The first query of your Study Question seems similar to the fundamental question regarding physical science: What is energy? We can describe positive and negative characteristic of "energy", but we can not define it. Same with "time." What is time? Does it even exist or is it an illusion of the mind to connect causality or locality? We can also describe characteristics of "time," but cannot define it. I guess it is like the Zen (I loath to use this form of mental mumbo-jumbo but . . .) concept of mu. "One cannot measure the height of Mt. Fuji, whilst standing on Mt. Fuji." As Heisenberg believed, there are limits to our observations and measures.