So modeling time seems to be easy, or at least probably possible.
In the obvious sort of (I don't know) Newtonian field theory, there's this four dimensional space, and associated with each point in it there are some numbers. One of the dimensions of the space is sort of special, in that there are laws that say things about what the numbers associated with some bunch of points are, given what the numbers associated with another bunch of points are, where the latter points are "before" (are at lower coordinates of the special dimension than) the former points.
And the same for post-Newtonian theories, mutatis mutandis. *8)
The hard and mysterious thing about time, it seems to me this morning, is modeling "now". Not only is the time dimension special, but a particular slice through the space, the locus of points with a particular coordinate in the time dimension, is additionally special, because it's now. And exactly which slice is special in this way changes with, urm, with time...
In the very wonderful "An Experiment with Time" (notes), J. W. Dunne courageously accepts the infinite regress here, with an unending stack of consciousnesses whose "nows" are each explained by the moving attentional focus of the next consciousness up. (And when we're asleep the bottom-level consciousness isn't paying attention to any slice in particular, so the other ones can roam around through the manifold and give us dreams of the past and future.) Which is perhaps too easy a way out of the difficulty.
The simplicity of time and the difficulty of "now" reminds me structurally (or something) of the simplicity of an objective characterization of consciousness (it's useful to have a relatively good model of yourself, and that leads to various interesting loops and feedbacks), and the corresponding difficulty of a subjective model of consciousness (notes).
I think Dunne's probably ("probably") right in thinking that the two are linked, that what time it is now is all about what it's like to be me (now), seen from here inside.
Which is, of course, infinitely far from actually having an understanding of either consciousness or nowness, or even of having an understanding of what an understanding might be like.
A brightly coloured fish.
not a giraffe
It's what's for dinner.
It's an empty space. No, wait, somebody's written something in it...
And, most tellingly for today's topic, a reader also writes:
Everything changed the day she figured out there was exactly enough time.
There's only one instant. Is that exactly enough time? That's undeniably the question.