So, the universe is expanding, and, from what I've heard, that expansion is accelerating. However, I'm unclear as to the specific mechanism involved, particularly as would be described in a Loop Quantum Gravity model. Many of the popular books I've read describe the situation in terms of a General Relativity based rising loaf of raisin bread, in which the raisins (galaxies and galaxy clusters) themselves are not moving, but rather, in which the bread (space) between them is expanding.
So, if this expansion of spacetime is translated from General Relativity to Loop Quantum Gravity, would it be more accurate to think of the number of "atoms" of spacetime increasing or to think of the individual units of spacetime becoming larger? Or is my sign flipped and the units of spacetime would actually be getting smaller, thus making the cosmic distances appear to increase?
If, at its most fundamental level, the speed of light is equal to the Planck length / the Planck time, then how would either the addition of extra units of spacetime or the expansion (or the contraction) of those basic units effect the ratio of length to time that is the universal constant of the speed of light? Must the clock rate of the universe shift to compensate for the expansion of the universe?
Or am I way off base and there's really no way to conceptualize of LQG Spin Foams in these terms?