“Colonel Sandurz: ‘Now’, sir. You’re looking at ‘now’. Everything happening now is happening ‘now’.
“Dark Helmet: What happened to ‘then’?
“Colonel Sandurz: We passed ‘then’.
“Dark Helmet: When!?
“Colonel Sandurz: Just now. We’re at ‘now’, now. …
“Dark Helmet: When will ‘then’ be ‘now’?
“Colonel Sandurz: Soon.”
– Spaceballs (1987)
On the surface of it, any theory that proclaims that time does not exist would seem to be madness. We know time exists, we can mark off seconds on a clock against the decay of caesium 133 atoms, we can see the flow of it in the cycles of our sleep and the graying of our hair. Time erodes all things. Within the limits of human perception and human consciousness, time is essentially entropy.
Yet time is also a dimension, one (or more) of several. Seconds then take on a parallel function to metres: a measure of a certain ‘distance’ of time. It confuses us because we perceive a location in time only in cross-section. At the same time, our perception is moving along the dimension of time, so our cross-section constantly changes.
Already we run into a problem that goes far beyond semantics. Movement is usually measured as distance covered in a certain amount of time: but how then can we possibly measure movement within time? To say that time covers precisely one second each second is meaningless. If we are moving through time, how can we possibly measure that movement? If time is ‘flowing’, what is it flowing relative to?
Even a simple concept such as a second demands a universality that simply cannot exist. If one twin remains on earth while the other travels to the stars and back, they will no longer physiologically be the same age. In exactly the same – call it a ‘container’ – of ‘time’, each will have counted off a different number of seconds: and each will be ‘objectively’ corroborated by his or her own personal pile of caesium atoms. A universal clock will rapidly become meaningless when we reach the stars.
It takes light years to reach us from even the closest star. What we see, ‘now’, happened years, or centuries, or millennia ago. To look into the universe is to look backward in time: yet those events may as well not have existed until they reach our human perception. From somewhere else in the universe somewhat closer to those stars, the travelling twin will see a later point in the lives of those stars: and that point will be his ‘now’.
The twins may still agree on what came before they parted ways: yet even at sublight speeds, a simple ‘before’ and ‘after’ based on causality is not nearly so clear as it first seems. Postulate a theoretical wormhole to give instant and equivalent communication between the home twin and the far travelling twin. Only with such instantaneous communication can the two twins agree upon a shared ‘now’: and yet the universe each twin sees exists at a different point in time. One may still see a burning star where the other sees only the spreading nebula left over from supernova and a slow spinning down star death – at the exact same ‘now’.
Time and simultaneity may be a paradox: but personal perception can always define a personal ‘now’.
So long as we limit our observations to our individual ‘now’, even so broad an individual ‘now’ as to be shared with our entire inertial frame (the earth, considered as point source): we have no issues with which event came first. For all practical purposes, the event and the perception of that event fits closely enough that our personal ‘nows’ more or less match, and events follow each other in a logical, causal fashion. This is familiar, Newtonian time: each second following the next in precise order.
(Although Newtonian time carries its own paradoxes and quandaries. If a second can be measured only in terms of itself, how can we possibly prove that all seconds are truly identical? When, exactly, does one second end and the next begin? What of the ‘time’ between seconds?)
Yet the moment we bring in a relativistic second source of observation, causality shudders. We suddenly discover that there is no objective way of differentiating between the event and the arrival of the information telling of that event. An individual ‘now’ becomes no more than a location, one of many, defined by the time dimension within spacetime.
We don’t even have to go to the stars to see it. All it takes is two people on a telephone: one watching The Tonight Show through an analogue signal and rabbit ears (which do still function, so long as you have a converter box), and the other watching exactly the same television show through the local cable provider. The two sets of signals are approximately four seconds apart. They are sharing a show: yet when one laughs, the same joke does not yet exist for the other. And yet who would dispute that these two people are sharing the same ‘now’?
Thus it is not time but an absolute ‘now’ which cannot exist except as a tapestry, an infinite array of cosmic ‘nows’ laid out in a velvet fabric of spacetime. Our personal perception of ‘now’ is necessarily a function of our consciousness, as fleeting as an instant, as indefinable as the distinction between ‘here’ and ‘there’.
We could take it even further. If there is no objective, absolute ‘now’, then there can be no objective separation between what was and what will be. Past, present, future are a matter of semantics. Before and after are given meaning only by defining some part of the spacetime continuum as ‘now’. In fact, within this configuration spacetime manifold, perception is the only reason there even is a ‘now’, and the asymmetry of perceptive knowledge the only reason we see an entropic difference between before and after. If we were to exist in a world without change, we might not notice even that difference: and ‘before’, ‘after’, and ‘now’ would all be one.
But we don’t, and they aren’t. In his seminal book “The Unreality of Time”, J.M.E. McTaggart defined the reliance on before/after as the B-theory of time. He tried to take it even further and argue that both the A-theory (the tensed temporal belief in past, present future) and the B-theory (the untensed belief in the before/after of temporal relations) were ultimately insufficient for any understanding of time: and concluded that time was unreal. Those who followed him were not willing to go quite that far. God may exist outside time. We do not.
