Equation 57 · Every Crystal Has Its Own Speed of Light
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Put the two numbers next to each other and the crystal stops being a curiosity and becomes a calibration. The best emergent-Lorentz window any measured crystal can show is of order one percent: a first-order drift anisotropy is a ten-percent effect at a tenth of the cone speed, and even graphene’s own Fermi velocity drifts by a factor of three as the Dirac point is approached. Our own vacuum is not merely somewhat better than that. Stefano Liberati’s review of Lorentz-invariance tests gives the best measured bound on a rotationally invariant electron Lorentz-violation coefficient as roughly one part in 10^{16} [ 10 ] — fourteen orders of magnitude tighter than the best window any measured…
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Put the two numbers next to each other and the crystal stops being a curiosity and becomes a calibration. The best emergent-Lorentz window any measured crystal can show is of order one percent: a first-order drift anisotropy is a ten-percent effect at a tenth of the cone speed, and even graphene’s own Fermi velocity drifts by a factor of three as the Dirac point is approached. Our own vacuum is not merely somewhat better than that. Stefano Liberati’s review of Lorentz-invariance tests gives the best measured bound on a rotationally invariant electron Lorentz-violation coefficient as roughly one part in 10^{16} [ 10 ] — fourteen orders of magnitude tighter than the best window any measured crystal has ever shown.
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