So I recently read that it is very difficult to formulate an abstract definition of time, and that one of the primary difficulties is avoiding circularity (using the time concept in the definition).
Keeping relativity in mind, why can't we just say that time is the perceived order of events? Admittedly, the perceived order may not be consistent for different observers, but we seem to be able to generate enough precision when desired.
One implication is that when nothing happens, there is no time, a concept that I find pleasing. Keep in mind that watching an empty room does not constitute a lack of events, as the the particles involved are constantly moving (if they weren't, you wouldn't experience anything).
Is there some way that this definition is not meaningful or usable that I'm missing? I have no training in physics, so please enlighten me.