Physics education research, electronic materials, and the musings of Christopher Moore, Ph.D.

I had a physics epiphony of sorts yesterday. I was thinking about the things I was reading in a book about relativity ("Why Does E=MC2") and what general relativity entails. Of course there is no absolute space, which would mean there is no absolute distance, as the definition of distance is the measurement between one location in space to another. And no absolute time. So, take the basic physics equation d=rt, which can be easily switched around to be rate equals distance over time. But, without absolute distance or absolute time, we have no rate, or speed. With that in mind, why is the speed of light considered a constant, or "special speed" that cannot be passed, if there is no such thing as absolute speed?