Here’s a question to give you a sense of scale. Which of the following would be brighter, in terms of the amount of energy delivered to your retina: A supernova, seen from as far away as the Sun is from the Earth, or the detonation of a hydrogen bomb pressed against your eyeball? Can you hurry up and set it off? This is heavy. Applying Dr. Spector’s rule of thumb suggests that the supernova is brighter. And indeed, it is . . . by nine orders of magnitude.
