If the Universe is closed, is it thereby self-contained as well?

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Main Question or Discussion Point

https://www.google.com/amp/s/phys.org/news/2019-11-universe-rethink-cosmos.amp


What do the results of the closed universe study tell us in terms of past cosmic sequences, if it is indeed the proper description of the universe?

Would it entail a self-contained universe? By self-contained I mean self supporting, always existing, neccesarily existing thing independent of any external source?

The theory of inflation suggested more along the lines of the universe being an event followed by entropy and summoned by different scenarios of "doom", including a possible heath death of the universe.

Supposing we do live in a closed universe, is the notion of an "event" jettisoned in favor of self-containment, brute facts, and eternity? Does it favor an infinite loop (oxymoron) of some kind?
 
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  • #2
PeterDonis
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Would it entail a self-contained universe?
Supposing we do live in a closed universe, is the notion of an "event" jettisoned in favor of self-containment, brute facts, and eternity?
The laws of physics don't work any differently in a spatially closed universe as opposed to a spatially flat one. I think that means the answer to these questions is "no". Although I'm not sure exactly what the questions mean, since "self-contained" doesn't seem to me to be a scientific term.
 
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The laws of physics don't work any differently in a spatially closed universe as opposed to a spatially flat one. I think that means the answer to these questions is "no". Although I'm not sure exactly what the questions mean, since "self-contained" doesn't seem to me to be a scientific term.
Sean Caroll used the term when asked how he ultimately views the universe
 
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phinds
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Since the universe is all there is, and it does not reside inside something else, I think it's reasonable to use the English language term "self contained" to describe it, but seems to me that term should have a mathematical meaning. I don't mean that it HAS that I know of, it just sounds like something that should be subject to a strict mathematical definition, not necessarily corresponding "exactly" to the English (to the extent that the English is exact or even really makes sense).

Also, Sean Caroll is, I think, a solid physicist but he does a LOT of pop-science presentations and in those he does not necessarily use the kind of precise language that he would use in a formal paper.
 
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PeterDonis
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Sean Caroll used the term when asked how he ultimately views the universe
Please give a reference.
 
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The laws of physics don't work any differently in a spatially closed universe as opposed to a spatially flat one.
It wasn't in regards to the laws but rather the finite scope this would involve and what consequences this would have for our notion of time and beginning of the universe.

In a curved universe, no matter which direction you travel in, you will end up at the starting point—just like on a sphere.

Does this not point to a four dimensional Minkowski block theory of time and space?
 
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Please give a reference.
He used it at least once in this debate defending his book.
 
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Since the universe is all there is, and it does not reside inside something else, I think it's reasonable to use the English language term "self contained" to describe it, but seems to me that term should have a mathematical meaning. I don't mean that it HAS that I know of, it just sounds like something that should be subject to a strict mathematical definition, not necessarily corresponding "exactly" to the English (to the extent that the English is exact or even really makes sense).

Also, Sean Caroll is, I think, a solid physicist but he does a LOT of pop-science presentations and in those he does not necessarily use the kind of precise language that he would use in a formal paper.
He was using self contained as an ultimate explanation of the universes existence, not simply function. Self containment can mean both function and explanation of existence and he obviously refers to both
 
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phinds
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He used it at least once in this debate defending his book.
So you expect us to watch a 2+ hour video to see where he says that? I don't think so.
 
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  • #11
PeterDonis
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the finite scope this would involve
A spatially closed universe has a finite spatial volume. That's all it means.

Does this not point to a four dimensional Minkowski block theory of time and space?
It has nothing whatever to do with whether a "block universe" interpretation is true or not. Such an interpretation can be formulated equally well for a spatially infinite universe as for a spatially finite one. In fact, Minkowski spacetime, the framework of SR, which is where the "block universe" interpretation originally came from, is spatially infinite.
 
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That debate was about philosophy/religion, not physics.
It was a debate about Carols cosmological models in relation to religion and philosophy. It got very technical and William Lane Craig went right into the nitty gritty in his rebuttal of Carolls physics book, which surprised me. He did alright, judging by Carolls rebutals.
 
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A spatially closed universe has a finite spatial volume. That's all it means.
Does this not have any implications for a theory of time/beginning?
 
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PeterDonis
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Does this not have any implications for a theory of time/beginning?
If you mean, implications that a model with a spatially infinite universe does not have, no.
 
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PeterDonis
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It was a debate about Carols cosmological models in relation to religion and philosophy.
Yes, as I said, a debate about philosophy/religion, not physics. The fact that cosmological models were discussed doesn't make it a debate about physics. It just means the debaters thought those models were relevant to the philosophy/religion being discussed.
 
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Let me explain what I mean; is finite spatial volume neutral with regards to contigency of an existing universe? That is a universe which exists but didn't need to exist/didn't always exist?

Could you really make a case for a past eternal cosmological model with an infinite spatial volume?
 
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If you mean, implications that a model with a spatially infinite universe does not have, no.
I don't see how a block theory of time is conceptually compatible with infinite volume. The analogy of a block only makes sense if it is of finite scope, which a block is, and in this case contains all events of the universe, and is the universe.
 
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PeterDonis
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is finite spatial volume neutral with regards to contigency of an existing universe? That is a universe which exists but didn't need to exist/didn't always exist?
"Needs to exist" is a philosophical question, not a scientific question. There's no scientific way to test whether the universe "needs to exist".

didn't always exist?
Whether or not the universe had a beginning in time is potentially testable, but we have not yet figured out how to test it and get a conclusive answer either way. Our best current models are compatible with both possibilities.

Could you really make a case for a past eternal cosmological model with an infinite spatial volume?
Of course. Mathematical models with this property already exist, such as de Sitter spacetime.

The analogy of a block only makes sense if it is of finite scope
First, analogy is not science.

Second, you are getting too hung up on the word "block". It doesn't mean a literal block of finite size. It's just a metaphorical description. As I've already said, it is perfectly possible to have a "block universe" model that extends infinitely in both space and time; indeed, the original "block universe" model, based on the Minkowski spacetime of special relativity, has exactly this property.
 
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Of course. Mathematical models with this property already exist, such as de Sitter spacetime.
First, analogy is not science.

Second, you are getting too hung up on the word "block". It doesn't mean a literal block of finite size. It's just a metaphorical description
A metaphor which does not fit the description nullifies the hole point of the metaphor. But anyway, that would lead you to a model of both eternity and infinity. Emanuel Kant, who I'm sure you know made several accurate cosmological inferences long before they could be verified, posited that the notion of both the infinite and eternally existing is not operationally possible, since it would take an eternity to reach "Now" or the present. Some claim others had made that inference before Kant, though.
 
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  • #20
PeterDonis
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A metaphor which does not fit the description nullifies the hole point of the metaphor.
Then go and convince all the physicists and philosophers who use the term "block universe" that they are using it wrong. Good luck.

Emanuel Kant
Was a philosopher, not a physicist.

who I'm sure you know made several accurate cosmological inferences long before they could be verified
Really? Which ones? Please give a reference.
 
  • #21
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Really? Which ones? Please give a reference.
Nebular hypothesis
https://en.m.wikipedia.org/wiki/Nebular_hypothesis

The theory was developed by Immanuel Kant and published in his Allgemeine Naturgeschichte und Theorie des Himmels("Universal Natural History and Theory of the Heavens"), published in 1755 and then modified in 1796 by Pierre Laplace. Originally applied to the Solar System, the process of planetary system formation is now thought to be at work throughout the universe.

Despite being a well-known Philosopher, his early works focused more on geology, astronomy, and physics. In his 1755 work, “The Universal Natural History and Theories of the Heavens,” Kant talks about astronomy and two noteworthy theories about the Heavens. The first is his “Nebular Hypothesis” on star and planetary formations, where he theorized that thin, dim clouds of dust and gas out in the cosmos would collapse in on themselves under the force of gravity, causing them to spin to form a disk. From this spinning disk, stars and planets would form, and from this type of formation, the rotation of Earth and the other planets would be explained.

Unlike the earlier great German philosophers, such as Gottfried Wilhelm Leibniz, Kant was not a mathematician in any way, shape, or form, so his nebular hypothesis was not given a mathematical equation until a French mathematician by the name of Pierre-Simon Laplace looked over Kant’s theory and figured it out. Ultimately, his theory became the well accepted model of star and planet formation. Today, we can even see this happening in stellar nurseries like the Orion Molecular Cloud. Despite this, some astronomy textbooks give the credit of the Nebular Hypothesis to Laplace only, and not the Kant-Laplace theory.

https://futurism.com/kant
 
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  • #22
PeterDonis
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Nebular hypothesis
As a very vague and general hypothesis about planetary system formation, which has since been greatly refined and modified in order to produce actual models that can be tested against data, yes. But you said "accurate cosmological inferences", which is going way beyond the facts.

In any case, the argument that Kant happened to get one thing right, therefore some other thing he said must also be right, is several different kinds of logical fallacy, so it carries no weight here.
 
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  • #23
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In any case, the argument that Kant happened to get one thing right, therefore some other thing he said must also be right, is several different kinds of logical fallacy, so it carries no weight here.
I can't be at fault with logical fallacies having never made an inference. You were the one referencing mathematical models by physicists as some kind of proof of internal consistency. It does not prove that the models works simply because a physicist formulated it.

Some modern-day physicists gross misuse of probability theory when it comes to cosmology is not to be overlooked and should cast serious doubt over the field as a hole. Although a theory of the world does not necessarily hinge upon getting probability theory right, it shows that their minds are susceptible to mental short-cuts.

I would like to label below as confessions of a statistican:

The sheer amount of things they know is amazing and the finely tuned intuition about physical reality with which they home in on the right answer despite getting logico-mathematical arguments usually wrong is amazing too.

Oh, heck, I can't resist taking a turn around the ring. Part of the reason theoretical physicists hallucinate power-law distributions and say bizarre things about Fisher informationand flat-out wrong things about compression algorithms is that we learn nothing about statistical inference or information theory. Part of the reason for that is that we actually learn very little probability theory, even those of us in statistical mechanics. Gill again:


I attended a fascinating advanced physics course on thermal and statistical physics and was amazed how one time the lecturer wasted half an hour (of his precious 2 times 3/4) by not being able to use standard (and basic) ideas from measure theory or differential geometry in order to explain concisely what he means by a uniform distribution on a curved manifold...the students are bright and realise something is being hidden from them. The lecturer is certainly not daft either, so it is really strange...
There are few mathematical topics that are as badly taught to physicists as probability theory. Maxwell, Boltzmann and Gibbs were using probabilistic methods long before the subject was properly established as mathematics. Their language, of ensembles, complexions, fluctuations and most probable state, are still used. When quantum theory came along, the same notions were fitted into the new theory, sometimes leading to confusion.

http://bactra.org/weblog/297.html
 
  • #24
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Perhaps Kant stole it from this guy:

Bonaventure showed that it is impossible to both add to an infinite number and to pass through an infinite series. For if the universe is eternal (with infinite events), then present events would be adding to the infinite number of past events. But the infinite cannot be added since to since it is already infinite. Also, if the universe is eternal (and infinite) then one could never reach the present moment since one would have to pass through an infinite series of past events to arrive at the present. This is impossible due to the fact that no matter how many past events are crossed, there will always be an infinite number more to pass through before the present moment can be reached.

https://books.google.se/books?id=oa...el kant eternity to reach the present&f=false
 
  • #25
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As a very vague and general hypothesis about planetary system formation, which has since been greatly refined and modified in order to produce actual models that can be tested against data, yes.
Unlike String Theory, right?
 
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