Uncle Al said a lot, in general he said everything is relative inclosing time. The fact that time was relative and not fixed across interval frames was a philosophical as well as a scientific bombshell. Most today do not realize how big it was. It was shocking to many.

Don't know why people have such philosophical problems with time refusing to recognize the obvious and trying to find some deep truth.

Time is events tied to reference points. Meet me here after the second sunrise from now, or meet me here 48 hours from now. Time is duration between events.

Reference points to meaure duration
Water Clocks
Sand Clocks
Mechanical Clocks
Electronic Clocks
Atomic Clocks
Sidewall time, duration between objects position in the sky repeating.

Accident structures gave a signal when it was time to plant crops. Sunlight passing through a slit illuminating a spot on only one day of the year.