Quantum gravity Definition and 482 Threads

Yesterday Meteor found this new paper of Rovelli's and added it to the "surrogate sticky" collection of links. In case there is need for discussion, it should probably have its own thread as well. The paper expands a key assertion made on page 173 of the on-line draft of Rovelli's book...

I have listed some requirements for a complete theory of quantum gravity. Anything anyone would like to add, subtract, or illuminate would be welcome. 1. A gauge group large enough to contain all known interactions, and all interactions predicted by the theory. 2. An action that generates...

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...

Papers in Loop Gravity and related research lines are coming out at an increasing rate. I've found this boolean search method useful at arxiv. It is a way of keeping up that takes less time since it combines the key words and phrases in a single search By searching arxiv with the same Boolean...

What do you think is currently going on in quantum gravity? Are we entering a post-String era in physics theory? Different opinions welcome. What alternative lines of research are showing promise. Here are some straws-in-the-wind----none of them particularly weighty in isolation. For one...

Just out: http://il.arxiv.org/abs/gr-qc/0401102

"Quantum gravity": an oxymoron? Just stumbled upon this paper while doing some lookarounds on quantum gravity: http://arxiv.org/abs/physics/0308042 The following words of the author induced quite a ruckus in my book: Seeing as his library of papers, spanning 18 papers, all deal in...

In trying to get my head round GR and quantum gravity, I'm puzzled about the following questions: Is the gauge group for gravity defined as the set of all possible Weyl tensors on a general 4D Riemann manifold? Which abstract group maps onto this set? Is it GL(4) or a subgroup of GL(4)? How...

In trying to get my head round GR and quantum gravity, I'm puzzled about the following questions: Is the gauge group for gravity defined as the group of all possible Weyl tensors on a general 4D Riemann manifold? Is it a subgroup of GL(4)? How do you derive the number of gravitational...

I read about the Loop Quantum Gravity theory in some science magazine during my break at work. I wasn't reading attentively enough to make anything out of it. All I know is it is another theory to unite General Relativity and Quantum Mechanics, I think. Anyone care to share their knowledge on...

There has been an increase in the resolution of 'singularities'and the problems it brings. here is a link to a very "average" paper at present. The authors(no relation to ''Jeff'' I hope! seem to be grasping in the dark? Nevertheless, issue's are trying to be tackled from a number of...

A very nice short paper, http://arxiv.org/abs/hep-th/0312114 giving an analytical (Wilson renormalization group) development of the fixed points of the quantum gravity models as previously suggested by numerical studies. Conclusions, 1) At very short distances, the coupling runs and...

Quantum Gravity: Evidence against Lets take a moment to consider the evidence used by others to try and disprove this theory Such as .. http://cosmos.as.arizona.edu/~thompson/pubdb/docs/ragazzoni03a.pdf http://www.spacedaily.com/news/cosmology-03i.html...

http://arxiv.org/list/gr-qc/0311 http://arxiv.org/PS_cache/gr-qc/pdf/0311/0311021.pdf http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=30467 http://www.cerncourier.com/main/article/42/7/18. -------------------------------------------------------------------- some...

http://www.spacedaily.com/news/cosmology-03i.html For the second time in as many months, images gathered by the Hubble Space Telescope (HST) are raising questions about the structures of time and gravity, and the fabric of space...

New Markopolou/Smolin: "Quantum Theory from Quantum Gravity" http://arxiv.org./gr-qc/0311059 "Planck's constant turns out to be a derived quantity"

Physics World magazine is by subscription but some of their stuff is free online. This month's issue focuses on Quantum Gravity surveying string approach and loop gravity approach in a kind of balanced way The string article is by Leonard Susskind The Loop Quantum Gravity article is by Carlo...

This book is an attempt to make a popular account of the seemingly difficult concept called quantum gravity. Lee Smolin (the author) have been working in two of the approaches to quantum gravity, (string theory and LQG), and in the book also explains a third approach, black hole thermodinamics...

I was wondering, why are there no books on LQG? For string/M- theory you have "The Elegant Universe", "Hyperspace", "Beyond Einstein", and numerous others. But, for LQG, the closest I may have found (and I'm not even sure about this, since I just got the book, and haven't really started...

A good place to begin might be with Enrique Alvarez recent survey "Loops versus Strings" given in July to an audience of HEP people at the Portoroz conference "What comes beyond the standard model?" http://arxiv.org/gr-qc/0307090 Alvarez is a recognized string theorist who has published...

Does anyone know of any good problem solving books on strings, branes and/or loop quantum qravity? I am looking for something that has a lot of actual solved problems, something in the spirit of Schaum's Outline Series, Zetteli's book on QM, or Peskin and Schroeder's book on QFT. Any...

"Quantum Gravity and Inflation"---a new paper The following paper appeared today in arxiv preprints Stephon Alexander et al "Quantum Gravity and Inflation" http://arxiv.org/hep-th/0309045 The paper could be important. By way of detail, it has been submitted to Physical Review Series D...

This is a thread for collective learning of the classical (i.e. non-quantum) theory of Gravity-----which means General Relativity. Reference material is Chapter 2 (pages 21-71) of Rovelli's book "Quantum Gravity" and John Baez GR Tutorial The title of Rovelli's book notwithstanding, the...

getting started in good order is difficult---reminds me of trying to furl sail in a high wind: there is a lot of subject-matter and it keeps flapping and getting out of hand----need to tie things down bit by bit The two Ashtekar-Lewandowski 1994 papers seem to be basic in fact Sahlmann...

Superfluid model of quantum gravity? This article is from the new Scientific American online magazine. Everything (and MUCH MORE) that the physicists in this article are explaining as a simple tentative direction of study has already been fleshed out in Sorce Theory. see...

I've posted a thread related to a simplified system of dimensional units using quantum mechanical phase, a length, possibly a time and plane angle; You don't need all that junk. and another about why gravity may occur in the world: Why does Gravity occur? Let's see what happens when...

LQG is based on a smooth compact manifold M The configuration space is A the connections on M: by choice here we use SO(3) connections----the smooth rotation-valued 1-forms on M. The connections represent all the possible configurations of gravity, or curvature, on the manifold-----in other...

this is a collective effort to hit the easy parts of LQG for anyone who has shown an interest in this approach to quantum gravity to add constructive input Lubos Motl has been a critic of LQG and has just published a clear presentation of it, plus made an important contribution to and he...

In the Physics forum, jby started a LQG thread which at one point included some discussion of Connections. It might be helpful to have a thread focused on the connection which is taking over the central role from the metric for some purposes. GR used to be the study of the metric on a smooth...

I don't know if I've come to the right place. I've posted this in the theoretical physics forum and yet to get a reply... I recently read this article http://www.sciam.com/article.cfm?ar...F71809EC588EEDF and came across this thing called spin network. Anyone with further explanation on...

Loop Dreams... Loop Quantum Gravity Dreams that is... So, many people ask me if they have what it takes to make it in the world of academic physics. Here's my little survey for helping people find out if they have the right stuff. How old are you? If you answered >= 35, and you're not...

¿is string theory the solution to quantum gravity? ..is the only way to reach to quantum gravity..?.or are another ways..(such as canonical quantization)..i say that to have another option studying the subject.