ABSTRACT
In the history of mankind, time has always played a crucial role either in explorations or quest for knowledge. Without a precise measurement of time, such activities as basic research, earth navigation and space exploration would hardly be feasible at the level of precision we know at the time of writing. Time plays a basic role in the universe’s physical laws that we have uncovered and particularly in relativity. Our understanding of those physical laws is based on fundamental constants, which, as their name would indicate, have been believed to be invariable with time. With the precision now reached in measuring frequency and time we can now challenge this concept.
