On Saturday, June 8, 2013 8:30:27 PM UTC-7, Tom Potter wrote: > > > 1. Light travels at a constant speed "c" > > of about 299 792.458 meters per second > > in the absence of matter, > > and in media with sparse matter, > > such as the Earth's atmosphere. >
How is it that you know this? Who told you this? Or did you measure it in every possible scenario?