Phys.org has a report on some research concerning the granularity of space; Spacetime: A smoother brew than we knew.

Observing photons from a gamma ray burst that arrived at the same time the researchers decided that they should not have arrived so close together after coming 7 billion light years, if the universe is granular at the Planck length (approximately 1.6 * 10^35 meters). The Planck length granularity should have scattered them so that they arrived at different times.

Probably not a definitive measurement, there will be people who disagree with them, but if their findings are upheld it will have a significant influence on quantum gravity research.

Bill Gill


C is not the speed of light in a vacuum.
C is the universal speed limit.