[ExI] Does Space-Time Really Exist?

[BillK]

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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