[ExI] Does Space-Time Really Exist?
Darin Sunley
dsunley at gmail.com
Sun Sep 14 19:19:55 UTC 2025
I certainly hope so. I keep all my stuff there.
On Sun, Sep 14, 2025 at 1:10 PM BillK via extropy-chat <
extropy-chat at lists.extropy.org> wrote:
> Does Space-Time Really Exist?
> By Daryl Janzen, University of SaskatchewanSeptember 14, 20253
> <https://scitechdaily.com/does-space-time-really-exist/#comments>7 Mins
> Read
>
> *Is time something that flows — or just an illusion? Exploring space-time
> as either a fixed “block universe” or a dynamic fabric reveals deeper
> mysteries about existence, change, and the very nature of reality.*
>
> <https://scitechdaily.com/does-space-time-really-exist/>
> Quote: Space-time is often described as the “fabric of reality.” In some
> explanations, this fabric takes the form of a fixed, four dimensional “block
> universe
> <https://www.preposterousuniverse.com/blog/2015/04/03/the-reality-of-time/>,”
> a complete map of all events in the past, present, and future
> <https://plato.stanford.edu/entries/time/>.
>
> In other explanations, it is a dynamic field that bends and curves in
> response to gravity. This leads to a deeper question: what does it mean to
> say that space-time exists? What kind of thing is it: structure, substance,
> or metaphor?
>
> ----------------------
>
> I had to ask my extra brain (GPT-5) to explain what this article is trying
> to say. :)
>
> Probably best to read the article first, before looking at the GPT-5
> comments below.
>
> I don't think the explanation helped much, but I'll reread it a few times
> first! BillK.
>
>
> ------------------------------
> What the article is doing
>
> -
>
> It’s not questioning Einstein’s math. Relativity still works, GPS
> satellites still need corrections, gravitational waves still ripple
> spacetime.
> -
>
> It *is* poking at the *conceptual side*: when we say “space-time
> exists,” what do we actually mean by “exists”? Is it like an elephant in
> the room (something enduring and present), or is it more like a catalog of
> events (something that just *occurs*)?
>
> ------------------------------
> Key moves in the argument
>
> 1.
>
> *Block universe vs dynamic fabric*
> -
>
> *Block universe* (eternalism): all past, present, and future events
> coexist in a four-dimensional structure. No “flow.” Time doesn’t pass — it
> just *is*.
> -
>
> *Dynamic fabric*: spacetime bends, curves, evolves. That picture
> suggests unfolding, change, maybe even a “now.”
> 2.
>
> *Existence vs occurrence*
> -
>
> Example with elephants: a living, enduring elephant “exists.” A
> flickering snapshot elephant “occurs.”
> -
>
> Applied to spacetime: does spacetime “exist” in the enduring sense,
> or does it merely record occurrences?
> 3.
>
> *Paradox of timeless existence*
> -
>
> If all of spacetime “exists” already, *when* does the block exist?
> -
>
> To make sense of it, you’re tempted to smuggle in a second time
> dimension to say “the block exists now,” which blows up the whole
> “timeless” idea.
> 4.
>
> *Pop culture reflections*
> -
>
> *The Terminator*: fixed timeline, no change possible → pure block
> universe.
> -
>
> *Avengers: Endgame*: timeline can change → assumes the block itself
> “exists” like a world you can edit.
> -
>
> Both lean on spacetime existing, but neither defines what kind of
> existence that is.
> 5.
>
> *Language problem*
> -
>
> Terms like “exist,” “timeless,” “change” carry baggage from
> everyday use. Physics borrows them without cleaning up the ambiguity, which
> leads to muddiness in both science communication and philosophy.
>
> ------------------------------
> What the article *isn’t* saying
>
> -
>
> It’s not denying relativity or spacetime curvature.
> -
>
> It’s not proposing a new physics model.
> -
>
> It’s highlighting that our *interpretation* of spacetime’s “existence”
> is messy, and that this matters when we drift into time travel,
> multiverses, or “does time flow?” territory.
>
> ------------------------------
> Where the tension lies
>
> -
>
> *Science vs philosophy*: equations give testable predictions, but what
> those equations *mean* about reality is up for grabs.
> -
>
> *Experience vs theory*: we feel time passing, but eternalism says that
> flow is an illusion.
> -
>
> *Existence as layers*: maybe spacetime “exists” at one descriptive
> level (physics), while at another level it’s more like a record, not an
> enduring substance.
>
> ------------------------------
> Bottom line
>
> The article’s question — “Does spacetime really exist?” — is less about
> physics being wrong and more about whether our everyday words are even
> equipped to describe what the math implies.
>
> Spacetime *works* as a model. But whether it “exists” like an elephant,
> like a song, or like a map — that’s where the fight is.
> ------------------------------
>
> Want me to sketch how different camps (physicists, philosophers, and “shut
> up and calculate” pragmatists) would each answer this “existence” question?
> That could give you a quick map of the landscape.
>
>
> Alright, here’s the quick map of camps and how they’d answer *“Does
> spacetime really exist?”*
> ------------------------------
> 1. *Physicists who lean realist (spacetime is real)*
>
> -
>
> *View:* Spacetime is a *thing* — it bends, ripples, and interacts with
> matter/energy.
> -
>
> *Reasoning:* If something has measurable effects (gravitational waves,
> time dilation, lensing), it’s as real as atoms.
> -
>
> *Answer:* *Yes, spacetime exists. It’s the fabric of the universe.*
>
> ------------------------------
> 2. *Physicists who lean emergentist (spacetime isn’t fundamental)*
>
> -
>
> *View:* Spacetime is a useful construct, but deeper down it dissolves
> into something else (quantum entanglement, causal sets, discrete networks).
> -
>
> *Reasoning:* At the Planck scale, smooth spacetime breaks down.
> “Space” and “time” may be secondary, like how “temperature” emerges from
> molecules.
> -
>
> *Answer:* *Spacetime exists the way “waves on the ocean” exist — real
> at our scale, not at the deepest one.*
>
> ------------------------------
> 3. *Philosophical eternalists (block universe crowd)*
>
> -
>
> *View:* All events past, present, future equally exist in a 4D block.
> -
>
> *Reasoning:* Relativity denies universal simultaneity. If there’s no
> privileged “now,” then every event is just as real as this moment.
> -
>
> *Answer:* *Spacetime exists timelessly — the whole block is real. The
> flow of time is an illusion.*
>
> ------------------------------
> 4. *Philosophical presentists (only “now” is real)*
>
> -
>
> *View:* Only the present exists. Past and future don’t.
> -
>
> *Reasoning:* Common-sense experience of change matters; without a
> flowing “now,” existence loses meaning.
> -
>
> *Answer:* *Spacetime is just a description of events, not an enduring
> entity. Only the present slice is real.*
>
> ------------------------------
> 5. *Instrumentalists (“shut up and calculate”)*
>
> -
>
> *View:* Don’t worry about “existence.” Spacetime is a model that
> predicts things accurately, and that’s enough.
> -
>
> *Reasoning:* Debating whether spacetime “really exists” is philosophy,
> not physics.
> -
>
> *Answer:* *Spacetime exists the way equations exist: useful,
> predictive, end of story.*
>
> ------------------------------
> So where does this leave us?
>
> -
>
> If you trust math + measurements → spacetime is real.
> -
>
> If you probe the foundations → maybe it’s emergent, not ultimate.
> -
>
> If you push philosophy → “existence” itself might be the wrong word
> for what spacetime does.
>
> ------------------------------
>
> Do you want me to also sketch how *quantum gravity theories* (like string
> theory vs loop quantum gravity) treat spacetime’s “existence”? That’s where
> physics really tests these ideas.
>
>
> OK —
>
> ------------------------------
> How Quantum Gravity Theories Treat Spacetime 1. *String Theory / M-Theory*
>
> -
>
> *View of spacetime:* Not fundamental — it emerges.
> -
>
> *Core idea:* The real ingredients are strings (or branes) vibrating in
> a deeper mathematical structure. Spacetime is a large-scale approximation.
> -
>
> *Evidence:* Holographic principle — what happens in a volume of space
> can be encoded on its boundary surface.
>
> Space-time is often described as the “fabric of reality.” In some
> explanations, this fabric takes the form of a fixed, four dimensional “block
> universe
> <https://www.preposterousuniverse.com/blog/2015/04/03/the-reality-of-time/>,”
> a complete map of all events in the past, present, and future
> <https://plato.stanford.edu/entries/time/>.
>
> In other explanations, it is a dynamic field that bends and curves in
> response to gravity. This leads to a deeper question: what does it mean to
> say that space-time exists? What kind of thing is it: structure, substance,
> or metaphor?
> -
>
> *Answer:* *Spacetime exists, but only as an emergent property, like
> “temperature” from molecules.*
>
> ------------------------------
> 2. *Loop Quantum Gravity (LQG)*
>
> -
>
> *View of spacetime:* Discrete, not smooth.
> -
>
> *Core idea:* At the Planck scale, spacetime is made of finite “chunks”
> (quantized loops of geometry). Areas and volumes come in indivisible units.
> -
>
> *Evidence:* Predicts minimum measurable areas/volumes (not yet
> experimentally confirmed).
> -
>
> *Answer:* *Spacetime exists, but it’s grainy — like pixels that look
> smooth from afar.*
>
> ------------------------------
> 3. *Causal Set Theory*
>
> -
>
> *View of spacetime:* Emergent from events.
> -
>
> *Core idea:* The universe is a vast network of discrete “events”
> connected by cause-and-effect. Geometry emerges from these connections.
> -
>
> *Answer:* *Spacetime doesn’t exist at the base level — it’s a shadow
> of causal links.*
>
> ------------------------------
> 4. *AdS/CFT & Holography*
>
> -
>
> *View of spacetime:* A projection.
> -
>
> *Core idea:* A universe with gravity (the “bulk”) can be completely
> described by a lower-dimensional system without gravity (the “boundary”).
> -
>
> *Answer:* *Spacetime exists as a hologram. Real enough for physics,
> but not the ultimate layer of reality.*
>
> ------------------------------
> 5. *Emergent Time Theories*
>
> -
>
> *View of spacetime:* Maybe only space is fundamental; time comes later.
> -
>
> *Core idea:* Some models suggest only correlations exist
> fundamentally, and “time” arises from relationships between systems.
> -
>
> *Answer:* *Time especially may not exist fundamentally — spacetime is
> just our bookkeeping of change.*
>
> ------------------------------
> Where They All Converge
>
> -
>
> No leading approach to quantum gravity treats spacetime as
> *fundamental*.
> -
>
> Each imagines a deeper layer (strings, loops, causal sets,
> entanglement) from which spacetime emerges.
> -
>
> Relativity still works beautifully at human/cosmic scales, but at
> Planck scales spacetime may dissolve into something else.
>
> ------------------------------
>
> In short: physics is drifting toward the idea that spacetime is more *map*
> than *territory*. The open question is whether that map is a convenient
> illusion, or an emergent phenomenon that’s “real enough” at the scales we
> live in.
> ------------------------------
>
>
>
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