSO.
Tae Suk Bae, 2003, Ohio State university.
Q-FFF Theory: Second:
Quantum Gravity should be based of TWO different forces.
A: The Axon-Higgs field pressure (also called Casimir effect) created by the oscillating vacuum lattice.
B: The photon based field like the Electro-magnetic transmission field, which is half of the Feynman diagram component .
Third:
Black Holes have not only hairs, but they repel all propeller shaped rigid string Fermions.