To obtain a formula reproducing the experimental results, he ends up using a trick that does not appear to make much sense: he assumes that the energy of the electric field is distributed in “quanta,” that is to say, in small packets, little bricks of energy. The size of the packets, he assumes, depends on the frequency (that is, the color) of the electromagnetic waves. For waves of frequency ν, every quantum, or every packet, has energy: E = hν This formula is the first of quantum mechanics; h is a novel constant, which today we call the “Planck constant.” It fixes how much energy there is in
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