TIME: CEASELESS PROGRESSION:
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.
What is 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.
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 .
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
As with space, an important characteristic of time is its homogeneity.
This simply means that all along its ceaseless flow the entity we call time is
uniformly the same. There is no difference, qua
time, between an hour or an
instant some eons ago and the same in our temporal locality.
Using a spatial analogy, time is like an interminable line, any sector of
which is identical in its essential nature to any other.
We may also look upon time as a smooth and flawless highway that is being
continuously created which in essence and rate of formation is the same at every
inch or mile of the path, though a host of different entities may be seen all
along it. Every instant of time has another whence it emerged, and yet another
into which it merges.
This implies that there was no beginning, nor will there be an end to
time, for terminal points are, by definition, different from all others in being
without a predecessor or successor. Even in the theological framework in which
the universe had a moment of creation, that was a significant point in
time, rather than the starting point of
time. God, the everlasting, is said to exist in Time.
Recall that space has local inhomogeneity, but this is not the case with
physical time. However, psychological time may be experientially
non-homogeneous, some durations appearing to be denser (longer) than others.
Like the spatial line again, time cannot be broken down to some ultimate
indivisible unit. We speak of instants and points, but they all merge into
neighboring dots in a smooth and inseparable continuity. That is why we have the
image of time flowing, rather than dropping like a series of pebbles. However,
it is important not to take the analogy between space points on a line and
time-instants too far: such identification has led to some paradoxes in the
history of human thought .
Some theoretical physicists have toyed with the notion of a fundamental
indivisible time interval, dubbing it the chronon
. Aside from some neat mathematical formulations, this has not led to any
significant insight or verifiable result of consequence .
Isaac Newton spoke of an "absolute
true and mathematical time," called duration, which flowed uniformly, and
he distinguished this from "relative, apparent and vulgar time... estimated
by the motions of bodies ." This is in accordance with our intuitive
grasp of the world, for one is normally inclined to imagine an instant of time
that is universally pervasive. Right now, there
is a fleeting moment in our conscious experience of the world corresponding to
which, we imagine, there is a
moment that ticks away at every nook and corner of all the universe. It is as if
there is a cosmic pulse, a steady stream of subtle seconds flowing imperceptibly, carrying the universe in its entirety along a single temporal course. It
seems as if there is a cosmic simultaneity.
The notion of absolute time through which an absolute space endures is an
ancient philosophical predilection, based no doubt on our common-sense grasp of
perceived reality, and it is sufficient for our everyday discourse. It has also
served as a cornerstone on which three centuries classical physics rested. But,
as happens so often in our interpretation
of the world, as we delve deeper into the roots of perceived reality, we find
that there is no such thing as absolute time, though for many practical purposes
one may assume such an entity. Physicists have discovered that the notion of
absolute time crumbles down upon probing analysis, strengthened by careful
observations of phenomena,.
It is remarkable that so much of significance and certainty was achieved
on what turned out to be an erroneous view of so fundamental an aspect of the
world. It should be noted here that though physics has established with
conceptual clarity and experimental certainty that there is no such thing
absolute time, the notion is still useful in speaking about the age of the
universe. For when current cosmology proclaims that the universe is some fifteen
billion years old, an unspecified absolute reference system is implied.
Theologically inclined writers in the past used to be more specific about
the date and time of cosmic creation. Recall the memorable assertion of Bishop
Usher that "The beginning of time fell on the beginning of the night which
preceded the 23rd day of October, in the year 4004 B.C." The Bishop was
merely echoing the with more specificity the belief of his age. He has his
counterparts in other theological systems.
Modern defenders of ancient world views have tried to explain the Book of
Genesis and its equivalents in other cultural contexts by suggesting that if we appropriately transform reference systems, the fifteen
billion years of current science could be made to correspond to a week and
whatever in the scale of the divine creator .
Our perception of reality requires sensory inputs, and light is a primary
information messenger for the goings on in the world around. This is especially
so when we take note of whatever is there in the skies above. When we fix our
eyes on a star at night our first impulse is to think we are seeing it such as
it is at the moment that flashes through our consciousness. But knowing that
light takes time to travel a distance, and that the distance to travel is
considerable here, we are reminded that what we see is a body such as it was a
few years or a few hundred years ago. We are indeed looking into the distant
past every time we cast our glance in stellar space.
What this implies is that even if there was an absolute time, our
knowledge and perception of events in the world depend on how far we are from
the point or region where the events occur, for it takes time for light to
travel the intervening distance.
This insight into the nature of perceived reality would be impossible if
we did not realize that light travels with a finite speed. If, as had once been
imagined, light traveled with infinite speed, then there could be instantaneous
transmission of information. Since it appears that nothing physical can travel
with a speed exceeding that of light, instantaneous transmission of information
becomes a physical impossibility .
This is a matter of some significance in our understanding of the world.
For it appears that, in principle, it will
take a finite interval of time, small or large, for information to pass
from one entity to another. This has always been one of the fundamental tenets
of physics. However, careful experiments with photons and electrons which have
been conducted during the past two decades, based on the fundamental theories of
20th century physics, suggest that in certain microcosmic phenomena, an event in
one point of space may affect the status at a distant point without any lapse of
The possibility of instantaneous transmission of information, even
between subatomic entities, opens up all kinds of possibilities . Some have
argued that this makes telepathy (the reading of one mind by another) more than
magic-mongering on a stage, for perhaps these experiments show that minds can
receive and send signals in instantaneous flashes. Scientific validation for
telepathy has been sought by its practitioners and subscribers for a long time
. Some have regarded the results of these experiments as confirming
mysticism, while others have described such interpretations as a "flurry of
And yet, serious physicists have also been tempted to come up with models
and processes in terms of which instantaneous information transmission would
become a possibility. One such idea was proposed by the brilliant and unorthodox
quantum physicist David Bohm who introduced the notion of implicate order which
is best understood by means of his analogy. Consider a table standing on the
floor. The universe we experience is analogous to what creatures constrained to
the flat floor would feel: to them the four feet of the tables are unconnected,
though in fact they are interconnected, via the table top. So too, suggested
Bohm, every event in the space-time world is intrinsically linked to every other
via dimensions beyond the modes of perceptual reality. Certainly not
inconceivable, and perhaps not an impossibility, but still only in the realm of
We have all experienced the truth in Pliny's words, but he was referring
here only to psychological time. It turns out that, in a different sense,
physical time also passes at different rates.
One of the intellectual revolutions of our century is embodied in what is
known as the special theory of
relativity, mentioned earlier. This theory uncovered a fundamental error
in the ancient view of space and time by which the two are separate and
absolute. The theory of relativity revealed an intrinsic intertwining of space
and time which results in the demolition of their independent absoluteness. What
this means is that an instant or interval of time makes sense only in relation
to a point in space. This discovery gave a death-blow to the classical notion of
An important consequence of this fact is that durations of an event, that
is to say, the time interval between two occurrences, will also depend on the
space frame or reference system. This means that if two observers set their
perfectly functioning watches synchronously, and one of them gets into a train
which begins to move at a certain speed, then the moving observer's watch (i.e.
time in the moving reference system) will be flowing at a slower rate than for
the stationary observer, and vice versa! Physicists call this puzzling
phenomenon time dilation. For this to be significant enough to be observable,
however, the train should be zooming at nearly three hundred million kilometers
a second which is a technological impossibility (as of now).
The veracity of time dilation is, nevertheless, an empirically verified
consequence of Einstein's theory since physicists track down and measure
particles that move with such uncommon speeds .
Our understanding of the underlying link between space and time follows
from the recognition that there is no such thing (in the observable sense) as
absolute motion . Every motion (or rest) that we can put into evidence by
any observation, simple or sophisticated, is with respect to something else. An
ant may be crawling on a table at rest, but the stationary table is moving along
with the earth. The earth's motion is with respect to the sun, and the sun
itself is voyaging with respect to our galactic center which in turn is receding
with respect to other galaxies, and so on.
The impossibility of absolute rest or motion leads to the non-existence
of absolute space or time. Though intuitively we may picture the stars as moving
in an absolutely stationary empty space, a crucial experiment performed in the
last quarter of the 19th century, and repeated many times since, established
beyond a reasonable doubt that
there is no observational evidence whatever for such a system at absolute rest
The intertwining of space and time leads to a new concept of the
perceived universe. The basis of perceived reality is not simply space and time,
but a complex of both which we call space-time.
Thus, as Herman Minkowski stated, "space
by itself, and time by itself must sink into the shadows, while only the union
of the two preserves independence."
Since both space and time have a non-discrete character, we refer to the
substratum of the physical world as the space-time continuum. We say that
space-time has a dimension of three-plus-one, to emphasize the fact that time as
a category is in essential respects different from space. The notion of
space-time, introduced by Herman Minkowski, admits of an elegant mathematical
formulation. To get a general idea of this, let us consider a pair of orthogonal
axes in which we take the horizontal axis to
represent space and the vertical one to represent time (both with respect
to a specified frame of reference). Then, any point on the plane would
correspond to a point in space at a specific time.
Rather than points in space and instants of time, we now describe the
world in terms of space-time events. Time, to use a phrase that has become
popular even in common parlance, is then the fourth dimension .
Imagine a line AB on this space-time graph [x: horizontal, t; vertical
axes] would correspond to a particle which was at a space point x1
at an instant t1
and moved to x2
A horizontal line EF makes no sense
since it implies that a particle moved from one point of space to another while
time stood still. A particle that stands still during an interval of time would
be represented by a vertical line like GH.
How, one may wonder, does this essential interconnection between space and
time remain hidden from our normal perceptual modes? The answer to this question
is to be found in the stupendous speed of light. Light travels at the incredible
speed of three hundred million kilometers a second, a fantastic speed compared
to anything we are familiar with. Furthermore, the formulas describing processes
in the world when the space-time connection is taken into account, and those
when the connection is ignored, become identical when ordinary speeds are
In other words, if the universe had been designed ( or had evolved) with a
much smaller value for the speed of light, or if we happened to be sentient
beings buzzing around with speeds comparable to the speed of light, then right
from our conscious stage in life we would have recognized the space-time nature
of the physical world.
is an important difference between spatial extension and temporal evolution.
Given a spatial line and direction one may move forward or backward with respect
to the direction. But this seems to be impossible on
the temporal line. We always move from the present into
the future or the future is always transforming itself into the
past, (whichever metaphor one wishes to choose), but never is the opposite true.
There is an asymmetry in the flow of time.
Shakespeare expressed the asymmetry of time with his inimitable power of words
when he spoke of "the dark backward and abysm of time.
This has two consequences: On the one hand, we cannot move back in time.
Whatever has transpired has left its relic, legacies, and records. No one can
bring back yesteryear, or even yestersecond, for as Milton wrote  in his Paradise
Yet, in another meaning of the word recall,
we all can and often do recall the past, for that is what memory is. Here we
recognize an interesting aspect of mind and consciousness: they accomplish
things that are impossible in the physical world. The scenes and events of days
gone by can be brought back in an instant to the mind's eye;
even ancient episodes of the
distant past that we never witnessed are brought back to vivid reality through
the powerful pages of history. "Oh, but this is mere imagery," one may
object, "it is not the past that comes back, but only its visions."
But then is not the present also a vision? True, it is tangible, but not for
more than an instant. Perceived reality may be looked upon as
fleeting transformations of the subtle into the concrete, of the
insubstantial into the tangible.
Like a myriad other things, sheer familiarity makes us feel that what has
happened cannot unhappen. However,
there is a problem: If we rely on the fundamental equations that articulate the
laws governing the physical world, there is something unacceptable (at least
logically) in this state of affairs, for it turns out that if we reverse the
direction of time in these equations, naught is affected . The most solid
laws of physics, crystallized in their mathematical purity, assure us that the
world can evolve along one direction just as easily as along the other!
Today's cosmologists and particle physicists have been grappling with this
paradox in ways that are different from their predecessors in another century
. Current thinking tries to link time's asymmetry with the initial
conditions of the universe. A theoretical solution to the paradox comes from the
application of microcosmic physics
(quantum mechanics) to the description the universe at large (cosmology). Though
wrought with conceptual
complexities such as fuzzy time and time seeping into space, this theory,
introduced by Stephen Hawking and James Hartle in the 1980s),
is more than an intellectual tour
de force. It is a penetrating peep into the birth-throes of the universe,
through ingenious interpretations of sophisticated mathematics that calculate
singularities in black holes. The essence of the theory is that time itself had
its origin with the big bang, and that it
was the starting direction that determined which would be the past and which the
Time and causality
Time going in the opposite direction is equivalent to the future occurring
before the past. Thus, if you fall down and hurt your knee, the reverse order in
the chain of events would be your knee bleeding first and then your falling.
This is obviously impossible,
because the hurt knee is a consequence of the sudden fall. Falling is the cause
of the hurt knee which is the effect. Two fundamental tenets of physics (indeed
of all science) are (a) that every
effect has a cause; and (b) that
the cause invariably precedes the effect.
The word precedes drags in the
notion of time in our conception. In other words, the forward march of time is
intimately related to the notion of cause and effect, or as we also say, to the
principle of causality. To imagine time moving in the backward direction is
equivalent to imagining that an effect has occurred before its cause. It is like
hearing what a person says before he or she has uttered a word.
Let us look a closer into something that was mentioned in the last
section: namely, that physical laws
permit equally the forward and the backward surge of time. This is quite
apparent in the case of the pendulum: if it swings one way, it does so with
equal ease the opposite way too. However, this does not seem to be happening in
all cases. A child grows into a full grown person, a full grown person does not
revert back to a child, like the pendulum does. In the case of most phenomena,
changes seem to occur only in one direction.
Mathematical analysis reveals that any source which emits electromagnetic
waves must also be receiving them at the same rate. This is very perplexing
because what it implies is that the antenna in the radio station is not only
emitting waves, but also absorbing the same waves. The emerging waves are called
because they take time to reach a destination;
and the incoming ones are known as advanced
because they are arriving even before they were emitted from a source. What is
intriguing is that according to mathematical reasoning both types of waves must
The paradox resulting from the
symmetry with respect to time in the mathematical formulation of physical laws may be understood by means of an
analogy. Suppose that you are continuously throwing upwards a series of balls.
The balls keep falling down and you keep throwing them. Both processes are
occurring and we find nothing strange in it. Suppose, however, that you keep
throwing the balls, and none of them is falling back to the ground. Wouldn't
this be very strange?
In the case of the electromagnetic waves, though one expects this from
mathematical analysis, it would be very strange if advanced waves arrived,
because that would be equivalent to effects preceding causes. The question then
is, is there a mechanism in the physical world that makes this impossible though
it is mathematically permissible and expected?
One explanation to the paradox was provided by the Wheeler-Feynman
dissection of the problem . These two physicists showed (by a technical
analysis of the situation) that in fact both advanced and retarded waves are
always present, but that because of the various masses distributed all over the
universe, electromagnetic waves are reflected back from everywhere in such
quantities that all advanced waves are (for all practical purposes) simply
canceled out (by interference effects), hence never observed. It is as if some
kind of a counter-process is continually taking place, instigated by matter all
over the universe, as if to prevent
the future from materializing itself prematurely. In order for this to happen,
however, there must be sufficiently large amounts of matter in the universe to
absorb and radiate. This leads to the intriguing conclusion that the principle
of causality is a natural consequence of the enormous quantity of matter in the
The roots of perceived reality can indeed be very different from the
superficial impressions it creates.
Que serÓ serÓ and precognition
- SHAKESPEARE (Macbeth)
The second consequence of time's asymmetry is that, in the phrase of a
popular song, "the future's not ours to see."
While we have footprints on the sands of time, there is no trace of
things yet to come. To be told that one recognizes the marks (to be) left by
events yet unborn smacks of psychic mumble-jumble, unacceptable, if not
offensive, to rational modes.
While even an omnipotent being may
not be able to undo the past, an omniscient being can know the future. But here
we may imagine two types of futures: One which is pre-ordained, and simply
remains hidden from our view, time serving as the unveiler of events already
determined. From this perspective, in the words of Omar Khayyam,
From this perspective, we are only witnessing what was pre-ordained. If
some religious traditions imagined a fate-etching God to have done the job of
writing the script for the universe, mechanistic physics attributed the credits
to its initial conditions. A ball projected in
air moves in accordance with the laws of gravity, but the particular path
it follows depends very much on the speed and angle of projection. So too, the
world evolves in accordance with immutable physical laws, but the specific modes
by which its countless atoms and molecules move and interact were determined by
the initial kick that each received.
This was the picture painted by physicists of the 18th and 19th centuries
who, on the basis of their understanding of physical laws cast as differential
equations, believed that the primordial push to the evolving universe determined
once and for all times how every single atom and molecule would behave at every
instant in the future. This implied that every aspect of the universe that is to
emerge could be foreseen by a calculating super-intelligence that could track
down the dynamic states of the constituents of the world. In a sense, such a
view does away with time as a significant entity, for the phenomenal world is
simply like the turning of the pages of a book since everything is already
inscribed. Time does not play a part in the evolution of phenomena, it is a
static course on which things appear to be happening. In this view, events in
the world are like images on the walls of a long tunnel through which the train
of consciousness is moving. Each of us, a passenger in the train, zooms past the
images, experiencing and recording the scenes that come our way. In the process
we feel as if the scenes are changing (i.e. that time is flowing) when, in fact
it is the conscious spirit that is hurtling forward.
This static view of time is mentioned by a character in a science fiction
who says, "...we think that
time 'passes,' flows past us, but what if it is we who move forward, from past
to future... ?"
another view, however, the future may take unplanned turns, yet an omniscient
mind can foresee what these would be. In a sacred book of Hinduism, the divine
principle Krishna reveals to a mere
mortal events that were to transpire on the battlefield where they stood .
It is easy to imagine an all-knowing God who, by definition, knows the future
also. But do human beings have this ability which is known as precognition? In
2600 BCE beautiful Nefertiti of ancient Egypt is said to have predicted that
"A king shall come forth from Upper Egypt called Ameni, the son of a woman
of the South ." Ancient Rome had its soothe-sayers too . The
prophesies of Nostradamus have impressed a great many . All through history,
knowledge of the future has ranged from the majestic spiritual splendor of
religious mythology, through foretelling of royal undertakings to journalistic
astrology spelling out occurrences in individual lives on the basis of birthdays
Aside from revered prophets, paltry astrologers, and calculating
physicists who can predict the precise spot where a missile will land or the
precise time when a comet will reappear in the skies, there are some people who
report flashes of recognition of events whose actual occurrence they themselves
witness only later. In various forms, prophecy, divination, psychic powers, and
the like have held an appeal to the
general public all through the ages and in all cultures.
Many honest people have had foreboding dreams, prescient insights, and dÚjÓ-vu
experiences. Most, if not all, premonitions can be brushed off as fantasies and
cute coincidences . Yet, one continues to wonder whether
the human brain and the related consciousness have capacities of which we
are as yet not fully aware .
Changes and the arrow of time
Let us pause to reflect over what I just noted: If there is no change,
there can be no measure of time. The implication is profound. Contrary to
general impression, it is not time that causes change, but it is change that
causes time to flow! Here is a dramatic instance of cause and effect being mixed
Heraclitus of Greece declared, "Everything flows, nothing stays the
same ." And Terence the Latin poet said, "Omnium rerum, heus, vicissitudo est!
(Mark this, that there is change in all things.) This ancient wisdom has
found a thousand reformulations among later philosophers and poets. But it was
not until the 19th century that the connection between perpetual change and the
direction of time was unraveled.
Careful observations put into evidence two kinds of changes. Consider
first the falling of a stone from a table top or a child drinking a glass of
milk. These are examples of irreversible
change. Irreversible changes are changes which cannot spontaneously occur in the
opposite direction. Thus, we cannot expect the stone to rise automatically back
to the table top, nor the milk to pour back into the glass from the child's
body. Indeed, if the transformation in an irreversible change happened
backwards, it would be equivalent to time going in the opposite direction. This
may be illustrated dramatically by running the film of a common event in the
reverse. What appears on the screen will be the equivalent of how the world
would appear if time were to change direction . Thus we note that
irreversible changes are what give time an arrow:
a direction of flow.
At first blush one might be inclined to think that if any brief event is
filmed and projected on a screen one can always say if the film was running in
the forward or in the reverse direction. A little reflection will reveal that
this may not always be possible. Consider, for example, a pendulum swinging in
an evacuated class case. If this change is displayed on a screen, one cannot be
sure in which direction the movie is running. This is an example of a reversible
change. Reversible changes are indifferent to time's arrow.
So if the notion of time arises only in the context of change, that of the
direction of time makes sense only where change is irreversible. It turns out
that irreversible changes are far more likely when large numbers are in any
system undergoing change. In particular, since ordinary matter consists of
unimaginably large numbers of atoms and molecules, all changes in which
atomic/molecular constituents participate are irreversible. Hence in most
natural phenomena that we observe on our scale, time does flow in one direction
If, however, we were to shrink down to atomic and subatomic dimensions and
observe the changes which those individual entities undergo, where collective
and mutual exchanges do not come into play, then we will be observing primarily
reversible changes. In such a world time may flow either way, and it would make
Irreversibility and return: cyclic time
When irreversible changes are examined from the molecular perspective,
another interesting insight emerges. This is best grasped through an analogy.
Consider a deck of cards in which the component cards happen to be in a
particular random sequence. Let us shuffle the deck, and the order becomes
altered. As we shuffle more and more, say a hundred time, a series of different
patterns of arrangement are generated after each shuffle. We are effecting an
irreversible change, because it is impossible for the same set of configurations
to arise during another hundred shuffles.
But is this really so? After all, the hundred shuffles correspond to a
hundred different sequential configurations of the cards. Since we have only a
finite number of cards, if we imagine performing the shuffling unceasingly, in
principle, these very hundred sequential configurations
will be repeated again in one of our future exercises.
In Hindu thought there was the idea of periodic creation (by Brahma) and
dissolution (by Shiva) of the cosmos: the cycle of birth and death was
not just for beings here below, but for the world at large too. This
would take incredibly long time-spans called yugas.
Heraclitus in ancient Greece spoke of cosmic conflagrations too, and the idea of
eternal recurrence was given an extreme literal interpretation by
some, as in the quote above. And Eudemus of Rhodes said:
Everything will eventually return in the
self-same numerical order, and I shall converse with you staff in hand, and you
will sit as you are sitting now, and so it will be in everything else, and it
reasonable to assume that time too will be the same."
Physicists call this the ergodic hypothesis . A rough analogy to this
would be that if one keeps walking indefinitely in a park, sooner or later one
will trace back the paths one has
already been through. In technical terminology the ergodic hypothesis states
that every system will pass as closely as one may stipulate to every possible
state. Using the mathematical theory of probability it is possible to calculate
after how many attempts a given sequence of configurations will be repeated.
This turns out to be a tremendously large number. And yet, as Bergson put it,
"A group of elements which has gone through a state can ... always find its
way back to that state... 
If now we replace the cards by the atoms, molecules and other
ultimate constituents of the material world, then the aspect of the
universe at any instant would correspond to a particular card configuration. The
processes in nature correspond to the shuffling. In principle, then, after a
mind-boggling series of transformations, the same configuration can (and indeed
must) re-emerge in principle! What this implies is that the universe will
eventually revert back to any of its current states, after a sufficiently long
(inconceivably large) lapse of time. In which case time reverts as in a cycle.
While this is very possible, even necessary in principle, in practice this
is beyond realistic recognition.
For one thing, the time-span required for such a cosmic recurrence is
unimaginable quintillions of times the age of the universe. Yet, that this is a
possibility implies a radical departure from our traditional view of linear
time: At the far, far distant future, time may turn back and bring the universe
back to one of its way back when distant past state.
In the cosmological models that were developed during the 1920s, Friedmann
and Einstein proposed a periodic model for the universe, by which the universe
would expand and contract, then expand and contract again, etc. . Such an
oscillating universe could in a way be regarded as creating cyclic time,
although it is also conceivable that after each oscillation the universe would
begin to function under a quite different set of physical laws such as we cannot
even imagine now. Such a circular model eliminates the paradox of the beginning
and end of time .
Time ranges in the universe
It takes but a few minutes to glance through the papers, a hour perhaps to
sit through a show, a few days or weeks to accomplish a task, a month for the
moon to return to its shape, a year for the season to reappear, and so on.
Things happen, events take place, episodes last in the phenomenal world in
varying durations of time. The range of time intervals, from the fleeting
life-time of a fundamental particle, to the immense age of the cosmos itself,
with human history and life-span in between, is impressive indeed.
We measure time in seconds or hours, in days or weeks or years, depending
on the context. Each of these units is human-made, contrived for our
convenience, provoked by our experience. In terms of these, we live for a
hundred years at most, while our species itself has been around for a million
years at least. But our recorded history is barely ten thousand years, and we
may reflect upon the wonders and wasteful atrocities we have wrought in this
relatively short opportunity we have had with civilization!
Mammals have been around for a few million years, and our planet itself
appears to have been spinning around for a few billion years. And, by current
reckoning, the age of the cosmos is between twelve and fifteen billion years.
All this is general knowledge, taught or should be taught in schools. We
need to remember here as elsewhere as we read these pages that all this
information - whether dependable or changeable - comes from an analysis of
perceived reality with the aid of concepts, mathematics, and ingenious
Now is there, or more exactly, can we define a natural unit of time that
is independent of human concerns and experiences? Yes, indeed we can. Consider
some very small distance in the physical world, say the radius of the electron
as it was pictured and measured by the beginning of this century. The time light
takes to traverse this standard distance turns out to be 10-23 (human-defined) seconds. We may take this as the natural unit of time.
In terms of this unit, we live, not for a mere hundred years, but for
natural times units: an impressive figure, but not any longer than a hundred
years. The universe, on this scale is about 1040 natural time units.
You are the origin of the worlds and you are Time, their destroyer.
No creature or thing we know of can disappear out of space, nor jump away
from the temporal axis. The notion of anything beyond the
touch of time is simply inconceivable.
The whole universe, from minute matter to gigantic galaxies, is embraced in the
arms of time, for who can imagine a world where time never ticks.
But would it be fair to say that what cannot be accommodated in the human
mind does not or cannot exist? An
entity that is both particle and wave is a conceptual oxymoron, for a particle
can be constrained to a narrow nook
in space, while a wave is smeared all over: yet the building bricks of the
material universe are corporundals: particle-waves, or so they seem to be.
Are they then right, those mystic meditators who declare there is a
reality that transcends space and
time? If change is what engenders time, if
time is a mere manifestation of change, then if there is something that
is changeless, it must be beyond time. Now if we define, or envision the Divine
as that which is immutable, as the
ever-unchanging principle behind the ceaselessly changing universe, then of
course the Divine is bound to be beyond time.
However, it is not even necessary to go into esoteric mysticism to talk of
transcendence beyond time. Fundamental physics, strengthened by hard core
mathematics, has dragged us willy-nilly to states in this very tangible universe
of ours where time as an entity naturally, not mysteriously, disappears. Yes, if
anything should ever fall into the dismal depth of a black hole, technically
known as a singularity, then, says a celebrated theorem of current cosmology,
it would be squeezed out of the temporal domain as well !
Unbelievable, inconceivable, fantastic, and whatever: but this is the
translation into plain English of what the mathematical telescope unveils.
So, as with everything pertaining to the beginning and end of things, as
with the ultimate essence of the most common experiences, time too is passive
and serving us well when we are indifferent to it, but it becomes a teaser and
baffling bully when we try to probe into its secrets.