Big Bang Non-Locality: Evidence for an Infinite Universe?

[Irishwake]

As I understand it the big bang happened "everywhere". It was not an explosion of matter, but a rapid and accelerating expansion of the space between matter. This is overcome by local gravity (solar systems / galaxies).

If this assumption is correct, is there anything preventing or any theory supporting the fact that the universe is in fact infinite and we just can't see beyond 13.7bya?

Perhaps there were an infinite number of galaxies that existed before our local big bang, they just exist outside our visible portion of the universe. What proof do we have supporting an edge of the universe other than "we can't see that far... yet".

This really bugs me. I'd prefer to just think the universe is infinite, because even if it isn't there's one of three things -

1) Nothing
2) Empty Space (something)
3) Other Universes

- outside our universe and it seems like more of a reality (cautious use of this word, heh) that we just can't see the rest of the universe. It seems logical to think that the radiation we interpret as the CMB is from distant stars/galaxies that lie beyond our visible portion of the universe that existed before our local "big bang".

You can tell a few things here, and this probably stems from my ignorance on the subject; but I don't like a finite universe and I don't like the BBT as a theory of the "birth of the entire universe" but rather a theory of the "rapid expansion of localized space."

 

[phinds]

All interesting stuff and all has been discussed here ad infinitum, so while I normally chime in on these discussions, I'm just not up for doing it for the umpteenth time again, but I DO want to comment on one of your statements.

The possibility that the universe is finite does NOT lead, necessarily, to one of the 3 things you listed. It is possible to have a finite but unbounded universe with no "outside", no other universes, etc.

 

[Irishwake]

Thanks phinds, you always seem to find my threads haha.

The possibility that the universe is finite does NOT lead, necessarily, to one of the 3 things you listed. It is possible to have a finite but unbounded universe with no "outside", no other universes, etc.

This however, was precisely what I meant by scenario #1, although I didn't word it as clearly as you did.

 

[phinds]

Thanks phinds, you always seem to find my threads haha.



This however, was precisely what I meant by scenario #1, although I didn't word it as clearly as you did.

Ah ... got it. "Nothing" was shorthand for "there would be nothing outside the universe", so we agree.

 

[Radrook]

No location and no bounderies delineating its form and yet it really exists?
Perplexingly and paradoxically fascinating!

 

[morningstar]

Perhaps our universe is the result of another universe's collapsing star or primordial black hole, and every black hole in our universe is the possibility of yet another universe- filled with untold more universes. Maybe the black holes themselves are acting as drains for space- from older universes to newer universes; and the whole magnificent creation is wilting from the outside in. That would leave you with the possibility of a finite universe in a potentially infinite system of universes. And that would be much more exciting than an infinite universe in the context that you describe because each universe could have different laws pending its fundamental material and energy- you could have entirely different types of beings, e.g. beings that resembled different types of energy, different than meat (like us).

Sorry for rambling, sounded like you needed something to chew on!

 

[Chronos]

There is no entirely satisfactory answer to the question. Each plausible answer has its own merits and demerits. In astrophysics, scientists prefer observables, so talk of other unobservable universes is unappealing until and unless supported by observation. Perhaps there are other universe, but, are completely cut off from any evidence of their existence in our universe. That means, of course, they are forever cut off from serious scientific inquiry. Observables do, however, tell us the CMB is not starlight. The CMB has a perfect black body spectrum, starlight does not.

 

[Irishwake]

Sorry for rambling, sounded like you needed something to chew on!

Heh yeah, I just like reading other peoples thoughts on the subject.

The CMB has a perfect black body spectrum, starlight does not.

Thanks for that, I knew someone would know the answer.

 

[Drakkith]

No location and no bounderies delineating its form and yet it really exists?
Perplexingly and paradoxically fascinating!

What are you referring to?

And that would be much more exciting than an infinite universe in the context that you describe because each universe could have different laws pending its fundamental material and energy- you could have entirely different types of beings, e.g. beings that resembled different types of energy, different than meat (like us).

Sorry for rambling, sounded like you needed something to chew on!

What is there to chew on? There's literally no way to observe any of it, gather any data, or anything. I'd say its the definition of starvation. Also, energy is not a "thing". You cannot make something out of it.

 

[Haelfix]

There is no entirely satisfactory answer to the question. Each plausible answer has its own merits and demerits. In astrophysics, scientists prefer observables, so talk of other unobservable universes is unappealing until and unless supported by observation. Perhaps there are other universe, but, are completely cut off from any evidence of their existence in our universe. That means, of course, they are forever cut off from serious scientific inquiry. Observables do, however, tell us the CMB is not starlight. The CMB has a perfect black body spectrum, starlight does not.

The immense majority of theories are formulated in some local causal patch. There is nothing preventing other inflationary bubbles from existing elsewere, however since they are completely decoupled from any sort of observable in our local patch, they can be for the most part safely ignored. Of course if you ask most physicists if they actually believe in their existence, I think you would see that most people answer in the affirmative. It's more a question about the topology of the universe then anything else.

Now, that is not entirely true either! There are classes of models where a multiverse is required, and that give testable predictions within our local patch... Eternal inflation and many of its subclass are the most famous, but far from the only ones.

 

[Chronos]

Without observables I think the multiverse idea lacks scientific merit, despite its logical appeal. I reserve the right to alter my opinion if and when sound observational support is offered.

 

[Haelfix]

Yes but my point is that typically there are local observables for most of these multiverse proposals.
There are the generic ones (eg look for bubble collisions, domain walls etc) that could occur in any multiverse theory, and then there are the nongeneric ones which have to do with the exact form and shape of the inflaton and its consequences on the CMB.

As usual, the inverse problem is large here, but nevertheless whole swaths of these models have been falsified before (the phi^4 chaotic inflation model is more or less dead for instance)

 

[JonDE]

Without observables I think the multiverse idea lacks scientific merit, despite its logical appeal. I reserve the right to alter my opinion if and when sound observational support is offered.

I'm most definately not saying you are wrong. Obviously any good theory should have some sort of proof or observation to go with it.
But, isn't the idea of the multiverse, the going explanation as of now? Or am I mistaken in that?

 

[Drakkith]

But, isn't the idea of the multiverse, the going explanation as of now?

No, the only fully accepted model is the standard model which only describes our own universe.

 

[Radrook]

What are you referring to?

I am referring to the concept of an all-inclusive, infinite, boundless universe as described by someone else on this thread.

 

[JonDE]

No, the only fully accepted model is the standard model which only describes our own universe.

I guess my confusion lies from being told that many worlds interpretation is accepted in quantum mechanics, and that no one really takes the Copenhagen interpretation seriously. Do you know if this is accurate? Can you have MWI without a multiverse? I don't really understand how, but wouldn't be the first thing i didn't understand.

 

[Drakkith]

I guess my confusion lies from being told that many worlds interpretation is accepted in quantum mechanics, and that no one really takes the Copenhagen interpretation seriously. Do you know if this is accurate?

I don't think that either interpretation is taken more or less seriously by a majority of people within QM. And even if it was, that means nothing, as an interpretation is not the same thing as a model or theory. There is quite literally NO evidence of any other universe other than our own. The MWI of QM is just that, an interpretation. The actual math and models used do not differentiate between the different interpretations as far as I know. Someone correct me if I'm wrong.

Can you have MWI without a multiverse? I don't really understand how, but wouldn't be the first thing i didn't understand.

Well, I can't say much on the details, but realize that Quantum Mechanics is not a model of the Universe like the BBT is. The Big Bang Theory is a model of the history of the Universe and how it got to it's present condition. The BBT uses other theories to describe HOW this happened, one of the main ones being General Relativity. QM is required to explain various things withing the BBT, such as how stars generate their power. However the interpretations of QM do not match up with different models of the Universe when it comes to cosmology.