Most precise test of Lorentz symmetry for the photon finds that the speed of light is indeed constant

(Phys.org)--The laws of physics are the same no matter which direction you're facing or how fast you're moving--it's such an intuitive concept that most people probably don't know that it has a name: Lorentz symmetry. Over the past several decades, physicists have been testing Lorentz symmetry at ever-higher degrees of precision, as violations of the foundational property are predicted by a number of proposals that aim to unify the two major theories of modern physics: general relativity and the...