What was the Big Bang

[gnostic]

No, this would only be true if the universe was closed. The universe to our best measurements is flat or open. Your statement goes with the now largely discarded thought of a universe that goes through endless series of Big Bangs and Big Crunches.

Otherwise known as the oscillating universe model, cyclical universe model, or the Big Bounce.

 

[Subduction Zone]

Otherwise known as the oscillating universe model, cyclical universe model, or the Big Bounce.

I think I saw this somewhere before. There seemed to be a strange blip in between the two posts.

 

[Ben Dhyan]

There you go and by ''flat'' they mean isometric.
View attachment 21281

So what does the black represent?

 

[gnostic]

There you go and by ''flat'' they mean isometric.
View attachment 21281

LOL

But no, they mean “homogeneity” and “isotropy”.

You got the “iso-“ part, right.

 

[gnostic]

I think I saw this somewhere before. There seemed to be a strange blip in between the two posts.

I think using my iPad, it didn’t refresh my screen, so I didn’t realise post this one before.

 

[`mud]

The Cosmos is not 'cyclic'.
It's unbounded in every direction to all, except for it's beginning.
That `direction` is unknown, as is the ending.
Just a little humor there.

 

[`mud]

There's a little girl out there chasing butterflies.
Maybe she will find answers to all your questions.
Remember who told you so.....

 

[Polymath257]

Why is it not possible for this possible finite universe in 'flat' space to be generally described verbally, or graphically?

It's actually fairly easy to describe the spatially flat, finite universe. It is a three dimensional version of a torus. The problem is that it is only locally isotropic and homogeneous, not globally so. A three dimensional torus has three 'special' directions which are periodic.

The easiest way to imagine this is to imagine all of flat, infinite, three dimensional Euclidean space to be filled with cubes stacked up and beside each other. If each cube is *identical* to every other cube, we can see this as a single cube with opposite faces identified.

In two dimensions, if you identify the opposite faces of a square, you get a torus (a bagel-shape). If you do the same for a cube, you get a three dimensional torus.

This is different than a spherical space in which you can 'go around' from any point and in any direction. For the torus, there are three 'special' directions where you can 'go around' once. Other directions can 'go around' more than once in different directions, or even in a path that goes around infinitely often, but gets close to every point.

Again, in such models, this torus would be the slice for a fixed time. In an expanding universe, the size of the cube increases over time.

For negatively curved space, similar tricks can give cases with finite space.

All of these tricks, though, have special directions, so are not globally isotropic, only locally so.

 

[ThePainefulTruth]

There isn't an 'open and closed' curvature. There is positive curvature, negative curvature, and flatness. In the presence of a non-zero cosmological constant, all of these are possible even in the case of an accelerating expansion rate.

"Within the framework of general relativity, an accelerating expansion can be accounted for by a positive value of the cosmological constant Λ, equivalent to the presence of a positive vacuum energy, dubbed 'dark energy' ".
In any case, expansion and curvature, as I said, two separate issues. I've seen the "open and closed" terminology used for both expansion and curvature, which is what is causing the confusion. It's essentially correct to refer to expansion as open or closed and that expansion can be accelerating, or not and still be open.

In any case, the acceleration of the expansion, which started about 5 billion ya, is happening; but is irrelevant to the point I was making in the OP, that the Big Bang resulted from the creation or sudden existence of divisibility at a point in the ether/Quantumland which initiated the 3Dspace and time of this universe, and "into" which our universe is expanding.

 

[`mud]

Is the Cosmos expanding, or being drawn into some enormous entity.
Could it be `flat` in these formats, and not be spherical ?
Spherical or not, same old question: Into what ? To what ? With what ?
It's the Cosmos, of which you speak, what contains it ?

 

[ThePainefulTruth]

Yes, actually, it does so quite nicely. that is simply the definition of a Hubble radius.

I'm talking about expansion openness. And if the Hubble radius accounted for said acceleration of the expansion, why was it such a surprise when it was discovered, and never even postulated as far as I can tell?

 

[ThePainefulTruth]

Your post does not address my point, the point is you stated that 'we don't know is there is an edge to the universe'. Now it follows logically if it does have an edge, than the finite universe in unbounded space does not exist. Iow, we don't know if there is a finite universe in unbounded space, if we did, we would know there is not an edge to the universe...and vise versa.

a

If the curvature is negative or closed, we could theoretically have an edge or "outside". Until the flat earthers were proven wrong by the spherical curvature of the surface of the Earth, an edge was theoretically possible.

 

[Subduction Zone]

I'm talking about expansion openness. And if the Hubble radius accounted for said acceleration of the expansion, why was it such a surprise when it was discovered, and never even postulated as far as I can tell?

Because it is rather counter-intuitive. We live in a Newtonian world, as far as our senses go. I am sure that I will be corrected if I am wrong, but Einstein's theories predicted that a non-expanding universe would collapse to keep the universe from doing so he added a Cosmological Constant to his work. Others pointed out that his theories worked with an expanding universe, but that was too much for him. He finally accepted it after Lemaitre's work was confirmed:

https://phys.org/news/2014-02-einstein-conversion-static-universe.html

 

[Ben Dhyan]

It's actually fairly easy to describe the spatially flat, finite universe. It is a three dimensional version of a torus. The problem is that it is only locally isotropic and homogeneous, not globally so. A three dimensional torus has three 'special' directions which are periodic.

The easiest way to imagine this is to imagine all of flat, infinite, three dimensional Euclidean space to be filled with cubes stacked up and beside each other. If each cube is *identical* to every other cube, we can see this as a single cube with opposite faces identified.

In two dimensions, if you identify the opposite faces of a square, you get a torus (a bagel-shape). If you do the same for a cube, you get a three dimensional torus.

This is different than a spherical space in which you can 'go around' from any point and in any direction. For the torus, there are three 'special' directions where you can 'go around' once. Other directions can 'go around' more than once in different directions, or even in a path that goes around infinitely often, but gets close to every point.

Again, in such models, this torus would be the slice for a fixed time. In an expanding universe, the size of the cube increases over time.

For negatively curved space, similar tricks can give cases with finite space.

All of these tricks, though, have special directions, so are not globally isotropic, only locally so.

Surely such a universe as you describe is not taken seriously by cosmologists and astronomers at large?

 

[Ben Dhyan]

a

If the curvature is negative or closed, we could theoretically have an edge or "outside". Until the flat earthers were proven wrong by the spherical curvature of the surface of the Earth, an edge was theoretically possible.

You seem still to be avoiding the point. So let me ask you point black with a yes no answer, is it theoretically possible for the universe to have an edge?
The second question is, is it theoretically possible there is not an edge to the universe because the universe is finite an unbounded?

 

[Polymath257]

Surely such a universe as you describe is not taken seriously by cosmologists and astronomers at large?

There was one report I saw that suggested evidence for a negatively curved, finite universe that was constructed in a way similar to this.

But most do not worry too much about these possibilities, no.

 

[Polymath257]

You seem still to be avoiding the point. So let me ask you point black with a yes no answer, is it theoretically possible for the universe to have an edge?
The second question is, is it theoretically possible there is not an edge to the universe because the universe is finite an unbounded?

This depends a bit on what you mean by the term 'edge'. There is a concept of a 'manifold with boundary' where there are points 'at an edge' with literally nothing on one side and space on the other. I don't know of any serious models that use such, however.

It is possible there is an edge to *matter*? Again, possible and more likely than the one above, but also not taken seriously by most cosmologists.

And yes, it is quite possible there is no edge while also being finite and unbounded. the work 'because' here reads strangely, though.

 

[Polymath257]

"Within the framework of general relativity, an accelerating expansion can be accounted for by a positive value of the cosmological constant Λ, equivalent to the presence of a positive vacuum energy, dubbed 'dark energy' ".
In any case, expansion and curvature, as I said, two separate issues. I've seen the "open and closed" terminology used for both expansion and curvature, which is what is causing the confusion. It's essentially correct to refer to expansion as open or closed and that expansion can be accelerating, or not and still be open.

In any case, the acceleration of the expansion, which started about 5 billion ya, is happening; but is irrelevant to the point I was making in the OP, that the Big Bang resulted from the creation or sudden existence of divisibility at a point in the ether/Quantumland which initiated the 3Dspace and time of this universe, and "into" which our universe is expanding.

This last paragraph is far from being demonstrated. There are many alternatives, none of which has convincing evidence to support them.

 

[atanu]

Is the Cosmos expanding, or being drawn into some enormous entity.
Could it be `flat` in these formats, and not be spherical ?
Spherical or not, same old question: Into what ? To what ? With what ?
It's the Cosmos, of which you speak, what contains it ?

If we knew the container, the question would still exist "What contains the container?" And our power of awareness powers this enquiry.

 

[Ben Dhyan]

This depends a bit on what you mean by the term 'edge'. There is a concept of a 'manifold with boundary' where there are points 'at an edge' with literally nothing on one side and space on the other. I don't know of any serious models that use such, however.

It is possible there is an edge to *matter*? Again, possible and more likely than the one above, but also not taken seriously by most cosmologists.

And yes, it is quite possible there is no edge while also being finite and unbounded. the work 'because' here reads strangely, though.

By edge in context of our exchange, means where cosmic physical manifestation, ie. galaxies,, dust, etc., ends, but empty space continues. Iow, the space which contains the physical universe extends beyond it.
The other theory is as you put it, there is no edge while also being finite and unbounded.