Is time something that flows—or just an illusion? Examining space-time as a fixed or dynamic fabric reveals deeper questions about existence, change, and the true nature of reality.
By, Daryl Janzen, University of Saskatchewan, The Conversation
Is time something that flows—or just an illusion? Examining space-time as a fixed or dynamic fabric reveals deeper questions about existence, change, and the true nature of reality.
Few ideas in modern science have changed our understanding of reality as much as space-time—the integrated unification of space and time at the core of Albert Einstein's theory of relativity.
Space-time is sometimes described as the "fabric of reality." In some explanations, it is a fixed four-dimensional structure—"Block Universe"—a complete map of all events past, present, and future. In other explanations, it is a dynamic field that bends and curves in response to gravity. This raises a deeper question: What does it mean to say that space-time "exists"? Is it a structure, a substance, or just a metaphor?
The core of modern physics
These questions are not just philosophical. They underlie the interpretation of physics today, influencing ideas ranging from understanding the theory of relativity to speculations about time travel, multiple universes, and the origin of the cosmos.
They also shape theories about how spacetime itself might have come into being, including suggestions that it could be a kind of “memory of the universe.” Yet the language used to describe spacetime is often vague, metaphorical, and inconsistent.
Philosopher Ludwig Wittgenstein noted that philosophical problems arise when “language goes on vacation.” Physics, in many ways, illustrates this statement well.
Over the past century, everyday words like “time,” “existence,” and “eternal” have been given special technical meanings—without addressing the assumptions that come from everyday language. This has led to widespread confusion about the true meaning of these concepts.
The problem with language
In the philosophy of physics, especially in the approach known as "Eternalism," the word "eternal" is taken literally. According to this view, time does not flow or pass; all events at all times are equally real within a four-dimensional structure known as a "block universe."
According to this approach, the entire history of the universe is already “laid out” in the fabric of space-time, eternally. “Eternal” in this context means that the universe itself is not continuous or unfolding. There is no “becoming.” There is no change. There is only a block, and within it all of eternity exists at once.
But this raises a deeper problem: if everything exists equally, what does it mean to say that space-time itself "exists"?
Elephant in the room
There is a difference between "existence" and "occurrence." The former describes a state of being, the latter a state of occurrence.
Imagine an elephant standing next to you. You could say, "This elephant exists." It is a three-dimensional object, but more importantly, it is an object that exists.
By contrast, a three-dimensional elephant that flickered and disappeared in the blink of an eye—a momentary cut from the life of an existing elephant—doesn't really "exist" in the usual sense. It happened.
In space-time terms, the existing elephant is described as a four-dimensional worldline—its trajectory in space and time. In contrast, an “occurring elephant” is only a momentary cut from within that same tube.
The question is: Does space-time itself exist like the elephant? Does it have its own "now"? Or is space-time just a descriptive framework that maps out events?
The problem of eternalism
Eternalism confuses this distinction: it treats all of eternity as an existing structure, and claims that the experience of the passage of time is an illusion. But this illusion is impossible if all of space-time occurs "at once."
To recreate the sense of time passing, the four-dimensional space-time must exist more like the existing three-dimensional elephant—which exists along its four-dimensional path.
All events
Now another question arises: If all the events throughout the history of the universe exist, when did the entire block exist? If it does not unfold or change, does it exist outside of time? If so, we are forced to add another dimension of time—a fifth dimension—to say that four-dimensional space-time exists in the same way that we say that an elephant exists in three-dimensional space.
But in doing so, we deviate from conventional physics. A deep problem is exposed: we have no coherent way to talk about the existence of space-time without bringing time back in through the back door.
It's like trying to describe a song that exists all at once, without being performed, heard, or developed.
From physics to popularity
This confusion also affects the images of time in literature and cinema.
In the film Terminator (1984), all events are considered predetermined: time travel is possible, but the timeline cannot be changed.
In contrast, in Avengers: Endgame (2019), the characters change the past and shape a new timeline, as if the block universe can both exist and change.
In both cases, the assumption is that the past and future are "out there," ready for the journey. But neither really grapples with the meaning of such "existence."
Understand reality
When physicists say that space-time "exists," they are using a vague framework that blurs the line between existence and occurrence. The result is an unclear metaphysical model that sometimes even obscures the nature of reality.
Einstein was still right—the equations work, and experiments confirm them. But how we interpret these equations matters, especially as it affects the discourse about reality and attempts to unify general relativity with quantum theory.
Defining space-time is more than a technical discussion—it is a question about what kind of world we think we live in.
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It's called cosmic radiation.
It's much simpler – time itself does not exist. What does exist is space-time. Time is a function of space.
1. Space-time only exists for those who are in a "block universe."
2. For an observer outside the "block universe", space-time does not exist - he "sees" the past, present, and future, and space as one object.
It is not time that flows, but rather the ray of creation that flows, and without interruption, from the moment of the creation of the initial vacuum that scientists call the Big Bang, a uniform line continues that does not cease and can be observed (if interested) for example on television when you cannot receive a station and there is a constant hum! And this is just one example of many!
If we assume for a moment that the universe was created from a big bang, the term block universe would not exist and space would be eternal like time, there would be no beginning or end. Most theories are based on the big bang and therefore are also limited to fitting this theory, there is really no proof that the universe had a beginning and that it has an end.