equivalence principle. Particles follow geodesics that are extremal paths in spacetime. These paths are the same for any mass m so long as this test mass is small m << M for M the mass of a central mass that defines a gravity field. If the spacetime curvature is due to a gravity wave or some other physics, the curvature of this field R is such that R >> 8πGm^2. If this test mass is sufficiently large it has its own appreciable curvature and this results in a highly complex problem similar to the 3-body problem in Newtonian mechanics.
I have though been thinking about this a bit differently. The equivalence principle states that the freely falling frame is equivalent to a frame in flat spacetime far removed from any gravity field. I have been thinking of this according to quantum field theory. A freely falling frame is one which has a vacuum equivalent to a quantum vacuum in flat spacetime. The geodesic the frame falls under is one which preserves this vacuum.
This may be extended to massive particles and massless particles. A massless particle is on a null geodesic and is then on a “null frame.” These frames are then projective varieties over massless quantum fields in that vacuum. These massless fields all have transverse modes, but no longitudinal modes. A massive particle has a longitudinal mode, and the vacuum modes have dispersion as a result. This is due to the presence of the Higgs field.
An accelerated frame is one which has a vacuum equivalent to a particular vacuum near a black hole. Depending on the acceleration parameter this can be a different vacuum. In this way aspects of spacetime physics can be thought according to quantum mechanical or quantum field properties. Spacetime is probably an emergent phenomenon of quantum physics.
To prepare for a trip, camels would be fattened up for the journey across the desert. Caravans moved at about three miles per hour and it took them 40 days to cross the Sahara Desert. Muslim traders spread Islam throughout Western Africa. Islamic law helped to lower crime rates and also spread the common language of Arabic, thus encouraging trade.
The final of the 10 amendments that constitute the Bill of Rights, the Tenth Amendment was inserted into the Constitution largely to relieve tension and to assuage the fears of states' rights advocates, who believed that the newly adopted Constitution would enable the federal government to run roughshod over the states
