Testing time to the limit

摘要

Albert Einstein tells us that clocks run slower the deeper they are in the gravitational potential well of a mass - the closer they are to a heavenly body, for example. This effect is described by Einstein's general theory of relativity as the gravitational red shift - it is detectable in spectral lines that shift towards the red end of the spectrum. General theory of relativity also predicts that the rates of all clocks are equally influenced by gravitation, no matter how the clocks are physically or technically made.