[Colin2B]

Starting everything at the BB, or any specific point, involves the something-from-nothing problem.

I think that’s why flummoxed was specific in saying ‘visible universe’; you could also call it the current universe, so no  something from nothing needed.
You need to be clear about what you mean by ‘the universe’.

Multiple, bouncing or otherwise repeating universes, run into "Turtles-all-the-way-down" problem.
What about an infinite, eternal, changeless cosmos, of which our Universe is a 3+1D "shadow". No creation from nothing, no infinite regression!   

To be honest it still doesn’t answer the question whether our something could emerge from nothing, or even what we might mean by that nothing.
We've had lots of debates on this and they generally go nowhere because none of us have a deep enough knowledge of the physics involved to make a reasonable contribution. Infinite debate 

[pensador]

Starting everything at the BB, or any specific point, involves the something-from-nothing problem.
Multiple, bouncing or otherwise repeating universes, run into "Turtles-all-the-way-down" problem.
What about an infinite, eternal, changeless cosmos, of which our Universe is a 3+1D "shadow". No creation from nothing, no infinite regression! 

No one was around in the big bang, to see it happen, it is not beyond the realms of possibility that it did not happen as described in the various models. You raise an extra dimension, is that like a collapsed dimension in a black hole, an unfolded dimension in string theory or a membrane connecting all points in space. We could live inside a BH with an extra dimension Podolsky russian guy.

Can you expand on what you mean.

Zero point energy of the vacuum, and gets around the laws of thermodynamics by only borrowing momentarily the energy then giving straight back.  BUT

[pensador]

We've had lots of debates on this and they generally go nowhere because none of us have a deep enough knowledge of the physics involved to make a reasonable contribution. Infinite debate

I learn a lot by speculating. I find in many instances some one theoretically clever has already had the idea. 

[Bill S]

You need to be clear about what you mean by ‘the universe’.

Using the “Universe, universe, cosmos” distinction is an attempt at clarity.  Here, I said “everything”, as I thought that might avoid confusion arising from interpretations of “universe”.  What could there be that is not included in “everything”?

To be honest it still doesn’t answer the question whether our something could emerge from nothing…

Of course it doesn’t, but it does remove the need to ask the question in the first place.

…, or even what we might mean by that nothing……. none of us have a deep enough knowledge of the physics involved to make a reasonable contribution. 

Surely, if physics is involved, we are already talking about “something”.  How would you define “the physics of nothing” without treating “nothing” as “something”? 
This is not just a facetious question.  Discussing “nothingness” or “infinity” does tend to cause heads to be firmly inserted up semantic arses, which is unfortunate.  As you rightly say: "Infinite debate".

[Bill S]

No one was around in the big bang, to see it happen, it is not beyond the realms of possibility that it did not happen as described in the various models.

That’s why they are models, not dogmatic statements.

You raise an extra dimension, is that like a collapsed dimension in a black hole, an unfolded dimension in string theory or a membrane connecting all points in space.

Nothing so complex; just 3 of space + time.

Can you expand on what you mean.

If you mean “The Infinite Cosmos”,  I’ll have to come back to you on that.

[pensador]

Discussing “nothingness” or “infinity” does tend to cause heads to be firm

This is an interesting philosophical statement, infinite (unfolded space time dimensions) + nothing (none space time dimensions ) could exist at the same time. Space does appear to be expanding between galaxies, and perhaps contracting near mass in some way causing the curvature of space time.

[Bill S]

Can you expand on what you mean.

Can we try an experiment?

I Posted the following some months ago, and got no response.  I’d like to try it from a different perspective.  Patience, please.  The idea is to look at the logic, or otherwise, of the whole line of reasoning.

Start be assuming that statements 1 – 4 are correct.  Their veracity can be demolished later!

For the moment, forget about mathematics, we can come to that later.

1. Something must always have existed.  Let’s call that “something” the cosmos.
2. The cosmos (everything that is, or ever can be) is infinite, unchanging and indivisible.
3. If the cosmos is indivisible; everything that we might consider as a part of the cosmos, is the cosmos.
4. The Universe (that which we perceive as starting at the BB) is “embedded” in the cosmos.

By the above reasoning, we must say that the Universe “is the cosmos”.
The only way in which this reasoning could be logically consistent would be if the Universe were a “shadow” of the cosmos.  (Think of the analogy of the people in a cave who could see only shadows on the wall).
Time, change and progression are features of this “shadow” reality.  They have meaning only in our perceived Universe.
It might be argued, from this, that our Universe is an illusion, but this has no real significance, because this illusion, is our reality.  It is all we are able to observe and study.  This, of course, is where we would re-introduce maths; and start questioning the initial statements.

[pensador]

By the above reasoning, we must say that the Universe “is the cosmos”.
The only way in which this reasoning could be logically consistent would be if the Universe were a “shadow” of the cosmos.  (Think of the analogy of the people in a cave who could see only shadows on the wall).
Time, change and progression are features of this “shadow” reality.  They have meaning only in our perceived Universe.

I accept your definition that the entire physical universe is this cosmos, it follows that the observable universe is a part of the cosmos. How does this reasoning lead to an illusion.

The analogy to shadows on wall implies 3 or more dimensions, being projected onto a 2D surface. Dimensions dont have to be spacial, take maybe time for instance, or maybe membranes or worm holes through space time. How would they appear reflected on a wall??

[Bill S]

Start be assuming that statements 1 – 4 are correct.  Their veracity can be demolished later!

I'm not suggesting that anyone should actually accept these statements, other than as a test of the logic, IF they were correct.

[Halc]

Start be assuming that statements 1 – 4 are correct.  Their veracity can be demolished later!

For the moment, forget about mathematics, we can come to that later.

1. Something must always have existed.  Let’s call that “something” the cosmos.
2. The cosmos (everything that is, or ever can be) is infinite, unchanging and indivisible.
3. If the cosmos is indivisible; everything that we might consider as a part of the cosmos, is the cosmos.
4. The Universe (that which we perceive as starting at the BB) is “embedded” in the cosmos.

I will ignore the fact that I have issues with the statements.
1 and 2 seem mutually contradictory.  1 defines cosmos not as 'all there is', but as something that has always existed, implying my mailbox is not part of the cosmos because it was created only 8 years ago.  I think #1 just needs to be worded more carefully.

By the above reasoning, we must say that the Universe “is the cosmos”.
The only way in which this reasoning could be logically consistent would be if the Universe were a “shadow” of the cosmos.  (Think of the analogy of the people in a cave who could see only shadows on the wall).
Time, change and progression are features of this “shadow” reality.  They have meaning only in our perceived Universe.

If time is a feature of this shadow reality, then time is not fundamental to the cosmos, in which case point 1 cannot have a reference to time.  By the usage of past tense, you imply a statement that there is not a time in which this thing did not exist, but if time is only part of the shadow reality started at the BB, then it is meaningless to reference times of the existence of the cosmos.  It's like drawing a graph on a computer screen and then asking for the x/y coordinates of the computer on that graph.

BTW, I've never seen 'cosmos' used as a synonym for a container for the universe.  I'm more likely to see universe as the container, and say 'inflation bubble' as all that 'started' and continues from the big bang.  Inflation bubble is still arbitrarily larger than 'visible universe'.  I'm fine with the nonstandard terminology, but find it unintuitive.

[RobC]

I recollect the words of John Wheeler, he concluded:

Can we ever expect to understand existence?
Clues we have and work to do, to make headway on that issue.

Surely someday, we will grasp the central idea of it all as so simple, so beautiful, so compelling that we will all say to each other, “Oh, how could it have been otherwise! How could we all have been so blind so long”!

[Bill S]

I accept your definition that the entire physical universe is this cosmos, it follows that the observable universe is a part of the cosmos. How does this reasoning lead to an illusion.

Try “accepting”:  2. “The cosmos (everything that is, or ever can be) is infinite, unchanging and indivisible.”
Think about the unchanging and indivisible aspect of the cosmos, and compare that with the obviously changing and divisible nature of the Universe.  Then ask how one could be “part” of the other.

[Colin2B]

Try “accepting”:  2. “The cosmos (everything that is, or ever can be) is infinite, unchanging and indivisible.”
Think about the unchanging and indivisible aspect of the cosmos, and compare that with the obviously changing and divisible nature of the Universe.  Then ask how one could be “part” of the other.

So you’re saying that people, plants, planets etc can’t be part of the ‘cosmos’ because they change?

Why do you think the ‘cosmos’ you’ve defined is unchanging? Experience says otherwise.

[Bill S]

I will ignore the fact that I have issues with the statements.

Thanks for doing that.  I have issues with the statements, as well.  Over a considerable number of years, I’ve reached a degree of satisfaction with a lot of these, but there are still a few to go. That’s what I’m trying to work on now.

.  I think #1 just needs to be worded more carefully

I would be very happy to consider rewording (I’ve done it several times, already) as long as the meaning remains, essentially, the same.  Is it “Something must always have existed” that causes problems? 
The concept it is meant to convey is:  There can never have been “nothing”, therefore, there must always have been “something”.  Do you have issues with that?

[Bill S]

Why do you think the ‘cosmos’ you’ve defined is unchanging? Experience says otherwise.

I think (hope) we may be working towards that, but, if not, don't let me overlook it.  It's an important point, but can lead down a lot of "blind alleys". 

[Bill S]

Surely someday, we will grasp the central idea of it all as so simple, so beautiful, so compelling that we will all say to each other, “Oh, how could it have been otherwise! How could we all have been so blind so long”!

Good thought, but I think I can confidently predict that I’ll not be around to see it.

[Halc]

.  I think #1 just needs to be worded more carefully

I would be very happy to consider rewording (I’ve done it several times, already) as long as the meaning remains, essentially, the same.  Is it “Something must always have existed” that causes problems?

That wording makes it sound like the cosmos is just one of a collection of things, one that has always existed, unlike some of the others.
This contrasted with number 2 that defined cosmos differently, as 'all that is', precluding these other things.

The change of verb tense is also inconsistent between the two.

[Bill S]

By the usage of past tense, you imply a statement that there is not a time in which this thing did not exist, but if time is only part of the shadow reality started at the BB, then it is meaningless to reference times of the existence of the cosmos.

Nice one, HalC!  You’ve hit the two problems that so often lead to circular arguments that never go anywhere.

Problem 1:  The only language we have in which to talk about infinity, is our finite-based language. 

Problem 2:  If the cosmos is changeless and indivisible; how can the changing Universe be part of it?  More fundamentally, how can anything be part of it, if it is indivisible?

Does problem 2 equate, in any way, to the reasoning in your quote, above?

1 and 2 seem mutually contradictory.  1 defines cosmos not as 'all there is', but as something that has always existed, implying my mailbox is not part of the cosmos because it was created only 8 years ago.

I think this is a matter of interpretation. 1 asserts that there must always have been something.  2 qualifies this by saying something about this “eternal something”.  Neither implies that your mailbox is not part of the cosmos.

Of course, using any tense, other than the “present indicative”, when referring to eternity is inappropriate, but just saying “Something is”, might well be interpreted as being different from saying “Something has always existed”.  Any suggestions for de-confusing it?

I’m not a great fan of John Gribbin, but I find that his terminology, in this case, can be useful, reduce verbosity.

Cosmos = everything that exists, or can exist.
Universe = our (in principle) observable portion of spacetime and its contents.
universe = any other universe that may, or may not, exist.

See https://www.thenakedscientists.com/forum/index.php?topic=73511.msg548859#msg548859 #107.

[Halc]

By the usage of past tense, you imply a statement that there is not a time in which this thing did not exist, but if time is only part of the shadow reality started at the BB, then it is meaningless to reference times of the existence of the cosmos.

Nice one, HalC!  You’ve hit the two problems that so often lead to circular arguments that never go anywhere.

Problem 1:  The only language we have in which to talk about infinity, is our finite-based language.

The mixing of tenses is unrelated to discussions about infinity.  There is a language for it, but it needs to be used correctly.  So saying that the 'cosmos is infinite' is a vague statement that there is some property of said cosmos that is not bounded, but without identification of the property in question.

Problem 2:  If the cosmos is changeless and indivisible; how can the changing Universe be part of it?  More fundamentally, how can anything be part of it, if it is indivisible?

Yes, your prior posts identified this problem.
 The statement asserts both that the cosmos exists in time and that it is in identical state at any pair of different times.  I find both assertions hard to defend, but you said not to worry about the veracity of the statements, so I didn't comment on it.  That problem is easily solved by putting time in the structure and not the structure in time.  The latter violates the cosmos being all there is: The cosmos and time are two things.  Three if you posit space that it occupies.

Does problem 2 equate, in any way, to the reasoning in your quote, above?

I think so yes.  Your problem 2 used wording implying time as a container for 'comsos', and my problem that you quote above talks about exactly that as well.  If cosmos is all there is, it cannot be in a container. Can't have it both ways, or you'll just keep running into these contradictions.

Mind you, I think I've found a solution to all these problems, but it's kind of a long journey where you need to choose compatible interpretations of time, mind, QM, and identity.  Don't need to understand them all, but you need to be aware of their respective implications.

1 and 2 seem mutually contradictory.  1 defines cosmos not as 'all there is', but as something that has always existed, implying my mailbox is not part of the cosmos because it was created only 8 years ago.

I think this is a matter of interpretation. 1 asserts that there must always have been something.  2 qualifies this by saying something about this “eternal something”.  Neither implies that your mailbox is not part of the cosmos.

By 'eternal', do you mean 'for all of time' (the cosmos being contained in unbounded time), or do you mean eternalism/block-universe/time being part of (contained by) the cosmos or parts of it?
If the former, you're on your own, because it demotes cosmos to an object within a larger thing.
If the latter, you cannot meaningfully use tensed verbs when discussing things, which is why I jumped all over the switching of verb tense.

Of course, using any tense, other than the “present indicative”, when referring to eternity is inappropriate, but just saying “Something is”, might well be interpreted as being different from saying “Something has always existed”.  Any suggestions for de-confusing it?

I say 'something is'.  Giving a reference to a preferred moment in time that doesn't exist under the view always leads to confusion.  There is no 'the past' in the view, so the dinosaurs exist as much as anything.  They're not in a state of 'existed', except in a relation to a specifically identified time in their future.

Cosmos = everything that exists, or can exist.
Universe = our (in principle) observable portion of spacetime and its contents.
universe = any other universe that may, or may not, exist.

As for Universe, the line isn't very abrupt.  It sort of fades away.  Sure, we have theoretical information on stuff 45 BLY away (depending how you measure it), but that doesn't mean planet X exists just because it's within that radius. Not if we cannot have knowledge of it. This gets into the sort of issues that come up with QM interpretations.  Some of them very much do say that X exists, despite our lack of knowledge of it.

[Bill S]

Thanks for that interesting post. There’s a lot in it I would like to return to, but time’s short. 

I must comment on one point, though.

By 'eternal', do you mean 'for all of time' (the cosmos being contained in unbounded time),

No! Eternity is not time.  The cosmos is not contained in anything.  In what way does "eternal" imply containment in anything?

If the former, you're on your own, because it demotes cosmos to an object within a larger thing.

I would be interested to see the process by which you reach that conclusion.