Is time real?

Perhaps the most significant piece of research this week was done by a team led by a postdoctoral fellow at one of my alma maters, NYU. No aspect of our lives is not affected in some way by the researchers’ findings.

The conclusions the team came to are very similar to those I arrived at in an article I wrote for an obscure and long-dead journal in 1987.

The flow of time from the past to the future is, obviously, a central feature of how we experience the world. This phenomenon, known as the arrow of time, arises from the microscopic interactions among particles and cells—it remains a mystery how it happens. The present researchers’ findings could have important implications in a variety of disciplines, including physics, neuroscience, and biology.

Fundamentally, the arrow of time arises from the second law of thermodynamics: the principle that microscopic arrangements of physical systems tend to increase in randomness, moving from order to disorder. The more disordered a system becomes the more difficult it is for it to find its way back to an ordered state, and the stronger the arrow of time (we become more aware of time and it flows perceptibly faster). In short, the universe’s tendency toward disorder is the fundamental reason why we experience time flowing in one direction.

What the researchers say: “The two questions our team had were, if we looked at a particular system, would we be able to quantify the strength of its arrow of time, and would we be able to sort out how it emerges from the micro scale, where cells and neurons interact, to the whole system?” said the paper’s first author. “Our findings provide the first step toward understanding how the arrow of time that we experience in daily life emerges from these more microscopic details.”

To begin answering these questions, the researchers explored how the arrow of time could be decomposed by observing specific parts of a system and the interactions between them. The parts, for example, could be the neurons that function within a retina. Looking at a single moment, they showed that the arrow of time can be broken down into different pieces: those produced by parts working individually, in pairs, in triplets, or in more complicated configurations.

Armed with this way of decomposing the arrow of time, the researchers analyzed existing experiments on the response of neurons in a salamander retina to different movies. In one movie, a single object moved randomly across the screen while another portrayed the full complexity of scenes found in nature. Across both movies, researchers found that the arrow of time emerged from the simple interactions between pairs of neurons—not large, complicated groups. Surprisingly, the team also observed that the retina showed a stronger arrow of time when watching random motion than in a natural scene. Lynn said this latter finding raises questions about how our internal perception of the arrow of time becomes aligned with the external world.

“These results may be of particular interest to neuroscience researchers,” said the researchers. “They could, for example, lead to answers about whether the arrow of time functions differently in brains that are neuroatypical.”

So, what? The interesting question that the researchers brought up is: How does our perception of time interact with our environment? The salamander example is very instructive in this regard.

I first became aware of this phenomenon by comparing the attitudes towards time of hunter-gatherers (with whom I lived for a year) in the Kalahari to people in my hometown of New York. The life of the H-Gs was, obviously, much simpler and much less chaotic.

I reasoned that perhaps as a result of this, the attitude of H-Gs and New Yorkers to the passage of time was, I discovered, very different. Like New Yorkers, H-Gs were aware of aging and had a concept of the linear nature of time. But a crucial difference was that they didn’t perceive it speeding up as they aged, it wasn’t such a factor.

This research shows why this should be so. Every physical system goes from simplicity and order to complexity, chaos, and entropy. Entropy is defined as the amount of energy unavailable to do work. It is also a measure of the number of possible arrangements the atoms in a system can have. It’s a measure of uncertainty or randomness. In a complex and chaotic society, any organization or system within it must ultimately become entropic.

Individually we perceptibly age faster within this complex and chaotic environment. We no longer have the energy to function within it and time—each day, each week and the overall time that we have left to live seems to pass faster. We become aware of our time and the fact that we have less of it.

An H-G of the same age as the New Yorker has perceptibly longer to live and has more energy for the lesser amount of work required. He is not so aware of the progression of time—the arrow of time.

Albert Einstein famously wrote: “People like us who believe in physics know that the distinction between past, present, and future is only a stubbornly persistent illusion.” A hunter-gatherer might agree.