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On the basis of recent precise data on the earth's magnetic field, a new upper bound on the mass of the photon is obtained using a method that was originally proposed by Schr\"odinger. The limit is 1.15 ×{} 10^-10 cm^-1{≡}2.3 ×{} 10^-15 eV{≡}4.0 ×{} 10^-48 g, which is four orders of magnitude better than the best laboratory measurement, that of Plimpton and Lawton.
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Goldhaber et al. (1968) studied this question.
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