I recently had a discussion about this so I wanted to ask a few things. I was asked what do i think what is time.I scratched my head a little bit and thought to myself. Time must be a physical thing just in a different form much like energy and matter.Also relativity views time as " space-time" that alone tellsme they are related.This is sort of a statement from me yet a question at the same time in the case if it's wrong. So I conclude that matter has energy as can be seen from the smallest parts of atoms , elementary particles up to bigger things like molecules and organisms fluids and solids everything changes so we can see that time ahs passed and then we decided so that it is easier for us we somehow would calibrate these changes into what we now know as seconds , minutes, etc. Also I thought about can one stop time, and judging by my previous wording I guess it should imply to stop all the vibrations , movement down till the smallest particles in all of universe correct? So one more question comes to mind , would a heat death of the universe cause time to stop ,or would there still be leftover even small rate of change in parts of the universe?