Life is in balance.... everything in this Universe is in balance..

so light and dark are two sides of the same coin... therefore, both of them have the same speed. Don't go with the wrong notion of c and -c... nope.. it's not true.

You take a torchlight.. press the switch..... the light will travel out of it at the speed of "c".. as soon as you release the switch.. the light stops emitting from the torch. and the tail portion of the light will keep on advancing forward with speed of "c", and then after dark follows the tail with again the same speed.