16. Dark Energy: The Variable Viscosity of Voids

Because "Dark Energy" is inferred from supernovae appearing dimmer than expected, it is actually a measurement of Variable Vacuum Viscosity.

Light traveling through cosmic voids (where Hydrogen density is low) experiences less drag. It travels a longer physical distance to accumulate the same redshift z. Since the source is physically further away than the redshift implies, it appears dimmer. We do not need an accelerating universe; we only need to acknowledge that the vacuum's optical density varies with matter density.