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I see a "this article does not cite any sources" template header at the top of the page, but at the bottom it gives both book referances and "see also" links. —Preceding unsigned comment added by 188.8.131.52 (talk) 13:10, 18 October 2007 (UTC)
When was this model first proposed?
Could you include some history of this theory? Your references point to recent developments, but who first came up with the model and when? Thanks. Tanyushka 09:15, 2 November 2007 (UTC)
From the article:
- Also, the collapse into a singularity would destroy most of the information in the previous universe.
As the article says earlier:
- However, research in loop quantum cosmology purported to show that a previously existing universe collapsed, not to the point of singularity, but to a point before that where the quantum effects of gravity become so strongly repulsive that the universe rebounds back out, forming a new branch. Throughout this collapse and bounce, the evolution is unitary.
So, there is no singularity.
And partial information loss is explained by a new uncertainty principle, as the article also explains.
So, this objection is an argument from an incorrect premise to an irrelevant conclusion.
-I agree with you, and I also disagree with this statement: "Another main objection is that a Big Bounce would reverse entropy by resetting the state of the universe, violating the second law of thermodynamics"
How does a collapsing universe violate the second law? If the universe returns to its original state, then the total entropy equals zero and does not violate the second law. This is demonstrated in a carnot cycle, which also returns to its original state, giving a total entropy of zero. The second law is not violated if the entropy is zero or positive. —Preceding unsigned comment added by 184.108.40.206 (talk) 14:28, 5 March 2010 (UTC)
- I think the issue at hand is the fact the second law does not allow the entropy change to be negative. That is, the entropy can be (and is) positive, or zero (as a singularity, like before the Big Bang), but once it reaches a certain point, it can never be lowered in value. That's why the Carnot cycle will always remain theoretical.
But, though I'm just an amateur, this doesn't compute for me. Why would the entropy (state of disorder) be lowered? Intuitively? All the stellar bodies have already been formed; space would collapse in on itself, and the entropy/disorder within that space would be even greater than before, wouldn't it? Until it collapsed into a singularity? (Mrfour44 (talk) 05:35, 19 February 2012 (UTC))
As a general reader, I found this sentence: 'This suggests that we might be living in the first of all universes, but are equally likely to be living in the 2 billionth universe (or any of an infinite other sequential universes)' needed clarification: I didn't understand how with infinity there could be a 'first' universe. ZephyrAnycon (talk) 14:32, 13 January 2010 (UTC)
Reply by a random: I think there are two possibilities, we could only really be the second onward, as I don't think we'd have the required data for a theory if we were the first. Or, there can be no number, being infinite times it has happened, and we have no data to explain the origin/original/catalyst, or even know if there could/couldn't be one.
On another note, this theory would surely be the closest explanation we have for Déjà vu. Our brains are not powerful enough to form patterns of the future based on statistics and experience...so time is the only explanation... —Preceding unsigned comment added by 220.127.116.11 (talk) 01:59, 6 August 2010 (UTC) Awesome!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! BIG BOUNCE! Mother fucker Couldn't the Big Bounce theory potentially prove the existence of a Multiverse? If the universe expands and contracts and re-'Bangs' itself continuously, it wouldn't matter if we exist in universe one or one hundred billion. If time could be perceived as a whole, rather than linearly, then the universe will have created it self an infinite number of times at the same time.
Relevant new study that should be added to article?
A couple of months ago this article was published:
- Rovelli, Carlo; Francesca Vidotto (8 Feb 2014). "Planck Stars" (PDF). arXiv. 1401.6562v4: 1-6. Retrieved 4 June 2014.
and it was covered in popular media, at least here (and perhaps elsewhere):
- Moskvitch, Katia (14 March 2014). "Black Hole 'Information' Paradox May Have Been Resolved". Retrieved 4 June 2014.
This popular article states:
A similar idea [to the Big Bounce] has now been proposed for the fate of the collapsing matter of a dying star.Researchers say that quantum effects — similar to those that prevent an electron falling into the nucleus of an atom — would stop the collapse of a star before it could shrink to a single point, or singularity. The star would then become a super-compact object, bounce back during the evaporation process of the black hole and finally explode. Eventually, everything that would have fallen into the black hole would be released.
"If the idea [is confirmed] with more detailed calculations, it will be further evidence that what we call singularities in general relativity are just situations where our current theory lack predictability, but are resolved successfully by quantum gravity," he told Space.com via email. "At that point, the Big Bang or the center of black holes would not be 'the end of physics' but just another door to be disclosed, leading us to a quantum leap in understanding the nature of our universe."
Should this be added to the current WP page on "Big Bounce"? If so, I am hoping someone else can add it, as I am concerned I lack the needed expertise to add it properly. Please help. -- Presearch (talk) 18:36, 4 June 2014 (UTC)
Critique (or general lack thereof)
This article lacks any meaningful critique, certainly the recent evidence over the last two years showing an expaning visible Universe (at the shell of our point of view) suffices as a critique that the Universe may not be shrinking but be expanding. Another theory suggests that given time and an expanding Universe that the Higgs field and variations thereof would collapse and all the leptons would end up zipping away from their masses at the speed of light, a majority toward the horizon, causing baryons that are not in black holes to quickly follow them. I am not necessarily singling these ideas out as counter-proofs, just pointing out there are a variety of contentions that could be used as a critique.
The critical question is: since the smallest possible length is planck's length below which length cannot be defined and an energy density which infinitely cannot be defined, why is this a violation of 2nd law. Short of approaching this limit from higher values, quantum uncertainty is a bigger player than relativistic phenomena. The second law is therefore not violated since it is not pertninent to extremely small scales. The only thing that the second law argues that in our visible Universe the quantum effects spread over reasonable small space and time should end up governed by the laws of mass action each other. Since an undefinable level of energy can be infinite if the space in which the energy is constrained is so small it cannot be defined, one volume of space is 0 and anything divided by zero is infinity. If we are talking about infinite energy density then this is possible. In a creative singularity the 3 dimensions of space and Time merge into one a single point. Whereever that singularity is, that is the entire 'universe' and all its dimensions and in that context where is one time, during. Heisenberg uncertainty allows the appearance and disappearance of energy on very small scales, like ripples in space time. According to the inflaton logic, space time does not exist in the singularity, so what uncertainty allows or disallows in our space-time is no longer relevant. If we remember that uncertainty also allows the universe to move between here and there over Planck time scales, or to be at many places and noplace at once, therefore infinity at uncertainy could be X/0 or X/100....00 at the same instance. The only real contradication in this logic is that time begins when the initial state decays, but there is no logic why it comes to existence and since there is no time, there is no logic on how stable it was.
The essential logic here is that: Heisenberg uncertainty is not an assumption, its a fact. On what scales does our laws of mass action prevail and on what scales do quantum mechanics prevail. In answering this question the relevance of quantum mechanics in the birth of the Universe becomes evident. Once uncertainty is defined then is there are certain ratio of uncertainty to material observation that makes further analysis 'impossible', are we then stepping over the line?
From this lack of initial background state then one explanation seeks to contrast itself with the popular other.
The popular theory is that during the Planck Epoch quantum energy ultimately decayed into our universe (transitioned from a non-dimensional form to the form which now can be described with space time and various other universal constants). The form of energy during that and immediately before that epoch was so different and so dense apriori structure is in quantum terms unreconcilable with any current observation (the limit being CMB and the closer edge of the opaque period)? Statistically it would be the null or empty set, not part of a classically defined Visible Universe. If it was a cycle then it was a completely fresh beginning.
The second logic is that somehow the Universe we see avoided the 'irreconcilable period' and deflated into a near-singularity and then expanded without imparting any structure evident in the previous incantations,........'crypto-irreconcilability'.
The problem with the second logic is that each expansion and contraction cycle would impart more information on the next Universe, and so on. The only way to avoid that, the previous encantation should collapse into a highly limited number of structure. If such a universe did not collapse into such structure uniformity relies on a limited number of singularities. But quantum mechanics prevents this from happening. Either you see complete uncertainty, or you don't, and aprior expansions and multiverses with their intrinsic uncertainties result from the initial uniform state in spatial fluctuations. For example a galactic black hole in galaxy X is traveling in a different time-frame than another black-hole. Thus on collapse the cores of gravemetric objects would be contracting at different rates and from different distances from each other. The initial quantum effects lend themselves greatly to perturbances just like the orbits of a shattered asteroid will create many different ellipses. But if the universe does not collapse into 1 then 2 or 3 singularities present the same logical problem, space-time begins to break down. Universe is no longer a 'dot' but an equally immeasurable line, or plane. In that standard model it is the interaction of feilds and particles that imparts the various properties of specialized matter. In the same way interacting singularities would impart various qualities, one of the qualities that must persist are dimensions (at least 2) and time. If a line then undergoes expansion, then the universe is not uniform (possibly polar anti and matter bells), a three point defined plane has the same problem, and any further addition of singularities would have the same problem. In addition there would be twists in space time, the Hubble rule would probably as one distanced in our visible universe.
The argument here is that quantum singularity explains the overall Euclidean flatness and CMB radiation, instead of an explosion there was a rapid and, in the context of disrupted space-time, quantum inflation of energy in the universe. The critical point is that CMB follows a period in which a form of expansion was occurring, but this did not involve the interation of quanta (e.g. two or more singularities, matter, energy collectives, etc.) that later materialized into energies and matters that essentially are expanding at a constant rate per differential distance (And personally, logically there has to be limits to the truth of this, but its something that physics wraps up in a shell game called the Visible Universe and that we are confined to).
The problem created by Big-Bounce is does not really explain the Visible Universe, it explains a larger construct. A single singularity is replaced by multiple singularities that are separated (analogous a binary star), and previous universe. If so our observations are best explained by one derived singularity (Visible Universe). The theory tries to explain something (Visible Universe) by explaining where might have come from, while avoiding the critical issue of how to get to a Visible Universe we see without energy disruptions from different inertia reference frames interfering with CMB, Euclidian flatness, and Hubble shifts.
The speculation about origin then gets wrapped up simulations that involve relativistic simulations, the problem is that Einstein has to share his universe with Heisenberg and Planck. None of these describe however what happens if you pummel an opaque era Universe with material derived from contracting previous universe. Their assumption is that most previous matter contracts to the same point and time.
Here is the point, Occam's razor relies on evidence that can be simplified to a most simple explanation. The issue of deity is an excellent example, and proofs thereof could be inevitably discounted as sophistry and obfuscation.
The essential problem is that our Visible Universe extends back to bright blue stars and CMB that putatively followed an opaque epoch, in which general relativity and quantum uncertainty can 'handwaving' explain just about everything going back to the quarks. This is the wizard of Oz.....What is certain is that every uncertainty begins to increase going further. Guessing what is behind the curtain (the little dog used its nose, fact gathering), this all but derived from the fact that it prexists most classical matter, subatomic particles that are never seen free 'lose their bindings' (and therefore may not have existed, even breifly), and the energy that gives rise to this, putatively, is not a form of energy that has been encountered at any time on earth other than the speculative invisible field(s) that constitute space. Even this is not certain, initial space may have been replaced by feild(s) and these may have been replaced by feild(s) of different energy. At which point a large number of hypothesis are tolerable (including an Ocammic nemesis individually placing little dots of energy in space and turning on time), this is the 13th century philosophy all over again. And there are a ton of unsupported claims. Critically we have to get behind the curtain before we can compare the validity of hypotheses.
I have been reading these wiki pages on fundemental forces of nature. There is Big-Bang of speculation contained within the pages that obfuscates and buries credible findings with garbage, and a general lack of clarity in the critiques. There are a few good articles, many of the articles I have read would, at best, be described as leading and unbalanced.
As an example, I would point out that the Higgs boson is immaterial (So why have a page named after the boson, when, in fact, the Field is the most important perspective and when scientist talk about electrons mass they talk about the interaction with the field), the boson may not have any meaning in origin of the Universe. The Higg's feild does interact with leptons and give them mass, unlike that which has been implied on certain wiki pages it does not give atoms their 'mass' (the majority of mass is imparted by energy mass equivilance; the interaction of gluons with quarks); the Higgs field constrains electrons to atoms at much higher energies allowing a Visible Universe. The second point is that many scientist are uncertain about the Higgs feild and its various flavors (or energies), since it is a scalar feild, it might have behaved very different at the beginning of the Universe than today. The Higgs field permeates the Visible Universe, that does not; however, say much, about its origin or its role in the Universes birth or how far it permeates beyond the Visible Universe. I would argue that the conjecture brought to these pages does not improves the articles, it makes many of them useless. The Higgs field may be very important in cosmology beyond allowing hot atoms, but that deserves more study.
Lay out the basic principles and facts as science describes them (the popular media is all but useless, the lie and embellish) Bring forth supporting and critical facts. Limit the amount of speculation, referenced speculation can be packaged into a simple paragraph.
Also page significance as stated (Top of talk page) is duplicitous and contradictory, one needs to be removed, I would also replace a high importance with a Mid importance. PB666 yap 20:34, 16 January 2015 (UTC)
- @Pdeitiker: Just saying I'll read this later, as I have no time right now. If you could sum the text up a little, it'd be nice Tetra quark (don't be shy) 21:15, 16 January 2015 (UTC)
OK 1. One of these is redundant
- WikiProject Cosmology|class=C|importance=High
- WikiProject Cosmology |class=Start |importance=High <-Probably this one.
2. Somewhere in the first paragraph this theory should be carefully contrasted with other cosmic creation theories.
3. The text of the article needs to be skimmed, to the bear essentials of support so that: New publications should not go uncritiqued. IOW what are the other contemporary theories arguing. For example to suggest that one can come up with a near complete origin without relying on quantum scale uncertainty appears biased. Other theories argue that you cannot begin to understand those early epoch without heavy reliance on small scale uncertainty and quantum thermodynamics (in contrast to statements made concerning the 2nd law).
4. More weight can be added concerning critiques.
5. It needs to be pointed out preferably at the beginng that: a. The Visible Universe shows Euclidian flatness in every direction (no large scale space-time perturbations). b. That Hubble redshifts suggest distant reference frames are moving away from us support an expansive rather than 'explosively' or chaotically. c. CMB supports a process of early inflation followed by expansion rather than non-inflative scenarios.
6. Bouncing Universe require 'Just so' deflation and timing as to prevent the mis-timed phenomena from radically perturbing CMB.