Page "General relativity" Paragraph 38

Gravitational redshift has been measured in the laboratory and using astronomical observations.

Gravitational time dilation in the Earth's gravitational field has been measured numerous times using atomic clocks, while ongoing validation is provided as a side effect of the operation of the Global Positioning System ( GPS ).

Tests in stronger gravitational fields are provided by the observation of binary pulsars.

All results are in agreement with general relativity.

However, at the current level of accuracy, these observations cannot distinguish between general relativity and other theories in which the equivalence principle is valid.