Could the real size of the universe be infinite?

[Airbrush]

23 hours ago, MigL said:

Where you 'went wrong' is considering the universe being finite with an 'edge', and that 'edge' expanding, or inflating, into something else ( other than the universe itself ).

The expansion/inflation is simply an increase in separation between things that are not gravitationally bound; Stringy gave the analogous description to your conjecture of an 'explosion', where the flame front travels outward.
This is the wrong view, as we can stand 'outside the explosion and see this effect; we cannot do so for the actual universe, as there is no 'outside' view that makes sense.

A lot of people seem to be unconfortable with the concept of infinity, and simply can't wrap their head around it.
But why is an 'edge' to the universe any less unconfortable ?
If you were at the 'edge', could you stick your hand through, or would there be a physical barrier ?
Is the physical barrier then, not part of the universe, needing another physical barrier beyond it ( and so on ... ) ?
And, if no physical barrier, once you've stuck your hand through, information has passed from 'beyond' to our universe, making'beyond' part of our universe ( and again, so on ... ).

Putting an 'edge' on the universe makes things infinitely more complicated.
Are you confortable with an infinity of complications ?

I've seen animations showing a multiverse of big bang blobs drifting in the bulk, or budding off another universes.  Expansion happens, but if the multiverse model is correct then you will certainly have big bang "leading edges" expanding away from a center region.  Each universe will have a center and edges.  Beyond the edge of a universe is simply the absence of matter or energy until you reach the next big bang.

I don't have any problem with infinity.  People who say there is no center or outside the universe are WAG'ing.  They are assuming that there is no multiverse.  That is a WAG.  I just reason there MAY BE higher levels or organization, rather than supposing the universe is the final structure with no center and no edge.  You don't know that.  Just like particles get smaller.  You can split atoms into smaller particles.  You can split protons and neutrons into quarks, etc.  This is a WAG, but guessing is all we can do beyond the level of observable universe.

Solar systems

Galaxies

Galaxy Clusters

Galaxy Superclusters

Universes

Multiverses

"The multiverse is a hypothetical group of multiple universes.^[a] Together, these universes comprise everything that exists: the entirety of space, time, matter, energy, information, and the physical laws and constants that describe them. The different universes within the multiverse are called "parallel universes", "other universes", "alternate universes", or "many worlds".

https://en.wikipedia.org/wiki/Multiverse

Here are universes, with centers and edges, drifting in the "bulk."

https://www.bing.com/images/search?view=detailV2&ccid=JThPqP%2bp&id=5B5387756B7B47E7448D1B75D5D0B27B53755333&thid=OIP.JThPqP-psD4jPsTwZZePKwHaEK&mediaurl=https%3a%2f%2fwww.sciencenews.org%2fwp-content%2fuploads%2f2019%2f09%2f101219_ts_reviews_feat.jpg&cdnurl=https%3a%2f%2fth.bing.com%2fth%2fid%2fR.25384fa8ffa9b03e233ec4f065978f2b%3frik%3dM1N1U3uy0NV1Gw%26pid%3dImgRaw%26r%3d0&exph=580&expw=1030&q=images+of+multiverse&simid=608023659644742442&FORM=IRPRST&ck=CA24EE2BDAEC178A07CE1562E97E8825&selectedIndex=42&ajaxhist=0&ajaxserp=0

 

Edited August 27, 2021 by Airbrush

[MigL]

I don't disagree that we are simply guessing ...
But I have to ask you how, exactly, do you think an 'edge' would work ?
Universe literally means ' all that there is', so if you are at the 'edge', and you can keep going, you are still in the universe, as information ( and all other effects ) can freely cross the 'edge'.
The concept of an 'edge' is simply non-sensical.

The representations you see of multiverse 'bubbles' expanding outward, are simply that ... representations.
More accurate, would be 4dimensional space-time hyperspheres, which have the propertiy of expanding in every direction, including 'inwards', while your 'bulk' would need to be 5 ( or more ) dimenional, but you can't have a graphical representation of that.

You can throw as many dimensions as you want at the problem, but quite often the simplest, less complicated, solution is the best 
( at least until we have observations/information that allows for more accurate predictions ).

[studiot]

4 hours ago, Airbrush said:

I don't have any problem with infinity.  People who say there is no center or outside the universe are WAG'ing.  They are assuming that there is no multiverse.  That is a WAG.  I just reason there MAY BE higher levels or organization, rather than supposing the universe is the final structure with no center and no edge.  You don't know that.  Just like particles get smaller.  You can split atoms into smaller particles.  You can split protons and neutrons into quarks, etc.  This is a WAG, but guessing is all we can do beyond the level of observable universe.

You should reread swansont's post about this several times as these are not guesses, wild or otherwise.

I endorse MigL's comments about representations as well, most especially geometric ones superimposed on topological set/theoretical notions. +1
This is where your idea of infinity and of edges is flawed.

1 hour ago, MigL said:

The concept of an 'edge' is simply non-sensical.

The representations you see of multiverse 'bubbles' expanding outward, are simply that ... representations.

 

Consider the following set  {1, 2}

Ths set is finite ie not infinite.

Let me 'expand' it

{1, 1.1, 1.2, 1.3, 1.4......1.9, 2}

Is the expanded thread set any 'bigger' geometrically ?   Edit:- oops I originally said thread when I meant set.
Does it take up more space ?

Does it have any geometric shape at all  (with or without edges) ?

Let me expand it again {1, 1.11, 1.12, ................1.99, 2}

Can you see where this is going ?

I can continue 'expanding' my set indefinitely yet I have no edges, or geometrical form.

I can even turn it into an infinite set if I wish

Theories of Big Bangs, Multiverses etc are about topological objects called manifolds which alway have non geometric properties and sometimes geometric ones as well.

That sometimes allows us to make rather poor geometric representations of the topology of the manifolds in question.

 

Edited August 27, 2021 by studiot
to correct wording

[geordief]

1 hour ago, MigL said:

I don't disagree that we are simply guessing ...
But I have to ask you how, exactly, do you think an 'edge' would work ?
Universe literally means ' all that there is', so if you are at the 'edge', and you can keep going, you are still in the universe, as information ( and all other effects ) can freely cross the 'edge'.
The concept of an 'edge' is simply non-sensical.

The representations you see of multiverse 'bubbles' expanding outward, are simply that ... representations.
More accurate, would be 4dimensional space-time hyperspheres, which have the propertiy of expanding in every direction, including 'inwards', while your 'bulk' would need to be 5 ( or more ) dimenional, but you can't have a graphical representation of that.

You can throw as many dimensions as you want at the problem, but quite often the simplest, less complicated, solution is the best 
( at least until we have observations/information that allows for more accurate predictions ).

You could maybe have an "edge" (wouldn't have to be a definite boundary-more an amorphous dynamic region) that  you couldn't cross ,only follow its progression.

But  how could we find that edge (or that amorphous region? If we had all  the time available to us in which direction we we point our craft? Away from the centre? Seems the centre is everywhere ,so that is no help.

 

Maybe someone designed the universe wrong😢

[studiot]

22 minutes ago, geordief said:

You could maybe have an "edge" (wouldn't have to be a definite boundary-more an amorphous dynamic region) that  you couldn't cross ,only follow its progression.

But  how could we find that edge (or that amorphous region? If we had all  the time available to us in which direction we we point our craft? Away from the centre? Seems the centre is everywhere ,so that is no help.

 

Maybe someone designed the universe wrong😢

Where is the 'centre' of my example set  ?

[geordief]

16 minutes ago, studiot said:

Where is the 'centre' of my example set  ?

I ? (or wherever you started from)

Can a set like that be seen as how it was made rather than an end product? (a chimera to boot)

 

Edit I thought a chimera was one of those retreating mirages that disappear the closer you get to them.🙄

Edited August 28, 2021 by geordief

[studiot]

6 minutes ago, geordief said:

I ? (or wherever you started from)

Can a set like that be seen as how it was made rather than an end product? (a chimera to boot)

 

Edit I thought a chimera was one of those retreating mirages that disappear the closer you get to them.🙄

But I could have written those numbers in a different order; the set would still have been the same.

It has no centre. That is the point.

It should be noted that it is also a representation if used to illustrate properties of the universe since it only shares some properties with whatever manifold the universe actually is.

Edited August 28, 2021 by studiot

[Lan Todak]

4 hours ago, studiot said:

But I could have written those numbers in a different order; the set would still have been the same.

It has no centre. That is the point.

It should be noted that it is also a representation if used to illustrate properties of the universe since it only shares some properties with whatever manifold the universe actually is.

The edges are 1 and 2 with 1.5 as the centre. Your set can't represent our universe. 😑

[Airbrush]

On 8/27/2021 at 4:19 PM, geordief said:

You could maybe have an "edge" (wouldn't have to be a definite boundary-more an amorphous dynamic region) that  you couldn't cross ,only follow its progression.

But  how could we find that edge (or that amorphous region? If we had all  the time available to us in which direction we we point our craft? Away from the centre? Seems the centre is everywhere ,so that is no help.

If big bangs are finite events, the edge is simply where you don't find any more galaxies, if you could travel so fast to reach the edge.

The way to find the "edge" is simply travel in a straight line.  But that assumes the big bang doesn't curve back on itself, which makes everything more complicated.

If the big bang is a finite event, there could be a theoretical center of the big bang (universe).

Edited September 5, 2021 by Airbrush

[geordief]

41 minutes ago, Airbrush said:

the edge is simply where you don't find any more galaxies

How would you know that there were no more galaxies? They might just  be moving too fast for you to see them.

 

Apparently in our own distant future  we will  longer be able to see any of the galaxies that we can see today as their speed of recession will have gone above the speed of light....

[StringJunky]

19 minutes ago, geordief said:

How would you know that there were no more galaxies? They might just  be moving too fast for you to see them.

 

Apparently in our own distant future  we will  longer be able to see any of the galaxies that we can see today as their speed of recession will have gone above the speed of light....

Ironically, Airbrush's flight of fancy will then appear to be true to a future observer with no prior knowledge of the earlier state.

[beecee]

On 8/28/2021 at 5:13 AM, Airbrush said:

I don't have any problem with infinity.

I have less of a  problem with infinity then I do with finite, and edges and flat Earths etc.

 

[Conscious Energy]

On 8/27/2021 at 12:21 PM, studiot said:

 

Euclid Book 1 definitions 1,2 & 3.

Another interesting property to consider.

Here is a version of the sketch I asked you to draw.

Although of different lengths, all three lines OA, OB and OC contain exactly the same number of points as shown by the dotted lines putting them into one-to-one correspondence.

This can only happen with an infinite number of points if the lines are composed of 'planck lengths of equal length'

So you mean that 1 cm2 has exactly the same amount of “space points” as 1 km2 since both has infinite points of space in them.

Does it mean that 1 cm2 = 1 km2 ?

How you prove this physically?

 

[MigL]

15 hours ago, StringJunky said:

Ironically, Airbrush's flight of fancy will then appear to be true to a future observer with no prior knowledge of the earlier state.

Flight of fancy ,indeed.
The observable universe has an 'edge', but it recedes as you move closer to it.
( it is always at the same distance )
 

25 minutes ago, Conscious Energy said:

So you mean that 1 cm2 has exactly the same amount of “space points” as 1 km2 since both has infinite points of space in them.
Does it mean that 1 cm2 = 1 km2 ?
How you prove this physically?

Correspondence of points is a useful tool when dealing with infinities.
That doesn't mean areas are equal.
So why would you need to prove it ( physically or otherwise ) ?

[Conscious Energy]

2 hours ago, MigL said:

Flight of fancy ,indeed.
The observable universe has an 'edge', but it recedes as you move closer to it.
( it is always at the same distance )
 

Correspondence of points is a useful tool when dealing with infinities.
That doesn't mean areas are equal.
So why would you need to prove it ( physically or otherwise ) ?

If different length has equal point as Studiot pointed out than why wouldn’t that be true for areas?

[studiot]

4 hours ago, Conscious Energy said:

So you mean that 1 cm2 has exactly the same amount of “space points” as 1 km2 since both has infinite points of space in them.

Does it mean that 1 cm2 = 1 km2 ?

How you prove this physically?

 

I'm not quite sure what you mean by prove physically or by 'space points'.

However mathematically things ae even weirder than your questions suggests since the cardinality of the Real numbers is the same as the cardinality of the Complex numbers.

This means that the set of numbers forming a line has the same number of points as the set forming an area (which includes many lines).

Perhaps a peano curve is a physial demonstation of this, if you want physical proof.

 

You can even take this one stage (or more) further and state that volumes have the same number of points.

 

And yet 1 cm² is not equal to 1 km², any more than 1cm is equal to 1km.

 

Edited September 6, 2021 by studiot

[Airbrush]

On 9/5/2021 at 1:41 PM, geordief said:

How would you know that there were no more galaxies? They might just  be moving too fast for you to see them.

Apparently in our own distant future  we will  longer be able to see any of the galaxies that we can see today as their speed of recession will have gone above the speed of light....

We don't know.  This is only a thought experiment.  This is only IF you could travel extreme distances in a second.  It is possible that the universe does not remain so isometric and homogeneous at great distances as the observable portion does, such as trillions or googols of light years away.  This is assuming it does not curve back on itself.  For that reason it is wrong to say there is no center or edge to the universe (big bang).  We don't know either way, both are guesses.

How do you know the universe is isometric and homogeneous very far beyond the observable universe?

Edited September 9, 2021 by Airbrush

[geordief]

5 minutes ago, Airbrush said:

We don't know.  This is only a thought experiment.  This is only IF you could travel extreme distances in a second.  It is possible that the universe does not remain so isometric and homogeneous at great distances as the observable portion does, such as trillions or googols of light years away.  This is assuming it does not curve back on itself.  For that reason it is wrong to say there is no center or edge to the universe (big bang).  We don't know either way, both are guesses.

How do you know the universe is isometric and homogeneous very far beyond the observable universe?

I we start with "we don't know " then all assertions can seem plausible.

 

 

Edited September 9, 2021 by geordief

[Airbrush]

2 minutes ago, geordief said:

If we start with "we don't know " then all assertions can seem plausible.

Yes, so the idea that there is no edge or center to the universe seems plausible because we don't know.  But it is no more plausible than a big bang with a center and edges.

[MigL]

No, assertions carry baggage.

A center, or an edge, implies homogeneity and isotropy fly out the window; and we lose two sides of the foundation of the Big Bang Theory.
They also imply a preferred frame, something which is not allowed by GR.
With GR no longer valid, we lose the third foundation of the Big Bang Theory.
We are left with a pretty wobbly structure.

Just because we don't know what something is, does not mean we don't know what it can't be.
That is the essence of science ( to wax Philosophical ), falsify what cannot be, and keep narrowing down the options of what it can be.

[beecee]

2 hours ago, MigL said:

No, assertions carry baggage.

A center, or an edge, implies homogeneity and isotropy fly out the window; and we lose two sides of the foundation of the Big Bang Theory.
They also imply a preferred frame, something which is not allowed by GR.
With GR no longer valid, we lose the third foundation of the Big Bang Theory.
We are left with a pretty wobbly structure.

Just because we don't know what something is, does not mean we don't know what it can't be.
That is the essence of science ( to wax Philosophical ), falsify what cannot be, and keep narrowing down the options of what it can be.

I was once informed by a noted astronomer on a now defunct science forum, that one of the stengths of the main models in cosmology today, was how GR and the BB go together like a finger in a bum, or a hand in a glove, take your pick! He also threw in the particle zoo with those two as obviously complimentary..

[Airbrush]

6 hours ago, MigL said:

No, assertions carry baggage.

A center, or an edge, implies homogeneity and isotropy fly out the window; and we lose two sides of the foundation of the Big Bang Theory.
They also imply a preferred frame, something which is not allowed by GR.
With GR no longer valid, we lose the third foundation of the Big Bang Theory.
We are left with a pretty wobbly structure.

Just because we don't know what something is, does not mean we don't know what it can't be.
That is the essence of science ( to wax Philosophical ), falsify what cannot be, and keep narrowing down the options of what it can be.

Why can't homogeneity and isotropy vary or end, over great distances?  We can see only about 46 billion LY.  Compared to infinity that is tiny.

To say the universe has no center and no edge is an assertion that carries baggage.  Why must we assume that homogeneity and isotropy continue to infinity?  All we can see is a tiny fragment of the universe, the observable portion.  Why must we assume that a trillion light years away the universe looks the same as here?   This is all assuming no curvature of space.  If space is curved then does that mean it has a finite size since the universe would be the distance traveling from Earth curving back to Earth?  That distance would be finite.

Did you see Neil deGrass Tyson interview Hawking?  This is a wonderful episode of Star Talk, even has Michio Kaku.  When asked about before the big bang Hawking said something like "Nothing was around before the big bang.  Space and time together form a space/time continuum which is not flat but curved by matter and energy."

Here is the Youtube of the interview.  Advance to 14:36 to hear Stephen answer this question:

Hawking doesn't think the universe is flat and extending to infinity, but rather curved.  Does that mean it is impossible to travel in a straight line to infinity, or must you necessarily return to your starting point no matter what directions you travel?  Is Hawking guessing?  But there was something around before the big bang, the potential for a big bang.

Edited September 10, 2021 by Airbrush

[MigL]

If the universe is not homogenous and isotropic, rewinding the clock back wll not lead to the Big Bang.
If the universe is not expanding equallyin all directions there is no Big Bang.

You don't seem to understand the Big Bang very well.
Maybe you should ask questions, or read up on it, before making assertions.

[Airbrush]

8 hours ago, MigL said:

If the universe is not homogenous and isotropic, rewinding the clock back wll not lead to the Big Bang.
If the universe is not expanding equallyin all directions there is no Big Bang.

You don't seem to understand the Big Bang very well.
Maybe you should ask questions, or read up on it, before making assertions.

I asked 7 questions in my post.  I love astronomy and cosmology and try to watch every documentary that I can.  I sincerely seek the truth.  I just have a few questions and so far nobody wants to answer them. 🙂

[MigL]

Yes,I count seven ...

10 hours ago, Airbrush said:

Why can't homogeneity and isotropy vary or end, over great distances? 

 

10 hours ago, Airbrush said:

Why must we assume that homogeneity and isotropy continue to infinity?

 

10 hours ago, Airbrush said:

Why must we assume that a trillion light years away the universe looks the same as here? 

These first three are the same question, and that has been answeed.

 

10 hours ago, Airbrush said:

If space is curved then does that mean it has a finite size since the universe would be the distance traveling from Earth curving back to Earth?  That distance would be finite.

Yes, positive curvature means parallel lines eventually meet, and, by travelling far enough, you can return to your starting point, as on the surface of the Earth.

10 hours ago, Airbrush said:

Did you see Neil deGrass Tyson interview Hawking? 

No, I did not.

10 hours ago, Airbrush said:

Does that mean it is impossible to travel in a straight line to infinity, or must you necessarily return to your starting point no matter what directions you travel?

Given an infinite space, you can most certainly travel in a straight line to infinity if given an infinite amount of time.
You can only return to your starting point in a positively curved space.

10 hours ago, Airbrush said:

Is Hawking guessing?

I don't know, and I can't really ask him anymore.
I would need to know what evidence he is basing his conclusions on.