Absolute Time:
One of the first outcomes of Einstein's speed-of-light axiom is the reality that there can be no such thing as an absolute time standard. It is not possible to synchronize the clocks of two observers therefore they will view both clocks as being in exact agreement unless both observers inhabit the precise similar point in space.
In latest decades we have construct atomic clocks, and we maintain they are precise to within billionths of a second (where a billionth is 0.000000001 or 10-9). Though this has meaning only whenever we are right subsequently to such a clock. When we move a small distance away from the clock, the light (or any other signal which we know of) takes a few times to obtain to us, and this throw the clock reading off.
The speed of EM-field propagation, fastest speed acknowledged, is around 3.00 x 108 m/s (i.e., 1.86 x 105 mi/s). The beam of light thus travels around 300 m (i.e., 984 ft) in 1.00 x 10-6 s (1.00 µs). When you move a slight more than the length of a football field away from a super-accurate billionth-of-a-second atomic clock, the clock will emerge to be in mistake by 1.00 µs. When you go to the other side of the world, where the radio signal from which clock should travel 20,000 km (i.e., 12,500 mi) to arrive at you, the time reading will be off by 0.067 s. When you go to the Moon that is around 4.0 x 105 km (2.5 x 105 mi) far-away, the clock will be off by around 1.3 s.
When scientists ever determine an energy field which can travel via space instantly regardless of the distance, then the conundrum of absolute time will be solved. In practical scenarios, though, the speed of light is the fastest possible speed. (Some current experiments recommend that certain effects can propagate faster than the speed of light above short distances, though no one has elaborated this on a large scale yet, much less used these effects to broadcast any information like data from an atomic clock.) We can say that the speed of light is the speed of time. The distance and time are inextricably associated.