Online copy? Background Independent Quantum Gravity: a Status Report

[marcus]

several recent papers have cited
Ashtekar and Lewandowski
"Background Independent quantum gravity: a status report"
as in preparation or
as a 2003 preprint not up on arxiv

Does anyone know of a draft version online?

I was reminded of their status report paper when I saw it
as the first reference cited in the new paper (25 February) of
Noui and Perez
"Three dimensional loop quantum gravity: coupling to point particles"
http://arxiv.org/gr-qc/0402111

But I believe it is also cited by Ashtekar and Lewandowski themselves in "Mathematical structure of Loop Quantum Cosmology" gr-qc 0304074
and by Perez in
"Spin Foam Models for Quantum Gravity" gr-qc 0301113

One can get some notion of how A&L present what might serve as a current standard of LQG by reading sections of Noui and Perez where they cite their reference [1] and arrange their form of 1+2 LQG so it will be as compatible and generalizable as possible to the full theory.

Any news of this?

 

[marcus]

the Noui Perez paper starts off with a reference to the A&L "status report" survey besides citing it other places too:

------exerpted from start of paper-------
Loop Quantum Gravity...of quantum theory of gravity [1, 19]. In contrast to usual quantum field theories, it is a background independent, non-peturbative approach to the problem of unification of general relativity and quantum mechanics. Loop quantum gravity is based on the canonical formulation of general relativity expressed in terms of connection variables.

The quantization program can be presented in terms of two (technically) distinguishable steps: in the first step the constraints governing general covariant dynamics are represented as quantum operators in a Hilbert space of kinematical states. The second step consists of characterizing the physical Hilbert space of solutions of the quantum
constraints.
-------end of quote-------------

reference [1] is the A&L survey
reference [19] is Rovelli's book
my bolding for emphasis

Again on page 15, at the beginning of a new section they restate this, again with a reference to the A&L survey.

---------from section 3. Loop quantization-----
3. Loop quantization

Loop quantum gravity is an attempt to describe a background independent quantization of general relativity (see [1] for a review). This program clearly distinguishes two different steps: the description of the kinematical Hilbert space in terms of spin-networks and the analysis of the dynamics using spin-foam models [18]. This section aims to adapt loop quantization techniques in the case of three dimensional gravity coupled to point particles. For that purpose, we decompose the first class constraints Φ (27) into its torsion part Φ_T and its curvature part Φ_C defined by...
-----end quote----

so they are saying "see the A&L status report for a review". It sounds like A&L description of Loop quantization is the "canonical" or exemplary one for them. Then again on page 19 they say, my bolding:

----exerpt page 19----
The kinematical Hilbert space of pure gravity H₀(Σ) is the subspace of gauge invariant functions of H_aux(Σ). Gauge invariant spin-network states provide H₀(Σ) with an orthonormal basis. The reader is invited to look at the review paper [1] to have a precise derivation of the kinematical Hilbert space in the four dimensional case. The next step consists of constructing the kinematical Hilbert space of the coupled system. For that purpose, we generalize the notion of space of cylindrical functions to...
-----end quote---

So it seems that the exemplar or paradigm of Loop quantization, for Noui Perez, is their reference [1], which they invite the reader to look at if interested in precise details.
And this reference [1] is, as I said,
Ashtekar and Lewandowski
"Background independent quantum gravity: a status report"

I assume Noui Perez have an early draft of this in hand, or that the thing is available online in preliminary form somewhere. Anybody know?

 

[ranyart]

Originally posted by marcus
the Noui Perez paper starts off with a reference to the A&L "status report" survey besides citing it other places too:

------exerpted from start of paper-------
Loop Quantum Gravity...of quantum theory of gravity [1, 19]. In contrast to usual quantum field theories, it is a background independent, non-peturbative approach to the problem of unification of general relativity and quantum mechanics. Loop quantum gravity is based on the canonical formulation of general relativity expressed in terms of connection variables.

The quantization program can be presented in terms of two (technically) distinguishable steps: in the first step the constraints governing general covariant dynamics are represented as quantum operators in a Hilbert space of kinematical states. The second step consists of characterizing the physical Hilbert space of solutions of the quantum
constraints.
-------end of quote-------------

reference [1] is the A&L survey
reference [19] is Rovelli's book
my bolding for emphasis

Again on page 15, at the beginning of a new section they restate this, again with a reference to the A&L survey.

---------from section 3. Loop quantization-----
3. Loop quantization

Loop quantum gravity is an attempt to describe a background independent quantization of general relativity (see [1] for a review). This program clearly distinguishes two different steps: the description of the kinematical Hilbert space in terms of spin-networks and the analysis of the dynamics using spin-foam models [18]. This section aims to adapt loop quantization techniques in the case of three dimensional gravity coupled to point particles. For that purpose, we decompose the first class constraints Φ (27) into its torsion part Φ_T and its curvature part Φ_C defined by...
-----end quote----

so they are saying "see the A&L status report for a review". It sounds like A&L description of Loop quantization is the "canonical" or exemplary one for them. Then again on page 19 they say, my bolding:

----exerpt page 19----
The kinematical Hilbert space of pure gravity H₀(Σ) is the subspace of gauge invariant functions of H_aux(Σ). Gauge invariant spin-network states provide H₀(Σ) with an orthonormal basis. The reader is invited to look at the review paper [1] to have a precise derivation of the kinematical Hilbert space in the four dimensional case. The next step consists of constructing the kinematical Hilbert space of the coupled system. For that purpose, we generalize the notion of space of cylindrical functions to...
-----end quote---

So it seems that the exemplar or paradigm of Loop quantization, for Noui Perez, is their reference [1], which they invite the reader to look at if interested in precise details.
And this reference [1] is, as I said,
Ashtekar and Lewandowski
"Background independent quantum gravity: a status report"

I assume Noui Perez have an early draft of this in hand, or that the thing is available online in preliminary form somewhere. Anybody know?

Marcus, at the bottom of this site, there is a ref to :"Background Independent quantum gravity: a status report"



go to :http://cgpg.gravity.psu.edu/people/Ashtekar/articles.html

http://cgpg.gravity.psu.edu/people/Ashtekar/publications_full.html

It is dated from some time ago, but I believe it will be along the lines of Smolins LQG 'report', which is updated when need be?

 

[marcus]

Ranyart, thanks for the links
perhaps surprisingly, this particular one is nowhere
there---it's not one the list either of A's scientific
papers or his semipopular articles! But if the paper
is not going to be made available in the near future then
why would Noui and Perez (researchers at Penn State where
A is, probably working closely with him) make it their
#1 reference on LQG? Guess we just have to wait and see.

 

[Stingray]

The paper is not yet finished, although drafts have been circulated to certain people.

 

[marcus]

Originally posted by Stingray
The paper is not yet finished, although drafts have been circulated to certain people.

dammit this is just what I suspected
people like Noui and Perez can have xerox copies but we cannot get it

 

[Stingray]

You might want to e-mail Ashtekar for it. He'll probably send you the pdf.

 

[marcus]

Originally posted by Stingray
You might want to e-mail Ashtekar for it. He'll probably send you the pdf.

Wow!
thank you for the information Stingray!
I would really like to have the pdf file for the draft of that survey
as I think its probably a good one