Beyond Big Bang gets a bit more visible

[marcus]

this 600-page book is now available for pre-order at Amazon
https://www.amazon.com/dp/3540714227/?tag=pfamazon01-20

It's not my perfect cup of tea, but I am glad it is coming out because it helps give substance to the research area of Quantum Cosmology and make the field more visible.

The editor, Rudy Vaas, has tried to cover the whole spectrum of ideas about what could have preceded the Big Bang and caused it to happen. He has invited 20-some prominent physicist/cosmologist experts to contribute chapters. From my point of view it is very broad-gauge-----not at all selective. There are several people in there whose work I can take seriously, but not all are in that category.

It is a hefty book. 600 pages.

Here is what the Amazon page says about it

Book Description

The Big Bang model is now both theoretically and empirically well established. However, the very beginning of our universe still remains mysterious. General Relativity breaks down at very small spatio-temporal scales and at high energy densities. That is why Quantum Cosmology is needed. Recent developments open up the exciting new prospect of going "beyond" the Big Bang and even finding a physical explanation for it. Surprisingly, the ancient idea of a past-eternal universe is being revived, and fascinating new approaches are also being developed. This book provides an up-to-date overview of the competing scenarios in cosmology and discusses their foundations, implications, and philosophical aspects. It gathers original contributions from the world's leading researchers in Quantum Cosmology, who describe their own work and results in a manner understandable even to non-specialists.About the Author

* Philosopher of science (Center for Philosophy and Foundations of Science, University of Gießen)
* Astronomy and physics editor of Bild der Wissenschaft, one of the largest/most influential monthly science magazines in Germany
* Many contributions to cosmology and philosophy of science and nature

The publisher is Springer Verlag. Here is Springer's page about the book:
http://www.springer.com/astronomy/general+relativity/book/978-3-540-71422-4

Here is a Springer page that gives a condensed version of the TABLE OF CONTENTS
http://www.springer.com/astronomy/general+relativity/book/978-3-540-71422-4?detailsPage=toc

- Introduction.
- Eternal Inflation and the Vilenkin-Borde-Guth theorem.
- The Self-Reproductive Universe: Chaotic Inflation.
- Issues in Inflation.
- The Big Bounce Model: Avoiding the Big Bang Singularity in General Relativity.
- The Emergent Universe: Expansion from a stationary state.
- Quantum Cosmologies - Once and now.
- Instanton models, many histories and the problem of time.
- The Fluctuating Universe: Thermodynamics, Cosmology, and the Arrow of Time.
- Loop Quantum Cosmology I: Avoiding the Big Bang Singularity from First Principles.
- Loop Quantum Cosmology II: Effective theories and oscillating universes.
- Cosmic Darwinism: A universal differential selfreproduction via Black Hole-Big Bangs.
- The Pre-Big Bang Model: How String Cosmology reaches for an eternal past.
- The Cyclic Universe: Brane Cosmology, Dark Energy, and the eternal (?) recurrence of Big Bang/Big Crunch oscillations.
- String Cosmology Scenarios and the Quest for the Big Bang.
- The Stringscape.- The Self-Created Universe: A Time-Loop instead of a Beginning?.
- The Quasi-Steady-State Universe: An alternative to the Big Bang Cosmology?.
- Laws of nature: Eternal and creative?.
- Eternal Existence: The ultimate future of the Cosmos

 

[jimgraber]

Hi, Marcus,
Do you have the list of contributors?
Jim Graber

 

[marcus]

Hi, Marcus,
Do you have the list of contributors?
Jim Graber

No but several of the contributors have posted at ArXiv
and doing a keyword search using phrases from some of the chapter titles
will likely dredge up some reasonable facsimiles---earlier work with similar concerns.

Anthony Aguirre is one who has posted his contribution at ArXiv.

I'll bet a diligent person could find several more.

Whooops! How about this? First try three hits:
http://arxiv.org/find/grp_physics/1/co:+AND+Bang+AND+Beyond+Big/0/1/0/all/0/1

 

[Wallace]

I realize this is somewhat of a banal question, but marcus, do you know of any of these kinds of proposals that have become sufficiently advanced as to predict definite observational consequences? Not just in terms of retrodicting the things we know already, such as Inflation, but making predictions about what we have not yet measured but could in the future?

 

[Haelfix]

Wallace, some of these proposals tend to put constraints on the exact form of the inflaton potential, or alternatively predict cmb spectrums (usually varying nongaussian profiles). The sensititivy of course is always just out of reach of current experiment (and sometimes not even detectable even in principle). Likewise, they tend to have different predictions for gravitational waves (differeing A and B modes, etc).

They're all sufficiently model dependant that its really hard to even make subclasses for them b/c there is quite a bit of overlap in the parameter spaces, and they all differ in theoretical motivation, plausibility, minimality and so forth (often trading off one quality for the other).

The wild west if you will.

 

[marcus]

I realize this is somewhat of a banal question,..

In no way is that banal! This is just the question to be asking, and prodding these various groups with. I think Haelfix has it right so I won't try to add anything at the moment.

Maybe, though, I can add some perspective limited just to the approach I have been reading most about---Loop Quantum Cosmology. I will think about it and see if anything especially stands out.

 

[hellfire]

LQC predicts a spectral index slightly greater than one. On the other hand the main predictions of the pre-big-bang cosmology are a definite shape of the spectrum of the gravitational wave background and large-scale primordial magnetic fields.

 

[Wallace]

LQC predicts a spectral index slightly greater than one.

Really? I wonder how that fits with the WMAP results showing then n<1 the a quite high sigma? I still hear things about LQC so I wonder how this is being reconciled?

On the other hand the main predictions of the pre-big-bang cosmology are a definite shape of the spectrum of the gravitational wave background and large-scale primordial magnetic fields.

Ah yes gravity waves. If we can ever get a good GW instrument that can map out the spectrum of the background that will be as exciting as COBE and WMAP put together, especially for some of these theories it seems.

 

[hellfire]

There is some way out for LQC, since what is predicted is a very slight deviation from unity that is related however only to a subset of the CMB anisotropies given by the highest multipoles. This is because the measured spectral index relates to the power spectrum of the perturbations that reenter the horizon after inflation, but the prediction relates to the original power spectrum generated during inflation. To be able to filter late changes in the equation of state, one should concentrate on highest multipoles that entered the horizon first. Strictly speaking I should have said that LQC predicts a superinflationary phase with w < -1 at some very early time, that may have a signature in the spectral index depending on the later conditions. See sections B and C of chapter VII in Primordial Density Perturbation in Effective Loop Quantum Cosmology of G. Hossain. I must say also that this is a very lively field of research and I might have missed important newer papers. marcus may probably provide an up to date reference.

 

[Chronos]

I too would love to see gravity wave map of the universe. The existence of gravity waves is not in doubt [e.g., Hulse], but the devil is in the detection details. Noise is a real headache with current detectors.

 

[marcus]

Four of the 18 chapters are now available free (as preprint or draft copy). Here they are

http://arxiv.org/find/grp_physics/1/co:+AND+Bang+AND+Beyond+Big/0/1/0/all/0/1

the Springer page shows that some of the chapters may be renamed, but it is not hard to guess which is which.
Chapter 11 looks like it might be by Lee Smolin, but I haven't seen the preprint for it yet.

Here is a Springer page that gives a condensed version of the TABLE OF CONTENTS
http://www.springer.com/astronomy/general+relativity/book/978-3-540-71422-4?detailsPage=toc

0.- Introduction.
1.- Eternal Inflation and the Vilenkin-Borde-Guth theorem.
2.- The Self-Reproductive Universe: Chaotic Inflation.
3.- Issues in Inflation.
4.- The Big Bounce Model: Avoiding the Big Bang Singularity in General Relativity.
5.- The Emergent Universe: Expansion from a stationary state.
6.- Quantum Cosmologies - Once and now.
7.- Instanton models, many histories and the problem of time.
8.- The Fluctuating Universe: Thermodynamics, Cosmology, and the Arrow of Time.
9.- Loop Quantum Cosmology I: Avoiding the Big Bang Singularity from First Principles.
10.- Loop Quantum Cosmology II: Effective theories and oscillating universes.
11.- Cosmic Darwinism: A universal differential selfreproduction via Black Hole-Big Bangs.
12.- The Pre-Big Bang Model: How String Cosmology reaches for an eternal past.
13.- The Cyclic Universe: Brane Cosmology, Dark Energy, and the eternal (?) recurrence of Big Bang/Big Crunch oscillations.
14.- String Cosmology Scenarios and the Quest for the Big Bang.
15.- The Stringscape.- The Self-Created Universe: A Time-Loop instead of a Beginning?.
16.- The Quasi-Steady-State Universe: An alternative to the Big Bang Cosmology?.
17.- Laws of nature: Eternal and creative?.
18.- Eternal Existence: The ultimate future of the Cosmos

I would guess that Chapter 9 if by Ashtekar et al, and Chapter 10 by Bojowald and Tavakol.

 

[Coin]

There was a book with the similar title of "https://www.amazon.com/gp/product/0385509642/?tag=pfamazon01-20", I assume it is not related though? (Although some of the string theory chapters sound like they might cover similar material.)

Anyway looks interesting!

 

[Coin]

Wallace, some of these proposals tend to put constraints on the exact form of the inflaton potential, or alternatively predict cmb spectrums (usually varying nongaussian profiles). The sensititivy of course is always just out of reach of current experiment (and sometimes not even detectable even in principle). Likewise, they tend to have different predictions for gravitational waves (differeing A and B modes, etc).

So gravity waves aside (since there's already a decent amount of work being done on that), are there any particular future experiments to watch out for that might begin to clear through some of these edge-of-detectability theories? For example how difficult is the "inflaton potential" to measure / how does one go about it?

 

[marcus]

Amazon says it will be available starting July 1.

Hi, Marcus,
Do you have the list of contributors?
Jim Graber

that arxiv link now gives 5 articles that have been contributed as chapters to the book
http://arxiv.org/find/grp_physics/1/co:+AND+Bang+AND+Big+AND+the+AND+Vaas+Beyond/0/1/0/all/0/1
==quote==
1. arXiv:0804.0672 [ps, pdf, other]
Title: Quantum Cosmology
Authors: Claus Kiefer, Barbara Sandhoefer
Comments: 29 pages, 9 figures, contribution to "Beyond the Big Bang", ed. by R. Vaas (Springer 2008); typos corrected, reference added
Subjects: General Relativity and Quantum Cosmology (gr-qc)
2. arXiv:0802.4274 [ps, pdf, other]
Title: Loop Quantum Cosmology: Effective theories and oscillating universes
Authors: Martin Bojowald, Reza Tavakol
Comments: 24 pages, 3 figures, Chapter contributed to: ``Beyond the Big Bang'', Ed.: Ruediger Vaas (Springer Verlag, 2008)
Subjects: General Relativity and Quantum Cosmology (gr-qc)
3. arXiv:0712.0571 [pdf, other]
Title: Eternal Inflation, past and future
Authors: Anthony Aguirre
Comments: 38 pp., 6 color figures. Contribution to R. Vaas (ed.): Beyond the Big Bang. Springer 2008
Subjects: High Energy Physics - Theory (hep-th)
4. arXiv:0711.1656 [ps, pdf, other]
Title: The Arrow Of Time In The Landscape
Authors: Brett McInnes
Comments: To appear in R. Vaas (ed.): Beyond the Big Bang. Springer: Heidelberg 2008
Subjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)
5. arXiv:hep-th/0703055 [ps, pdf, other]
Title: String Theory and Pre-big bang Cosmology
Authors: M. Gasperini, G. Veneziano
Comments: 34 pages, five figures. Contribution to the book: "Beyond the Big Bang", ed. by Ruediger Vaas (Frontier Collection Series, Springer-Verlag, Heidelberg, 2007). Two figures and four references added. Also added new subsections and typos corrected
Subjects: High Energy Physics - Theory (hep-th); Astrophysics (astro-ph); General Relativity and Quantum Cosmology (gr-qc)

here again is the Springer page giving TOC
http://www.springer.com/astronomy/general+relativity/book/978-3-540-71422-4?detailsPage=toc
the amazon page says available 1 July, so in just about a month from now
https://www.amazon.com/dp/3540714227/?tag=pfamazon01-20

different people will gravitate to different parts of this book and get different things out of it, I'd guess.
I might relish only 20-25 percent of the chapters. But I will want to get ahold of a copy and at least look it over.

 

[Chronos]

So gravity waves aside (since there's already a decent amount of work being done on that), are there any particular future experiments to watch out for that might begin to clear through some of these edge-of-detectability theories? For example how difficult is the "inflaton potential" to measure / how does one go about it?

In a word, GLAST.

 

[marcus]

Just 2 posts back I listed the FIVE chapters I think we have preprints for.
what looks like another one has shown up, so now we appear to have SIX

This would correspond to what is listed in the TOC as Chapter 13
"13.- The Cyclic Universe: Brane Cosmology, Dark Energy, and the eternal (?) recurrence of Big Bang/Big Crunch oscillations."

I found this at Paul Steinhardt's Princeton website.
http://wwwphy.princeton.edu/~steinh/
It is not on arxiv and seems only available in PDF here at his site
http://wwwphy.princeton.edu/~steinh/vaasrev.pdf

The title given here is "The Cyclic Theory of the Universe" (not as catchy and journalistic as Vaas chapter title)
The draft here refers to itself as "this chapter" but does not indicate WHICH BOOK it is intended to be a chapter in. The URL tag "vaasrev.pdf" does sound like Vaas, though, suggesting a review of Cyclic written for Vaas book.

It is interesting that Steinhardt has developed a new version of Cyclic which does not involve string theory. It is based on ordinary quantum field theory and has only one extra spatial dimension. The surroundspace is 4D and within that context there are embedded two ordinary 3D spaces that collide. This energizes them producing matter and radiation. They bounce apart and both of them expand while they are apart.

Expanding tends to disperse the matter and energy in them, as well as smooth and flatten them. So locally they look cold, nearly empty, and nearly flat, when they again fall together.

It is written for undergraduate students AFAICS and a lot of it is fairly easy to read and get something out of---though you may not understand every detail.
I don't accept or promote Steinhardt cosmology myself, but there has been some interest expressed and this is a good recent introduction.

He discusses both the stringy and the stringless versions.

Another interesting feature is a lengthy and outspoken critique of INFLATION. Steinhardt makes a very good case against the prevailing inflation scenarios. This helps motivate his Cyclic model because it solves the same riddles that inflation was invented to take care of, but without inflation.

It could be that both Inflation and Steinhardt Cyclic are wrong and that there are yet other solutions to those puzzles (flatness, uniformity of temperature, absence of mag monopoles...)

Indeed we were just reading 't Hooft's 2005 essay and he hinted at other alternatives for addressing some of the same puzzles.
We seem less and less compelled to accept inflation scenarios, as time goes on.

 

[marcus]

production schedule slipped---Springer now says April 3, 2009

To recall, the publisher is Springer Verlag. They now say the book will be available as of 3 April 2009.

Here is Springer's page about the book:
http://www.springer.com/astronomy/general+relativity/book/978-3-540-71422-4
and here is a Springer page that gives a condensed version of the TABLE OF CONTENTS
http://www.springer.com/astronomy/general+relativity/book/978-3-540-71422-4?detailsPage=toc
I made a trivial copy error when I posted the TOC earlier, here is the corrected version.

- Introduction.
- Eternal Inflation and the Vilenkin-Borde-Guth theorem.
- The Self-Reproductive Universe: Chaotic Inflation.
- Issues in Inflation.
- The Big Bounce Model: Avoiding the Big Bang Singularity in General Relativity.
- The Emergent Universe: Expansion from a stationary state.
- Quantum Cosmologies - Once and now.
- Instanton models, many histories and the problem of time.
- The Fluctuating Universe: Thermodynamics, Cosmology, and the Arrow of Time.
- Loop Quantum Cosmology I: Avoiding the Big Bang Singularity from First Principles.
- Loop Quantum Cosmology II: Effective theories and oscillating universes.
- Cosmic Darwinism: A universal differential selfreproduction via Black Hole-Big Bangs.
- The Pre-Big Bang Model: How String Cosmology reaches for an eternal past.
- The Cyclic Universe: Brane Cosmology, Dark Energy, and the eternal (?) recurrence of Big Bang/Big Crunch oscillations.
- String Cosmology Scenarios and the Quest for the Big Bang.
- The Stringscape.
- The Self-Created Universe: A Time-Loop instead of a Beginning?.
- The Quasi-Steady-State Universe: An alternative to the Big Bang Cosmology?.
- Laws of nature: Eternal and creative?.
- Eternal Existence: The ultimate future of the Cosmos.

I've bolded the chapter headings of particular interest to me---since I watch Loop Quantum Cosmology (LQC) research comparatively closely. I would guess that the authors of these chapters, assuming they appear as listed in the final version of the book, will include Abhay Ashtekar, Martin Bojowald, and Lee Smolin.

Some likely prospect preprints by others, which might appear as chapters, are listed in an earlier post, #14, on this thread.
https://www.physicsforums.com/showthread.php?p=1750120#post1750120

 

[robheus]

The only problem with the cyclic model, probably, is that it is based on string theory.

Steinhardt cyclic model
http://wwwphy.princeton.edu/~steinh/vaasrev.pdf

But some things not completely clear to me:

P.33 and further

The notion of an eternally cycling model raises the specter of a perpetual motion and violations of the laws of thermodynamics. In this section, we explain why the cyclic does not correspond to a perpetual motion machine of the first kind (violation of conservation of energy) or second kind (conversion of stored energy to kinetic energy without dissipation).
First, it is important to realize that the cyclic model is not truly periodic. The extra dimension expands and contracts at regular intervals, but the branes undergo a net stretching from cyclic to cycle; that is, a ±are increasing from cycle to cycle, as shown in Fig. 2.1. Local observables, such as temperature and density, depend only on the expansion and contraction of the extra dimension; so they return to the same value once per cycle. Global quantities, like the total energy, total entropy, total number of black holes, and the cosmological constant, depend on the brane scale factors directly; so they vary monotonically. The facts that the branes are stretching from cycle to cycle and the total entropy and black hole increase over time are signs that there is more than the interbrane force providing energy to the system. Indeed, gravity is playing a critical role.
Gravity is the reason why the cyclic universe is not a perpetual motion machine of the first kind. Energy is conserved as the universe cycles even though the brane collisions are inelastic because gravity supplies extra energy during each contraction phase. During contraction, the kinetic energy of particles or, in this case, branes, is blue shifted due to gravity. So, when the branes collide, it is with greater energy than would be obtained with the interbrane force alone. Gravity provides the extra kinetic energy needed so that matter and radiation can be created at the collision, and the branes have sufficient kinetic energy remaining to return to their original positions. The cycles can repeat forever because gravity is a bottomless pit. In Newtonian gravity, for example, the gravitational potential energy is unbounded below. Similarly, in general relativity, there is no physical limit to how much energy can be drawn from the gravitational field. Because this regular (non-cyclic) creation of kinetic energy manifests only itself as the expansion of the branes and does not affect measurable quantities, like the matter density, temperature, and expansion rate, any local observer interprets the universe as being exactly cyclic. Behind the scenes, though, gravity is acting like an engine that keeps supplying more energy to keep the cycles going while respecting the conservation of energy.
(...)

- The model seems to not violate energy principle, yet is able to "eternally" pull energy from gravity.
(so if gravity is an eternal source of energy, couldn't we find a way of using that energy??)
- Is the model eternal? Same cycle length every time (and what is the fine tuning that every cycle the branes distantiate the same amount, else they would either distantiate further and further each cycle, or become closer and closer distantiated) ?
- Every cycle a same kind of universe, or is there some overall development?
(next page or so says issue is not settled regarding eternal cycling)

And some issue that was brought op by Andrei Linde on (previous?) ekpyrotic models was brane stability.
But perhaps not an issue in this model?

- Black holes seem to survive a cycle (and would probably seed galaxy formation). Wonder if that is consistent (and visible) in CMBR.

- Wouldn't this model somehow (after very many cycles) repeat itself indefinately forming a closed time loop? Or is there perhaps some "higher order" cycle (embedded in even higher order cycles indefinately).