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Upholding Einstein, so far
Andrew Brookes, National Physical Laboratory/SPL

By Anil Ananthaswamy

22 March 2017

OUR most accurate clocks are probing a key tenet of Einstein’s theory of relativity: the idea that time isn’t absolute. Any violation of this principle could point us to a long-sought theory that would unite Einstein’s ideas with quantum mechanics.

Special relativity established that the laws of physics are the same for any two observers moving at a constant speed relative to each other, a symmetry called Lorentz invariance. One consequence is that they would observe each other’s clocks running at different rates. Each observer would regard themselves as stationary and see the other observer’s clock as ticking slowly – an effect called time dilation.

Einstein’s general relativity compounds the effect. It says that the clocks would run differently if they experience different gravitational forces.

 

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