Velocity is one of the factors that contributes to the phenomenon of time dilation, as predicted by Einstein's theory of relativity. Time dilation refers to the effect that causes time to appear to pass differently for objects or observers in relative motion.
According to the theory of special relativity, as an object's velocity approaches the speed of light, time dilation occurs. This means that for an observer who is stationary relative to the object, time appears to pass more slowly for the moving object compared to a similar object at rest. Similarly, from the perspective of the moving object, time appears to pass normally, but it seems as if time is passing faster for the stationary observer.
The key concept to understand is that the speed of light is constant in all reference frames. This means that the laws of physics, including the speed of light, are the same for all observers, regardless of their relative velocities. To maintain this constancy, when an object is moving at a high velocity, the observed passage of time is affected.
To illustrate this, let's consider an example: Suppose there are two observers, A and B. Observer A is stationary, while observer B is moving at a high velocity relative to A. If they both have identical clocks, observer A would measure the passage of time normally. However, observer B, who is moving, would perceive their clock to be ticking slower than observer A's clock.
This effect occurs because, as an object's velocity increases, its relative motion affects the way it experiences time. The faster an object moves, the more "time slows down" for it. This phenomenon has been experimentally verified, most notably through experiments with high-speed particles and atomic clocks.
In summary, velocity causes time dilation because the faster an object moves relative to another observer, the more time appears to slow down for that object, as predicted by Einstein's theory of relativity.