Understanding time – Part I – Objectivity
From times immemorial, few concepts have obsessed mankind more than time. Nothing else is as hard to elucidate. Imagine a creature who is unaware of what time is and try seeing if you can actually explain time to such an entity. Time seems to be such an evanescent thing and yet it is as integral a part of our perception of reality as space or matter. Even in alluding about time, one can seldom refrain from associated time based analogies such as passing, change etc. But despite its seeming perspicuity, Time has still managed to befuddle humanity. Science, philosophy, poetry, metaphysics, psychology etc. abound in literature that attempt to come to grips with time but time seems to evade all of them. It is at once comprehensible and yet remains strangely undefinable.
Obviously, this blog post, by its very scope and size, is not foolhardy enough to even attempt at any elucidation of time. Such an exercise in futility is not my endeavor here. But I did want to present some thought processes about time here. A desultory ramble through them would lead to a discussion of lots of associated topics as well. We would cover a lot of ground about physical laws and their philosophical ramifications. I would attempt to synthesize this knowledge by reconciling this with a more religious viewpoint.
Time & Change
From ancient times, Time has been rightfully equated with “change”. How can we know that time elapsed if there is nothing that has changed? Change, in fact, mandates us to know about Time. There is a Now which can be called a theoretical representation about the current state of the Universe. This Now slowly seems to shift position as the Universe changes. If the Universe were to remain static then there is no need for us to visualize time. Hence time, by this definition, is a projection in our mind, of the changes that are occuring around us. This may, initally sound counter-intuitive since we tend to think that we would be aware of Time even if nothing changes around us. (The age old cliche about the tree in the forest making a noise if no one were around to observe it) What if we are sitting still on a lazy day? Aren’t we still aware of the fact that time has elapsed? The answer is that the very fact that we are aware of our thoughts means that the Universe is not constant even if our body is seemingly stationery. Our thoughts are still changing constantly and hence we are aware of the passage of time. In this context, Rene Descartes’ statement “Cogito ergo sum” (I think therefore I am) can be paraphrased as “I think therefore time exists”. Hence it is quite scientific to equate time with change.
From a western viewpoint, ruminations about time can be traced (as with most other things) to the Greeks. Greeks attempted to synthesize our understanding of time initially. The Greeks correctly understood that time and change co-exist. Most of their philosophical views stem from an understanding of this equivalence.
Parmenides had this notion of Being which is slightly analogous to the Hindu concept of Brahman. Parmenides argued that Being can neither arise nor pass away. When a being neither arises nor passes away then it is beyond time. But if this Being was the only thing present in the Universe, then Time cannot exist because the Being is “neither arising nor passing away” and the only thing in this Universe is this Being. This is more like a static Being whose apparent motion is perceived by the sense organs but who in reality does not exist thereby making the sense organs as unreliable perceivers of reality. Thus Parmenides in effect denied the existence of time and belied the seeminingly important role played by the sense organs in preceiving reality. (Note: Some of the conclusions from Parmenides’ immovable postulated Being are mine and not necessarily the arguments of Parmenides.)
Heraclitus supported the opposite doctrine – one of constant change. To Heraclitus, change is everything. Hence in Heraclitus’s world, time stands exalted as the ultimate substratum around which the entire Universe exists. The philosopher Zeno invented his famous paradoxes of motion where he argued that reality cannot be perceived correctly. Then there were others who continued this discussion further. But let us move on..
The Greeks were great philosophers rather than scientists. Philosophy, whilst attempting to comprehend nature, constrains itself to more of logical dissertations than scientific proofs in support of its doctrine. Hence, over a period of time, the pragmatic west relegated philosophy to the side roads and started earnestly pursuing a more practical approach – an approach that would yield tangible verifiable rewards rather than create literary tomes of erudite treatises based on the intuitions of individual philosophers. This is not to deny the logical basis of philosophy. It is just that philosophers kept arguing about the “why” without a substantial concentration on the “how” and “what” of the Universe. The rise of scientific philosophy lent the much needed scientific temper to philosophical ruminations. But this would not really take place till the advent of Galileo and Copernicus.
Time and Causality
Most science evolved from an objective view of the universe – a view which states that the person (or entity) perceiving things, does not affect the behavior of the perceived. According to the objective view, if someone were to measure the speed of the earth around the sun, for instance, then the measuring process does not affect the earth’s motion. Hence going by this view, if time were to exist, there should be a physical manifestation of it that can be measured objectively. Since change and time go hand in hand, it was not very far fetched to theorize that if we can objectively “measure” change, then we would be able to objectively prove the passage of time. This lead to discussions on Causality. A cause is an event that eventually culminates in an effect. So cause can be called a “prior” state of the Universe before the effect. So if a known cause and a known effect are always separated by the “same” amount of time then the occurrence of this cause and effect combination can be used to calibrate time. For instance, if we know that it always take the same amount of time for some event to occur, then the event can be used to calibrate time. Example: A quartz crystal always oscillates with the same frequency. Hence this can be used to calibrate time intervals precisely. (There is a certain amount of circular reasoning involved here. If we start reckoning time in terms of the frequency of quartz crysals then a change in the frequency would not be noticed by us. For instance, if the oscillations take “longer” then we would not observe it since our seconds would also automatically get “longer”)
To summarize, Causality offered two advantages:
- It was a way of observing time objectively by linking two events in a causal chain
- It allowed a way of precisely calibrating time using well known events that have the same periodicity
Causality & Determinism
To recap, Causality is the theory which states that a cause would lead to effect and that the cause “precedes” the effect in time. But can any cause trigger any effect? A world, where cause and effect are not properly linked, would be arbitrary. Hence there should be definite laws which link the causal chain together. The discovery of these causal laws occupied the minds of people and lead to the emergence of physics as an important part of gathering knowledge. Physical theories attempt to make sense out of causal chains. Scientific philosophy used the discoveries of physics to ruminate over the “why”. It is one thing to talk about gravitation and quite another thing to think why gravitation should exist in the first place!
Causality also leads us to the question of “determinism”. If physical theories are precise (i.e. given a cause they predict the effect with 100% accuracy) , then given the current state of the Universe and the knowledge of all the physical laws, it should be possible to predict the future state of the Universe with perfect accuracy. Hence causality and deterministic physical laws will lead to a very predictable universe where the future is as well known as the past. This argumentation is succintly captured by the statement below (attributed to Laplace)
We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.
See the Wikipedia article on Laplace’s Demon for instance. Most of the arguments evinced above, can be found in Dr. Hans Reichenbach’s Direction of time which is a recommended read (though it gets a little bit heavy later on).
Thermodynamics and time – The Probabilistic Conundrum
Laplace’s Demon received a slight jolt with the advent of thermodynamics. The laws of thermodynamics and statistical mechanics are probabilistic rather than deterministic. This means that the effect does not always follow from a cause. It is one of multiple outcomes and which effect actually gets chosen is determined by probability. So according to thermodynamics, nature is perpetually at the crossroads trying to choose which path to take from multiple alternatives! Now this is quite a different view of the Universe rather than the ambitious deterministic one.
Time & Quantum Mechanics – The complexity posed by Uncertainty
Quantum mechanics introduced another nugget into the causality and determinism discussion by bringing uncertainty into the picture. Imagine a blind man with a stick in an empty room with a ball moving around somewhere on the floor. The ball is moving in a circular motion around the center of the room. The intent of the blind man is to determine the precise position of the ball along with the velocity of its motion. So the man walks with precise steps from a point with known co-ordinates and tries to grope for the ball using his stick. As he feels the ball, his stick disturbs the motion of the ball and hence he cannot know its velocity. The idea here is that it is impossible for us to know about nature without disturbing it. The disturbance may be too subtle to be perceptible at the macroscopic level. But as we approach the realm of microscopic particles, the disturbance is palpable enough to bely the purpose of our measurement.
Objective Measurement of time – a summarization
As we approach the end of our travails using objective ways of measuring time, we start getting a glimpse of some of the complexities involved in the process. We see how time can be equated to “change” and how time and causality go hand in hand. We also see the important role played by determinism, probability and uncertainty in our understanding of the world and of time. In the next article, we will delve into more of the philosophical, religious and moral implications of the time conundrum.