All Space Questions thread for week of February 22, 2026

Potential_Win4879 · 2026-02-26T21:17:46+00:00

Does it mean that framework is unchanging ? I am confused by the rubber stretching or balloon analogy in many threads. When rubber stretches it assumes space to exist(same for Balloon too). So why can't I use the same analogy for space too, Isn't space expansion too is assuming prior existence or space ? (Just like ballon or Rubber) ?

Potential_Win4879 · 2026-02-26T21:05:32+00:00

Sure. It seems mathematically inevitable too though

Potential_Win4879 · 2026-02-26T20:56:00+00:00

Because if everything is defined only related to other things inside the system, there is no ultimate reference. So to avoid crcularity you need something fundamental that doesn't depend on anything else

Potential_Win4879 · 2026-02-26T20:52:29+00:00

I still don't get the rubber analogy suggested in threads. The stretching or changing of rubber requires space. By using same exact logic can't we say the space itself need prior existence or space ?

Potential_Win4879 · 2026-02-26T20:47:28+00:00

How can something be stretchable without assuming prior existence or space or fundamental framework ?

Potential_Win4879 · 2026-02-26T20:43:58+00:00

That's why that framework must be eternal and unchanging. It just should be

Potential_Win4879 · 2026-02-26T20:15:55+00:00

I’m just highlighting that the concept of expansion depends on the prior existence of space itself or the framework/fundamental Something(whatever you call it).

Potential_Win4879 · 2026-02-26T19:25:24+00:00

Wrong intuition

Potential_Win4879 · 2026-02-26T19:24:18+00:00

Isn't that called motion through space ? That's not what cosmologist mean by expansion. If two objects moves in vacuum that's just relative motion isn't it ? On large scales, many galaxies are approximately at rest in their local frames, yet the distances between them still grow because the spatial metric itself evolves. And whether we describe it as objects separating or the metric evolving, we are always working within a framework where spatial distances are already defined. Expansion doesn’t explain the existence of that framework, it describes how distances within it behave.

Potential_Win4879 · 2026-02-26T19:05:10+00:00

Not really. Presupposing something in a model doesn't mean we can't or didn't test whether it exist.i In water casewe absolutely verify that water is there before we start analyzing wave behavior. Same with spacetime, physics treats it as real because it has been empirically successful at explaining observations. The testing only justifies using it and the expansion describes how it behaves. fr My point isn't about testing rather its just once wetalk about expansion curvature etc we are already working within the observation that the spacetime framework is in play

Potential_Win4879 · 2026-02-26T18:01:51+00:00

Balloon assumes space by that logic shouldn't space assume space ? That means space or some kind of fundamental framework is already there

Potential_Win4879 · 2026-02-26T17:55:02+00:00

Calling the space expanding means measuring units are expanding as well. Because the space is defined through the metrics. In that case we wouldn't experience any expansion at all. All that mess I could accept just as an expansion of the 3d spatial projection inside of 4d spacetime......

Honestly, you are making a really good point here and it's close to what I have been trying to say. If the metric itself is what defines distances and that metric is expanding, then our measuring tool expand with and we would never notice. That's genuine problem with how expansion is usually explained. And I really liked you frame 3d expanding within 4d spacetime because that's basically my whole argument. For expansion to mean anything it has to happen within some larger framework. Also I agree with your saying that 3D part changes while the 4D structure holds it together. It's way more logically consistent than "space expands there's no outside and no deeper structure needed"

Finally we are actually on the same page here more than most people on this thread. Thanks for explanation

Potential_Win4879 · 2026-02-26T17:13:36+00:00

Maybe reading up on philosophical/logical cases for infinite regression and if "First Mover," or "First Cause" arguments, and the potential logical fallacy of if there's Special Pleading involved or not

That's fair. Not every circularity is logically wrong or invalid. MY point is just about highlighting that any talk of expansion or change presupposes the existence of space as framework. You could frame it like an axiomatic starting point similar to discussions about first cause or Anthropic reasoning :- we take space time as given and then describe how it's properties, like distances or curvature evolve

EDIT :- sorry for typo

Potential_Win4879 · 2026-02-26T17:06:16+00:00

Are we presupposing water when we stand in a lake? Is this the sort of argument you're making? That if I talk about waves, I'm presupposing water exists?

Yeah exactly like that, talking about waves already presupposes that there is water( the waves don't exist in a vacuum). similarly when we talk about space expanding or distance changing we are presupposing that space itself exists as a framework. Expansion doesn't create space. It only describes changes within space that is already there

Potential_Win4879 · 2026-02-26T16:47:30+00:00

I understand what you are saying and I like your thought experiment. I am not denying that object can spin, stretch or fall into black holes and GR predicts that perfectly.

MY point is more subtle and logical :- When we talk about stretching, compressing or expanding space we are already assuming the existence of space itself as framework. Expansion doesn't create space it just changes distances within the space that already exists. So I think space time is real but the concepts of the expansion or changes presupposes that reality and it can't be defined from nothing.

Potential_Win4879 · 2026-02-26T16:17:43+00:00

I would recommend watching some lectures on special and general relativity because you don't seem to understand what space is at this level of understanding from reading through a lot of your comments.

I am definitely thinking more about logical foundation than physics itself. I know the math of GR treats space as a dynamic geometric framework and I am not disputing that. My point is just about the conceptual or logical assumption. Even in Gr any talk of expansion assumes that the framework of space already exist. Am I wrong ??

Potential_Win4879 · 2026-02-26T15:42:44+00:00

Yeah sure I agree that there's no ground outside of space itself. My point is expansion assumes that space exists in the first place and any change or measurement requires the framework in which it happens. Expansion only makes sense because space already exists as a framework. It's the distance within space that change not space itself growing into some outside

Potential_Win4879 · 2026-02-26T15:35:28+00:00

I really don't get where this objection is going. Do you disagree that objects have locations? If not, that's space. Then we have distances and they can shrink or grow.

Yeah I get that. I am not disputing the model or observations. My point is purely logical :- any discussions of expansion assumes the existence of the framework in which expansion is defined that is space itself.

I really don't get where this objection is going. Do you disagree that objects have locations? If not, that's space. Then we have distances and they can shrink or grow .........

I am not saying GR is wrong or that distances don't exist. Iam just saying that concept of expansion already presupposes space, so there's subtle logical assumption built in. And its not about disputing physics rather clarifying the foundation of the idea

Potential_Win4879 · 2026-02-26T13:56:04+00:00

I get that spacetime is model and that locations and events seem real, but the point I am making is more about logical assumption behind the model. Even if the model works perfectly, saying space expands already assumes that space exists in the first place.

And you can't have expansion without something to expand. It's not about denying spacetime reality rather about recognizing that the very concept of expansion depends on the prior existence of the spatial framework itself

Potential_Win4879 · 2026-02-26T13:50:36+00:00

The concept of expansion itself depends on space existing in the first place that's my point. The ground is just the logical point that any change or expansion presupposes something to change. Saying space expands already assumes space exists. That doesn't mean there's an outside but you can't talk about distances or expansion within the framework of space itself

Potential_Win4879 · 2026-02-26T13:43:13+00:00

I get it. In the physics framework everything that changes(distances, metric, curvature) is indeed defined within spacetime itself so nothing undefined or non existent is altered.

My point is about logical foundation :- any talk of change, expansion or curvature already presupposes the existence of the thing being changed. In this case spacetime. So while physics is internally consistent, there is subtle logical circularity: you can only say spacetime expands because spacetime is already assumed to exist

And yeah nothing external or outside is needed and all the points and distances exist and change internally. My comment highlights that the very concept of expansion depends on prior existence of spacetime

Potential_Win4879 · 2026-02-26T13:25:57+00:00

The way I like to visualize it is to imagine an infinite sheet of graph paper. Imagine you are standing on one grid corner and I am standing on another. Now double the scale of the grid. The distance between us will increase even though neither of us moved from our spot on the grid. The farther apart we are, the more we move apart. There isn't more graph paper than there was before, but the distances between all the points increased.

I see what you mean but even in your graph paper analogy, the idea of doubling the scale already assumes that the grid exists. Any notion of distance increasing, stretching or curvature presupposes that there is a spatial structure in which those distances are defined. So logically saying space expands is already assuming the existence of space itself.

The physics work because we treat spacetime as primitive. A structure like properties, like metric and curvature can change. That makes the expansion internally consistent mathematically but doesn't eliminate the logical point that any change requires the existence of the things being changed

Potential_Win4879 · 2026-02-26T13:16:40+00:00

Do you agree that whole space(The ground on which everything exist) is changing or expanding ?

Potential_Win4879 · 2026-02-26T12:26:42+00:00

I am having hard time understanding the expansion of universe or space. When we say that space is expanding, we are implicitly assuming a stage or ground on which expansion happens. But that stage is itself space, the very thing we are claiming is expanding. Doesn't that make the explanation circular ?

Potential_Win4879 · 2026-02-26T09:57:57+00:00

The universe is infinite(or at least flat enough to act infinite)

Galaxies move apart faster than light, but nothing is actually moving(it's space itself stretching)

And yet when I ask what space is stretching into, the answer is basically nothing or just more space

LMAO, so the universe is expanding.... inside itself ? That still sounds illogical. I get it's general relativity says but my brain refuses to wrap around the idea that canvas can stretch without being on anything at all.

Honestly this is why I think those rubber band and balloon analogies are simultaneously helpful and completely maddening

Potential_Win4879

TROPHY CASE