According to the theory of relativity, time dilation occurs when an object moves relative to another observer at speeds close to the speed of light. The observer's clock that is moving relative to an outside observer will tick slower compared to the outside observer's clock.
Let's consider two observers: Observer A and Observer B. Observer A is stationary relative to an outside observer, and Observer B is moving at a high velocity relative to Observer A, approaching the speed of light.
From Observer A's perspective, Observer B's clock will appear to tick slower than their own. This is because as an object approaches the speed of light, time dilation occurs, causing time to slow down for the moving object relative to the stationary observer.
However, from Observer B's perspective, they would consider their own clock to be ticking normally, and it would be Observer A's clock that appears to be ticking slower.
This phenomenon is a consequence of the theory of special relativity, where the perception of time is dependent on the relative motion between observers. The observer who is in motion relative to another observer experiences time dilation, perceiving the other observer's clock to be ticking slower.
It's important to note that these effects become significant only at speeds close to the speed of light, and in everyday situations with ordinary speeds, the differences in clock rates are negligible.