Cosmological Crisis - Flat or Round?

[LogicalFallacy]

Is the universe a closed sphere or flat and infinite?

 

https://www.newscientist.com/article/2222159-cosmological-crisis-we-dont-know-if-the-universe-is-round-or-flat/?utm_campaign=onesignal&utm_medium=alert&utm_source=editorial

[Joshpantera]

 

What would a bubble universe look like, flat or a sphere? 

 

What the article doesn't seem to address is how space could be infinite with bubble universes expanding into the infinite space. What is the crisis and why? Wouldn't the CMBR data pointing at a curved universe be in support of eternal inflation? 

 

@WalterP

[WalterP]

10 minutes ago, Joshpantera said:

 

What would a bubble universe look like, flat or a sphere? 

 

What the article doesn't seem to address is how space could be infinite with bubble universes expanding into the infinite space. What is the crisis and why? Wouldn't the CMBR data pointing at a curved universe be in support of eternal inflation? 

 

@WalterP

 

I was posting something about the Cosmological Constant in the 'Failed Cosmology' thread, when you posted this Josh, so I'm in a good place to answer your question. 

 

I'll do it with a series of diagrams.

 

Cheers.

 

Walter.

 

 

[WalterP]

The simple answer to the question, Is the universe Closed, Flat or Open? is that it's too soon to say for sure.

Our observable universe is simply too small a volume of space for us to say for sure, as of today.  It's possible that future observations may pin the answer down, but as far as I'm concerned, the jury's still out.  I tend to take what the NewsScientist says with a pinch of salt.  They have something of a reputation for sensationalizing issues and over-simplifying complex topics.    

 

Anyway, why is the observable universe too small?  Well, since Inflation is the currently-accepted paradigm of mainstream cosmology, I'll use that to illustrate why we don't measure up. 

 

 

[WalterP]

[WalterP]

[WalterP]

 

This graph illustrates the conundrum faced by cosmologists who are trying to find out if the entire universe is Closed, Flat or Open.

Even though four different possibilities are shown, please look closely at what we see can of each of them, Now.  Yes, they all look the same to us.  By looking at the curvature of space inside the observable universe, we simply cannot tell which type of curvature entire universe possesses.  The size of the red ellipse (or circle) in the second and third diagrams I posted is far, far too small to see even the slightest degree of curvature.  

 

Even though the grid of squares I used to represent the wider universe looks flat, it could curve closed or open on scales far larger than I can show on any computer screen.  Think of an ant trying to find out if the planet Earth is flat or curved by measuring what it can see from the top of a blade of grass.  It's just impossible!

 

So, when it comes to trying to find answers, we are forced to rely upon what we can see within the observable universe.  To do that we have to use measurements of things like the Cosmic Microwave Background Radiation.  Sure enough, the NewScientist article is about the 2018 data release from the Planck satellites' measurements of the CMBR.  Catch is, for all the precision of that data, there's still enough leeway for different interpretations and there are still many assumptions involved in making these interpretations.  The issue of Closed, Flat or Open is far from settled.

 

Thank you.

 

Walter.

[pantheory]

On 11/5/2019 at 2:47 AM, LogicalFallacy said:

Is the universe a closed sphere or flat and infinite?

 

https://www.newscientist.com/article/2222159-cosmological-crisis-we-dont-know-if-the-universe-is-round-or-flat/?utm_campaign=onesignal&utm_medium=alert&utm_source=editorial

 

Is the universe flat or curved? Mainstream cosmology generally agrees that in either case, a flat universe, or one that curves into a fourth dimension, both would be consistent with the Big Bang model since a flat universe is just a single, special case of Einstein's equations.

 

From my point of view as a cosmologist, the universe is far simpler than any presently known model of it. Essentially there would be nothing complicated about it. or within it. Only our misunderstandings of its simplicity are unnecessarily complicated.

 

Curved space (warped space) is a foundation conceptual idea of Einstein's General Theory of Relativity (GR), his theory of gravity. Of course his equations can be very good (excellent) but his concept of warped space could be all wrong. My related paper asserts that the details of gravitational lensing, in the above link, are simply based upon  misunderstands concerning the existence of dark matter and dark energy.

 

If space is not curved, it is described as being flat, which simply means there is no fourth dimension to it. And if it is flat, does not mean that it is infinite. Based upon what I consider the simplest definition of space, it is simply the distance between matter and the volume that matter encompasses, and nothing more. IMO it is not some imaginary thing that goes on forever. Rene De Carte called space an extension of matter. Einstein said that Space, Time, and Gravity have no separate existence  from matter.

 

So is space flat or curved?  To date all observations have indicated that it is perfectly flat.  Of course many  have pointed out that at a scale beyond the possibly observable universe space could still be curved on a far larger scale, but IMO observational evidence should be more important than nebulous theory concerning the likelihood of something. Most would agree that a four dimensional universe (four dimensional sphere or shape) would likely involve much more complicated and nebulous theory beyond GR.

 

 

[older]

I once read, but have been unable to verify, that Einstein thought the universe was a mobius sphere. (Is that correct?) Thus if you left a given point and travelled long enough you would end up where you started. While a mobius band is easy enough to make (Just take the belt off your pants, turn one end over 180 degrees and reattach. Trace along with your finger and you'll go over both "sides" of the belt and end up at the starting point. But the belt now only has one side.), visualizing a mobius sphere is something that doesn't work for my limited brain.

[pantheory]

18 hours ago, older said:

I once read, but have been unable to verify, that Einstein thought the universe was a mobius sphere. (Is that correct?) Thus if you left a given point and travelled long enough you would end up where you started. While a mobius band is easy enough to make (Just take the belt off your pants, turn one end over 180 degrees and reattach. Trace along with your finger and you'll go over both "sides" of the belt and end up at the starting point. But the belt now only has one side.), visualizing a mobius sphere is something that doesn't work for my limited brain.

 

One of Einstein's 10 equations of General Relativity involves Riemann geometry, the basis for his warped-space proposal. Riemann was credited as being the first person to provide a comprehensive, mathematical model of a fourth physical dimension. A mobius sphere would be a four dimensional sphere and Einstein did believe the universe bent around on itself in a fourth dimension, but don't know if he ever used the word mobius,  even though the word also exists in German as I have read.

[WalterP]

https://www.nature.com/articles/s41550-019-0906-9.epdf?referrer_access_token=qwhMEJ0wzDHdfB97wJVustRgN0jAjWel9jnR3ZoTv0NqA1r1vCcOgNn4LDpENPnwoeHNKdiccffHhZYAzAfWirButjQZIlE_kiDrG2iFXHU26guoLHtcK-8Bd16B0iBJXq0caiLWtJzstN0I7uk0LQxGEBosJTSceW-apXV_94PvsFmpVcGaw28tdjMSFwnpofsTl3o-XTORTfdjxoPw_sOoF3uj6pyMdfiy1SOFQKs%3D&tracking_referrer=www.livescience.com

 

Above is a link to the paper that this thread is all about.

 

I can't seem to copy and paste from the body of the text, so I'd like to draw attention to a sentence beneath paragraphs beneath Figure 8, on page 6.

 

"Fortunately, future measurements will fully confirm or falsify current tensions and the PL18 evidence for curvature."

 

This agrees with the closing comments of my last post, yesterday.  'The issue of Closed, Flat or Open is far from settled.'  In a nutshell, the jury is still out and we need more and better measurements to discover what the universe is telling us.

 

Thank you.

 

Walter.

 

 

 

 

 

 

 

 

[pantheory]

6 hours ago, WalterP said:

https://www.nature.com/articles/s41550-019-0906-9.epdf?referrer_access_token=qwhMEJ0wzDHdfB97wJVustRgN0jAjWel9jnR3ZoTv0NqA1r1vCcOgNn4LDpENPnwoeHNKdiccffHhZYAzAfWirButjQZIlE_kiDrG2iFXHU26guoLHtcK-8Bd16B0iBJXq0caiLWtJzstN0I7uk0LQxGEBosJTSceW-apXV_94PvsFmpVcGaw28tdjMSFwnpofsTl3o-XTORTfdjxoPw_sOoF3uj6pyMdfiy1SOFQKs%3D&tracking_referrer=www.livescience.com

 

Above is a link to the paper that this thread is all about.

 

I can't seem to copy and paste from the body of the text, so I'd like to draw attention to a sentence beneath paragraphs beneath Figure 8, on page 6.

 

"Fortunately, future measurements will fully confirm or falsify current tensions and the PL18 evidence for curvature."

 

This agrees with the closing comments of my last post, yesterday.  'The issue of Closed, Flat or Open is far from settled.'  In a nutshell, the jury is still out and we need more and better measurements to discover what the universe is telling us.

 

Thank you.

 

Walter.

 

The article’s title in your link explains the basis for the article and related conjecture: Planck evidence for a closed Universe 

The article's lead paragraph ends with this quote:

“Future measurements are needed to clarify whether the observed discordances are due to undetected systematics, or to new physics or simply are a statistical fluctuation.”

It's hard to argue with the statement that future measurements are needed, but there are several additional nebulous words in this sentence. The word "discordances" may not be a problem word because it means observational anomalies that are contradicted by other observational interpretations. But the word "systematics" is uncommon to astronomy and more akin to biology. Here I think the meaning of it is:  looking for "evidence" for the evolution of the universe in such a way that the discordant observations might make sense in accord with present theory.  And the words "statistical fluctuations" appear to be code words for statistical miscalculations concerning the meanings of what they interpreted as being observational anomalies.

My prediction is that new measurements will not settle this controversy because misinterpretations are involved with the meanings of the "excessive" bending (lensing) of light, 99%+ confidence level concerning a curved universe comes to mind. I also predict that a far-simpler cosmological model is needed along with related new physics.

 

 

[WalterP]

12 hours ago, pantheory said:

The article’s title in your link explains the basis for the article and related conjecture: Planck evidence for a closed Universe 

The article's lead paragraph ends with this quote:

“Future measurements are needed to clarify whether the observed discordances are due to undetected systematics, or to new physics or simply are a statistical fluctuation.”

It's hard to argue with the statement that future measurements are needed, but there are several additional nebulous words in this sentence. The word "discordances" may not be a problem word because it means observational anomalies that are contradicted by other observational interpretations. But the word "systematics" is uncommon to astronomy and more akin to biology. Here I think the meaning of it is:  looking for "evidence" for the evolution of the universe in such a way that the discordant observations might make sense in accord with present theory.  And the words "statistical fluctuations" appear to be code words for statistical miscalculations concerning the meanings of what they interpreted as being observational anomalies.

My prediction is that new measurements will not settle this controversy because misinterpretations are involved with the meanings of the "excessive" bending (lensing) of light, 99%+ confidence level concerning a curved universe comes to mind. I also predict that a far-simpler cosmological model is needed along with related new physics.

 

 

 

Pantheory,

 

The word 'discordances' isn't really nebulous.  It stems from the usage of the Lambda Cold Dark Matter model being referred to as the Concordance Model of Cosmology.  Therefore, data which doesn't seem to fit this model is said to generate 'discordance'.

 

References 17 and 18 show how the words are used.

 

https://arxiv.org/abs/1806.04649 Concordance and Discordance in Cosmology

https://arxiv.org/pdf/1703.05959.pdf Planck Confronts Large Scale Structure : Methods To Quantify Discordance

 

Thank you.

 

Walter.

 

 

 

https://www.researchgate.net/figure/How-the-Concordance-Model-of-Cosmology-was-developed-Theories-and-observations-motivated_fig2_308806912

[pantheory]

On 11/7/2019 at 5:31 AM, WalterP said:

 

Pantheory,

 

The word 'discordances' isn't really nebulous.  It stems from the usage of the Lambda Cold Dark Matter model being referred to as the Concordance Model of Cosmology.  Therefore, data which doesn't seem to fit this model is said to generate 'discordance'.

 

References 17 and 18 show how the words are used.

 

https://arxiv.org/abs/1806.04649 Concordance and Discordance in Cosmology

https://arxiv.org/pdf/1703.05959.pdf Planck Confronts Large Scale Structure : Methods To Quantify Discordance

 

Thank you.

 

Walter.

 

 

 

https://www.researchgate.net/figure/How-the-Concordance-Model-of-Cosmology-was-developed-Theories-and-observations-motivated_fig2_308806912

 

You're right, I see how they are using the word discordance. Makes sense. Also nice graphics on your part.

 

As a cosmologist, you probably know that I think the Big Bang model is entirely wrong in every way possible that I can think of.  Besides the universe not being curved IMO, you can review my paper (link below) concerning the almost endless problems we found with the BB theory and present cosmology. For instance the only things on your graph above which I think are both conceptually and observationally valid are the "Flat universe," related to this thread, and the "Copernican Principle."

 

https://www.aijcrnet.com/journals/Vol_4_No_9_September_2014/2.pdf

 

 

 

[WalterP]

6 hours ago, pantheory said:

 

You're right, I see how they are using the word discordance. Makes sense. Also nice graphics on your part.

 

As a cosmologist, you probably know that I think the Big Bang model is entirely wrong in every way possible that I can think of.  Besides the universe not being curved IMO, you can review my paper (link below) concerning the almost endless problems we found with the BB theory and present cosmology. For instance the only things on your graph above which I think are conceptually and observationally valid are the "Flat universe," related to this thread, and the "Copernican Principle."

 

https://www.aijcrnet.com/journals/Vol_4_No_9_September_2014/2.pdf

 

 

 

 

That's fine, Pantheory.

 

Just for the record, since my declared position on cosmology is one of wait-and-see, I hope you'll understand that I was asked by JoshPantera to comment on LogicalFallacy's opening post.  By doing that I'm just explaining things, as best as I understand them and not necessarily claiming that this or that theory is the right one.

 

Thank you.

 

Walter.

[pantheory]

5 hours ago, WalterP said:

 

That's fine, Pantheory.

 

Just for the record, since my declared position on cosmology is one of wait-and-see, I hope you'll understand that I was asked by JoshPantera to comment on LogicalFallacy's opening post.  By doing that I'm just explaining things, as best as I understand them and not necessarily claiming that this or that theory is the right one.

 

Thank you.

 

Walter.

 

Yes, I understand. Staying exactly on topic is sometimes difficult to realize whether the universe is flat or curved  

 

I like the quality of your posts. When you ask questions, they usually are good ones. And when you explain theory you generally add appropriate comments. Because of your profile I understand cosmology is a keen interest of yours. I know you will continue with your good postings and keen interest.

 

best regards,  Forrest,   AKA pantheory

[Joshpantera]

On 11/5/2019 at 6:41 AM, WalterP said:

 

I was posting something about the Cosmological Constant in the 'Failed Cosmology' thread, when you posted this Josh, so I'm in a good place to answer your question. 

 

I'll do it with a series of diagrams.

 

Cheers.

 

Walter.

 

 

 

So what are we looking at with the bubble universe proposal? Obviously for all of the infinite bubbles to each expand to flat and infinite would interfere between individual universes. One would run right into the others with them all literally flat, right? So they'd have to be spherical bubbles which only appear flat from observation within or right near the edge of any given bubble, looking outward. But they couldn't actually be flat, could they?

 

Is that what you were trying to explain with all of the diagrams? 

 

I'll reproduce all of the diagrams below. 

 

 

[Joshpantera]

On 11/5/2019 at 6:29 AM, Joshpantera said:

 

We would have this image from external a given universe. Looking at all of the nearby universes from the outside. New bubbles continuously forming. 

 

On 11/5/2019 at 6:57 AM, WalterP said:

 

 

The flat appearance in the above, is just an appearance if all universes are bubbles that never actually flatten out. It looks like approaching the spherical earth from space until you get close enough that the sphere starts looking flatter. So bubbles, where a bubble can look flat from one perspective. But for all bubbles to ever get to literally flat, like I said, it seems to follow that they'd all merge into one instead of remaining as individual. I'm curious what the cosmological (standard model) answer to this inquiry can entail. 

 

 

[pantheory]

Belief in the multiverse: a form of blind faith?

Many or most mainstream astronomers and physicists dislike multiverse theory because they assert that such hypotheses are not science, but instead unjustifiable speculation, described in the link below, like the blind faith of religion.

There are several avenues that lead to multiverse speculation, that also involve open (flat) and closed (curved) universes/ space.

Nearly all multiverse hypothesis assert curved-space bubble universes  that  are closed in a fourth dimension and cannot interact with other such universes. Some have also proposed that bubble universes could in their future begin to flatten. A few theorists have proposed that flat multiverses might at some future time of their evolution be able to interact with each other. The former is pure speculation if such bubble universes could never be observed, but the second although mere speculation proposes possible observation. But what is the reason to even consider multiverses in the first place? Don’t we have enough answers with our present theories and hypotheses without having to come up with additional ad hoc speculation, gods of the gaps so-to-speak?

There are several well-known hypothesis that lead to multiverse conclusions. Most propose curved, bubble-like universes.

The first speculative avenue to multiverses involves the Inflation hypothesis. There are a number of different inflation models by a number of individuals but most theorists prefer Allen Guth’s version since he was the first to propose a model of Inflation to solve the number of problems in cosmology that were thought to exist as that time which seemingly could not otherwise be explained.  The Inflation Model proposes an expansion of space event of all energy and matter at the beginning of the universe at countless times the speed of light, then  this inflation stopped. No reasons for Inflation in the first place or why it should stop are contained in the proposals.  Inflation does not predict multiverses but can allow for them. Inflation models are known to lead to flat universes.

The second speculative avenue to multiverses is called the Many-Worlds interpretation of quantum mechanics.  This hypothesis proposes that anything that can statistically happen does happen in this and other universes producing an almost infinite number of other universes. There are a few mainstream followers of this model, the most well-known of these might be the theorist Sean Carroll.

A third speculative avenue relates to the proposed Big Bang beginning and how it supposedly originated. Some have proposed that our universe spontaneously generated from the Zero Point Field, and likewise that other universes have generated from this same field, or that one universe can generate from another in an unending chain of events.

IMO; Multiverse speculation is considered reasonable by some  theorists because present theory observations and theory in cosmology and quantum theory sometimes cannot otherwise be explained so they look to find otherworldly god-of-the-gaps type explanations like multiverse hypotheses to explain what they do not understand.

Curved or flat space concerning multiverses may not be a real issue, for instance, if there is no such thing as curved space in the first place, contrary to the related conceptual foundation of General Relativity. And it also would be a non-issue if this universe was the only one, which I think it is.

Another big problem in logic seen in much of present-day science theory is called the "follow the leader fallacy" and the "Appeal to Authority" fallacy. Most of such logical-fallacy failings I believe are more obvious in the interpretations of modern physics (special relativity, general relativity, cosmology, particle physics, and quantum theory) than with other sciences

https://www.irishtimes.com/news/science/belief-in-the-multiverse-a-form-of-blind-faith-1.2153271

https://en.wikipedia.org/wiki/Many-worlds_interpretation

The main problem with multiverse theory is that it is not science, having little or no recognized observational, theoretical, or consensus justification for such speculation.

https://www.prospectmagazine.co.uk/science-and-technology/the-problem-with-multiverse-theories-theyre-just-not-science

[WalterP]

Hello Josh.

 

I think we may have got our wires crossed.  I did answer your question, but from the only reasonable scientific viewpoint that we have - our own.  I showed from the diagrams that it's impossible for us to tell if our own universe is closed, flat or open.  To us, there is no appreciable curvature of space.  I also qualified this by adding that our particular universe could be curved closed or open, but on scales that are simply far too large for me to show on a computer screen.

 

The fallout of this is that it's just an exercise in speculation for me to go way beyond the confines of our universe.  If there's insufficient information for us to determine the geometry of our own universe, then it logically follows that that there's NO information to guide us about what lies beyond it.  Re-reading your question in the context of the graphic you posted I now see that you wanted me to talk about the geometries of bubble universes, as seen from a viewpoint somewhere out in the multiverse itself.  Is that right?

 

If so, then I'm sorry, but I really don't think that I can do more than politely decline your request.  

 

However, I can give you an answer (of sorts) to this.

 

The flat appearance in the above, is just an appearance if all universes are bubbles that never actually flatten out. It looks like approaching the spherical earth from space until you get close enough that the sphere starts looking flatter. So bubbles, where a bubble can look flat from one perspective. But for all bubbles to ever get to literally flat, like I said, it seems to follow that they'd all merge into one instead of remaining as individual. I'm curious what the cosmological (standard model) answer to this inquiry can entail. 

 

If you look back, I posted a diagram explaining the origin of the Concordance Model, in response to something mentioned by Pantheory.  The lowest yellow box (Lambda Cold Dark Matter) is today's currently accepted model for mainstream cosmology.  If that's what you meant by the standard model, than I have to inform you that in terms of evidence and data, it says nothing about a multiverse.  An examination of the function of the diagram shows that each stage in the development of our cosmological theories was prompted by Observations (purple boxes, on the right) and Theories (blue boxes, on the left) that attempt to explain what was observed.  

 

So, starting with Observations, everything from Expansion of the Universe, down to Accelerating Expansion and Flat Universe deals with things within our observable universe.  How could it be otherwise?  Theories, from General Relativity and the Copernican Principle, down to Inflation are the theories that are used to explain the right-hand column, what is observed within our universe.  And this could be the point where you're getting confused.

 

By definition, it impossible for us to say whether other universes are expanding, what their elemental abundances are, what their galaxy rotation curves are, whether or not they have their own CMB's, whether their expansions are accelerating or if they are flat universes or not. That covers the Observations column. That being so, it logically follows that the theories designed to explain these things in our universe cannot be used to say anything meaningful about other universes. That covers the Theories column, but with one important caveat.

 

The last box, Inflation, does have the potential to predict that our universe is not the only one that there is.  However, there is a very serious and immovable roadblock in the way of rigorous science, when it comes to an Inflationary multiverse.  Scientific rigor demands that a theory be testable by experiment.  Clearly, in the case of cosmology, that does not mean experimentation in a Earthbound laboratory.  No, what is meant is that, to be properly scientific, a theory must make testable predictions that can be confirmed or ruled out on the basis of observed evidence.  

 

Where no observations are possible, no testing of the theory in question is possible.  The theory is therefore impossible to verify or falsify.  The merit of such a theory is, to say the least, very questionable.  When it comes to what lies beyond the visual limits of our own universe, Inflation is just such an un-testable theory.  As is Roger Penrose's Conformal Cyclic Cosmos theory or Paul Steinhardt's Ekpyrotic theory.  None of these three theories can be falsified or verified by observations made of what lies outside of our universe.  They stand or fall on the basis of what they predict about this universe.

 

Josh, to reinforce the point I've just made, think back to our discussions about William Lane Craig's cosmology and why he cannot use Hawking and Penrose's singularity theory.  If you recall, that theory was falsified in 1998 by supernova observations.  That data came from within our universe, not from outside of it.  That's the only standard that counts - if you want to talk rigorous cosmology.

 

I hope that this does give you some kind of answer.

 

Thank you.

 

Walter.

 

 

[WalterP]

19 hours ago, pantheory said:

 

Yes, I understand. Staying exactly on topic is sometimes difficult to realize whether the universe is flat or curved  

 

I like the quality of your posts. When you ask questions, they usually are good ones. And when you explain theory you generally add appropriate comments. Because of your profile I understand cosmology is a keen interest of yours. I know you will continue with your good postings and keen interest.

 

best regards,  Forrest,   AKA pantheory

 

Thank you, Forrest.

 

I appreciate what you say. 

 

Walter.

[Joshpantera]

4 hours ago, WalterP said:

I think we may have got our wires crossed.  I did answer your question, but from the only reasonable scientific viewpoint that we have - our own.  I showed from the diagrams that it's impossible for us to tell if our own universe is closed, flat or open. 

 

As to the bubble universes, the diagram suggests a hard boundary. But we've been discussing no hard boundary elsewhere.

 

So is that what the diagram of bubble universes is suggesting or does it only looks as if that is the case? 

 

 

 

[pantheory]

12 hours ago, Joshpantera said:

 

As to the bubble universes, the diagram suggests a hard boundary. But we've been discussing no hard boundary elsewhere.

 

So is that what the diagram of bubble universes is suggesting or does it only looks as if that is the case? 

 

 

 

 

Hi Josh, I thought I would put in my two cents here but Walter can properly answer your question.

 

The bubbles are 3D depictions of 4D universes (like ours according to Einstein) that are closed upon themselves (if you traveled in a straight line long enough you would end back where you started). And if they remained 4D they could never interact with each other.

 

The bubbles could also represent 3D flat universes which would spread out and expand until there was no matter or energy left at the spherical exterior boundary. There would be no hard boundary. Between these universes, like ours for instance, the space between them would also be expanding so that even light from one universe could not reach any of the others.

 

The above idea is only one of the many dozens of multiverse proposals. Some are 3D proposals, some are 4D proposals, and some are other dimensional proposals, etc. Some propose that these multiverses might in some way be able to interact with our own universe and be observable in some way, but others propose such universes could never interact or be observed by another universe.

 

 

[WalterP]

13 hours ago, Joshpantera said:

 

As to the bubble universes, the diagram suggests a hard boundary. But we've been discussing no hard boundary elsewhere.

 

So is that what the diagram of bubble universes is suggesting or does it only looks as if that is the case? 

 

 

 

 

Josh,

 

As far as I understand, Pantheory has it right.  These are 2D depictions that are drawn to look 3D, but I think they're representing 4D hyperspheres and not ordinary, three dimensional spheres.  I've tried to explain this to Justus, who favors a 3D, spherical universe with a hard boundary.  But that model violates the Copernican principle, which requires that no location be central or special in any way.

 

https://www.ex-christian.net/topic/82672-robin-collins-and-fine-tuning-for-discoverability/

 

Thank you.

 

Walter.

 

 

 

[WalterP]

On Tuesday, I wrote this.

 

The simple answer to the question, Is the universe Closed, Flat or Open? is that it's too soon to say for sure.

Our observable universe is simply too small a volume of space for us to say for sure, as of today.  It's possible that future observations may pin the answer down, but as far as I'm concerned, the jury's still out.  I tend to take what the NewsScientist says with a pinch of salt.  They have something of a reputation for sensationalizing issues and over-simplifying complex topics.   

 

Today, after skimming over articles on various science forums I noticed this.

 

 https://arxiv.org/pdf/1903.12097.pdf

 

It's extremely technical and I can't claim to understand much of it, but this section is relevant to this thread.

 

Our measurements support a value of H0 that is closer to that one found by the BAO methodology rather than the higher value from the Cepheids. Interestingly, the 8 H0−Ωm contours from γ-ray attenuation are roughly orthogonal to results from other techniques, which makes our results nicely complementary to those from other probes. In order to improve the H0 measurement we need to measure optical depths up to the largest possible energies. This is difficult with LAT because of the limited photon statistics. However, it may be possible with the future Cherenkov Telescope Array (CTA, Hinton et al. 2019). 

 

In a nutshell, this paper seems to be supporting the Flat universe of the LCDM Concordance Model.  Please note that I do not necessarily support any particular cosmological model, so all I am pointing out here is what I said on Tuesday - the jury's still out. If different measurements appear to be coming to different conclusions about the geometry of the universe, then the issue is still in a state of flux and further, better measurements are needed to settle things.

 

Thank you.

 

Walter.