So say physicists, for time was born along with its inseparable twin, space, in a well-known event branded as the "Big Bang," which occurred about 14 billion years ago. Thus, like space, there must have been no time before this cosmic juncture. Though the majority of physicists agree on the birth of time, battle lines are being drawn over the nature of time, and even on the fundamental question of what time is. Now, some theorists even argue that time doesn't exist at all.
Throughout human history, the topic of time has captivated many. Numerous books have been written on the topic, yet the debate rages on. Our generation has seen some of the finest minds alive conceive bestsellers dealing with the mystery of time. However, none of these intellectual exercises has been able to put an end to the perpetual discussion that time presents.
Since time immemorial, the enigma of time appeared in philosophy, metaphysics, and mythology. The Sanskrit word "kala" is synonymous with time. In Hindu mythology, Kala is also identified with Yama, the personified god of death, who reigns over the kingdom of the dead. When the mortal beings near the end of their earthly lives, this god escorts them to his kingdom, a dictum every creature has to follow, though it's not at all easy to conclude what was intended to be represented by these stories.
When confronted with the question of time, the dilemma of modern scientists is as ambiguous as that of the authors of the mythological stories, though they have many tools in their arsenal, from the second law of thermodynamics to the many-worlds theory in quantum mechanics, to explain the arrow of time.
In classical physics, time is like a river flowing simply in the forward direction. External forces (such as gravity) have no impact on the flow of time. Like an arrow shot by the hunter "Big Bang," time traveled (or existed) for about 14 billion years, along with its anomalous twin space. While space provides freedom to move back and forth along its three dimensions, time has commanded a one-way march since the bang, at least in our universe.
Contrary to our expectations, the laws of physics, with very few exceptions, do not discriminate between past, present, and future, though we are obsessed with time and time keeping. We identify time as something that follows us like a shadow. Physics tells us that all moments exist equally, at once -- it's only our perception that distinguishes the present from the past or future. Or, as Einstein wrote, "[We] physicists believe the separation between past, present, and future is only an illusion, although a convincing one."
It's often said that there is no absolute truth; each of us is conditioned to adopt a biased judgment about truth based on our experiences. Is this true of time, too? Is it doomed?
Some theoretical physicists argue that information about the measurement of time could be replaced with correlated observations in space. In other words, the dynamics of the universe are not progressing as evolution in time but as a network of correlated variables. Time emerges as an effect of the actions of the correlated variables. This is analogous to saying that temperature appears from the interaction of a large number of molecules. Similarly, time is the manifestation of the interaction of some variables, rather than a fundamental quality of the universe.
Perhaps "time" is not the biggest mystery in the universe but our ability to recognize and envision the unknown.
A similar thought is displayed in the dialogue between Yama and Yudhishtira in the epic Mahabharata. In disguise, Yama asks many questions to challenge Yudhishtira:
Yama: "What is the greatest wonder in the world?"
Yudhishtira: "Every day, men see creatures depart to Yama's abode and yet, those who remain seek to live forever. This verily is the greatest wonder."
The enigma of time expressed in mythology, philosophy, and science may holds the key to the ultimate truth that humanity is seeking. It remains to be seen whether time will persist forever or fade away, as in the Salvador Dali painting "Persistence of Memory." In the fundamental realm, time could be the result of some missing knowledge about reality rather than a feature of the reality.