Quote:
Originally Posted by Barrykgerdes
That's easy to find out if you send a 1 us pulse of light down a great long light corridor. Is it still 1 us long when it reaches the end or has it been stretched or shrunk. Whatever follows the light must be the dark
QED   
Barry |
You could equally argue its the same as the speed of light since the dark is in front of the light, so it must travel at the same speed to get out of the way...
Al.