In the Quantum
FFF Model, mass is the capacity of rigid stringy Fermion particles to mutate
oscillating Higgs vacuum field particles into as many rigid gravitons per time
unite in a continuous collision process. (FFF = Function Follows rigid paticle Form)

The collision
process is assumed to be the origin of the spin and eigen energy of Fermions
and fully in line with General Relativity (GR).

Around
massive objects like star and planets, the Higgs field oscillation strength is
diluted and polarized by the graviton radiation influence creating a “Local Anti
Symmetric Oscillating vacuum Frame” ( LASOF) as the origin of a so called
lightspeed mass/drag effect, which is not in line with GR. and the origin of
the so called “Michelson Morley null result”

Outside the
LASOF ellipsoidal area around the earth however, this effect should be
observable by Michelson interferometers.

This
difference with GR is subject to future (LISA) research in space.

As a consequence, it is assumed that the LISA Pathfinder satellite, soon will be able to test light speed differences around the sun even at
its orbit location L1 ( Lagrangian L1) and as a result its absolute speed
related to the local LASOF vacuum of the sun.

see:

http://sci.esa.int/lisa-pathfinder/