Dear Wandaqueen:
at http://www.innerx.net/personal/tsmith/cnfGrHg.html
We find:
"Spin Networks are defined by Baez as "...graphs embedded in a manifold S (the space of spacetime) with edges labeled by representations of a Lie group G and with vertices labeled by intertwining operators. Spin networks define gauge-invariant functions on the space A of connections of any G-bundle over S...".

I added boldface to show the definitions of this are geometric map abstractions rather than physical descriptions of the behavior of particles or waves. In other words, it's a map of the convergence of equations.
I do not deny the possibility of a SpaceTime physical medium at all, yet there are many
versions. Can you clarify whether it is true that properties of matter create the effects of gravity, curvature etc. and everything else we try to describe with equations, and that
no substance called space time is known to exist?
Mike
in Vantage