
Test can show if the speed of light has changed - lucodibidil
https://www.engadget.com/2016/11/27/test-for-change-in-speed-of-light/
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wcoenen
1 meter is defined as the distance travelled by light in 1 / 299,792,458
seconds. Doesn't this mean that "light slowing down" would be
indistinguishable from "space expanding"?

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oceanswave
Continuous Intrgration for the universe. Interesting.

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euyyn
Well it doesn't really tell whether it's changed from a moment ago. Rather
whether it was much faster when the cosmic microwave background radiation was
emitted, almost at the beginning of the Universe.

