The Big Bang... Just a Thought


by Randomtask94
Tags: bang
Randomtask94
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Apr4-13, 05:23 PM
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Ok so, I'm no astrophysicist (I'm only a High School senior, but I have a decent knowledge of Physics and I plan on studying Physics at Purdue University starting in the fall), but let me start...

The Big Bang theory says that the universe began as a singularity (or close enough to one if it wasn't exactly one point) and then suddenly erupted outward (Depending on the expansion rate that one would consider "correct". Although support can't necessarily be shown to favor either side more.), yes? Please do correct any errors in this, but either way that's that.

Now to Black Holes (stay with me because I'm looking for some input here); I've read Stephen Hawking's A Brief History of Time and his theories (more like hypotheses) state that black holes are basically singularities that absorb everything from electromagnetic radiation to matter. They also (these are Hawking's theories, if I understand them correctly), "spit-out" bits and pieces of matter (and corresponding anti-matter because of the Uncertainty Principle of Quantum Mechanics... I think that's the reason, but don't quote me on that). Eventually, again from Hawking's book, a Black Hole could "erupt" and all that pretty supernova-type junk.

My thought is this; Is it plausible that The Big Bang was actually just one massive Black Hole that erupted and created what we know as the universe, or at least our portion of it? If so, is it not also plausible that EVERY Black Hole is a potential "Big Bang" and in-effect a new portion of the universe? Thirdly, is it not also plausible that our Big Bang was only one "Bang" in a much larger picture of more "Bangs"? These "Bangs" could've begun ages (forgive my wording if that isn't technically a "large" enough time-span) ago and could be still happening is far off places of the universe. The only way I could see of having any support of this is looking for places in the universe where the matter is moving in different directions than the Big Bang Theory could explain, which doesn't seem too likely. But, like the title says, this is just a thought.

Any input? This is more of just a fun conversation to expand the mind than one meant to "prove" anything.

Feel free to correct any of my mistakes regarding Physics or anything of that nature because I'm still learning (Aren't we all?) and I'd prefer that it be pointed out than me continue to make the same mistake and not learn anything.

Thanks for reading :D
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phinds
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Apr4-13, 05:36 PM
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The singularity was not a point. "Singularity" means "the place where our theories/knowledge break down and we don't know WHAT is going on". The big bang singularity and black hole singularities are related in name only.

The thought of the big bang singularity being a black hole is shot down here a couple of times a month. Do a forum search.

By the way ... welcome to the forum. Sorry if I seem abrupt, but this question comes up freqently.
marcus
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Apr4-13, 08:26 PM
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Quote Quote by Randomtask94 View Post
Ok so, I'm no astrophysicist (I'm only a High School senior, but I have a decent knowledge of Physics and I plan on studying Physics at Purdue University starting in the fall), but let me start...
...
...
Is it plausible that The Big Bang was actually just one massive Black Hole that erupted and created what we know as the universe, or at least our portion of it? If so, is it not also plausible that EVERY Black Hole is a potential "Big Bang" and in-effect a new portion of the universe? ...

Any input? This is more of just a fun conversation to expand the mind than one meant to "prove" anything.

...
I think what you are talking about is quite plausible. The spitting out would rather be out the back door, so to speak, rather than back at us in our region of space. There is a school of thought that resolves the "singularity" or mathematical breakdown problem by having quantum effects at high density cause a BOUNCE.

So according to that quantized GR (geometry with quantum effects) theory the start of our own universe's expansion can be traced to a bounce from some earlier collapse.

This "quantum cosmology" approach has been getting a lot of attention from researchers. Here is a Stanford/SLAC database literature search with a lot of that kind of research paper
http://inspirehep.net/search?ln=en&a...=50&sc=0&of=hb

Anyway it certainly is, as you say, PLAUSIBLE, and respectable people have studied the idea and written research articles about it. But that doesn't mean it's RIGHT. For an idea to be science you have to be able to test it, with a fair chance of proving it wrong.

Some people think that one version of this black-hole-rebound-to-new-expanding-region idea has been falsified by finding neutron stars with larger mass than was originally predicted by that version of the idea. But that version failing that observational test does not carry over to other versions---so the ball is still in play. I heard the idea come up again in a different context just this past week.

Geometry is evidently dynamic and we humans don't yet have a very good understanding of what really happens in the pit of a black hole (including quantum effects) or of what happened around the start of our own cosmos' expansion (again including effects of very high density). The bounce idea has been getting increasing attention and people are trying to derive predictions that can be tested by future CMB observation like that of the Planck spacecraft. There's a lot more to be found out about what really happens instead of "singularities".

BTW congratulations on going to Purdue in Fall to study physics. You might have a good time.

Randomtask94
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Apr5-13, 11:23 AM
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The Big Bang... Just a Thought


No its fine phinds, I should've at least googled the idea first (duh... i feel stupid xD). I wasn't aware that it was a common idea. I"ll make sure I do better research before I fill the forums with more of the same questions.
And thanks marcus for taking the time to read my post and send back all that input. Thanks :3 I'm certain that it'll be a great experience :D
marcus
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Apr5-13, 05:20 PM
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Quote Quote by Randomtask94 View Post
...(duh... i feel stupid xD). I wasn't aware that it was a common idea...
This is not necessarily a case of "duh"
There are different versions of nonsingular cosmology, different bounce ideas, and even some other (non-bounce) ideas for resolving (getting rid of) the singularity.
Singularity, meaning breakdown of a manmade mathematical theory, is normally taken as a symptom that something is wrong with the model---i.e. equations being pushed into territory where they do not apply---that the theory needs fixing or replacement by a better theory.

I don't know what Phinds had in mind when he said (I think) that we at the forum had considered the bounce idea several times already and disposed of it (!) It certainly hasn't been rejected by the professional community---it's one of the most studied ways of curing the singularity and delving back in time to before start of expansion.

Sometimes you may not get the full or straight story by googling and you just need to ask your question in the appropriate forum and see what answers you get.
==============

BTW, at Purdue, as a physics major, you will surely take courses that include Thermodynamics and Statistical Mechanics. You seem interested in expansion cosmology, IOW largescale dynamic geometry. In my reading lately I'm increasingly seeing that geometry has temperature and geometry has entropy (but we don't yet have a satisfactory quantitative definition of the geometrical/gravitational entropy.) So my advice, if I may be so bold as to offer some, would be to get a good understanding of Thermodynamics (along with all the other physics stuff) because by the time you are Senior you might want to be applying it to universe. There are some puzzles, and that's always good
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Apr5-13, 05:39 PM
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Quote Quote by marcus View Post

I don't know what Phinds had in mind when he said (I think) that we at the forum had considered the bounce idea several times already and disposed of it (!)
I was talking about the idea that our universe came from a black hole, not the bounce theory.
marcus
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Apr5-13, 06:00 PM
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Quote Quote by phinds View Post
I was talking about the idea that our universe came from a black hole, not the bounce theory.
I see! so please refresh my memory: has that been ruled out? Did we, at Physicsforums, provide sound arguments that this is impossible and needn't be considered? Maybe you can give me a link to some posts.
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Apr5-13, 06:08 PM
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Quote Quote by marcus View Post
I see! so please refresh my memory: has that been ruled out? Did we, at Physicsforums, provide sound arguments that this is impossible and needn't be considered? Maybe you can give me a link to some posts.
Well, for starters, our universe has a singularity in the past, while if the universe were a black hole, it would have a singularity in the future...
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Apr5-13, 06:23 PM
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Quote Quote by cristo View Post
Well, for starters, our universe has a singularity in the past, while if the universe were a black hole, it would have a singularity in the future...
Hi Christo, here's the idea: in some versions of QG quantum effects at high density cause gravity to be repellent and if the collapse reaches an extremely high density (near Planck) there is a rebound, resulting in a new region of spacetime.
It's an old idea going back to John Archibald Wheeler and used by Smolin in a specialized variant of it called CNS (cosmic natural selection).

In that specialized variant there is another feature brought in, another key assumption made, but that is not to the point.

I don't recall seeing an airtight case made against the original J.A. Wheeler idea that at least some BHs can result in "baby universes".

Maybe it is not such an interesting idea! It is not one that's on my mind much these days. But has it actually been ruled out?
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Apr5-13, 06:35 PM
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Quote Quote by marcus View Post
I see! so please refresh my memory: has that been ruled out? Did we, at Physicsforums, provide sound arguments that this is impossible and needn't be considered? Maybe you can give me a link to some posts.
Well, you're here more than I am so if you don't remember it that way, I have to consider that perhaps I'm MIS-remembering it. I have always thought of the idea that our universe came from a black hole was just silly and I was sure that I had seen agreement with that point of view here several times, but I'd rather admit to a lapse in memory than try to track down the threads.
Mordred
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Apr5-13, 06:47 PM
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For interest of the OP. The model I believe they are referring to is a model supported by Poplowski. Its a model that involves torsion as the expansion factor generated by the inside of a BH. Where bubbles universes form.
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Apr5-13, 07:30 PM
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Quote Quote by phinds View Post
... the idea that our universe came from a black hole ...
Phinds, to a large extent I AGREE with you, at least on several points! I think the OP idea was basically just what you said that [somehow] our universe came from a black hole.
Honestly to tell the truth that idea DOES seem silly! The scale is all wrong.

But I can't remember that idea, in its simplest most general form, having been ruled out. I have the feeling that we have not seen the last of it.

I guess it goes back to circa 1970 at least. And it was picked up in the early 1990s by Smolin, who formulated it in terms of LQG. For him that was the mechanism by which the BH collapse bounced and led to inflation and subsequent expanding region separate from the region in which the BH formed. And Smolin's LQG version could be wrong and yet the general idea still survive.

Mordy, I'm not all that informed about this and I don't know the work by Poplawski you mentioned. But there must be quite a few versions of this general scenario.
It's not an especially active interest of mine at the moment, but if you give me some links to recent Poplawski articles relating to this BH-bounce-universe idea, I would be happy to look at them!
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Apr5-13, 08:26 PM
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And by the way, I'm very aware that the fact that I think something is silly had NO bearing on whether it's right or not
Mordred
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Apr5-13, 09:27 PM
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Heres one that that describes the torsion model.

http://arxiv.org/abs/1007.0587
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Apr5-13, 10:09 PM
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Quote Quote by Mordred View Post
Heres one that that describes the torsion model.

http://arxiv.org/abs/1007.0587
Thanks Mordy! I was not properly aware of this. Is there anyone you know around PF who has taken an interest (favorable or unfavorable)?
I see that it is a 5 page paper, that was published in Physics Letters B, and that it has 25 CITES.
Here is the record at Inspire:
http://inspirehep.net/record/860461?ln=en
Cosmology with torsion - an alternative to cosmic inflation
Abstract: We propose a simple scenario which explains why our Universe appears spatially flat, homogeneous and isotropic. We use the Einstein-Cartan-Kibble-Sciama (ECKS) theory of gravity which naturally extends general relativity to include the spin of matter. The torsion of spacetime generates gravitational repulsion in the early Universe filled with quarks and leptons, preventing the cosmological singularity: the Universe expands from a state of minimum but finite radius. We show that the dynamics of the closed Universe immediately after this state naturally solves the flatness and horizon problems in cosmology because of an extremely small and negative torsion density parameter, ΩS ≈−10−69. Thus the ECKS gravity provides a compelling alternative to speculative mechanisms of standard cosmic inflation. This scenario also suggests that the contraction of our Universe preceding the bounce at the minimum radius may correspond to the dynamics of matter inside a collapsing black hole existing in another universe, which could explain the origin of the Big Bang.

I see that 12 of the 25 cites were by Poplawski himself in his subsequent papers. One of his followup papers is this, which already has 12 cites:
http://inspirehep.net/record/946770?ln=en
Nonsingular, big-bounce cosmology from spinor-torsion coupling
Nikodem J. Poplawski (Indiana U.)
Nov 2011 - 4 pages
Phys.Rev. D85 (2012) 107502
Abstract: The Einstein-Cartan-Sciama-Kibble theory of gravity removes the constraint of general relativity that the affine connection be symmetric by regarding its antisymmetric part, the torsion tensor, as a dynamical variable. The minimal coupling between the torsion tensor and Dirac spinors generates a spin-spin interaction which is significant in fermionic matter at extremely high densities. We show that such an interaction averts the unphysical big-bang singularity, replacing it with a cusp-like bounce at a finite minimum scale factor, before which the Universe was contracting. This scenario also explains why the present Universe at largest scales appears spatially flat, homogeneous and isotropic.

Called to supper, have to go...
...Back now.
Of the 12 cites of the more recent (2012) paper only FOUR were self-cites. So 8 were by other author(s). By my standards this is pretty good. The paper has only been out some 16 months.
So on average other author(s) are citing it every couple of months.
And one must confess that there is no definite reliable meaning to these quantitative measures, but I make them anyway in addition to other ways of evaluating research.
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Apr5-13, 10:36 PM
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Quote Quote by marcus View Post
Hi Christo, here's the idea: in some versions of QG quantum effects at high density cause gravity to be repellent and if the collapse reaches an extremely high density (near Planck) there is a rebound, resulting in a new region of spacetime.
It's an old idea going back to John Archibald Wheeler and used by Smolin in a specialized variant of it called CNS (cosmic natural selection).
Interesting. I'm not an expert in quantum gravity, and am not familiar with the work that you mention, but was more answering the question from a classical point of view where, for example, a black hole is defined as a Schwarzschild, Kerr (etc) solution of GR.

Quote Quote by Mordred View Post
Heres one that that describes the torsion model.

http://arxiv.org/abs/1007.0587
Again, interesting work, but for the sake of the OP and others, it should be noted that this is highly speculative. First, it relies on Einstein-Cartan gravity, which is a modification to our currently accepted theory of gravity (general relativity). Is there any evidence for gravity with torsion; any observation that favours a torsionful gravity? But secondly, from glancing through that paper, the technicalities are derived assuming a closed FLRW solution, and only in the discussion does the author mention how this is somehow hidden inside the event horizon of a black hole.
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Apr5-13, 11:00 PM
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Just to be clear I dont advocate Poplowki. For several of the reasons you mentioned.
I came upon it in another thread found it interesting in some of the torsion spin modelling.
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Apr5-13, 11:49 PM
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Quote Quote by Mordred View Post
Just to be clear I dont advocate Poplowki. For several of the reasons you mentioned.
I came upon it in another thread found it interesting in some of the torsion spin modelling.
Thanks for spotting it and pointing it out to me! Cristo is on target about speculative. But at this point just about every approach is, that gets rid of the cosmological singularity.
Quote Quote by phinds View Post
... had NO bearing on whether it's right or not
I think I learn from other people's intuitive feelings, including yours. I kind of gather an aggregate sense of the group mind and it may have SOME bearing, if not a lot. And sure it is not reliable but it helps judge the odds. So I hope that smiley means you are speaking lightly and not with fully solemnity
At some level all we have is our own and other people's hunches about the future promise of certain research.

Do you have any impression regarding this Poplawski gambit? It's new to me, somehow I didn't register it earlier.


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