Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels.Nov 7, 2017
Einstein's Theory of General Relativity: A Simplified Explanation
Test
http://php.net/manual/en/features.commandline.webserver.php
Reply
Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels.Nov 7, 2017
Einstein's Theory of General Relativity: A Simplified Explanation
https://www.space.com/17661-theory-general-relativity.html