The concept of time dilation in special and general relativity does not suggest that time itself is in motion or has a speed or velocity in the same way that matter or energy do. Instead, time dilation arises due to the curvature of spacetime caused by massive objects or relative motion.
In special relativity, time dilation occurs due to relative motion between observers. When two observers are moving relative to each other at high speeds, they will measure different elapsed times for the same events. This effect arises from the fundamental postulate that the speed of light in a vacuum is constant for all observers, regardless of their relative motion. The constancy of the speed of light is a fundamental principle in special relativity, and it is denoted by the symbol "c."
General relativity extends the concept of time dilation to include the effects of gravity and accelerated motion. In the presence of a gravitational field, time runs slower in a stronger gravitational field compared to a weaker one. This effect has been experimentally verified through various observations, such as the time dilation experienced by atomic clocks on Earth's surface compared to clocks in orbit.
The constancy of the speed of light, c, is a fundamental property of our universe. It means that the speed of light in a vacuum is always the same value regardless of the motion of the source or the observer. The constancy of the speed of light is supported by a vast range of experimental evidence and observations.
Regarding the measurement of events and the order of occurrence, it is important to note that time itself is a fundamental dimension in our universe. We measure events and the order of their occurrence using time as a reference. While time dilation can affect the perception of time for observers in different reference frames, it does not negate the ability to measure events or determine the order in which they occur.
In practical terms, we use synchronized clocks and well-established measurement techniques to accurately measure the time interval between events. These measurements can be made across different reference frames, and although time may appear to pass differently for observers in different frames, the order of events can still be determined.
The constancy of the speed of light, c, as the maximum speed in our universe is a consequence of the underlying symmetries and principles of special relativity. It emerges from the mathematical framework of the theory and has been consistently confirmed by numerous experiments and observations. The constancy of the speed of light is a foundational concept in modern physics and forms the basis for our understanding of the universe at relativistic speeds.