I was contemplating the nature of time the other day and trying to turn relativity on its head. It occurred to me that it might be possible to restate the Lorentz transformation (the time dilation effect) in terms of quantum time and avoid the necessity of thinking of time as a fourth dimension.
Time does not seem to be a fourth dimension to me. We cannot move in it, cannot change pour position along the dimension and are much more aware of travelling along it than other dimensions While standing still on earth seems stationary, we are actually travelling in all three spatial dimensions relative to the sun and other stars but are unaware of it. Time passing, however, we are aware of as long as we are conscious (and actually even when we aren't) , But we cannot translate along the time line...neither forward nor back. It is much more as if time 'flows' under us rather than we travel along it.
If we want to discard this notion of time as a fourth dimension, we must still deal with the dilation effect...it is, after all, demonstrable and real. But the mathematics of dealing with it are just a theoretical representation. The interpretation is that time moves more slowly for a faster moving body.
If, however, we consider time as quantized into units (commonly called chronons) then we might take a different interpretation perhaps increased speed causes a body moving through space to skip chronons, literally jumping across moments in time. Since a body could age only during these chronons, these quantized intervals of time, the effect of skipping a few would be to delay aging, to slow down time with respect to the moving body.
I am not sure how to test this. It should be possible to determine if time dilation actually occurs in quantized steps, but measuring events in the 10E-35 seconds range is just a bit difficult. But I do believe that looking at time as a more fundamental quantity than the spatial dimensions makes sense. Time IS different and not just our perception of it. I suspect we will not make great strides in theoretical physics again until we change our point of view on this.
Of course all aspects of time-dependent effects we measure now must be accounted for in any new model that changes the interpretation of time. But understanding time as a substrate for existence (anything that exists must exists for some minimum amount of time) could significantly change our understanding of cosmological structure and events.
There are new theories of physics which are trying to go beyond the horizons that even string theory have painted. Loop quantum gravity treats time in a different fashion than traditional physics. While I have a certain appreciation for M-Theory and its associated Branes, LQG is the first theory I've seen that seems to truly try to interpret time as more fundamental than space.
Another, somewhat random, thought occurred to me in thinking about all this. Special Relativity and Quantum Mechanics have both proven very useful in the last century. but General Relativity has not proven very useful in the day to day world. QM gives us semiconductors, electronics, and lasers...soon quantum computing. special relativity gives us accurate GPS systems 9among other things). But GR has been less helpful. While quite beautiful and very well demonstrated, it just has not provided the real world benefits one would have expected of a theory of gravity (anti-gravity for example). And, cosmologically, it has become something of an embarrassment. Its irreconcilability with QM is becoming increasingly problematic. We need a new theory of gravity which delivers usable effects as well as explanations.