Exploring the Edge of the Big Bang: What is it Expanding Into?

[venomxx]

I come from an experimental backround with no astronomy so I am hoping this question makes sense!

If the theory of the big bang is correct and space started off at a singularity and is now expanding, there must be an outer edge to this? If this is true then what is it expanding out into?

My main wonder is what is the thing its expanding into? Is it endless?

I know its probably asking a question like "what is the meaning of life" but I am interested in opinions from those who would know more then me about the relavent theorys!

 

[russ_watters]

If the theory of the big bang is correct and space started off at a singularity and is now expanding, there must be an outer edge to this? If this is true then what is it expanding out into?

That is an incorrect interpretation of the Big Bang...or perhaps more fundamentally, an incorrect interpretation of geometry: There is no edge and nothing to expand into. Objects (expanding or not) need not have edges if they are curved in a higher dimension. You can drive around a circle and never hit a wall(1d), sail around the world and never fall off the edge (2d) and fly across the universe and never come to an edge either (3d).

 

[Chronos]

We already are at the temporal edge of the universe [the most ancient observable region] and what do we see? - the past in every direction. Of course every other observer in the universe sees the same thing.

 

[Drakkith]

From what I've read, this expansion isn't an Expansion of the Universe INTO space, but it is an actual Expansion OF Space itself. Look up some videos on youtube about the expansion on space and you should be able to find some good ones.

 

[bapowell]

It's important to keep in mind that the current Big Bang model does not address the initial singularity or offer an explanation for the origin of space and time themselves. Rather, it is a model that describes the evolution of the universe from a hot dense initial phase to the present day. It models the expansion of a previously existing spacetime. A useful way to imagine the big bang is to consider a balloon. The balloon already exists at the beginning of the demonstration. The big bang corresponds to the moment this balloon begins inflating. And so the Big Bang addresses this initial expansion -- it does not attempt to answer the question of where you bought the balloon in the first place. (And don't worry about what the balloon is expanding into, as russ has already said, it need not be embedded in any higher dimensional space!)

 

[Radrook]

That is an incorrect interpretation of the Big Bang...or perhaps more fundamentally, an incorrect interpretation of geometry: There is no edge and nothing to expand into. Objects (expanding or not) need not have edges if they are curved in a higher dimension. You can drive around a circle and never hit a wall(1d), sail around the world and never fall off the edge (2d) and fly across the universe and never come to an edge either (3d).

So you reject the possibility of multiple universes as suggested in Carl Sagan's Cosmos?
If so why?

 

[DaveC426913]

So you reject the possibility of multiple universes as suggested in Carl Sagan's Cosmos?
If so why?

One cannot "reject" something that was not tabled in the first place. No one has mentioned multiple universes. And if you planned to, you would first have to show how that's relevant to this discussion.

 

[Dr Lots-o'watts]

...You can drive around a circle and never hit a wall(1d), sail around the world and never fall off the edge (2d) and fly across the universe and never come to an edge either (3d).

This suggests that one (or maybe a photon) can fly into space in a straight line and eventually come back to its starting point, doesn't it?

 

[bapowell]

This suggests that one (or maybe a photon) can fly into space in a straight line and eventually come back to its starting point, doesn't it?

Yes, that would be true in a closed universe.

 

[Chronos]

Even assuming a closed universe, it is expanding at a rate that appears to forbid a photon from circumnavigating it.

 

[Dav333]

When i picture space & time expanding, the distance between everything gets bigger. And from any place in space it appears to be center? So if you went to the edge of the visible universe it would also appear to be center? And you can keep going further out & the same thing. So wouldn't this mean that the whole universe must be infinite in size since the big bang which only happened a finite amount of time ago?

please help clear it up for me.

 

[Drakkith]

When i picture space & time expanding, the distance between everything gets bigger. And from any place in space it appears to be center? So if you went to the edge of the visible universe it would also appear to be center? And you can keep going further out & the same thing. So wouldn't this mean that the whole universe must be infinite in size since the big bang which only happened a finite amount of time ago?

please help clear it up for me.

We don't know for sure yet. That's one of the things we are trying to find out.

 

[DaveC426913]

When i picture space & time expanding, the distance between everything gets bigger. And from any place in space it appears to be center? So if you went to the edge of the visible universe it would also appear to be center? And you can keep going further out & the same thing.

All true.

But this:

So wouldn't this mean that the whole universe must be infinite in size since the big bang which only happened a finite amount of time ago?

please help clear it up for me.

does not follow.

I'm not sure how you drew that conclusion.


You are correct in that, according to what we think is the geometry of the universe,
1] we will alsways appear to be at its centre, never reaching any edge, no matter how long we travel, and
2] even if it is closed, we may never even come back to our starting point since it will have expanded faster than we can traverse it.

 

[Dr Lots-o'watts]

I agree that expansion is pretty much a fact, but can it be concluded that, proportions being kept, the distance between my face and my computer screen is also expanding?

Is this a reasonable deduction? Can the change in distance and rate of expansion between common-sized object be calculated?

 

[Drakkith]

I agree that expansion is pretty much a fact, but can it be concluded that, proportions being kept, the distance between my face and my computer screen is also expanding?

Is this a reasonable deduction? Can the change in distance and rate of expansion between common-sized object be calculated?

The rate of expansion is negligible in local space. We cannot measure it on the scale of our galaxy, much less in two feet.

 

[DaveC426913]

... can it be concluded that, proportions being kept, the distance between my face and my computer screen is also expanding?

Is this a reasonable deduction? Can the change in distance and rate of expansion between common-sized object be calculated?

The rate of expansion is negligible in local space. We cannot measure it on the scale of our galaxy, much less in two feet.

The rate of expansion locally is not simply neglible; it is zero.

The expansion of space does not happen independently of gravity. Gravity still holds things together.

Think of it like this:

You sticky-tack a bunch of pennies to a balloon, then inflate the balloon. Do the pennies pull apart into copper powder? No. The cohesion of the penny's structure (analogous to gravity) is far stronger than the tiny impetus of the balloon expanding underneath it (expansion of the universe). In fact, if you scotch-taped bunches of pennies together into clusters and then sticky-tacked the clusters to the balloon (the scotch tape is analogous to the gravity that holds a galaxy together), the scotch taped clusters would even hold up against the inflating balloon - the clusters of pennies would remain clustered, though unattached clusters would drift away from each other as the balloon expanded.

It is only when you try at attach something gossamer, like cobwebs, that the balloon can pull them apart (cobwebs are analogous to the incredibly weak gravity between superclusters of galaxies that are millions of light years apart).

Only on the largest scale, where gravity is virtually nil, do you see objects pulling apart from each other.

 

[Drakkith]

Dave, is space still expanding though? Even in local space? Is it just far too small to pull things apart, but still expanding?

 

[DaveC426913]

Dave, is space still expanding though? Even in local space? Is it just far too small to pull things apart, but still expanding?

There is no space "thing" to be expanding. Space does not have a substance. All the things you hear about the "fabric" of space are simply metaphors.

Space expanding simply means the distance between stuff is getting greater.

 

[Dr Lots-o'watts]

There is no space "thing" to be expanding. Space does not have a substance. All the things you hear about the "fabric" of space are simply metaphors.

Space expanding simply means the distance between stuff is getting greater.

This makes so much sense.

But at a certain distance from us, there should then be a point (spherical surface) where things are at a balance between the gravitational pull of our galaxy and the "pull"(?) of (Hubble's) expansion.

Is there a name to that distance?

 

[DaveC426913]

This makes so much sense.

But at a certain distance from us, there should then be a point (spherical surface) where things are at a balance between the gravitational pull of our galaxy and the "pull"(?) of (Hubble's) expansion.

Is there a name to that distance?

Well, gravity is only that weak in the vast gulfs between galactic clusters. So, way out there.

 

[JaredJames]

Well, gravity is only that weak in the vast gulfs between galactic clusters. So, way out there.

Out of curiosity (I'm about to lose any credibility I had left), something was mentioned on a TV show once _{*cough* sci-fi *cough*} which mentioned a point in space where all forces are neutralised. The "all forces nullification point".

Which is basically a point (stationary or otherwise) where, for example, all gravitational force in the universe cancels itself out (sort of like being at the centre of the earth, only involving the entire universe).

Load of BS as far as I've considered so far, but it seemed a good point to bring it up.

So could such a point hypothetically exist (even if it was constantly moving because of the expansion)?

(And this following all the crap I gave over the crystal skulls earlier)

 

[Dr Lots-o'watts]

Not a single point as I understand the Universe.

But I have to believe in "null force quasi-spherical surfaces" around galaxies that move away from each other.

 

[Chronos]

Expansion of space is complicated. Only general relativity provides an adequate description - and GR is very counterintuitive. Charles Lineweaver has published some excellent papers on the subject -
re: http://www.mso.anu.edu.au/~charley/papers/DavisLineweaver04.pdf

 

[Dav333]

All true.

But this:


does not follow.

I'm not sure how you drew that conclusion.


You are correct in that, according to what we think is the geometry of the universe,
1] we will alsways appear to be at its centre, never reaching any edge, no matter how long we travel, and
2] even if it is closed, we may never even come back to our starting point since it will have expanded faster than we can traverse it.

I drew that conclusion by picturing the universe flat. Just the way I think. I knida understand the 2d sphere analogy where there is no edge, but I am not sure the universe is curved.
If its truly flat & any place looks like the center where everything is moving away from you. I just thought that it must go on & on forever.

There is no space "thing" to be expanding. Space does not have a substance. All the things you hear about the "fabric" of space are simply metaphors.

Space expanding simply means the distance between stuff is getting greater.

But what about all the talk about quantum foam, & virtual particles activity? Isn't space still some kind of fabric? Sorry if this is off topic. Just Curious.

 

[DaveC426913]

Which is basically a point (stationary or otherwise) where, for example, all gravitational force in the universe cancels itself out (sort of like being at the centre of the earth, only involving the entire universe).

It would require the universe having a centre.

 

[Chronos]

The edge and center of the universe is everywhere, hence irrelevant.

 

[TheTechNoir]

You sticky-tack a bunch of pennies to a balloon, then inflate the balloon. Do the pennies pull apart into copper powder? No. The cohesion of the penny's structure (analogous to gravity) is far stronger than the tiny impetus of the balloon expanding underneath it (expansion of the universe). In fact, if you scotch-taped bunches of pennies together into clusters and then sticky-tacked the clusters to the balloon (the scotch tape is analogous to the gravity that holds a galaxy together), the scotch taped clusters would even hold up against the inflating balloon - the clusters of pennies would remain clustered, though unattached clusters would drift away from each other as the balloon expanded.

Just felt it couldn't hurt to be noted, while what you said is obviously correct wanted to add (this is correct, right?) that electromagnetism and the strong nuclear force also counteract spatial expansion.