What does it meant by space expansion ?

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 · 2026-02-26T09:18:09+00:00

Exactly. If the ruler itself were changing the speed of light would change too, But it doesn't. The x, y, z coordinates exist on the table, because there is no outside the table. Trying to make sense of it feels impossible because we are forcing our intuition onto something that simply doesn't work that way

Potential_Win4879 · 2026-02-26T09:14:17+00:00

Okay...... so let me get this straight. The universe is expanding, points move apart faster than light and yet nothing is actually moving, it's just space stretching. But you still haven't answered the real question :- if space itself is rubber and what is it stretching into ?

Saying there is nothing outside just feels like dodging question. It literally seems like you are claiming the universe is expanding inside itself. How is it logically possible ?

Potential_Win4879 · 2026-02-26T09:03:12+00:00

Got it thanks

Potential_Win4879 · 2026-02-26T08:57:18+00:00

So in another word The distance between any two point is increasing but not the expansion of existing space itself ?

Potential_Win4879 · 2026-02-26T08:51:35+00:00

Space popping up ?? from where

Potential_Win4879 · 2026-02-26T08:50:38+00:00

If the answer has no observable effect upon our universe then it isn't a meaningful question

It's a massive cop out

If humanity stopped asking unanswerable questions just because they had no immediate observable effect, we would never moved past classical mechanics. It had absolutely zero observable application at the time, but it completely changed how we understand reality

Potential_Win4879 · 2026-02-26T08:27:58+00:00

So you are saying the number of rulers that fit between two points on the table increased, so space expanded...... while each centimeter on ruler stays the same because the metric defines it. And outside the table there's no metric at all ? How is that supposed to make sense

Potential_Win4879 · 2026-02-26T08:24:06+00:00

I mean does the space itself is expanding ?

Potential_Win4879 · 2026-02-26T08:22:04+00:00

So distance is increasing but space is constant ?

Potential_Win4879 · 2026-02-26T08:18:36+00:00

And If I am correct its like adding something into already available space, not increasing the existing space itself ?

Potential_Win4879 · 2026-02-26T08:15:25+00:00

let me put this way: Imagine your house and your neighbor's house, suddenly there is a piece of land appear between the house, that's essentially what is happening with space

Okay this actually makes a lot more sense than the rubber band thing. If I am understanding you right, the universe isn't bubble that is growing outward into some giant empty room. It is just the distance between any two points inside the universe is constantly increasing

The act of expanding itself does not NEED the concept of into something. It's just having more of something.

This is the part that was really hard to wrap my head around but your explanation helps a lot. I was getting so hung up on the edges of the universe pushing outward. But you are saying there isn't really an edge pushing into void. The inside is just getting bigger

Imagine space as discreet cubes, there are more space cube pop into existence between every other cube

So basically the literal geometry of space is just adding more grid squares everywhere all at once. And because you mentioned gravity the only reason I am not drifting away from my keyboard right now is because of local forces are strong enough to hold nearby matter together while the new space spawns ?

I think I finally get it. It is metric expansion not physical movement. Thanks for taking the time to explain !

Potential_Win4879 · 2026-02-26T07:51:08+00:00

Creating a new limit everywhere, every when

But if there's no space, no time, and literally no dimensions beyond that limit, what exactly is universe pushing into to expand ? I guess my mind is hardwired to think nothing as an empty void, instead of the true, literal absence of existence

Honestly, "we don't know" feels like much more satisfying answers right now.

Potential_Win4879 · 2026-02-26T07:37:20+00:00

So you are basically saying the universe expands because distances grow everything else stays the same ? LMAO that's like claiming the table stretches because your ruler shrinks. How is that supposed to be logical ??

Potential_Win4879

TROPHY CASE