Can you elaborate on what you see as the significance of the fact that "even the most complex interactions appear to proceed at the same rate of speed", please? Just curious.
A computer program solving a physical evolution problem will run shorter or longer depending on how complex the situation is. The more variables that are relevant to that situation, the more complex it will be and the more processing is needed to reach a solution. Add in that multiple variables that affect each other make the situation non-linear, with a solution that can only be approximated by linear processing. By having the universe be granular, being quantized in all aspects, including space-time, gets around the approximation issue by having reality be only an approximation of a hypothetical continuum, describable only by real numbers.
While the approximation issue can be circumvented by requiring total quantization, it is still the case that computer processing time will increase with increasing the number of variables involved and also with the changes in those variables while the processing is going on. An atom that is subject to acceleration will experience a change of state, mostly stress on its electronic interactions with other atoms. Enough acceleration will break those bonds and material failure will take place. Subject the atom to heat, i.e., stress on its electronic bonds due to vibrations of other atoms and the bonds will break faster not slower, even though more processing is needed to figure out what to do. Have the atom get hit by neutrons from some radioactive source and even more stress is involved, making the electronic bonds fail even sooner. Add in that there are loads of other influences going on, like the constantly shifting gravitational field as the local atoms and the entire hierarchy of gravitating bodies up to heavenly bodies themselves move.
Complicating situations typically makes things happen faster. Considering that in the example above, it is not just one atom involved but a huge number of them and the state of each atom is influenced by the changing states of all the other atoms, the amount of computation to reach a result increases very rapidly as the situation becomes more complex. There should be some discernible increase in the rate of processes as complexity increase but there does not seem to be any. Rather things tend to go faster.
Reality being computation driven cannot explain this. Reality being fundamentally geometric stands a better chance in that there is no need to compute anything to arrive at a result. The shapes of things change continuously in accordance with the plethora of simultaneous influences. The ‘shapes’ here would not be simply 3D spatial shapes but would exist in multi-dimensional phase spaces. A universe being the embodiment of a particular Calabi-Yau manifold – complicated higher dimensional shapes sort of like Swiss cheese – could explain the specific properties of that universe. Possible particles and forces (which are quanta remember) would be those that fit the ‘holes’.
