How does the universes expand?

Originally posted by sonhouse
And your conclusion based on all that?

I will let you so-called scientists do the speculating.

Originally posted by humy

Expansion is self contained?

correct

It expands into itself?

what does that mean?

How does that work
since when something expands it [b]typically moves into previous areas it
wasn't before?

but this is not 'typical' expansion i.e. not expansion like you would see on a smaller scale i ...[text shortened]... l chosen frame of reference because there is no absolute space -just hope you understand that! )[/b]

Nope do not understand that, and I'm not trying to be difficult or to jerk
yours or anyone else' chain on this. I'm quite serious I don't see how you
or anyone else can say something is expanding if it is isn't moving into
new areas prior to expanding, hence the word, "expanding".
Kelly

Originally posted by KellyJay
Nope do not understand that, and I'm not trying to be difficult or to jerk
yours or anyone else' chain on this. I'm quite serious I don't see how you
or anyone else can say something is expanding if it is isn't moving into
new areas prior to expanding, hence the word, "expanding".
Kelly

I'm quite serious

what makes you think I didn't know that?

I don't see how you
or anyone else can say something is expanding if it is isn't moving into
new areas prior to expanding, hence the word, "expanding".

WHY don't you “see” that? Are you incapable of understanding the simple concept of the space between objects itself expanding? I find it hard to believe that you cannot understand nor visualize that. I could draw you a simple diagram with arrows to make you visualize it if only I could post you diagrams.

Originally posted by KellyJay
Expansion is self contained? It expands into itself? How does that work
since when something expands it typically moves into previous areas it
wasn't before?
Kelly

If you'd like to understand how it works you will have to study some general relativity and cosmology.

Originally posted by KellyJay
Nope do not understand that, and I'm not trying to be difficult or to jerk
yours or anyone else' chain on this. I'm quite serious I don't see how you
or anyone else can say something is expanding if it is isn't moving into
new areas prior to expanding, hence the word, "expanding".
Kelly

The problem with this is that I can't really add anything to my earlier posts. You could regard the universe as being embedded in and expanding into a larger space, but then you just have the larger space providing the distance rule (aka metric function) for our universe, so there's no real point in assuming it's there.

Originally posted by vivify
For example, a balloon can expand if there's more space outside of the balloon to expand in; doesn't this apply to the universe?

A balloons surface is 2-dimensional. It has a certain area at every given time. When this balloon expands, it just does. The area will grow. A two dimensional creature of the surface doesn't care if there is another 3rd dimension or not. For this creature the 3rd dimension isn't necessary. He isn't even aware of it.

The space is 3-dimensional. And it has a certain volume at every given time. When this space expands, it just does. The volume will grow. A three dimensional creature (us) in the 3-dim space doesn't care if there is another 4th dimension or not. (Is there?) For this creature the 4th dimension isn't necessary. He isn't even aware of it.

I see universe as a 3-dimensional surface, like a balloon, wrapped up in a self contained sphere. No 4th dimension is necessary. Therefore nothing else is needed. The universe isn't expanding out in something, it's just expanding, creating more space as it's needed.

This is how I see it, how I understand it. I can easily imagine how it works.

Originally posted by FabianFnas
A balloons surface is 2-dimensional. It has a certain area at every given time. When this balloon expands, it just does. The area will grow. A two dimensional creature of the surface doesn't care if there is another 3rd dimension or not. For this creature the 3rd dimension isn't necessary. He isn't even aware of it.

The space is 3-dimensional. And it h ...[text shortened]... as it's needed.

This is how I see it, how I understand it. I can easily imagine how it works.

The problem with your analogy, is that it doesn't matter whether or not the creature "cares" about, or is "aware" of a third dimension. A third dimension is still necessary for the balloon to expand, regardless of what the creature thinks.

Originally posted by vivify
The problem with your analogy, is that it doesn't matter whether or not the creature "cares" about, or is "aware" of a third dimension. A third dimension is still necessary for the balloon to expand, regardless of what the creature thinks.

But not the 4th dimension because, just he just said if you have being paying attention, "...No 4th dimension is necessary...." i.e. the 3D 'balloon' doesn't need to moving 'through' a 4th dimension because there is no 4th dimensional space outside it. The fact that, in 3 dimensional space, there is a 3 dimensional space outside the 2D curvature of a balloon simply means that, just like all analogies, this is not a perfect analogy so it isn't safe to extrapolate too much from it.

Originally posted by humy

I'm quite serious

what makes you think I didn't know that?

I don't see how you
or anyone else can say something is expanding if it is isn't moving into
new areas prior to expanding, hence the word, "expanding".

WHY don't you “see” that? Are you incapable of understanding the simple concept of the space between ...[text shortened]... raw you a simple diagram with arrows to make you visualize it if only I could post you diagrams.

You can put dots on a balloon and blow it up, the balloon expands into areas
it did not occupy before! The area between the two dots move away from
each other as balloon fills. You can put two pieces of paper next to each
other and move them apart, the paper occupy new areas where they were
not before. Either way, something is moving into a place it was not before.
Kelly

Originally posted by KellyJay
You can put dots on a balloon and blow it up, the balloon expands into areas
it did not occupy before! The area between the two dots move away from
each other as balloon fills. You can put two pieces of paper next to each
other and move them apart, the paper occupy new areas where they were
not before. Either way, something is moving into a place it was not before.
Kelly

I just covered that in my previous post (to vivify ) with:

"...The fact that, in 3 dimensional space, there is a 3 dimensional space outside the 2D curvature of a balloon simply means that, just like all analogies, this is not a perfect analogy so it isn't safe to extrapolate too much from it...."
humy

In other words, what is true in 3 dimensions is sometime, as in this particular case, NOT true in 4 dimensions.

Originally posted by DeepThought
Imagine a series of rulers each 1 light year long, initially laid end to end all the way to the edge of the observable universe. As space expands gaps will appear between the rulers. Suppose the rate of expansion is such that the gap increases by 1 light second every billion years (~1 foot per year). We sit at the centre of one of the rulers and look ...[text shortened]... themselves.

Note, be wary of the numbers in this - I haven't checked it all adds up properly!

If space is appearing between the rulers is getting larger, that is expanding
space, space/area that wasn't there before. You still have areas that are
new, this new area which wasn't there before means it is new. You stretch
out a sheet pulling it on all edges that sheet will spread out as far as the
sheet will stretch and it will move into areas that it didn't occupy before.
Kelly

Originally posted by humy
I just covered that in my previous post (to vivify ) with:

"...The fact that, in 3 dimensional space, there is a 3 dimensional space outside the 2D curvature of a balloon simply means that, just like all analogies, this is not a perfect analogy so it isn't safe to extrapolate too much from it...."
humy

In other words, what is true in 3 dimensions is sometime, as in this particular case, NOT true in 4 dimensions.

You can tell me how something gets larger without it getting larger by
occupying more area I'd ready to read it.
Kelly

Originally posted by KellyJay
If space is appearing between the rulers is getting larger, that is expanding
space, space/area that wasn't there before. You still have areas that are
new, this new area which wasn't there before means it is new. You stretch
out a sheet pulling it on all edges that sheet will spread out as far as the
sheet will stretch and it will move into areas that it didn't occupy before.
Kelly

in which dimensions? -see my previous post to see my point (imperfect analogy because different rules for different dimensions )

Originally posted by KellyJay
You can tell me how something gets larger without it getting larger by
occupying more area I'd ready to read it.
Kelly

That makes absolutely no sense whatsoever.

You can tell me how something gets larger without it getting larger

No, I don't say that. We are saying that the 3D Space DOES get 'larger' (expands ) and there is clearly no “without it getting larger “ implied by that so you are not making any sense here. We are not in any sense saying the 3D space is NOT getting larger, ONLY that it IS getting larger -and I have no idea how you got confused here!

Do you understand the concept of "expand"? -there really isn't anything difficult to understand here -all extremely basic stuff!

Originally posted by KellyJay
If space is appearing between the rulers is getting larger, that is expanding
space, space/area that wasn't there before. You still have areas that are
new, this new area which wasn't there before means it is new. You stretch
out a sheet pulling it on all edges that sheet will spread out as far as the
sheet will stretch and it will move into areas that it didn't occupy before.
Kelly

That picture was designed to explain why points past the cosmological horizon are moving away faster than light, in apparent contradiction of special relativity. It doesn't really help with the notion that space can expand without anything to expand into.

One resolution is that if the universe is infinite, then expanding it doesn't change the overall size of the universe - it's still infinite. Although since standard cosmological theories have it starting out small this isn't really satisfactory.

So what do we mean by distance? Well it's what one measures by laying rulers end to end. I think the problem is that you are trying to hang on to the Newtonian notion of space as just being the background that stuff happens in. Which is reasonable enough, since that is what one's everyday experience suggests. But space-time is a dynamic thing - it can be curved - what does it curve around? The answer is that the curvature is intrinsic it doesn't require an embedding space, if you can get your head around that then the expansion isn't really a problem.

Sorry, I can't really do better than this. It's more of a concept one gets used to rather than one that one understands.