I’m often asked two very natural and related questions.
- Why is the speed of light, usually denoted c, so astonishingly fast?
- Why, in Einstein’s famous equation relating energy and mass — E=mc2 — does c2, a gargantuan number, appear?
It’s true that the speed of light does seem fast — light can travel from your cell phone to your eyes in a billionth of a second, and in a full second and a half it can travel from the Earth to the Moon.
And indeed the energy stored in your body is comparable to the Earth’s most explosive volcanic eruptions and to the most violent nuclear bombs ever tested — enormously greater than the energy you use to walk across the room or even to lift a heavy suitcase.
What in the name of physics — and chemistry and biology — is responsible for these bewildering features of reality? The answer is fascinating, and originates in particle physics and the resulting structure of matter. It is surprisingly intricate, though, so I’m going to approach this step-by-step over three blog posts. Here’s the first.
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