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What is Real? Past? Present? Future? Or All Encompassing?
Discussing Presentism, Eternalism, Temporal Evolvism, and Eternal Presentism from the perspectives of Philosophy and Physics and help of Gravity!
The past few weeks, I have obsessed over the concept of time. This led me to writing two articles exploring the concept of time both from a physics as well as philosophical perspective.
So if you haven’t already, you can read the two articles as a precursor to this one.
It is not a strictly ordered series so if choose NOT to read the two articles above, you will have NO trouble following this one.
In the previous two articles, we discussed the arrow of time and the existence of time itself from a macro perspective.
In this article, we will delve a little deeper, introducing the concept of gravity and it’s interplay with time. We will also discuss differing understandings between physicists and philosophers regarding the objective existence of the past, present, and the future and its implications on our understanding of the spacetime continuum. Let’s get started.
The Fascinating Link between Gravity and Time Dilation
At first glance, one might think that there is no correlation between gravity and time, forces that seem fundamentally different from each other. But in fact, there is a significant correlation between the two. Newton had a notion of this, but he avoided investigating this correlation in depth because he couldn’t see any particular benefit to this endeavour. Einstein, however, saw the potential in investigating this correlation. Today, Einstein’s theory of general relativity holds great importance in the field of physics.
In this theory, gravity is not merely a force acting at a distance, but a manifestation of the curvature of spacetime caused by mass and energy.
Imagine the cosmos as a vast trampoline, where celestial objects, like stars and planets, rest, imparting a curvature to the fabric beneath them. As a result, other objects traveling nearby, including light itself, follow curved paths through this warped spacetime, giving rise to the force we recognise as gravity.
Near massive objects, where the curvature of spacetime is more pronounced, time appears to flow differently compared to regions with weaker gravitational fields. This phenomenon, known as time dilation, challenges our intuition and has profound consequences for both our scientific understanding and philosophical contemplations.
One of the most iconic illustrations of time dilation is the phenomenon observed near black holes. These cosmic entities possess gravitational fields so intense that even light cannot escape their grasp. As we approach the event horizon, the boundary beyond which nothing can return, time itself appears to slow down drastically. To an outside observer, it would seem as though time comes to a standstill for an object approaching the event horizon, suspended forever in a frozen state.
But the concept of time dilation extends beyond black holes, impacting the entirety of the cosmos. From planets and stars to galaxies, the influence of gravity on the passage of time permeates through the cosmos.
Even here on Earth, the minute effect of time dilation has been confirmed through precise experiments and measurements, demonstrating that gravity's gentle pull touches everything in the universe, albeit to varying degrees.
Where we go from here
Now that we understand the link between gravity and also the correlation between space and time, we can start discussing in depth, the topic of this article. In the following sections, we will discuss 4 concepts that have their roots embedded in both philosophy and physics.
Presentism - the understanding that in ‘time’, only the present truly exists.
Eternalism - the block universe theory, i.e., the understanding that in ‘time’, the past, present and the future, all exist.
Temporal Evolvism - the growing block universe theory, i.e., the understanding that in ‘time’, the past and the present are existent but the future is neither existent nor determined.
Eternal Presentism - the understanding that the universe is in a perpetual ‘now’ with each event always unfolding in the present.
Presentism - Time as a Moving Point in the Present
In the realm of philosophical discourse, Presentism stands as a captivating perspective on the nature of time, rooted in the conviction that only the present moment exists. According to Presentism, the past is but a collection of fading memories, and the future remains a realm of uncertainty, yet to unfold. The present is the only temporal reality that holds true, with time flowing as a continuous stream, carrying us forward into the ever-evolving moment.
At first glance, Presentism may seem to align naturally with our everyday experience of time. We perceive the passing of moments as we move through life, and memories of past events become part of our personal narratives. The future, laden with potentialities and aspirations, drives us forward, imbuing our lives with a sense of direction and purpose. Yet, the implications of gravity's time dilation, as revealed by Einstein's theory, pose intriguing challenges to this intuitive view.
In the presence of strong gravitational fields, such as those near massive celestial objects, time dilation challenges the notion of a universally flowing present. As we venture into regions where gravity's pull is more pronounced, time seems to slow down relative to distant observers.
For a Presentist, this revelation confronts the notion of an absolute and universal present. If time flows at different rates in different gravitational environments, is there a singular "now" that encompasses the entire universe? The answer, from the perspective of time dilation, becomes more nuanced, suggesting that the passage of time can vary across the cosmos.
Further contemplation on time dilation reveals that the notion of "simultaneity" becomes relative, no longer universally applicable. Events that seem simultaneous for one observer may appear staggered for another, depending on their relative positions and the gravitational fields they inhabit. Thus, the very concept of the "present moment" becomes entangled with the observer's frame of reference and their position in the cosmos.
This interplay between gravity and time dilation challenges Presentism's view of time as a continuous and objective progression. Instead, it beckons us to embrace a more intricate understanding of time, where the observer's location and gravitational context play a defining role in shaping their temporal experience.
Eternalism - Time as a Block with All Events Existing
Within the philosophical landscape, Eternalism emerges as a contrasting perspective to Presentism, offering an intriguing alternative to our understanding of time. According to Eternalism, past, present, and future events all coexist in an eternal, unchanging block universe. Time is not a flowing stream but a timeless, four-dimensional structure where all events, past, present, and future, are equally real and interconnected.
Eternalism draws inspiration from the revelations of modern physics, especially from the insights of Einstein's theory of relativity and its implications for the nature of time. In the context of time dilation and gravity, the concept of the block universe gains significant traction, as massive objects influence the fabric of spacetime, creating a permanent structure that includes all temporal moments.
In this block universe, the effects of gravity on time dilation manifest as a timeless intertwining of events across the spacetime fabric. While an observer near a massive celestial body may experience time passing at a different rate compared to a distant observer, all moments, past, present, and future, coexist eternally in the unyielding block.
From the perspective of Eternalism, the very idea of a singular "now" or an objective present moment loses its significance. Instead, the block universe presents a vast tableau, where every event occupies its own unique position in the spacetime continuum. Past events are not erased but exist as permanent fixtures in the universe. Similarly, the future is not an unfolding sequence of events, but a realm of possibilities already present within the block.
This view of time challenges our conventional intuitions about the passage of time and presents a profound reconciliation with the effects of gravity and time dilation. It leads us to question whether time is an illusion, merely a human construct arising from our limited perspective within this infinite block of spacetime.
For the Eternalist, the concept of gravitational time dilation reinforces the interconnectedness of all events. The slow ticking of clocks near massive objects is not a mere peculiarity but a testament to the unyielding nature of time, where every moment retains its place in the block, irrespective of its relation to other moments.
Temporal Evolvism - Unfolding the Present, Expanding the Future
Within the cosmic interplay of time and gravity, a fascinating philosophical perspective emerges, fusing elements of Presentism and Eternalism into a unique and captivating theory - "Temporal Evolvism." It is a term that I came up with as an alias for what is known as “the growing block theory”. So if you don’t see “temporal evolvism” showing up in your textbooks or the internet, fret not. Simply look up “the growing block theory” and you will get the answers you are looking for.
At its core, Temporal Evolvism embraces the reality of the present and the past, akin to both Presentism and the Block Universe Theory (Eternalism). The present is experienced as a moving point in the flow of time, and the past is acknowledged as a fixed and unchangeable record of events that have transpired.
What distinguishes Temporal Evolvism is its vision of the future. As per Temporal Evolvism, the future is not perceived as a predetermined and fixed entity, as it is in Eternalism. Instead, Temporal Evolvism invites us to view the future as an open and evolving realm of possibilities, where potentialities await to be actualised as time unfolds.
Eternal Presentism - The Eternal Now
In the vast realm of philosophical perspectives on time and reality, an intriguing and lesser-known theory emerges - "Eternal Presentism," also known as "Eternal Now."
At its core, Eternal Presentism challenges our traditional understanding of time by asserting that only the present moment exists. The past and the future, in this perspective, are regarded as illusory constructs rather than independently existing entities.
Eternal Presentism posits that the universe is in a perpetual state of the "now," with each moment unfolding in an eternal present. The past, rather than being fixed and unchangeable, is perceived as a fading memory, shaped by our perceptions and interactions with the present. Similarly, the future is not seen as a predetermined and fixed trajectory but as an open realm of possibilities continuously unfurling before us.
What is the difference between Presentism and Eternal Presentism?
Presentism posits that only the present moment is real, while the past and future lack objective existence. According to Presentism, the past was real when it occurred, but it has ceased to exist as an objective reality, existing only as memories and historical records. Similarly, the future is seen as a realm of possibilities yet to be actualised and, therefore, lacks objective reality.
In contrast, Eternal Presentism shares the belief that only the present moment is real, but it diverges in its treatment of the past and future. Eternal Presentism contends that both the past and future are continuously real and exist eternally alongside the present moment in an unchanging "eternal now." This perspective envisions a timeless reality where all moments in time coexist simultaneously in an eternal and unchanging now.
What is the difference between Eternalism and Eternal Presentism?
Eternalism posits that all moments in time, past, present, and future, are equally real and have objective existence. Time is seen as a static and unchanging block or four-dimensional spacetime, where all events in history and the future coexist simultaneously. Past events are considered just as real as present events, and the future is perceived to be just as real, although yet to be experienced.
In contrast, Eternal Presentism acknowledges the reality of both past and future moments, but it differs in its view of the present. According to Eternal Presentism, only the present moment is real and eternal, with past and future moments existing alongside it. However, the past and future are not equally real; they are continually updated and realigned as the present moment moves forward in time. This perspective envisions a timeless reality where all past and future events exist in an unchanging "eternal now," while the present is the continually shifting boundary between the two.
Reconciling Our Understanding of Time with the Notion of an Ever Expanding Universe
The notion of an ever-expanding universe, first postulated through the observations of distant galaxies receding from one another, challenges our understanding of time as a universal constant. As galaxies drift further apart, the fabric of spacetime stretches with them, leading to the expansion of the universe. This cosmic expansion brings us face to face with the concept of cosmic time - a timescale that transcends the localised experiences of time dilation and beckons us to consider the temporal vastness of the cosmos.
In the context of gravity and time dilation, the cosmic expansion adds new layers of complexity to the philosophical debate between Presentism and Eternalism. From the perspective of Presentism, the expansion of the universe raises questions about the dynamic nature of the present moment on a cosmic scale. As the universe evolves and expands, does the present moment remain a moving point, unique to each observer, or does the block universe of Eternalism encompass the entirety of cosmic time?
For the Eternalist, the expansion of the universe deepens the connection between time and gravity. As galaxies drift further apart and spacetime stretches, the immutable nature of the block universe accommodates the ongoing changes within the cosmos. Events unfold within the spacetime block, while past, present, and future remain eternally connected, forming a timeless canvas of existence.
Additionally, the cosmic expansion has implications for the concept of "horizons" in the universe. The observable universe is limited by the finite speed of light, and beyond a certain distance, events are beyond our reach due to the cosmic expansion. The existence of an "observable horizon" raises intriguing philosophical questions about our place within the cosmos and the boundaries of our knowledge.
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