The concept of time being relative is a fundamental aspect of Einstein's theory of relativity, which has been extensively supported by experimental evidence. According to this theory, time is not an absolute quantity but rather depends on the relative motion of observers and the gravitational field they are in.
In special relativity, the theory that describes the behavior of objects moving at constant velocities, time dilation occurs as an object's velocity approaches the speed of light. As an object's speed increases, time for that object slows down relative to a stationary observer. This phenomenon has been experimentally confirmed in various ways, such as with atomic clocks on high-speed airplanes or satellites.
In general relativity, the theory that includes gravitational effects, the presence of mass and energy curves the fabric of spacetime, affecting the flow of time. Clocks in a stronger gravitational field tick more slowly compared to those in a weaker gravitational field. This has also been experimentally verified, such as through precise measurements of time dilation using atomic clocks at different elevations.
Regarding the concept of absolute zero temperature, it is important to note that temperature and time are different physical quantities. Absolute zero refers to the lowest possible temperature, where molecular motion ceases in a system. It is defined as 0 Kelvin (K) or approximately -273.15 degrees Celsius. However, the existence of an absolute zero temperature does not imply an absolute measure of time or other variables.
The speed of light in a vacuum, denoted by 'c,' is indeed considered an absolute constant in the theory of relativity. It plays a crucial role in defining the relationship between space and time. However, this does not provide a basis for an absolute measure of time. The constancy of the speed of light is a fundamental principle, stating that the speed of light is the same for all observers, regardless of their relative motion.
In summary, while temperature can have an absolute reference point at absolute zero, time is relative according to the theory of relativity. The constancy of the speed of light in a vacuum is a fundamental property of nature, but it does not imply an absolute measure of time or other variables.