I still need to take Physics for Dummies, nonetheless my perception is: there is no such medium where dark travels like Elf pointed out. Hence, no one has given a thought about coming up with darkness-measurement. But hey if an apple on head makes someone Newton, I bet if you keep on pondering "how things work" I am sure we'll have another Newton in the making! ;)

Munching on oily chips can only brain damage - BEWARE!