(New York Times)
The standard illustrations of Einstein’s equation—bombs and power stations—have perpetuated a belief that E = mc² has a special association with nuclear reactions and is thus removed from ordinary activity.
This isn’t true. When you drive your car, E = mc² is at work. As the engine burns gasoline to produce energy in the form of motion, it does so by converting some of the gasoline’s mass into energy, in accord with Einstein’s formula. When you use your MP3 player, E = mc² is at work. As the player drains the battery to produce energy in the form of sound waves, it does so by converting some of the battery’s mass into energy, as dictated by Einstein’s formula. As you read this text, E = mc² is at work. The processes in the eye and brain, underlying perception and thought, rely on chemical reactions that interchange mass and energy, once again in accord with Einstein’s formula.