You raise a valid point regarding the nature of time at the speed of light. Since we cannot directly observe or experience events at the exact speed of light, we rely on scientific theories and experimental evidence to understand the behavior of time in such situations.
Special relativity provides a theoretical framework for understanding the behavior of objects moving at speeds close to the speed of light. According to this theory, time dilation occurs as an object's velocity approaches the speed of light relative to an observer. As the velocity increases, time for the moving object appears to slow down relative to the observer's time.
While it is true that we haven't observed time coming to a complete stop at the speed of light, the predictions of special relativity have been extensively tested and confirmed by various experiments. These experiments include observations of particle accelerators, high-speed particle collisions, and experiments involving high-precision atomic clocks.
For example, particle accelerators routinely accelerate particles to velocities that are a significant fraction of the speed of light. The behavior of these particles, as predicted by special relativity, has been verified through measurements of their lifetimes, decay rates, and interactions.
Additionally, high-precision atomic clocks have been used to measure time dilation effects. Experiments involving synchronized atomic clocks placed on fast-moving vehicles, such as airplanes, have demonstrated the predicted time differences compared to stationary clocks.
It is important to note that while special relativity accurately describes the behavior of objects moving at speeds close to the speed of light, it does not provide insight into the nature of objects traveling precisely at the speed of light. According to the theory, objects with mass cannot reach or exceed the speed of light.
In summary, while we cannot directly observe time at the speed of light, the predictions of special relativity have been supported by a wealth of experimental evidence. These experiments consistently demonstrate the time dilation effects associated with objects moving at relativistic speeds, providing confidence in our understanding of time in such situations.