Time is rhythm: the insect rhythm of a warm humid night, brain ripple, breathing, the drum in my temple – these are our faithful timekeepers; and reason corrects the feverish beat.

– VLADIMIR NABOKOV

What is time?

Time seems to be with me, within the very core of our being, all through my waking hours; and to all appearances, it is also  drifting silently and unhaltingly out there in the external world as well as. It is the most insubstantial element in human consciousness that is experienced very profoundly. Each one of  us tastes a slice of time and then suddenly drops out or strays away from its course.

When Saint Augustine declared, “If no one asks me, I know  it; if someone asks me, I know not.” He was not talking about God, but about Time. Countless thinkers before and since have wondered about the nature and mystery of time. From the Upanishadic seers of ancient India and Pythagoras of reflective Greece through medieval scholastics to countless philosophers and scientists down to our own age, human minds have pondered on the nature and mystery of Time, and acquired but glimpses of its essence.

At the one extreme, thinkers have wondered and argued about the reality of time. Some have contended that time is mere illusion while others have insisted that it is as much an entity in the external world as the sun and the moon which help us measure it. No matter what, time is surely is an ever-present feature of perceived reality, powerful and useful in the scientific grasp and description of the world.

Time has been compared to a steady stream, gliding smoothly or rushing torrentially, for on occasion it seems to linger on, while on others we feel it  galloping away at undue speed. Slow or fast, in the phrase of a poet,  “there is no arresting the wheel of time.”  Historians have referred to chunks of time as stagnant or tumultuous. Time has been called a robber of our possessions, a poison, the  dissolver and destroyer of all, for it seems to gobble up every thing and event and episode. Inimitable Shakespeare described time as “the king of men, he’s both their parent, and he is their grave…” Yet time has also been called precious, and praised as a healer of heartache, a consoler in grief. In the words of Ovid, temporis ars medicina fere est: time is generally the best medicine.

We feel intuitively that it is time that keeps the world going, that it is time that makes things happen, for a world where time did not move  would be static and lifeless, more still  than a painted scene on canvass, more frozen than a sculptured bust.

Our minds cannot picture a moment beyond which there will be no moment, nor one before which no time there was. Unending time seems to have had no beginning either. Such at least is what the purely reflecting mind seems to suggest. Time, we are inclined to think, is eternal. Like expansive space and never-ending numbers, time is a baffling infinity.

Time reckoning and measuring

We have all been touched by the rising and setting of the sun, the waxing and waning of the moon. Some of us have even observed the changing configurations of constellations in the skies during different zodiacal periods. From the shedding of leaves and the blossoming of flowers we conclude that all nature is struck by seasonal changes, the ambient cold or warmth clearly provoking respite or activity. But it is not as obvious that the behavior patterns of some animals are affected by solar activity and lunar phases also. It has been well established, for instance, that oysters, even when in the depths of  water where there is no light,  open and close,  shell-dancing, as it were, with lunar phases [1].

Time is one of the first parameters of the physical world that came to be measured by the human mind.  Over the ages, in all societies and civilizations, time has been recognized, recorded and reckoned. Aside from the biorhythm that subtly governs our moods and potencies, periodic changes in our environment have provoked temporal units and insights into the nature of time.

It is interesting that linear time is registered with cyclic changes. We have the hour, inspired by the rising of a star before daybreak; the day, inspired by sunrise and the sunset;  the week, resulting from the naked-eye visibility of five planets, the sun, and the moon; the month, related to the periodic reappearance of the full moon; and the year, provoked by seasonal cycles. Astronomers speak of the great year which consists of 26,000 years, while the civilization of ancient India defined still larger time units, stretching to the yuga  and the kalpa which span several million years.

At the other extreme, we have defined and measured mind-bogglingly small fractions of a second,  touching fleeting  periods of picosecond and nanosecond durations in our experiments. Modern physics has tracked down elementary particles with pathetically brief lifetimes . These breakthroughs would be impossible from mere speculative discourses on the ephemeral nature of experienced life. While philosophers debate about the reality of time, experimentalists, taking perceived reality as the starting point, go forward and accomplish the most fantastic things.  At the same time, at the conceptual level, modern cosmologists unhesitatingly talk of Planck time, whose magnitude, though simple to write out on a piece of paper, is beyond the visualization by  normal  human minds.

Countless measuring devices have been constructed for the measurement of time: from sundials and hour glasses to pendulum chronometers, spring watches, digital clocks and more. What is important to note is that all time measuring devices have one thing in common: change. One cannot measure time if there is no change.

This empirical intertwining of motion and time measurement is the origin of what is known as the relational theory of time, according to which the concept (and reality) of time is intimately related to changes in the world. Time, in this view, is merely “the order of succession of perceptions.” This has been the source of endless arguments among philosophers: some have regarded time as no more than an impression created by a series of changes while others have given it a more independent status.