Time dilation can be tested using various experimental setups, including a light clock. A light clock is a simplified thought experiment that involves a beam of light bouncing between two mirrors. By measuring the time it takes for the light to make a round trip, one can analyze the effects of time dilation.
In the context of special relativity, time dilation occurs due to relative motion between two observers. If one observer is moving at a significant fraction of the speed of light relative to the other, they will perceive time passing more slowly compared to the stationary observer. This effect has been experimentally verified through a variety of experiments, including those involving atomic clocks.
While a light clock can provide a conceptual understanding of time dilation, directly testing it using a light clock experiment may not be feasible in practice. This is because constructing a physical light clock with mirrors and measuring devices that can operate at speeds close to the speed of light is technologically challenging. The precision required to measure the time intervals accurately in such experiments is beyond current capabilities.
Instead, experiments involving atomic clocks and high-speed relative motion are more practical for testing time dilation. For example, the experiments you mentioned that flew atomic clocks around the world (such as the Hafele-Keating experiment) are actual tests of time dilation. These experiments involved comparing the time measured by highly accurate atomic clocks on airplanes with clocks on the ground, taking into account the relative motion and gravitational effects experienced by the clocks.
In summary, while a light clock can help understand the concept of time dilation, practical experiments to directly test time dilation often involve atomic clocks and high-speed relative motion rather than physical light clock setups.