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Is the light speed the same, constant, in all the universe locations? I mean, is it he same in the surface of the Sun compared with speed in space inter galaxies?

Also: is light speed now the same as, let's say, half of the Universe life ago? (i.e. about 6500 million years ago)

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marked as duplicate by Qmechanic Jun 25 at 21:10

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Speed of light is c always when measured locally in vacuum.

This is true everywhere in the universe, and it was and will be true as long as the universe exists.

Though, if you measure it from far away, it might be different from c (Shapiro effect). Please see here: https://en.wikipedia.org/wiki/Shapiro_time_delay

It is different from c too, when measured not in vacuum.

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