It is interesting how we can shorten a scientific concept so that it encompasses more than it originally intended to be. According to my understanding Einstein has postulated that one will measure the same value for the speed of light relative to any reference frame. This was shortened to "light speed is a universal constant of nature"; however, does "the same value measured relative to different reference frames" imply that light speed should not change with time? I do not think so. I will not be surprised if light speed is slowly becoming less with time.

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