Written by Sritama & Swarnadeep
Since the dawn of civilization, it has been a fascination for mankind, to understand the world we live in. It has been our nature to question the various aspects of the world, to question the causes behind the natural phenomena and that has been one of the prime causes for our upliftment from one of the weakest species of apes to modern dominant beings.
But yet, we stumble to fully comprehend reality. Many questions remain unanswered, many mysteries remain unsolved. And one of those is the mystery of TIME!
Time is something which we all know well about. We speak of the value of time. We say '' Time and tide waits for none''. We reach our schools and offices at a fixed time. We sleep for a duration of time. But the most deceptively simple question is that of time.
Have you ever wondered what time is?
Why is it always flowing? Or is it? Is time real? Or is it elusive? Why do we appear to remember the past; experience the present; and anticipate the future? And not the other way round?
How is time-related to reality? How would our understanding of time and reality help our present state of living??.....
So let's explore this perplexing puzzle of TIME as it evolved with time (whatever it may mean).
Early Approach and The Way to Relativity
Time has been entangled in our daily life since the existence of mankind. And with every age, scholars of various disciplines have pondered over its nature. And that's why its origin can be traced to religion, poetry, philosophy, Natural Science, and even Social Sciences. We live in time, we think with respect to time.
Most of the early scholars including Aristotle and Sir Issac Newton, quite naturally assumed time to be something eternal- something that existed forever; something which is always flowing unidirectionally- towards the future. Something which existed even before the universe.
And that ought to appear natural to any layman from what he sees and infers from his day to day life.
But science is not governed by so-called common sense, rather; nature seems to be elusive. For instance, the earth appears to be flat but actually is 'geoid'. The sun appears to be moving across the sky but in reality, it's the other way around and to be in specific motion is relative. Similarly, the matter which appears to be smooth is composed of discrete atoms that are again divisible to more fundamental particles.
And, on the same note, as we progressed in our understanding of the cosmos, our notion of Time changed- and is still changing, becoming more and more perplexing as we probe deeper into the mysteries of the universe.
And it all initiated with the proposal of the ''Theory of Special and General Relativity'' in the early part of the 1900s by one of the greatest physicists of all time- Albert Einstein who succeeded in defying all common sense and uniquely reimagined the universe through his thought experiments.
This theory turns out to be one of the most important ideas in modern science, changing our understanding of motion, space and time and unifying the two into a single space-time continuum, suggesting the ''weird'' existence of 'block universe' and thus portraying Time as an Illusion.
Relativity and Einstein's Ideas on Time
At the age of 16, Einstein then a schoolboy dreamt of traveling in a beam of light and wanted to see how the world looks like. And this dream of a "so considered'' blunt schoolboy turned out to be the turning point in our understanding of the world.
The theory of relativity consists of two interrelated theories by Albert Einstein - special relativity and general relativity. Special relativity applies to all physical phenomena in the absence of gravity whereas General relativity explains the law of gravitation and its relation to other forces of nature.
The theory of special relativity explains how space and time are linked for objects that are moving at a constant speed in a straight line. In other words, as an object approaches the speed of light, its mass becomes infinite and it is unable to go any faster than light travels. This cosmic speed limit has been a subject of much discussion in physics, and even in science fiction.
After his work on special relativity, Einstein kept pondering, what would happen if one introduced acceleration. This formed the basis of his general relativity, which explains gravity based on the way space can 'curve', or, to put it more accurately, it associates the force of gravity with the changing geometry of space-time and is the basis of the BigBang, and the idea behind BlackHoles.
The Space-Time Continuum
Fig.1. 4-Dimensional model of Spacetime
One of the most baffling outcomes of special relativity was the unification of Space-time. It's a conceptual model arising directly from the 'principle of relativity' which combines the three dimensions of space with the fourth dimension of time.
According to Maxwell's equation on electromagnetism, the speed of light is constant and for this to be true, space and time had to be combined into a single framework that conspired to keep light's speed the same for all observers.
For example, if one observer sees two events occur at the same place, but at different times, a person moving with respect to the first observer will see the two events occurring at different places, because (from their point of view) they are stationary, and the position of the event is receding or approaching. So who is right in the case? The first or the second observer??.
Relativity says both are right from their frame of reference because they are at different coordinates of space and time which are not independent of each other but are the different faces of the same coin.
But the relation between space and time becomes clearer as we progress with the understanding of the massive gravitational giants: The Blackholes which would be introduced shortly.
The Theory of relativity supports something called the block universe, which is a four-dimensional space structure. This means that every event has its coordinates not only in space but also in time.
So, now the question arises, What is the Block Universe?
According to this theory, the universe is a giant block of all the things that ever happen at any time and any place. In this view, the past, present, and future all exist — and are equally real.
Fig.2. Theoretical model of Block Universe
This concept can be best explained using a cuboid shape. Let's visualize a cuboidal block that has four dimensions: length, height, and width, plus a fourth temporal dimension, rather known as time. The height and width of the cuboid represent two of the universe's three spatial dimensions and the length represents a temporal dimension. At one edge of the cuboid is the big bang (i.e the beginning of space-time ) whereas at the other is the very last moment of the universe (i.e the end of space-time ).
Every event that ever happened is located at a corresponding point in the cuboid. Thus a place in space and a place in time is the same.
In the model of the block universe, time doesn't change or goes anywhere, it stands still.
The thing which changes is our consciousness which keeps on moving through the dimension of time and thus it appears that time is flowing.
So, in a nutshell, it can be said that:
''Everything is eternal, but perspective, and that's time."
But, wait for a second! What nonsense are you talking about!! Quite mystical!
Nope! Not nonsense but bets are high that this is the actual case.
It's quite like a motion picture i.e. still pictures being projected on-screen with rapid succession such that it appears to be a moving one.
But all these are not out of controversies. Many physicists have resisted Einstein's view on ''Block Universe'' and the portrayal of time as an illusion. And even, 'Lee Smolin' has written a phenomenal book ''Time reborn'' against it.
Whatever may be the nature of time; illusive or probabilistic, only time would unravel it.
The Gravitational Giants: Black Holes
Fig.3. Graphic Illustration of a 'Blackhole'
So the 2020 'Nobel prize' has already been announced. Right? And we all know that this year it's for the research on Blackhole.
We all know what a black hole is. But do we know what is inside it? And how would time behave if you were lurking inside the black hole (provided you don't get torn into spaghetti)?
Black holes are perhaps the strangest consequence of General Relativity. First understood by the new laureate Roger Penrose using a complex mathematical technique. It's the region in space-time where the gravity is so intense that it bends the fabric of space-time such that even light cannot exit.
And thus, is surrounded by an event horizon which sweeps the mass inside like a veil and well protects a singularity at the center; the region where all the known laws of physics fail.
It's believed that beyond the event horizon, the spatial dimension changes to that of time, and the dimension of time changes to that of space.
Thus inside a black hole, you are not allowed to move in space but you do a sort of time travel!!
Quantum Entanglement: A Challenge to Relativity
One of the foundational results of the theory of relativity is the cosmic speed limit of light. The speed at which when a body moves, time ceases for it. And yet nothing has been observed to travel at a speed more than light.
But then comes a new challenge; another perplexing gift of nature: Quantum entanglement.
It's being found both theoretically and experimentally that the subatomic particles including the bosons come in pairs such that they cannot be described independently to each other.
That is, changing the state of one particle leads to the change of the entangled particle, whatsoever may be the spatial separation of it and that too instantly.
Now, here comes the question: How's that possible when light is the universal speed limit.
We Don't Know!!
But does it give some hints of some different subtle nature of the universe?
Does it give some hindsight that our understanding of time is yet farfetched?
Professor Amit Goswami deals with these puzzles of quantum entanglement in his book 'The Everything Answer Book' and comes out with an innovative solution to a new order of reality.
We yet don't know of its correctness but with time the mysteries are deepening.
We are stumbling to answer the moments before the big bang( as there are controversies with Hawking's argument of the Big bang being the starting of time). We know nothing of quantum entanglement. And the age-old question of the nature of TIME & REALITY continues to exist. We have some hindsight but nothing more.
Some unknown theories of an '' infinite superset of the universe'' of ''C Peter O' Connor ''do exist; which speaks of an infinite outer universe with Relativity failing there; describing the moments before Bigbang and with no speed limit.
But are they legitimate? Or would contrast our learnings about the Universe? Are they enough to explain Time? Reality?.
We know not. But can only hope for some new theory that would unlock these mysteries from the heart of nature.
Why are We Investing So Much in These Questions Which Would Hardly Affect Us?
So, that's a question. How may the understanding of time affect the lives on Earth?
Well, to quote Faraday, one of the profound physicist of all time:
"What's the use of a newborn baby? Why should we nourish it when we know that it's of no use to us?"
Faraday said these words in context with the newly discovered phenomenon of electromagnetic induction to a reporter at the royal society. Interestingly, shortly after these EMI proved why its worthed investing, is the principle of electric generators, electric motors, transformers, and many more; which drove the scientific and technological revolution throughout the 20th century and even beneath.
Research in basic science gave us The World -Wide-Web (which consists of most of the internet) as the byproduct of CERN.
Is that answer not enough to justify all the expenses?
But still, these kinds of ignorant questions are asked worldwide and even this year Noble Laureate Andrea Ghez was asked: "How the discovery of Blackhole could change the life on Earth?"
Well, perhaps our understanding of the reality of time would not be of any use for mankind instantly. But slowly it would surely change our life to a great leap.
Basic Science always played the role of mother to Technology and surely our understanding of time, consciousness, the nature of reality, and phenomenons of quantum entanglement would be affecting the present development of AI and quantum technologies to a great extent.
Perhaps it'd pioneer some new science, would unravel some new questions, or would explore some newer dimension of truth.
A short conversation with C Peter O'Connor
TimeReborn by Lee Smolin
The Everything Answer Book by Amit Goswami
Quantum Reality by Jim Baggot