My Opinion on the Existence of Time

For 4000 years, humans have been measuring time and mapping it with their daily routine, but none of them truly understood what they were measuring. Even now, time remains an elusive concept, a fundamental dimension whose mechanics remain largely theoretical. Einstein in his General Theory of Relativity refers to it as an ‘illusion’ that differentiates the past, the present and the future. Presently, there exists two schools of thought among those curious of its nature. The Presentists believe that only the present is real, while the Eternalists maintain that all three time periods - the past, present and future - are equally existent. This essay, through the dispassionate analysis of all viewpoints, will evaluate whether time is a fundamental physical quantity that exists in the universe, or an emergent property of the human conscience. 

What is time? 

The question of time’s ‘true’ nature has ironically sprung much after humans first discovered its existence. It dictates our daily life, yet we have only a tiny inkling of what it actually is. We generally understand time as the progression of events from the past to the present and onto the future. Yet, it is this very definition of time that physicists refute. 

Physicists such as Einstein maintain that “the distinction between past, present, and future is only a stubbornly persistent illusion”. This perspective on time represents the idea that the universe is a static, four-dimensional "block" where time is woven into the three dimensions of space. In this model, every moment - from the Big Bang to the death of the last star - exists simultaneously as a fixed coordinate. Rather than a moving 'now,' time functions much like a map where 'here' and 'there' are equally real, regardless of where the observer stands. However, many also believe that while time is like a block, the future is a layer built upon the present, which is in turn built upon the past. This represents the varying interpretations of time among physicists and intellectuals alike. 

Interpretations of Time Through the Ages 

Till the twentieth century, Newtonian Physics was the dominant conceptual model. In his book Principia, Isaac Newton described time as absolute, a ‘mathematical entity’ that flows calmly without relation to anything external. While intuitive, subsequent findings would undermine this theory of time being constant for everyone, everywhere. 

James Maxwell made a shocking discovery in the 19th century that the speed of light is a constant, independent of the speed of the reference frame. This created a mind-bending paradox; if the speed of light were constant, then time itself must be flexible. This was the beginning of the downfall of the absolute time theory. 

Next, it was Hermann Minkowski (Albert Einstein’s mathematics professor) who first introduced the idea of a four-dimensional world, referred to as ‘spacetime’, in 1908. Spacetime is the collection of all the things in the universe combined with the extra dimension of time. 

Minkowski concluded that the critical concepts of the Relativity of Simultaneity (two events spatially separated and occurring at the same time is not absolute, but depends on the observer’s frame of reference) and Length Contraction (a phenomenon where an object moving at speeds closer to that of light appears shorter than its length when it is at rest) were a direct implication of this 4D structure. 

Another significant landmark in the study of time was the General Theory of Relativity published by Albert Einstein in 1915. It is the basis of our modern understanding of time and it explains, quite counterintuitively, that the faster an object moves, the slower the time measured on it, relative to objects at rest. Further, it introduces the idea of “Gravitational Time Dilation”, which states that an object with mass bends spacetime due to its gravity, and the greater the mass, the greater the curve. This is why time is said to pass extremely slowly near black holes, as there is a lot of mass concentrated into a tiny volume, creating a great curve. 

A final major study, that slightly deviates from Einstein’s view, was released in 1927 by Sir Arthur Eddington, which talks about “The Arrow of Time”, the idea that time moves in one direction, forward, and the universe towards chaos, or specifically a state of maximum Entropy. 

Evidently, many philosophers and physicists have disagreed and debated over what time actually is, and how it works. The evolution of our understanding of time has been remarkable, moving from the simple mechanics of time being the past, present, and future to a multiplex of Block Universes and spacetime. 

The grand theories discussed earlier have gradually coalesced and, over time, two primary schools of thought have come into existence. These are Presentism and Eternalism, with each having completely differing views on the nature of time. As yet, neither argument has been conclusively refuted, making for a fascinating debate that has stretched for decades. 

Presentism vs Eternalism 

Presentism is the idea that only the present is real, and is a view derived from the everyday experience of time, as against strict physics. Formalised in the 20th century by Arthur Prior, it believes that, as said by physicist Sean Carroll, “the present moment is real, the past is a memory, [and] the future is prediction”. Although this idea is appealing and intuitive, it also presents an obvious logical conundrum - if the past is not real, then how real are the philosophers whose thinking gave rise to this philosophy? Moreover, for a Presentist to be correct, Einstein's equations would likely need to be incomplete, as they do not distinguish the present moment as being physically superior to any other point in history. 

Eternalism, on the other hand, is grounded on a more solid scientific basis and posits that the past, present and future are equally real. A view widely held by physicists, Eternalism argues that if someone knew how the universe was right now, they could predict accurately how it would be in the future, and also how it was in the past. While the Eternalist model is largely consistent with Einstein's theories, it falls foul of the laws of quantum mechanics - if the microscopic building blocks of our universe are inherently probabilistic and non-deterministic, can the macroscopic future truly be considered a finished, existing fabric? 

So, what is Time? 

Time, for me, is both real and abstract, both universal as well as individual. One's lived experience is very real and materially impacts one's present as well as future. However, since no two lived experiences are alike, "the past” or "the present” will mean different things to different people, potentially implying that time is real for the individual but abstract at the group level. Despite these seemingly infinite possibilities, however, the aggregate of lived experiences tends towards a probabilistic common truth, thus rendering time ‘universal’ and real even at a group level. This puts me somewhere in the Eternalist camp. 

Where I differ from Eternalism is in its confidence of accurately predicting the future because neither do we possess all the information needed and nor do we have the wherewithal to model all the casualties inherent in an entity as complex as the universe. Moreover, if the Eternalist view were entirely true and everything could be pre-determined, then what about free will? 

In essence, then, Time is both a theoretical construct and a tangible reality - we are as much shaped by it as we shape it ourselves.