Time. What’s the time right now? I have all the time in the world. Listen, what time is it? Didn’t your alarm clock wake you up on time? Time. Time. Time. We utter and refer to this word a gazillion times each day. That might be a slight exaggeration but it’s safe to deduce that all of us are very much familiar with the term. However, if you were to take a minute to ask yourself and think about what time really is, would you be capable of coming up with a fitting definition of time? I think not, because even Google has failed to do it. Does this indicate that time actually is just in our heads, an illusion, perhaps?
The Merriam Webster definition of time is “the measured or measurable period during which an action, process, or condition exists or continues”. Our general understanding of time is as vague as this definition. Many physicists share my opinion. When Michele Besso, a dear friend of Albert Einstein passed away, he wrote a letter to Besso’s family in which he wrote, “Now he has departed this strange world a little ahead of me, that signifies nothing. For us believing physicists, the distinction between past, present and future is only a stubbornly persistent illusion.”
This simply means that the now, the present which we hold so dear to us because we perceive it as the only setting which exists and matters is not so special after all. This is to say that the past in which you read the title of this article, the present in which you’re reading this sentence and the future in which you will have finished reading it, all exist on the same plane and are no less real than the present.
Einstein, with his groundbreaking theory of relativity, propounded that time is not absolute but only relative to the observer and is directly influenced by the force of gravity. How time passes can be perceived differently between two observers from different points. This is why we see that the time passed in minutes near a high-gravity field, like a black hole, could mean years passed by on Earth. The relativity theory, over the years, gave birth to the concept of space-time, i.e., time is the fourth dimension in space, also commonly known as the “block universe”.
In layman terms, this essentially means that time, just like the other three dimensions of length, breadth and width, has coordinates and an address, hence supporting the idea that all points (past, present and future) are equally relevant and real. Such a view of time is called eternalism and is directly in contradiction to the philosophical concept of free will because it proposes that future isn’t something which we can chalk out on our own terms; we have to comply with it since it already exists.
Our belief that things are constantly changing and that the future hasn’t happened yet and past happened ages ago, also known as presentism in the field of philosophy, could be nothing but a mere illusion. The MIT physicist Max Tegmark said, “We can portray our reality as either a three-dimensional place where stuff happens over time or as a four-dimensional place where nothing happens [‘block universe’] — and if it really is the second picture, then change really is an illusion, because there’s nothing that’s changing; it’s all just there — past, present, future.
Now, you might be thinking that well, what is time then? If time isn’t real per se, then it could very well be just a social construct existing in our brains. Neurologically speaking, time is a feeling. We associate time with past experiences, memories, the biological processes of birth and death, clocks, days and nights, among other things.
It won’t be a reach to conclude that our whole sense and understanding of time could very well be heavily influenced by our state of mind, stimuli, mood, etc. Think about it- why do we dread waiting in a queue for 20 mins because it feels like an eternity and we think that our whole day spent having fun with friends “flies away” when in hindsight, it’s the latter which we ultimately remember with no special memory of waiting in the queue whatsoever? Further, if we break it down, the past is nothing but the memories in our brain. So, is time an illusion? Is it simply an invention of our human brains?
Physics has attempted to find the answer to this long-standing mystery of time. Supporters from both sides of the debate have expressed their contrasting views over the years. Avshalom Elitzur, a physicist and philosopher, voiced his disagreement when he said, “I’m sick and tired of this block universe. I don’t think that next Thursday has the same footing as this Thursday. The future does not exist. It does not! Ontologically, it’s not there.”
On the other hand, many physicists argue that none of the fundamental equations of physics ever mention the direction of time flow and those which do are time-symmetric, insinuating that maybe time can move backwards just like it can move forward. This is in direct violation of the second law of thermodynamics, called entropy, which refers to the measure of disorder in a system. Entropy is always supposed to increase as we move forward.
We know that a broken cup can’t be unbroken. You can’t un-jump out of a swimming pool. A scrambled egg can’t be unscrambled. We view the world from a macroscopic sense and thus, these scenarios seem in accordance with the laid-out rules. However, if you were to keep zooming into the scene until you can see the particles moving in the air, you won’t be able to differentiate if they are moving forward or backwards. In a microscopic world, time is indeed an illusion.
It can be quite hard to grapple with the notion that maybe time isn’t a linear passage and that the universe is a big and static timeless block. We don’t know if time is something fundamental or emergent and that’s exactly why it’s important to question things. Maybe time is indeed “just a series of Nows” as phrased by Julian Barbour, a British physicist or maybe only the present is what matters. We’ll never know, but maybe the world could do more good with science and philosophy working together to find these answers.