Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
Dunno...I haven't been en-light-ened yet...
Dark, per se, is a human perception indicating the absence of acceptible energy photons striking the retinal cones and initiating chemical reactions therein. infra-red photons and or ultra-violet photons have too little and too much energy to initiate these reactions and are perceived as darkness by humans. red, green, and blue photons not entering the eye are also perceived as dark, as in a laser beam viewed laterally. even intergalactic space is filled with EM radiation and not dark except to human senses
bikerbabe, while you are not actually measuring the speed of the void you can measure the decrease of the voidness of the glass. it's just the inverse of the fill speed. add one photon to a cubic meter of space and it is no longer a total void. thus the speed of dark is the same as the speed of light in the medium in question
What came first the hen or the egg?
What came first the hen or the egg?