Topics Time

Question I LOVE this site. Wish I'd stumbled across it sooner! Ok, I have a question that I've wanted to ask for some time (ahem) but have been afraid to ask, assuming it would be duplicative. But I've gone through all the questions (26 at this point) and I don't think it's really been asked -- at least the way I'd like to ask it -- though one answer (cited below) touches on it directly then backs away. My question is "Isn't everything always happening or not happening at a given time and for a given duration from a God's (or someone greater than God) Eye perspective? Even if Time "stopped", wouldn't it be stopped for a certain amount of time? Even if time reversed (i.e., the Superman example and Stephen Hawkings old theory that time would reverse and broken objects would re-form etc. if the universe contracted (I know we now believe it's expanding and won't contract) wouldn't that take a certain amount of time? Even if someone went back in time, wouldn't they be gone for a certain amount of time that's continuing forward with or without her? If everything ceased to exist, wouldn't TIME still be there (and I hope it doesn't sound silly, but even if TIME ceased to exist , wouldn't it still be there?). Sorry for the long winded question. Now that I've typed this I guess this is the same as asking if time is relative or absolute. I'm comfortable with the assertion that for any particular individual time is relative (and I know that the Response from Peter S. Fosl on November 28, 2005 says "relative") but I still like the idea of Mr. Garfield's "Supertime" and would like to hear the argument for it (even if I have to wait some amount of time to hear it, yuk yuk). Am I missing something simple? Am I just conflating different definitions of time and causing my own confusion? Thanks! Bobby M.

Accepted:
July 11, 2006

Comments

Let's distinguish between physics and common sense: an adequate physics might or might not include a temporal dimension along which events occur, and this dimension might or might not possess various of the features that common sense attributes to time. That much is familiar from Einstein: it's not automatic that the commonsense conception of "time" is an accurate one---that it correctly captures some real aspect of the physical world. So we have to be careful when answering questions like "Does time have a preferred forward direction?". If we're exploring common sense the answer has to be "of course!", but if we're doing physics then it's a question of whether there really are important asymmetries in a physically real temporal dimension (which is actually a controversial matter: a fascinating discussion is David Albert's Time and Chance). Similarly for questions like "Did time have a first (or last) moment?". As a commonsense matter, the answer is "surely not!", but here too physics might require revision of common sense.

Your questions ask if anything would count as the stoppage of time, or the beginning (or end) of time, or the reversal of time, or travel backwards in time? Distinguish:

Physical: could the physics of a universe have a temporal character that includes these phenomena?

Commonsense: does time as common sense conceives it allow these phenomena?

It's fairly plausible that the answers to the physical questions are all yes: there are possible universes that work in such a way that there is something that counts as "time", which in a good sense sometimes stops, or has a start and an end, or reverses, or admits of time-travel. What counts as "time" in these universes departs in various ways from our commonsense conception, but not so badly as to lose the right to be called "time" by their inhabitants. If our universe turned out to be these ways, we'd want to say it was time that had these surprising features, not that there is no time after all.

What about the commonsense questions? Does time as ordinarily conceived allow these things? Surely not a beginning or an end. But the issue is less clear as regards stoppage, reversal, and time-travel. There we run into interesting interactions between two important strands in the commonsense picture of time. On the one hand, time is an infinite, objective dimension along which events occur. This dimensional conception of time seems to rule out not only a beggining and end, but also stoppage, reversal, and time-travel (one's being at an earlier time after being at a later one). On the other hand, time is what orders the progression of a process, from its earlier stages to its later stages. This narrative conception of time seems to allow reversal and time-travel. While the standard way of reconciling the dimensional and narrative conceptions of time requires that narratively "later" maps to dimensionally "later", nothing obviously precludes a different mapping, on which some processes unfold or jump backwards in dimensional time.