time

In the SD
Hello Rabbi,
I wanted to ask what time is? We experience changes all the time, so seemingly time is a parameter that reflects the changes.
But what exactly is it? You certainly have an understanding of the field. Time is supposedly something to which the entire world is subject, but as I recently asked here, modern science shows that it is relative to several parameters.
I assume this topic is long, so I would appreciate a reference if you have a post about it here or something along those lines.
Wishing you a healthy winter time