The Deception of Time

Appearances can be misleading, a key lesson in science. For example, if you rely only on your eyes, you might mistakenly think the world is flat. The same misconception applies to time. We often see time as a constant, like a never-ending ticking clock. But this view is incorrect. Time moves at different speeds depending on your location. For instance, a clock at sea level will run slower than one placed high up in the mountains. Similarly, a clock on the floor will run slower than one on a table. Though these differences are tiny and require precise instruments to measure, they are real. The effect is not just about time; all processes slow down at lower altitudes. Imagine two friends of the same age who part ways. One lives at the beach, and the other at the top of a mountain. When they reunite years later, the mountain-dweller will have aged less and lived longer, and even his houseplants will have grown more.

Nature of Time and Heat

It might sound unbelievable, but there's no single "true" measure of time that works everywhere, like in the mountains or at sea level. This is because time is relative; different locations have their times. This idea was a key part of Albert Einstein's theory of general relativity. Adding to the complexity, heat also affects time. Both time and heat share a key feature: they move in one direction only. Time goes from the past to the future, and heat travels from hot objects to cold ones.
In both cases, reversing movement is impossible. What’s fascinating is that we can only tell the past from the future because of heat. Here’s how it works: The past is different from the future due to change. Change happens with motion, and motion is just heat molecules moving at a tiny level. Without heat, nothing would move, and we wouldn’t be able to tell past, present, and future apart; they would all blend into one.

The Reality of Time and Speed

We know that time moves differently in various locations, but did you know it also varies in the same place? Albert Einstein discovered this in the early 20th century. He found that time slows down when objects move quickly. So, for someone in motion, time passes more slowly compared to someone standing still. This link between time and speed means our idea of "now" or "the present" might not make sense. For example, if you think about your sister on a distant planet, Proxima B, which is four light-years away, and wonder what she’s doing "right now," you would see a past image of her through a telescope.

Understand the Relativity of Time

A light-year measures how far light travels in a year. Proxima b is four light-years away from Earth, so when you look at it through a telescope, you’re seeing what happened there four years ago. Even if you tried to predict what will happen on Proxima B in four years, you still wouldn’t be seeing the present moment there. By then, your sister might be back on Earth and at a different point in time. This shows that “the present” only makes sense concerning what’s around us. Einstein revolutionized our understanding of time by showing that it’s not an absolute measure as previously thought. Before Einstein, time was considered fixed and separate from space. He introduced the idea that space and time are linked in a complex way.

Understand Time Through Quantum Mechanics

We now know that time isn't just a smooth, orderly flow from past to present to future. We also understand that an event in time can't be separated from the space where it happens. So, what exactly is time? To answer this, let’s look at how modern physicists view it. The best starting point is quantum mechanics. This field studies nature by focusing on its smallest parts, called quanta. These tiny components include light and energy packages, as well as elementary particles that make up everything around us. By studying these quanta, scientists have made three major discoveries.

• Physicists have discovered that energy and matter are "quantized," meaning they exist in small, discrete packets rather than flowing smoothly. This idea extends to time, which also doesn't flow continuously but is made up of tiny, separate units. The smallest measurable unit of time is called Planck time, which is incredibly brief, just 10^-44 seconds, or one with 44 zeros after it!
• Indeterminacy means we can't precisely predict where an electron observed at one moment will be a millisecond later. Scientists can only make guesses based on probabilities because the electron’s exact position is unknowable between observations. Time is also indeterminate, meaning it doesn't move in a straight line but fluctuates, with events sometimes happening before or after others.
• To observe electrons, scientists must study how they interact with other objects. Electrons are understood through their relationships with other forms of matter. Similarly, to analyze time, you need to examine the network of relationships that define it.

The Nature of Change

Ancient Egyptian pharaohs and French monarchs might have believed they were eternal, but even the most powerful empires and institutions eventually faded away. History is marked by constant change. Physicists view the world differently—they see it as a series of events rather than static objects. What matters are not fixed substances but ongoing processes. For instance, a stone is usually considered a permanent object, while a kiss is an event that lasts only a moment. However, over long periods, even a stone, which seems solid, will eventually break down into dust as its particles interact and change. Thus, from a broader perspective, even something as seemingly permanent as a stone is a very long event.

Presentism vs. Eternalism in the Context of Physics and Time

The way we perceive the world influences our understanding of time. Commonly, we consider something real only if it exists in the present moment, with everything else either concluded or hypothetical. This viewpoint is known as presentism. However, this perspective doesn't align with the discoveries made by physicists. An alternative view is that the present can't be universally defined since each location in space has its own sense of time. Moreover, time doesn't progress in a simple, linear sequence from past to present to future. This implies that all moments past, present, and future are equally real, a concept known as eternalism.

Consequently, physicists have moved away from using independent time variables in their equations. In emerging fields like quantum gravity, scientists have shifted focus from mapping changes over time to describing how things change relative to one another.

Understand Time as an Emergent Phenomenon

The concept of emergent phenomena helps us bridge the gap between our everyday experiences of time and the insights from modern physics. Think of a group of schoolchildren deciding to play soccer. To form two teams, they simply flip a coin. Once the teams are set, it wouldn't make sense to ask where the teams were before they existed—they weren't anywhere yet. The teams emerged from the coin toss, becoming an emergent phenomenon. Similarly, time can be viewed as not existing independently "out there" but rather as something that emerges from our specific perception of the universe.

The Flow of Time and the Role of Entropy

Central to our understanding of time is the idea that it flows, which physicists attribute to entropy. The distinction between past, present, and future is only apparent when we observe changes; without change, these time frames become indistinguishable. This change is driven by an increase in entropy, a measure of disorder. For instance, as a new car begins to rust and deteriorate, entropy rises, indicating a loss of order. The second law of thermodynamics tells us that entropy in the universe always increases, creating the perception of time moving in a single direction. However, this perspective might be influenced by our specific viewpoint on the universe. From a different vantage point, the flow of time might not appear as we currently understand it, suggesting that increasing entropy doesn't necessarily mean time is moving in the direction we think it is.

The Role of Energy and Entropy in Change and Time Perception

You likely encountered two fundamental principles in high school physics: everything requires energy, and energy cannot be created or destroyed, only transferred, such as into heat. This principle means energy is always conserved. So, why do we need to continually supply energy? The answer lies in entropy. It's not just energy that keeps things moving, but rather low entropy or high orderliness. The real driving force is concentrated energy sources that transform into more disordered forms. Essentially, every change on Earth, every cause and effect, is driven by increasing entropy. Human history has evolved from states of low entropy to increasingly higher entropy, up to the present day. Without this rise in entropy, change would not occur, and without change, we wouldn't experience the flow of time, making the very concept of history unimaginable.

The Sun's Role in Driving Entropy on Earth

What drives entropy on Earth? The primary driver is the sun, a source of low entropy that is conveniently close to our planet. Here's how it works: The sun emits high-energy photons—light particles—toward Earth. In response, Earth radiates out ten lower-energy photons for each high-energy photon it receives, thus maintaining an energy balance.

A high-energy photon has significantly less entropy compared to ten low-energy photons. Therefore, the sun provides a supply of low entropy that Earth utilizes to fuel various processes, such as burning wood or generating power through hydropower. This transformation of low entropy into high entropy is fundamental to all life forms. For example, human bodies rely on the sun’s low entropy energy through chemical reactions, while photosynthesis in plants captures and stores this energy, which animals and humans access by consuming plants.

Our Perception of Time and Its Connection to Identity

As we conclude our exploration, let’s revisit the central question: our relationship with time. Although time isn’t a universal aspect of the world, it’s integral to human experience. So, where does our perception of time originate? It primarily stems from our subjective view of the world, which is essential to our human identity. This perception involves three main components. 

• First is our perspective on how we view the world and process information from a particular standpoint. 
• Second, we simplify and categorize information to better understand it. For instance, we group rocky matter into a concept like "Mont Blanc" and consolidate various traits to define what it means to be human. This intellectual categorization influences our worldview and interactions with others, indicating that our sense of self is shaped more by interaction than introspection.
• The third component is memory. Our experiences, such as those with Mont Blanc or other people, are not stored randomly but are organized chronologically, like index cards marking different chapters of our past. This organization allows us to view the world as a sequence of historical events and our lives as narratives linking past, present, and future.

Thus, our understanding of time is rooted in the systematic organization of personal and subjective experiences. Time, therefore, is a construct of the mind that helps define our species and our identities.