Ti– i– ime Is On My Side, Yes It Is
Mick Jagger, certain that his baby would “come running back” to him and willing to wait as long as it took, freed her to “light up the town”. Apparently, he had time to burn, was killing time, had time on his hands, and so on. But what kind of time was that?
As it happens, I had plenty of time on my own hands today to put virtual pen to virtual paper and try to express some of the things I’ve been thinking about for a long time, as it were.
As long as 50,000 years ago, aboriginal Australians may have considered the world to be timeless, a seamlessly connected fabric of past, present, and future. The spirits of long–dead ancestors, for example, were believed to inhabit the living. From another perspective, the end of one’s life might be seen as a portal for the living to join those ancestral spirits in an afterlife, thus inextricably commingling past with future while departing the present.
So, what is the “true” nature of time? In many Eastern cultures, time is considered to be “cyclical”, while in most Western cultures time is considered to be “linear”. What do these mean?
Cyclical Time
The cycles of nature have been known to humans for hundreds of thousands of years, and the nature of those cycles pondered just as long . The daily cycles of the sun and stars, the monthly lunar cycle, the yearly cycle of the earth, these were at first all measured by astronomical phenomena, clearly and unmistakably so. Likewise, people are born, grow old, and die, but they live on corporeally in their children, and less tangibly in the memories of their loved ones and friends. On this viewpoint, the universe itself can be thought to do the same, being born anew as it dies, like some cosmic phoenix rising from its own ashes. There is no well defined start or end, and one may choose to start the clock ticking, so to speak, at an arbitrary point within a given cycle.
Linear Time
In much of the Western world, our own common short–term experiences seem to make genuine distinction between past, present, and future. Events seem to unfold consecutively, having originated or been caused, then existing or unfolding for some finite period, then coming to a close, to exist no more. All things seem to have a definite beginning and end, and at least in modern times, this is thought to characterize the universe as a whole.
The History and Philosophy of Time
The ancient Egyptian Pthahotep (around 2600 BCE), may have been the first to write about time, but he dwelt more on the proper use of time than on its actual nature. Hindu texts not much younger describe cycles of creation, destruction, and rebirth lasting over four million years each. Incan culture made no distinction between space and time, a single entity called pacha.
Greek philosophers considered the measurement of time as its essence, using astronomical cycles (Timaeus, Plato) and considerations of temporal change (Physics, Book IV, Aristotle). The Greek dualistic worldview also distinguished between temporality, that is, chronological time marked by change in the physical world below, and the eternal, associated with the Platonic realms of Forms or Ideas above. Indeed, there are several words for “time” in Greek. The word χρόνος (chronos) means clock time, while καιρός (kairos) means the right time, opportunity, or the time in which we exist. Also, φορά (phora) can mean a tendency or motion, ώρα (ora) means hour, and ἐποχή (epoche) is an era or period of time, from which we get our word epoch.
In St. Augustine’s Confessions, Chapter XII of Book XI is devoted entirely to the mystery of time. Augustine believes that God created time along with everything else but refuses to speculate on details:
I answer him who asks, “What was God doing before He made heaven and earth?” I answer not, as a certain person is reported to have done facetiously (avoiding the pressure of the question), “He was preparing hell,” said he, “for those who pry into mysteries.” It is one thing to perceive, another to laugh — these things I do not answer. For more willingly would I have answered, “I know not what I know not, …”
And again,
For what is time? Who can easily and briefly explain it? Who even in thought can comprehend it, even to the pronouncing of a word concerning it? But what in speaking do we refer to more familiarly and knowingly than time? And certainly we understand when we speak of it; we understand also when we hear it spoken of by another. What, then, is time? If no one asks me, I know; if I wish to explain to him who asks, I know not.
Fast forward to Isaac Newton, who regarded space and time as distinct and absolute, independent of how either one is measured. But measured they must be, with both characterized as continuous and linear, especially time, which moves or proceeds or elapses at a fixed rate. Tick and tock represent the same intervals of time, anywhere in the universe and at any instant of past, present, or future.
These notions persisted as gospel until the advent of the 20th century, when Albert Einstein’s great works on Special and General Relativity showed that to explain the outcomes of well–defined experiments, space and time must be considered to be intertwined in a single four–dimensional “spacetime”. Consequently, perceived intervals of time and length are not the same when measured by observers moving at large velocities relative to each other (compared to the speed of light), or in the presence of large masses (equivalently, large gravitational fields).
Still, in our familiar world of low relative velocities and weak gravitational fields, Newtonian notions of absolutism and linearity hold. What we mean by this is that predictions of the outcomes of experiments using Newtonian physics are consistent with the actual outcomes in the laboratory or in nature, at least to the limits of precision of the measurement instruments.
Quantitative vs. Qualitative
The passage of time is above all else a measure of the rate of change of a physical, mental, or spiritual process. Clocks are the quintessential embodiment of this notion — tick and tock are defined by changes in a mechanical or electronic process, such as the motion of a pendulum or balance wheel, or the oscillation frequency of a resonant circuit. Without change there can be no time. The physics of space and time is necessarily quantitative, measurable, represented by numbers. But we all are familiar with the indefinite nature of experiential time. Who hasn’t felt the excruciating, interminable passage of an unpleasant or tedious experience? “Will this never end???” And yet, tempus fugit, which in English is usually translated “time flies”. The expression comes from Virgil’s Georgics as fugit inreparabile tempus: “it escapes, irretrievable time”. In contemporary vernacular, “Time flies when you’re having fun.” or “Where did the time go?”.
The Beginning and End of Time
So, has the universe existed for all “time”, for lack of a better word, or was there actually a beginning to the universe as we know it? It seems there was, by numerous lines of evidence. It seems to have begun with the sudden appearance of an unimaginably tiny volume of space and time, with incomprehensibly large density and temperature. All the matter and energy that exists now or ever will exist was there at that cosmic birth, which we commonly call “The Big Bang”. Since then, the universe has expanded and cooled to the size and with the structure we observe today.
So what happened “before” the Big Bang? It is not all that sensible a question to ask, for it seems space and time both came into existence simultaneously in the Big Bang. Even so, St. Augustine already answered:
But if before heaven and earth there was no time, why is it asked, What did You then? For there was no “then” when time was not.
In modern studies of cosmology, there is a useful device, a graph called a “worldline”. Imagine that the universe has only two spatial dimensions, and that time is the third dimension. In fact, this is how Special Relativity theory treats time, as an independent dimension along with our three spatial dimensions. But back to our hypothetical universe, suppose that it is just a flat circle, with length and breadth but no depth. As it expands with time, the radius of the circle steadily increases.
In our three dimensional graph, we can plot the size of the circle as a function of time. Let the x– and y–axes lie in the plane of the circle, and let time increase along the z–axis. Then the surface swept out as time passes is that of a paraboloid of revolution:
Any horizontal cross section through the surface is a circle, our universe with the radius it has at that time. Now imagine you are going back in time – as you approach t = 0, the moment of the Big Bang, the circle defined by the horizontal cross section is getting smaller and smaller, and at the same time the curvature of the surface is also getting smaller, that is, the small piece of remaining surface is appearing flatter and flatter. As you reach exactly t = 0, the surface collapses into a point, which has no length or breadth (space), and which also has no height (time). The spatial dimensions of the universe vanish at the same time that time itself vanishes. You can’t have space without time. And you can’t have time before time exists, if the word “before” has any meaning here.
These are just a few of the mysteries of time that have fascinated and confounded scientists and philosophers since, well, since the beginning of time, and will continue to do so until the end of time. But wait a minute! Will there be an end of time? The universe seems to have had a beginning, but is there a finish line to cross? Currently it seems not, that the universe will continue to expand forever, becoming less dense until all the matter in the universe is spread out so far it cannot interact with itself anymore. Actually, matter itself does not seem to be eternally stable, and it is thought that all matter will ultimately decay into photons of light, although those photons will have such low energies that they could not be detected by any means, even if there were any means left by then.
So, what is the apparent ultimate state of the Universe? “World without end, Amen, Amen”, or so it would seem. But fear not, we will be long gone by then. What should we do now, while we and everything we know and love are still intact? Carpe diem! Or at the least, seize your sweetheart and give him or her a big hug and a looooooong kiss.
All the best,
On Saturday, 01/15 at 7:00 PM from Broomall, PA
Rex
