Non-ballistic big bang and expansion not from a center

[marcus]

... And yet you say that you find it easier to think of our universe as the surface of a [STRIKE]4D hypersphere or[/STRIKE] 4-ball.

I too find it easier to think of our 3D space as a 3-sphere. Which if you like you can imagine as the surface of a 4-ball. I find it easier for several simple reasons.

1. We see no signs of space having a boundary. Normal science behavior is not to assume something unnecessarily that there is no evidence for.

2. 3-sphere is the simplest FINITE VOLUME model of 3D space without boundary.

3. The simplest math models in accordance with the accepted law of gravity (gr) assume uniformly distributed matter throughout space. ( No evidence of any largescale non-uniformity has been confirmed.) 3-sphere is the simplest finite volume space for modeling purposes. If you like finiteness, anything else is unnecessary extra complication.

4. I suspect the basic reason folks find the 3-sphere picture easiest to understand is probably that an infinite volume universe doesn't appeal to them: with its infinite amount of matter and energy distributed approximately uniformly throughout space and infinite number of stars like the sun (with its infinite number of planets closely resembling the Earth except for little details like Julius Caesar being a girl and the South winning the Civil War etc.)

Many folks prefer to imagine finite spatial volume with finite amount of matter. The local experience is essentially the same. Nobody and no light would ever circumnavigate because of how the thing is expanding.

So far the observational data is consistent both with infinite 3D and with large finite S³. Both finite and infinite versions of the standard model are favored about equally. So you can't SAY one is right and the other is wrong, but you can have a private preference as to which you think is easiest to think about.

 

[ThomasT]

I too find it easier to think of our 3D space as a 3-sphere. Which if you like you can imagine as the surface of a 4-ball. I find it easier for several simple reasons.

1. We see no signs of space having a boundary. Normal science behavior is not to assume something unnecessarily that there is no evidence for.

Good point, imho. I'm not really assuming anything. Just proposing the occasional conjecture.

2. 3-sphere is the simplest FINITE VOLUME model of 3D space without boundary.

What I was talking about would be termed a 2-sphere, I think. Correct me if I'm wrong about the terminology.

That is, I find it easiest to envision our universe as an expanding 3D wave shell. With us being somewhere in the volume bounded by this wave shell.

An analogy of this would be our universe as a balloon expanding in the atmosphere with us being somewhere inside the balloon.

3. The simplest math models in accordance with the accepted law of gravity (gr) assume uniformly distributed matter throughout space. ( No evidence of any largescale non-uniformity has been confirmed.)

I remember seeing reproductions of a mapping of the very (very) large scale structure of our universe in a Yale publication. It might also have been published in Science or Nature. I don't know.

Anyway, it depicted a 'lacelike' structure of connected 'filaments' (the width of the filaments themselves would be thousands of light years, or more) of radiating matter, and incomprehensibly vast 'voids' or areas absent of radiating matter.

3-sphere is the simplest finite volume space for modeling purposes. If you like finiteness, anything else is unnecessary extra complication.

What about the idea that we're part of a 3D volume bounded by a 2-sphere? Isn't that both simpler and more easily visualizable -- as well as corresponding to observations and our normal sensory apprehension of things?

4. I suspect the basic reason folks find the 3-sphere picture easiest to understand is probably that an infinite volume universe doesn't appeal to them: with its infinite amount of matter and energy distributed approximately uniformly throughout space and infinite number of stars like the sun (with its infinite number of planets closely resembling the Earth except for little details like Julius Caesar being a girl and the South winning the Civil War etc.)

I enjoy reading your stuff because not only have you obviously done a lot of homework and are therefore capable of making connections that don't appear to most of us, but you have a sense of humor as well.

A consideration that comes to mind is whether envisioning our universe as a 3D volume bounded by a 2-sphere is ruled out. Is this ruled out?

Infinite volume, matter, and energy doesn't present a problem for me. Maybe our universe isn't bounded/finite. But, does that precude thinking of it as being 3D?

Many folks prefer to imagine finite spatial volume with finite amount of matter. The local experience is essentially the same. Nobody and no light ever circumnavigates because the thing is expanding.

Ok.

So far the observational data is consistent both with infinite 3D and with large finite S³. Both finite and infinite versions of the standard model are favored about equally. So you can't SAY one is right and the other is wrong, but you can have a private preference as to which you think is easiest to think about.

Point taken.

 

[chaszz]

Chaszz, I'm sure you understand that simply knowing a percentage expansion rate does not tell you the size today, unless you have exact knowledge of the size at some time in the past.

I should qualify with some clear reservation when I say "know". What I mean is estimates derived from a simple equation model of expansion that fits an immense amount of data surprisingly well, and checks with several different kinds of observations. But it's only the best we have so far and there are
1. questions it does not answer, like the overall size of the U, and
2. ongoing efforts to develop improved models to replace it if they can be shown to give an even better fit.

So this is not some kind of absolute knowledge, it is just the best so far from work in progress.

The equation model tells us the expansion history in terms of proportion. It gives a function of time called the scale-factor. The scalefactor is written a(t).

By convention it is defined so that a(now) = 1

And there are good physics reasons to estimate that there was a clearing event around year 380,000 of expansion when the hot gas cooled enough to become transparent and to estimate that

a(then) = 1/1100 ≈ 0.0009

The physics reasoning and the model does not give an estimate of the absolute overall size at that point in time. It does not give a figure in miles or feet or meters. It just tells us the history of the scalefactor as it grew from small values like 0.0009 in early days up to the present value of 1.

So it says that whatever the size was back then, say in year 380,000, it is 1100 times as big now. And other largescale distances have increase in proportion.

That includes the size of the presentday observable region, which is something we can estimate. But the observable region is not the whole thing!
======================

I think you understand (since as you say you have been following cosmology for quite some time) that what people are talking about are proportional expansion rates (like percentage growth) and not absolute. So therefore there is no need to expect an absolute estimate of overall size in miles or meters or lightyears or whatever unit. We are talking expansion ratios.

That is what "acceleration" refers to as well. what is being calculated is the time derivative or slope of a(t). The first derivative a'(t) and the second derivative a''(t). You probably know the notation used in freshman calculus where they use prime and double prime. If not, please let us know.

I found this post very interesting and informative. I don't have any calculus at all.

I'm back from the bed bug war. Hopefully they are gone but only time will tell. I'm now doing a lot of running clothes thru the dryer at high heat which will take a few days.

The run of posts in general has been very interesting. Both infinity and varieties of non-infinity are very hard to conceive. I suspect we are in a position analogous to that of intelligent ants crawling about in darkness in the basement of a large skyscraper and trying to extrapolate the nature of the building from evidence such as the concrete floor and the particles of dust and dirt they encounter there. But it is very good to find here both knowledgeable people like Marcus who are willing to be gentle and helpful to a layman like myself, and other laymen who are fascinated by these things. Thank you all.

 

[G. E. Hunter]

A balloon squished to a single point, suddenly expands in all directions. The surface of the balloon is the outer edges of the universe- if there is such a thing, and the internal contents is the universe. So we can find a center of the universe if we can find it's finite edges, then calculate the diameter assuming it's a circular expanse, then use half that to approximate the center of the universe. But the point of the 'big bang' was the outer edges of the universe all at one center. That should be easy to understand.

 

[G. E. Hunter]

We will never be able to see the edge of the universe since photons and electrons did not exist at the beginning, but it does exist; it just changes from matter to energy to non-space-time. So physical instruments cannot detect things that are in space-time, but are not matter or energy. Negative matter and negative energy are hints as to other contents in space-time but not detectable by our present instruments. Life, thoughts, love - are not considered to be scientific, nor do they affect the universe as far as we can tell yet. But as we learn more about dark matter and dark energy, there will be more discoveries. We have more to find.

 

[phinds]

G.E.Hunter,

You have clearly misunderstood the baloon analogy and it has been explained many times on this forum, so do a forum search if you want to understand it.

There is no edge to the universe and there is no center.

your posts are, from the point of view of modern science, utter nonsense and you would do well to learn some basics before making such statements.

 

[G. E. Hunter]

G.E.Hunter,

You have clearly misunderstood the baloon analogy and it has been explained many times on this forum, so do a forum search if you want to understand it.

There is no edge to the universe and there is no center.

your posts are, from the point of view of modern science, utter nonsense and you would do well to learn some basics before making such statements.

Thank you. Good to hear you know everything. I'll keep that in mind.

 

[cephron]

Hey G.E.Hunter, instead of taking phind's words as gospel truth, why not read the FAQ and see for yourself what the current model of the universe is?

https://www.physicsforums.com/forumdisplay.php?f=206

It sure helps me out a lot.

 

[pmghss]

Our universe is contained within an infinite area.

 

[phinds]

Our universe is contained within an infinite area.

You really should not make an unspportable claim of personal opinion as though it is a fact. If you have evidence that what you say it true, I'd be very interested in seeing it and in fact, I suspect that the Nobel Prize Committee would too.

 

[juanrga]

Thanks. It's an interesting explanation. And another example that at both very small and very large scales, common sense cannot wrap itself around or sometimes cannot even approach what is being discussed. At this rate within fifty years no one will understand physics on any rational level at all except physicists. Possibly we are there already. As someone without training or math aptitude, I have lived for many years via popularizations. Many times now I can't even understand the popularizations anymore.

I believed that «common sense» do not play any role in physics since Galileo epoch or so... but was substituted by scientific method.

About popularizations of science, I am sorry to say this but almost all of them are wrong.

 

[Imax]

In a recent thread, it is stated that the universe did not start its expansion in a ballistic type event, and it did not expand from a center.

The BB can’t be ballistic. The Universe can’t expand from a single point, a BB singularity, and be homogenous and isotropic.

 

[ThomasT]

A balloon squished to a single point, suddenly expands in all directions. The surface of the balloon is the outer edges of the universe- if there is such a thing, and the internal contents is the universe. So we can find a center of the universe if we can find it's finite edges, then calculate the diameter assuming it's a circular expanse, then use half that to approximate the center of the universe. But the point of the 'big bang' was the outer edges of the universe all at one center. That should be easy to understand.

Afaik, the 'big bang' refers to a point of no particular size/extent but of calculable temporal separation from the current, observable, universal epoch. There appears to be a discernible very large scale structure wrt the currently visible universe. And I wouldn't call that structure itself either homogeneous or isotropic. But it does seem to be a consequence of particular fundamental wave dynamics, IMHO.

 

[ThomasT]

The BB can’t be ballistic. The Universe can’t expand from a single point, a BB singularity, and be homogenous and isotropic.

First, there's no particular reason to assume that our universe has expanded from 'a single point'. Second, our universe isn't necessarily altogether homogeneous and isotropic. There's what we can see and map. Which suggests fundamental dynamics. But there's no way of knowing if our universe is or isn't part of some preexisting, perhaps infinite, medium.

To elaborate, lawful wave dynamical evolution in an isotropic medium suggests observational isotropy, which is more or less what's observed -- wrt cmb anyway.

And insofar as this is a characteristic of all explosive/ballistic events, the origin of our universe could be ballistic/explosive. We just have no way of knowing, afaik.

 

[ThomasT]

I believed that «common sense» do not play any role in physics since Galileo epoch or so... but was substituted by scientific method.

I think you might be quite wrong about that. Study the development of the quantum theory. There's more 'common sense' classical reasoning involved in it than you might suspect. Anyway, ordinary categorical deductive logic/inference, as well as inductive inference are both part of the scientific method.

 

[juanrga]

I think you might be quite wrong about that. Study the development of the quantum theory. There's more 'common sense' classical reasoning involved in it than you might suspect. Anyway, ordinary categorical deductive logic/inference, as well as inductive inference are both part of the scientific method.

It is just as I said. Quantum mechanics was developed following the scientific method, not using an ill-defined «common sense». The bibliography about the impact of quantum mechanics on people (and their «common sense») is very vast.

 

[pmghss]

You really should not make an unspportable claim of personal opinion as though it is a fact. If you have evidence that what you say it true, I'd be very interested in seeing it and in fact, I suspect that the Nobel Prize Committee would too.

It is simple. Either this universe is itself the infinite area, or it may be just a glob of matter contained in an infinite area.

I use my own quote. Outside does not stop.

 

[phinds]

It is simple. Either this universe is itself the infinite area, or it may be just a glob of matter contained in an infinite area.

I use my own quote. Outside does not stop.

You really should read some basic cosmology. As for posting this stuff, you should stop while you are behind (that is, before you get further behind).

 

[ThomasT]

Either this universe is itself the infinite area, or it may be just a glob of matter contained in an infinite area.

From what knowledgeable posters here have said, and from what I've read, either of these do seem to be possible, as there doesn't currently seem to be any definitive reason(ing) for favoring one scenario over the other.

However, I take it that you favor the view that our universe is finite, which I do also. And this view seems to me to suggest that our universe is part of a preexisting medium ... which might also be a finite 'disturbance' in a still larger preexisting medium, or itself infinite, and so on.

The hook for me is the apparent expansion of our universe. That is, why would there be apparent expansion in an infinite universe? Why would observable matter be getting farther apart on very large scales in an infinite universe?

Note: Following my viewing of some computer simulations which extend what's known of the very large scale structure of our universe, I might have to revise my opinion, as stated in post #43, that the very large scale structure (that is, the stellar distribution) of our universe doesn't seem to be particularly isotropic or homogeneous. I was basing this on my limited knowledge of some apparently anomalous and vast 'wall' structures, and the irregularly organized (to me at the time anyway) filament-like structures of galaxies and galactic groups revealed by surveys. But maybe I just wasn't thinking big enough. The computer simulation suggests a fairly even distribution of the filament-like structure wrt its very very large scale view of our universe. Sort of like the cross section of a sponge. But then I got to thinking that maybe the simulation isn't 'thinking' big enough. If the simulation is based on some 'fractalization' assumptions (is it? ... I have no idea), then is it possible that a still much larger view will reveal the wall structure anomalies that are evident from observations ... and so on?

Wrt this, one thing that came to mind was that the filament-like structure suggests regions of constructive and destructive wave interference. Is this an acceptable/possible inference from the data?

 

[pmghss]

You really should read some basic cosmology. As for posting this stuff, you should stop while you are behind (that is, before you get further behind).

I have studied basic cosmology and the standard model. That's why I choose to use common sense instead.

From what knowledgeable posters here have said, and from what I've read, either of these do seem to be possible, as there doesn't currently seem to be any definitive reason(ing) for favoring one scenario over the other.

However, I take it that you favor the view that our universe is finite, which I do also. And this view seems to me to suggest that our universe is part of a preexisting medium ... which might also be a finite 'disturbance' in a still larger preexisting medium, or itself infinite, and so on.
...

I'm not sure about what is defined as a "finite" universe. What I was hinting at was that our "universe" might be blob of matter, similar to solar systems or galaxies, floating around other blobs of matter. This could possibly explain dark energy.

Picture a blob of matter a billions of times more massive than our universe. And this blob passes close to our blob (universe). The immense amount of gravity/dark energy (take your pick) could cause our blob to distort, stretch, bend, or any other number of contortions. From our view we could be seeing this event and explaining it as the "everything accelerating away" theory.

 

[phinds]

... Picture a blob of matter a billions of times more massive than our universe. And this blob passes close to our blob (universe). The immense amount of gravity/dark energy (take your pick) could cause our blob to distort, stretch, bend, or any other number of contortions. From our view we could be seeing this event and explaining it as the "everything accelerating away" theory.

This is even MORE nonsensical. You say you have studied basic cosmology but you apparently have never heard of isotropy.

 

[Cosmo Novice]

I'm not sure about what is defined as a "finite" universe. What I was hinting at was that our "universe" might be blob of matter, similar to solar systems or galaxies, floating around other blobs of matter. This could possibly explain dark energy.

This is complete rubbish and does not fit with ANY current observations. It would require mass that was not part of our Universe and I am not sure how this is "common sense"

Picture a blob of matter a billions of times more massive than our universe. And this blob passes close to our blob (universe). The immense amount of gravity/dark energy (take your pick) could cause our blob to distort, stretch, bend, or any other number of contortions. From our view we could be seeing this event and explaining it as the "everything accelerating away" theory.

As phinds has stated this would completely disgree with the cosmological principle of homogeneity. In fact the whole idea of "matter that's is not part of our Universe" is ridiculous. The Universe = the totality of everything, a unified spacetime in which all bosons/fermions exist and I think talking about "outside" is pointless.

 

[pmghss]

This is complete rubbish and does not fit with ANY current observations. It would require mass that was not part of our Universe and I am not sure how this is "common sense"

As phinds has stated this would completely disgree with the cosmological principle of homogeneity. In fact the whole idea of "matter that's is not part of our Universe" is ridiculous. The Universe = the totality of everything, a unified spacetime in which all bosons/fermions exist and I think talking about "outside" is pointless.

One of the points I was trying to make is that "outside" is infinite, and what we call "universe" may just be a blob of matter floating around other blobs of matter.
I am not meaning a multi-verse, in which each "universe" is separate and travel to and from each one is impossible.

Oh, and apparently I am not the only one who has these so called "rubbish" theories. Have a look at the episode of "The Universe: God and the Universe", and start around 09:50.

 

[phinds]

One of the points I was trying to make is that "outside" is infinite, and what we call "universe" may just be a blob of matter floating around other blobs of matter.

Which is exactly what is nonsensical, by definition. "Universe" is by definition, all there is. There IS no outside.

Oh, and apparently I am not the only one who has these so called "rubbish" theories. Have a look at the episode of "The Universe: God and the Universe", and start around 09:50.

Uh ... dude, if you plan on learning physics from sensationalized popularizations of fanciful theories, then I can only say good luck with that.

 

[pmghss]

Which is exactly what is nonsensical, by definition. "Universe" is by definition, all there is. There IS no outside.

Then quit using the term "Universe". Call it Gobbledeegook, Blather, Blob-o-muk. Make something up. You seem to be stuck on the definition of a word. I'm calling everything we can see or detect a "Blob of Matter". Or how about - The Big Blob.

As I stated before, outside does not stop.

Uh ... dude, if you plan on learning physics from sensationalized popularizations of fanciful theories, then I can only say good luck with that.

That episode was released weeks after my previous posts. My opinions are not based on "sensationalized popularizations of fanciful theories" as you call them. I was merely pointing out that some others in the world have similar theories. And in fact, I do not agree with some of the mainstream theories suggested on that show.

 

[Drakkith]

Then quit using the term "Universe". Call it Gobbledeegook, Blather, Blob-o-muk. Make something up. You seem to be stuck on the definition of a word. I'm calling everything we can see or detect a "Blob of Matter". Or how about - The Big Blob.

As I stated before, outside does not stop.

You're saying that everything we can see, aka the Observable Universe, is a blob of matter floating around with other blobs elsewhere? We already have a word describing your blob of matter; The Observable Universe. The Universe as a whole is defined to be everything, everywhere, no matter what. You are 100% free to imagine something else outside of the "Universe", however if you are going to post here then you are must stick to the rules of the forum which do not allow for personal theories.

And in fact, I do not agree with some of the mainstream theories suggested on that show.

Such as? The current mainstream model is based off of observations of the observable universe. They are not simply made up. Feel free to disagree, but you really don't have a good reason to other than you just don't want to believe it's true.

 

[pmghss]

You're saying that everything we can see, aka the Observable Universe, is a blob of matter floating around with other blobs elsewhere? We already have a word describing your blob of matter; The Observable Universe. The Universe as a whole is defined to be everything, everywhere, no matter what. You are 100% free to imagine something else outside of the "Universe", however if you are going to post here then you are must stick to the rules of the forum which do not allow for personal theories.

Ok, then nobody should be allowed to post any theories about The Big Bang. That is exactly what it is - personal theories! There is no 100% proof of evidence the Big Bang even happened! It sounds like all you want is YOUR safe standard model theories that everyone learns in school and REPEATS it over and over again until you think it's FACT. My theories are just as valid as any of this magical-universe-was-created-from-a-single-point-of-infinite-density so-called-theory.

Everything we have witnessed in the universe "so far" has obeyed the laws of physics. And yet when it comes to the (so called beginning of the) universe itself, the realm of supernatural and fantasy seem to invade thought. Anyone can believe what they want and repeat what they have heard.
Some try to find real solutions.

To answer your question - What we see as the observable "universe" may only be because our technology can only see that far. If there are blobs of matter that are 100s of billions or even trillions of light years away, we may not be able to see them... yet.

Such as? The current mainstream model is based off of observations of the observable universe. They are not simply made up. Feel free to disagree, but you really don't have a good reason to other than you just don't want to believe it's true.

No, it's about conclusions taken to the extreme. The clues we have, CBR, point to "some" kind of event that happened to spread the cosmic background radiation throuout the universe. Hubble's Law points to "some" event that led to objects speeding away from one another. For some reason, these points were taken to the extreme to invent the Big Bang theory and everything starting from a dot. pfft!

 

[phinds]

Ok, then nobody should be allowed to post any theories about The Big Bang. That is exactly what it is - personal theories! There is no 100% proof of evidence the Big Bang even happened! It sounds like all you want is YOUR safe standard model theories that everyone learns in school and REPEATS it over and over again until you think it's FACT. My theories are just as valid as any of this magical-universe-was-created-from-a-single-point-of-infinite-density so-called-theory.

The term "big bang" really has two meanings. The first is the "singularity" which is a term we use for the "start" of it all, or "t=0", and pretty much means "we don't know"

The second refers to everything this that happened starting at one Plank Time AFTER the singularity. If you contend that that is not at all well understood and is personal therories, you will need to find another forum on which to have that discussion since that point of view will be looked at hear as what I think would be called something like low level crackpottery. It's not a bad a promoting perpetual motion, but it is not mainstream physics.

No, it's about conclusions taken to the extreme. The clues we have, CBR, point to "some" kind of event that happened to spread the cosmic background radiation throuout the universe. Hubble's Law points to "some" event that led to objects speeding away from one another. For some reason, these points were taken to the extreme to invent the Big Bang theory and everything starting from a dot. pfft!

Nonsense. See above regarding the second concept.

 

[Fuzzy Logic]

He doesn't mean outside the universe, he means beyond the observable universe.

Am I wrong in saying that based on the standard model, there is no evidence to suggest there is anything different that what we already observe but BBT says nothing about what is beyond the observable universe? It's possible that there could be larger cosmological structures than galaxies, but the standard model doesn't predict them.

 

[twofish-quant]

Am I wrong in saying that based on the standard model, there is no evidence to suggest there is anything different that what we already observe but BBT says nothing about what is beyond the observable universe?

The "standard model 2012" says nothing about whether there are universes outside of the observable universe. There are people that are working on these sorts of things, but right now its in the "we are guessing" stage.

see http://arxiv.org/abs/1107.2593 for one weird idea

Also what the "standard model" refers to, changes from year to year. In 2012, the "standard model of cosmology" is that the expansion of the universe is accelerating, which contradicts the "standard model of cosmology 1995."

If one of these weird ideas gets observations support, then they'll be part of "standard model 2025."

It's possible that there could be larger cosmological structures than galaxies, but the standard model doesn't predict them.

They do. One of the "standard model 2012" is that there are large cosmological structures, and that galaxies formed "top down". Which is to say that the largest structures in the universe were formed around the time of the BB, and that galaxies formed in these filaments. The alternative model was that there were no large structures, and galaxies formed bottom up.

The "top down model" of galaxy formation was added to the "standard model" around 1990. It wasn't part of "Standard Model '85" but was part of "Standard Model '95"