Physicists (as well as philosophers) have had a problem reconciling our experience of time with a big-picture description of how the world works. I have come to see this “problem” as evidence of the fundamental and irreducible character of subjective experience itself.
Recall that while classical physics assumed a background of absolute time and space, Einstein’s relativity theory replaced this with a description in which there was no absolute time. Passage of time was relative to the motion of the system in question. It doesn’t make sense to speak of one simultaneous present for the whole world.
Interestingly, the other major revolutionary theory in 20th century physics, quantum mechanics, still assumed a background time dimension. Note that this theory also was bound up with questions related to the observer’s experience, causing difficulties in interpreting what it meant in terms of a description of the “objective” reality of the world (see my earlier post).
Efforts to formulate a complete physical theory which reconciles general relativity and quantum mechanics without assuming a background time seem to end up dispensing with the notion of time completely. I’m reminded of Julian Barbour’s book of a couple of years ago, which ended up concluding time didn’t exist and our perception of it is an illusion. Now, in his forthcoming book on quantum gravity (online version here), physicist Carlo Rovelli describes a theory which dispenses with time as a foundational concept.
In reflecting on this, I am completely comfortable with the fact that these efforts to create a complete theory which describes reality cannot do so while also including a concept of time which correlates with our intuitions. My thought is that this is an inevitable outcome of trying to formulate an “objective” theory of the world in which we participate. Time is bound up with subjective experience. To incorporate time one must modify one’s theory of physical reality to include as a foundational concept the fact that systems in the world have experience. Time is the dimension of experience.