Physicists propose method to measure variations in the speed of light

The speed of light, c, is one of the best-known constants, having a value of just under 300,000,000 meters per second in a vacuum. But in some alternative theories of cosmology, the speed of light is not actually constant, but varies throughout time and space. Observational data in support of variations in the speed of light are lacking, but in a new paper, physicists have proposed a way to constrain possible speed-of-light variations and show that future experiments might be able to detect these variations, if large enough.

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