- Physicists repurpose everyday words like "exist" in ways that create confusion.
- The block universe treats past, present, and future as equally real.
- Whether spacetime "exists" or merely "occurs" remains unresolved in physics.
What does it really mean to say that spacetime "exists"? This deceptively simple question opens a philosophical can of worms that reaches into the heart of modern physics, challenging how we understand reality itself.
A thought-provoking analysis from The Conversation explores how physicists and philosophers have inadvertently created conceptual chaos by repurposing everyday words like "time," "exist," and "timeless" in technical contexts without carefully examining their original meanings. [Editor's note: The article is in French.]
The result is widespread confusion about what spacetime actually represents.
When Physics Language Goes on Holiday
Philosopher Ludwig Wittgenstein warned about problems that arise when "language goes on holiday."
In physics, this manifests in the eternalist view of spacetime as a fixed four-dimensional "block universe" where all events - past, present, and future - are equally real and exist timelessly.
What is the block universe?
The block universe is a way of picturing spacetime as a single, unchanging four-dimensional structure. In this view, every event that has happened or will happen already exists within the block. There is no special "now" moving through time. Past, present, and future are all equally real.
But here's the puzzle: if everything that happens across eternity is equally real and already "there," what does it mean for spacetime itself to exist?
The author uses a clever analogy to illustrate this dilemma.
The Elephant Problem in Spacetime
Consider an elephant standing beside you. It exists as a three-dimensional object enduring through time.
Now imagine a purely three-dimensional elephant that appears for just an instant like a ghost. This phantom elephant doesn't really exist in the ordinary sense; it merely occurs or appears.
Applying this distinction to spacetime reveals a fundamental problem. Does four-dimensional spacetime exist like the enduring elephant, persisting through some higher dimension of time?
Or does it simply occur? Like a framework for cataloging events rather than a thing with its own existence?
It's like trying to describe a song that exists at a given moment, without being played, heard, or unfolded.
Daryl Janzen, In The Conversation Article
From Science to Science Fiction
This confusion permeates popular culture's treatment of time travel. Films like "Terminator" assume a fixed timeline where everything already exists timelessly, while "Avengers: Endgame" depicts a changeable timeline.
More On Space & Time
Why Time Might Be an Illusion We Created
What if the moment you call 'now' doesn't actually exist in the universe's fundamental structure?
→Both scenarios sidestep the deeper question of what kind of existence this implies.
Importantly, this critique doesn't challenge Einstein's equations or their empirical success. Rather, it highlights how imprecise language can obscure our understanding of what these mathematical tools actually describe.
When physics grapples with fundamental challenges like reconciling relativity with quantum theory, conceptual clarity becomes crucial.
Perhaps the real question isn't whether spacetime exists, but whether we're asking the right questions about the nature of reality itself.
Fact Check: Claim-by-Claim Verification Verified
The article accurately summarizes a real article by physicist Daryl Janzen in The Conversation, correctly presenting philosophical concepts like the block universe and spacetime existence without factual errors.
Commentary
- Elephant analogy is illustrative philosophy, not empirical claim; accurately conveys debate on spacetime ontology.
- Block universe is interpretive, not unanimous; some physicists prefer presentism or evolving block models.
- Time travel depictions in films are pop culture examples, correctly noted as sidestepping deeper issues.
Sources used for verification
Academic/Peer-reviewed:
- A Critical Look at the Standard Cosmological Picture - arXiv
- The quantum theory of time, the block universe, and human experience - royalsocietypublishing.org
- The Block Universe from Special Relativity - academic.oup.com
Other reliable sources:
- Eternalism | Internet Encyclopedia of Philosophy - iep.utm.edu
- What is a block universe? | plus.maths.org - plus.maths.org
- What, exactly, is space-time? - phys.org
Fact-checked by Perplexity Sonar Pro on 2026-03-11
