What was there before Big Bang?

[Safamm]

Can anyone explain to me in easy terms a couple of things?
1- five minutes prior to the big bang, what was there?
2- did matter exist before the big bang?
3- if no matter existed prior to the big bang, what was there?

 

[phinds]

It depends on what model you use. The most commonly accepted cosmological model (the "Big Bang") says nothing about anything that happened up until one Plank Time after the singularity. Some people seem to interpret this as meaning there WAS nothing prior to the singularity.

I suggest you read the FAQ in the cosmology section

 

[DARKSYDE]

Time did not yet exist. You would have to find a different way to ask your question.

 

[jackmell]

Can anyone explain to me in easy terms a couple of things?
1- five minutes prior to the big bang, what was there?
2- did matter exist before the big bang?
3- if no matter existed prior to the big bang, what was there?

You guys mind if I try to address these questions in a logical fashion that I believe eliminates the paradoxes?

Well here goes:

When we study dynamics in the Universe, on earth, stars, galaxies, we observe frequently, dynamics which are NOT smooth-flowing but rather exhibits "shocks", that is, points where the behavior of the system changes qualitatively. For example, at the critical point of freezing, water suddenly changes to ice. When this happens the property of "swimming" looses meaning beyond this critical point. These types of dynamics (I believe) are prevalent throughout the Universe.

This phenomenon may also pertain to the Big Bang: it represents a critical point, a "shock" of some larger pre-existence and passing through it, at the Big Bang, changes qualitatively the properties of the system and therefore, properties we now observe in the Universe such as time, matter, energy, and physical laws in general may NOT apply on the other side of that critical point. From this perspective we can now attempt to answer the questions:

(1) On the other side of the Big Bang may reside something qualitatively different then our own existence,

(2) matter is a property of our Universe and may not exist on the other side of the Big Bang for the reason I stated above,

(3) if this scenario applies, then due to the possibly qualitative change that occurs during a critical-point transition, the Big Bang, that something you pose "before" the Big Bang may be so qualititaively different than what we now experience that we simply do not have the words yet to describe it.

 

[Safamm]

You guys mind if I try to address these questions in a logical fashion that I believe eliminates the paradoxes?

Well here goes:

When we study dynamics in the Universe, on earth, stars, galaxies, we observe frequently, dynamics which are NOT smooth-flowing but rather exhibits "shocks", that is, points where the behavior of the system changes qualitatively. For example, at the critical point of freezing, water suddenly changes to ice. When this happens the property of "swimming" looses meaning beyond this critical point. These types of dynamics (I believe) are prevalent throughout the Universe.

This phenomenon may also pertain to the Big Bang: it represents a critical point, a "shock" of some larger pre-existence and passing through it, at the Big Bang, changes qualitatively the properties of the system and therefore, properties we now observe in the Universe such as time, matter, energy, and physical laws in general may NOT apply on the other side of that critical point. From this perspective we can now attempt to answer the questions:

(1) On the other side of the Big Bang may reside something qualitatively different then our own existence,

(2) matter is a property of our Universe and may not exist on the other side of the Big Bang for the reason I stated above,

(3) if this scenario applies, then due to the possibly qualitative change that occurs during a critical-point transition, the Big Bang, that something you pose "before" the Big Bang may be so qualititaively different than what we now experience that we simply do not have the words yet to describe it.

Jack, thank you very much for your insightful explanation. My understanding was that pre Big Bang there was nothing which I found unreasonable as nothing may be composed from nothing. You have clarified it very well. Here is a couple of more questions.

Is it commonly thought that universe is infinite? If so why why is it presumed that the universe was created through one Big Bang? Why should we believe that such events do not occur regularly (relatively speaking)?

 

[Safamm]

You are implying by your response that nothing existed. Is that so?

 

[phinds]

You are implying by your response that nothing existed. Is that so?

Who are you asking?

The POINT is, it matters what model you are using. There are cyclical models in which there IS time before the big bang. The conventional model says there was not, and yes, I agree that's just WEIRD.

I think more to the point, we not only don't KNOW, we haven't yet figured out how to even go about finding out.

So, the bottom line is, it's not all that useful a question unless you are into metaphysics more than physics.

 

[Safamm]

Phinds,

I was asking Darksyde but I do appreciate both of your responses. I'm not a scientist (far, far from it) but have always enjoyed learning about sciences.

It is however much interesting that you bring up the issue of metaphysics. Why do you think my interest is more of metaphysical nature?

 

[phinds]

It is however much interesting that you bring up the issue of metaphysics. Why do you think my interest is more of metaphysical nature?

Because your question has no answer in physics, but please read what I said ... I said UNLESS ... I did not say that your interest IS in metaphysics.

 

[Safamm]

Because your question has no answer in physics, but please read what I said ... I said UNLESS ... I did not say that your interest IS in metaphysics.

I don't have a problem with your answer at all. You taught me well!

 

[jackmell]

Jack, thank you very much for your insightful explanation. My understanding was that pre Big Bang there was nothing which I found unreasonable as nothing may be composed from nothing. You have clarified it very well. Here is a couple of more questions.

Is it commonly thought that universe is infinite? If so why why is it presumed that the universe was created through one Big Bang? Why should we believe that such events do not occur regularly (relatively speaking)?

My explanation for your questions falls back to the qualitative change that often occurs during critical-point transitions: the Big Bang may have been such a critical-point transition and if so, may have given rise to a qualitative change we perceive in the Universe now as the "something", the "existence" we observe. I could then conclude the pre-existence was qualitatively different than this "something" and therefore the "nothing" people often suggest which could have given rise to the Big Bang is not really the absence of "something" but rather just qualitatively different than something.

With this definition, one could perhaps suggest dark matter is "nothing" as it appears to be qualitiatively different than matter but that may be an improper statement.

And in a likewise fashion, your suggestion of a "finite" or "infinite" Universe may BOTH be wrong. It could be something qualitatively different in the same manner that a plane is applicapable to the description of a small section of the earth, but at a larger scale, in order to describe the earth, a qualitatively different concept, a sphere, must be used.

 

[Safamm]

My explanation for your questions falls back to the qualitative change that often occurs during critical-point transitions: the Big Bang may have been such a critical-point transition and if so, may have given rise to a qualitative change we perceive in the Universe now as the "something", the "existence" we observe. I could then conclude the pre-existence was qualitatively different than this "something" and therefore the "nothing" people often suggest which could have given rise to the Big Bang is not really the absence of "something" but rather just qualitatively different than something.

With this definition, one could perhaps suggest dark matter is "nothing" as it appears to be qualitiatively different than matter but that may be an improper statement.

And in a likewise fashion, your suggestion of a "finite" or "infinite" Universe may BOTH be wrong. It could be something qualitatively different in the same manner that a plane is applicapable to the description of a small section of the earth, but at a larger scale, in order to describe the earth, a qualitatively different concept, a sphere, must be used.

Thank you Jack. I have a much better understanding because of your and other's comments.

 

[J Griz 757]

You guys mind if I try to address these questions in a logical fashion that I believe eliminates the paradoxes?

Well here goes:

When we study dynamics in the Universe, on earth, stars, galaxies, we observe frequently, dynamics which are NOT smooth-flowing but rather exhibits "shocks", that is, points where the behavior of the system changes qualitatively. For example, at the critical point of freezing, water suddenly changes to ice. When this happens the property of "swimming" looses meaning beyond this critical point. These types of dynamics (I believe) are prevalent throughout the Universe.

This phenomenon may also pertain to the Big Bang: it represents a critical point, a "shock" of some larger pre-existence and passing through it, at the Big Bang, changes qualitatively the properties of the system and therefore, properties we now observe in the Universe such as time, matter, energy, and physical laws in general may NOT apply on the other side of that critical point. From this perspective we can now attempt to answer the questions:

(1) On the other side of the Big Bang may reside something qualitatively different then our own existence,

(2) matter is a property of our Universe and may not exist on the other side of the Big Bang for the reason I stated above,

(3) if this scenario applies, then due to the possibly qualitative change that occurs during a critical-point transition, the Big Bang, that something you pose "before" the Big Bang may be so qualititaively different than what we now experience that we simply do not have the words yet to describe it.

Well put.

I'm still pretty much a laymen in these fields, although I am much more educated than the average (astrophysics/astrology/cosmology) I still have no degree, but I believe most scientifically literate people can understand how you put it.

As I have often pondered the "what before the big bang" question, you put into words what I was thinking well imo, "we simply do not have the words yet to describe it.".

 

[marcus]

Can anyone explain to me in easy terms a couple of things?
1- five minutes prior to the big bang, what was there?
2- did matter exist before the big bang?
3- if no matter existed prior to the big bang, what was there?

There is an active field of research called Quantum Cosmology (QC) that is addressing this type of question with physical models (not philosophical speculation). There are a bunch of new models that don't fail mathematically at the start of expansion but crank on back to earlier time.

If you are at all interested in this type of question then I'd suggest you scan down the list of recent research papers by the people who've devoted their careers to investigating this, running computer models of QC around the start of expansion including immediately before (in the spirit of your question about "five minutes prior"), and so on.

Phinds is right. The older (non-quantum) model fails mathematically around the start of expansion. But it would be naive to imagine that there wasn't anything happening merely because the usual (non-quantum) model breaks down. The failure of some equation doesn't imply there was nothing there, it can simply be that the old model is wrong and needs replacement.

It depends on what model you use. The most commonly accepted cosmological model (the "Big Bang") says nothing about anything that happened up until one Plank Time after the singularity. Some people seem to interpret this as meaning there WAS nothing prior to the singularity.

I suggest you read the FAQ in the cosmology section

The FAQ is a good suggestion. Also you could google "tale of two big bangs" and get a pretty good public outreach essay from a German institute--AEI, a branch of their national research establishment that focuses on this kind of thing.

Or you could jump in and have a look at the listing that you get with a "quantum cosmology" keyword search at a professional research library. Here are 379 papers in QC that appeared in 2009 or later, ordered by number of times the paper has been cited in other research. (citecount is a rough indicator of importance, so you tend to get the most significant papers listed first).

http://www-library.desy.de/cgi-bin/spiface/find/hep/www?rawcmd=FIND+DK+QUANTUM+COSMOLOGY+AND+DATE%3E2008&FORMAT=www&SEQUENCE=citecount%28d%29

This search simply uses the keyword "quantum cosmology" so you get all kinds of quantum cosmology. However the first 30 or 40 papers are mostly all "loop" qc (LQC). That's a particular type of model that a lot of people are currently working on. LQC goes back before the big bang in a fairly straightforward way---quantize the normal cosmology equation to include quantum effects working at extremely high density, so then the model does not fail mathematically and you can crank on back in time thru a kind of "bounce" and get to a familiar type of universe like what we see except contracting.

If you look further on the list, past the first 30 or so you will find OTHER kinds of quantum cosmology models, not only LQC. As I said the search currently lists some 379. Unfortunately sometimes this link does not work, or is slow. I might copy some of the list here as a sample, in case you can't get the link to work.

 

[marcus]

Here's the first 25 of the list of 376 recent quantum cosmology papers you get with that search. You can examine almost any paper you want by clicking on "pdf" or on the "arxiv" link. there is an electronic research archive called "arxiv.org" that has most of them online.
Or you can just scan down the list of titles, see how many times each paper has been cited, see who the main authors are, see what kind of topics keep recurring, and so on.

So here is the raw list (just the first 25 ):

Paper 1 to 25 of 376
| Next 25 | Last |
1) Loop quantum cosmology of Bianchi I models.
Abhay Ashtekar, Edward Wilson-Ewing, (Penn State U.) . Mar 2009. (Published Mar 2009). 33pp.
Published in Phys.Rev.D79:083535,2009.
e-Print: arXiv:0903.3397 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 64 times

2) Towards Spinfoam Cosmology.
Eugenio Bianchi, Carlo Rovelli, (Marseille, CPT) , Francesca Vidotto, (Marseille, CPT & Pavia U. & INFN, Pavia) . Mar 2010. (Published Oct 15, 2010). 8pp.
Published in Phys.Rev.D82:084035,2010.
e-Print: arXiv:1003.3483 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 48 times

3) Spectral dimension of a quantum universe.
Leonardo Modesto, (Perimeter Inst. Theor. Phys.) , Piero Nicolini, (Frankfurt U.) . Dec 2009. (Published May 15, 2010). 4pp.
Published in Phys.Rev.D81:104040,2010.
e-Print: arXiv:0912.0220 [hep-th]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 42 times

4) Loop Quantum Cosmology: A Status Report.
Abhay Ashtekar, (Penn State U.) , Parampreet Singh, (Louisiana State U.) . Aug 2011. 136pp.
Published in Class.Quant.Grav.28:213001,2011.
e-Print: arXiv:1108.0893 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 42 times

5) Entropy-Corrected Holographic Dark Energy.
Hao Wei, (Beijing, Inst. Tech.) . Feb 2009. 12pp.
Published in Commun.Theor.Phys.52:743-749,2009.
e-Print: arXiv:0902.0129 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 36 times

6) Loop Quantum Cosmology and Spin Foams.
Abhay Ashtekar, Miguel Campiglia, Adam Henderson, (Penn State U.) . IGC-09-9-1, Sep 2009. 11pp.
Published in Phys.Lett.B681:347-352,2009.
e-Print: arXiv:0909.4221 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 35 times

7) Casting Loop Quantum Cosmology in the Spin Foam Paradigm.
Abhay Ashtekar, Miguel Campiglia, Adam Henderson, (Penn State U.) . IGC-10-1-1, Jan 2010. 36pp.
Published in Class.Quant.Grav.27:135020,2010.
e-Print: arXiv:1001.5147 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 35 times

8) Are loop quantum cosmos never singular?
Parampreet Singh, (Perimeter Inst. Theor. Phys.) . PI-QG-100, Jan 2009. 17pp.
Published in Class.Quant.Grav.26:125005,2009.
e-Print: arXiv:0901.2750 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 34 times

9) Loop quantum cosmology of Bianchi type II models.
Abhay Ashtekar, Edward Wilson-Ewing, (Penn State U.) . Oct 2009. (Published Dec 15, 2009). 26pp.
Published in Phys.Rev.D80:123532,2009.
e-Print: arXiv:0910.1278 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 33 times

10) Loop quantum cosmology and slow roll inflation.
Abhay Ashtekar, David Sloan, (Penn State U.) . Dec 2009. 8pp.
Published in Phys.Lett.B694:108-112,2010.
e-Print: arXiv:0912.4093 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 32 times

11) A Geometric perspective on singularity resolution and uniqueness in loop quantum cosmology.
Alejandro Corichi, (Morelia U., Inst. Math. & Penn State U.) , Parampreet Singh, (Perimeter Inst. Theor. Phys.) . IGC-09-5-3, PI-QG-134, May 2009. (Published May 2009). 17pp.
Published in Phys.Rev.D80:044024,2009.
e-Print: arXiv:0905.4949 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 28 times

12) Possible observational effects of loop quantum cosmology.
Jakub Mielczarek, (Jagiellonian U., Astron. Observ. & LPSC, Grenoble) . Aug 2009. (Published Mar 15, 2010). 11pp.
Published in Phys.Rev.D81:063503,2010.
e-Print: arXiv:0908.4329 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 27 times

13) Physical evolution in Loop Quantum Cosmology: The Example of vacuum Bianchi I.
Mercedes Martin-Benito, Guillermo A.Mena Marugan, Tomasz Pawlowski, (Madrid, Inst. Estructura Materia) . Jun 2009. (Published Oct 15, 2009). 22pp.
Published in Phys.Rev.D80:084038,2009.
e-Print: arXiv:0906.3751 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 26 times

14) Thermodynamics of interacting entropy-corrected holographic dark energy in a non-flat FRW universe.
Mubasher Jamil, (NUST, Rawalpindi) , Ahmad Sheykhi, (Shahid-Bahonar U. & RIAAM, Maragha) , M.Umar Farooq, (NUST, Rawalpindi) . Mar 2010. 14pp.
Published in Int.J.Mod.Phys.D19:1831-1842,2010.
e-Print: arXiv:1003.2093 [physics.gen-ph]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 26 times

15) Bouncing Cosmologies in Palatini f(R) Gravity.
Carlos Barragan, (Madrid, Autonoma U.) , Gonzalo J. Olmo, (Madrid, Inst. Estructura Materia) , Helios Sanchis-Alepuz, (Valencia U. & Valencia U., IFIC & Graz U.) . Jun 2009. (Published Jun 2009). 8pp.
Published in Phys.Rev.D80:024016,2009.
e-Print: arXiv:0907.0318 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 25 times

16) Observational constraints on loop quantum cosmology.
Martin Bojowald, (Penn State U.) , Gianluca Calcagni, (Potsdam, Max Planck Inst.) , Shinji Tsujikawa, (Tokyo U. of Sci.) . IGC-11-1-1, AEI-2011-004, Jan 2011. (Published Nov 18, 2011). 4pp.
Published in Phys.Rev.Lett.107:211302,2011.
e-Print: arXiv:1101.5391 [astro-ph.CO]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 25 times

17) Inflation in loop quantum cosmology: dynamics and spectrum of gravitational waves.
Jakub Mielczarek, (Jagiellonian U.) , Thomas Cailleteau, (LPSC, Grenoble) , Julien Grain, (Paris, Inst. Astrophys.) , Aurelien Barrau, (LPSC, Grenoble) . Mar 2010. (Published May 15, 2010). 11pp.
Published in Phys.Rev.D81:104049,2010.
e-Print: arXiv:1003.4660 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 24 times

18) Triangulated Loop Quantum Cosmology: Bianchi IX and inhomogenous perturbations.
Marco Valerio Battisti, Antonino Marciano, Carlo Rovelli, (Marseille, CPT) . Nov 2009. (Published Mar 15, 2010). 21pp.
Published in Phys.Rev.D81:064019,2010.
e-Print: arXiv:0911.2653 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 23 times

19) Loop quantum cosmology of Bianchi type IX models.
Edward Wilson-Ewing, (Penn State U.) . May 2010. (Published Aug 15, 2010). 20pp.
Published in Phys.Rev.D82:043508,2010.
e-Print: arXiv:1005.5565 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 23 times

20) Big Bounce and inhomogeneities.
David Brizuela, Guillermo A.D Mena Marugan, Tomasz Pawlowski, (Madrid, Inst. Estructura Materia) . Feb 2009. 4pp.
Published in Class.Quant.Grav.27:052001,2010.
e-Print: arXiv:0902.0697 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 22 times

21) Inverse volume corrections from loop quantum gravity and the primordial tensor power spectrum in slow-roll inflation.
J. Grain, (APC, Paris & Paris, Inst. Astrophys.) , A. Barrau, (LPSC, Grenoble & IHES, Bures-sur-Yvette) , A. Gorecki, (LPSC, Grenoble) . Apr 2009. (Published Apr 2009). 15pp.
Published in Phys.Rev.D79:084015,2009.
e-Print: arXiv:0902.3605 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 21 times

22) Observational constraints on a power spectrum from super-inflation in Loop Quantum Cosmology.
Masahiro Shimano, Tomohiro Harada, (Rikkyo U.) . Sep 2009. (Published Sep 15, 2009). 17pp.
Published in Phys.Rev.D80:063538,2009.
e-Print: arXiv:0909.0334 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 21 times

23) Dynamics for a 2-vertex Quantum Gravity Model.
Enrique F. Borja, (Erlangen - Nuremberg U., Theorie III & Valencia U. & Valencia U., IFIC) , Jacobo Diaz-Polo, (Penn State U.) , Inaki Garay, (Erlangen - Nuremberg U., Theorie III) , Etera R. Livine, (Lyon, Ecole Normale Superieure) . Jun 2010. 28pp.
Published in Class.Quant.Grav.27:235010,2010.
e-Print: arXiv:1006.2451 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 21 times

24) Black Holes and Phase Space Noncommutativity.
Catarina Bastos, Orfeu Bertolami, (Lisbon, IST) , Nuno Costa Dias, Joao Nuno Prata, (Lusofona U.) . DF-IST-7-2009, Jul 2009. 13pp.
Published in Phys.Rev.D80:124038,2009.
e-Print: arXiv:0907.1818 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 20 times

25) Cosmic recall and the scattering picture of Loop Quantum Cosmology.
Wojciech Kaminski, (Warsaw U.) , Tomasz Pawlowski, (Madrid, Inst. Estructura Materia & Warsaw U.) . Jan 2010. (Published Apr 15, 2010). 19pp.
Published in Phys.Rev.D81:084027,2010.
e-Print: arXiv:1001.2663 [gr-qc]
References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Keywords | Cited 20 times

 

[jackmell]

LQC goes back before the big bang in a fairly straightforward way---quantize the normal cosmology equation to include quantum effects working at extremely high density, so then the model does not fail mathematically and you can crank on back in time thru a kind of "bounce" and get to a familiar type of universe like what we see except contracting.

So basically just a bounce? Is that all? And how would a Universe like ours but contracting behave? Would it be just like ours except blue-shifted? And that's it? Nothing else would be different? Would the laws of thermodynamics still flow in the same direction in such a Universe?

 

[marcus]

... Would the laws of thermodynamics still flow in the same direction in such a Universe?

Fascinating line of questioning! Thermodynamics has not yet been formulated in fully general relativistic context! Here is a recent paper working towards formulating both Statistical Mechanics and Thermodynamics in GR context

Rovelli http://arxiv.org/abs/1209.0065 (General relativistic statistical mechanics)

Abstract: Understanding thermodynamics and statistical mechanics in the full general relativistic context is an open problem. I give tentative definitions of equilibrium state, mean values, mean geometry, entropy and temperature, which reduce to the conventional ones in the non-relativistic limit, but remain valid for a general covariant theory. The formalism extends to quantum theory. The construction builds on the idea of thermal time, on a notion of locality for this time, and on the distinction between global and local temperature. The last is the temperature measured by a local thermometer, and is given by kT = hbar dτ/ds, with k the Boltzmann constant, hbar the Planck constant, ds proper time and d tau the equilibrium thermal time.​

Interesting stuff comes up. Concept of entropy probably becomes observer-dependent leading to modification of 2nd law. Geometry itself can have temperature (we already knew that from Hawking Bekenstein Unruh etc.) and can itself have entropy. Of course we do not have energy conservation globally in GR, so that gets modified. It's an exciting area of research. The GR equation itself could turn out to be an "Equation of State" describing macro behavior of micro geometry&matter d.o.f. There's a famous paper of Ted Jacobson that derives the Einstein field equation from thermodynamics assumptions, which is suggestive.

So you are asking a great question. The first thing to decide on is what ARE the "Laws of Thermodynamics" in full GR context. How are the quantities defined? In particular when the cosmological singularity is removed.

 

[marty1]

Jut before the big bang the Universe would have had minimum entropy, I suppose. What could be before that? Any change in entropy from that point would be the start of the bang. Asking or even knowing how "long" it was in that "pre-bang" state or how it got there is inconsequential because no matter how long it was like that or what the conditions were that led it there from that moment on nothing in its history affects its future.

 

[marcus]

Marty that is the point I just made in post #17, immediately preceding yours. Before you can reason as you are doing you must define the geometric entropy. You have to say what the entropy of the geometry MEANS, and the temperature of the gravitational field (which is the geometry). It appears (the people writing about the thermodynamics of gravity seem to agree) that to make meaningful definitions in this case you need an OBSERVER.
And the quantities measured will be observer-dependent. there may be discontinuities in what you can or cannot define. Interesting bunch of problems.

Check out some of the Quantum Cosmology articles I brought up in the preceding search (see around post #14) Have to go, back later.

 

[marcus]

Or you could jump in and have a look at the listing that you get with a "quantum cosmology" keyword search at a professional research library. Here are 379 papers in QC that appeared in 2009 or later, ordered by number of times the paper has been cited in other research. (citecount is a rough indicator of importance, so you tend to get the most significant papers listed first).

http://www-library.desy.de/cgi-bin/spiface/find/hep/www?rawcmd=FIND+DK+QUANTUM+COSMOLOGY+AND+DATE%3E2008&FORMAT=www&SEQUENCE=citecount%28d%29

This search simply uses the keyword "quantum cosmology" so you get all kinds of quantum cosmology. However the first 30 or 40 papers are mostly all "loop" qc (LQC). That's a particular type of model that a lot of people are currently working on. LQC goes back before the big bang in a fairly straightforward way---quantize the normal cosmology equation to include quantum effects working at extremely high density, so then the model does not fail mathematically and you can crank on back in time thru a kind of "bounce" and get to a familiar type of universe like what we see except contracting.

If you look further on the list, past the first 30 or so you will find OTHER kinds of quantum cosmology models, not only LQC...

So basically just a bounce? Is that all? And how would a Universe like ours but contracting behave?...

That's right, the simplicity of the model is one of the most appealing things about it. The contracting phase behaves as an ordinary classical universe (same physical laws) until quantum corrections to GR take over very close to bounce.

The key person in this context is Abhay Ashtekar, who discovered an equivalent formulation of General Relativity (around 1980) which has become the basis for the canonical quantization of GR that was adapted for Quantum Cosmology.

Here's a New York Times piece on Ashtekar.
http://www.nytimes.com/1999/04/20/s...e-for-the-cosmos.html?pagewanted=print&src=pm

An essential point is that when GR is formulated using "Ashtekar variables" and quantized, there are quantum corrections to gravity. In the quantum cosmology developed by Ashtekar and others (see the literature list in post #15) at extreme density quantum effects dominate and gravity becomes repellent. There is a non-equilibrium regime where the universe continues to contract (as if by a kind of momentum) even though gravity is repelling and trying to force everything apart---black holes are coming unbound and smoothing out, the geometry is trying to be as uniform and even as possible.
This repellent effect of quantum gravity at extremely high density eventually stops the collapse and causes a rebound. By that time the metric and matter are smooth, evened out, by the non-equilibrium process I described.
Since 2006 there has been a lot of numerical simulations of the bounce by Ashtekar's group. You may be able to find more if you google Ashtekar or search for his papers in the preprint archive: http://arxiv.org
Here is my post #15 which has QC papers from 2009 to present.

 

[firelyte]

Hi I'm new here to this forum and I'm afraid this might seem kind of dumb,
But I was thinking about lhc and how they say they recreate the conditions of the big bang with two particles slamming into each other and this also sometimes creates a small amount of anti-matter from what I've heard. And they say right before the big bang all the matter in the universe was packed into a very small point now what if it was caused by two extremely super massive black holes colliding with each other? This would create anti-matter and create a huge amount of energy right? It wouldn't seem impossible to me that there was more than just one singularity before the big bang. Would this explain why there ended up being less anti-matter than matter and explain why the universe spread out in a flat pattern? I have no idea but it was just a thought I had. I'm just a curious fan of physics and these are just the random things I think about while I'm at work and must just be ridiculous.

Maybe when I go to college I'll get a better understanding of the math and mechanics behind all of this. But for right now It's just something I find interest reading about.

 

[phinds]

Hi I'm new here to this forum and I'm afraid this might seem kind of dumb,

As they say, there are no dumb questions.

But I was thinking about lhc and how they say they recreate the conditions of the big bang with two particles slamming into each other and this also sometimes creates a small amount of anti-matter from what I've heard.

On a VERY tiny, localized scale, yes they create conditions similar to just after the singularity, including anti-matter

And they say right before the big bang all the matter in the universe was packed into a very small point

No, unless "they" are on TV, which presents sensationalism and not actual physics, they most emphatically do NOT say that. What they do say (assuming "they" are knowledgeable physicists) is that it was unbelievably hot and dense, but of completely unknown dimensions and topology.

now what if it was caused by two extremely super massive black holes colliding with each other? This would create anti-matter and create a huge amount of energy right? It wouldn't seem impossible to me that there was more than just one singularity before the big bang. Would this explain why there ended up being less anti-matter than matter and explain why the universe spread out in a flat pattern? I have no idea but it was just a thought I had. I'm just a curious fan of physics and these are just the random things I think about while I'm at work and must just be ridiculous.

Yeah, this last part has no basis in physics as it is currently understood. you would do well to read the FAQ in the cosmology section.

Maybe when I go to college I'll get a better understanding of the math and mechanics behind all of this. But for right now It's just something I find interest reading about.

Good ... keep reading !

 

[Chronos]

I agree with marcus, science is a convergence of mathematics and observational evidence. We can no more ignore one than the other.