Question about QG :books-Rovelli's in particular

[marcus]

Question about QG books---Rovelli's in particular

Fra posted this question:

Does anyone have an opinion on wether Rovelli's book Quantum Gravity, is best up to date description of the fundamentals of the ideas on which Rovelli builds his LQG? Or should I read something else to complement this?

I just ordered his book but haven't received it yet. I'm not sure if there are any revisions, but I think the one I ordered is printed, or reprinted 2005. I'd like to judge for myself his original line of reasoning and wording that leads to this construct.

Would anyone recommend something else, to complement such an analysis? I'm not setting out to buy into anything, I rather want to analyse the logic behind his approach, and then I am curious to see if one can generalize the notion of spinnetwork to generic self-preserving information systems.

Suggestions? papers? any other books? or is his book sufficient to give a fair representation of the logic of his reasoning (which is really my focus)?


Comment would be welcome if anyone has have about using Rovelli's or alternative QG texts, such as Thiemann's.

 

[marcus]

A few simple thoughts come to mind.

One is that if you go to Rovelli's website there is a link to ERRATA
and also a downloadable draft version from December 2003.

Large parts of Rovelli's book are devoted to the HISTORY of quantum gravity thinking and the philosophical foundations (what is space, what is time, what is geometry in the absence of a fixed background space, how can one quantize geometry...)

My impression is that the chapters of the book that are historical and philosophical are among the most interesting and enlightening. They will remain relevant for many decades, I suspect, even after the technical chapters are superseded.

The technical chapters deal with particular approaches to classical and quantum relativity. The particular mathematical formalisms have evolved since 2004 since the book was published, so while these chapters are a valuable preparation they are not complete and up-to-date.

My impression is that the interesting historical general discussion was not changed very much between the freely downloadable 2003 draft and the published version. Thus if one only wants the non-technical parts of the book, one can save some money. But the book is much nicer to handle than a stack of computer printout. It's one you will want to own if you can afford it, IMO.

About editions. The PAPERBACK version is available, costing less than the hardbound.

About alternatives, the book of THIEMANN has come out, and we have had a thread here at Beyond forum discussing that book. Jim Kata started the thread. It turned out that several people had already bought the book and were using it. IIRC the comments were entirely favorable. I will get the link to the thread discussing Thiemann's book.
https://www.physicsforums.com/showthread.php?t=196209

 

[Fra]

Thanks Marcus, I shortened my post in the other thread. I didn't realize it was a special thread.

If anyone has and opinons on my question I'm interested to hear. My focus is to analyze the approach advocated by Rovelli, in a scientific and philosophical setting.

I've already ordered the book, so I'll skim that either way. But if anyone thinks I should read anything else regarding the foundations of the approach I'm interested. I'm looking to sort of evaluate the original line of reasoning, rather than some "pedagogical" or "techical" rewritings.

I found Rovelli's -97 LQG summary paper already - http://arxiv.org/abs/gr-qc/9710008, but that's older then the book so I'd assume the book would cover and conceptual things older than the book itself?

/Fredrik

 

[marcus]

Hi Fra,
Thanks, BTW you have raised some interesting questions like what other QG books are out there that also deal with the general foundations questions and which could supplement Rovelli's. I hope we hear from a few other people about this.

I'll gather a few links together. Here is Rovelli's homepage
http://www.cpt.univ-mrs.fr/~rovelli/
Here he has the draft, and the errata. Here also he has links to some reviews.

And I see from the amazon page
https://www.amazon.com/dp/0521837332/?tag=pfamazon01-20 that there are some more QG books which cite Rovelli---books that have come out since 2004 when his was published.
I won't give the links----they are at the Amazon page. Here is a sample of three titles.
# The Structural Foundations of Quantum Gravity by Dean Rickles on 10 pages
# Towards Quantum Gravity: Proceedings of the XXXV International Winter School on Theoretical Physics, Held in Polanica, Poland, 2-11 February 1999 (Lecture Notes in Physics) by Jerzy Kowalski-Glikman on 10 pages
# Physics Meets Philosophy at the Planck Scale: Contemporary Theories in Quantum Gravity by Craig Callender on 7 pages

I am puzzled by the fact that I don't see a paperback edition listed. I thought the paperback was out.
GOOD! I see the paperback edition page now:
https://www.amazon.com/dp/0521715962/?tag=pfamazon01-20
This is considerably cheaper, and it is possible that there have been some minor corrections, like fixing typos. I don't know how much revision there has been. The paperback is much more recent---17 December 2007.
It just came out in the past few weeks!

 

[Fra]

Thanks Marcus,

I ordered the hardback, mainly because the softback books generally tend to disintegrate with time if you want to flatten it properly while reading (like I do), I hate that, and the price was still reasonable as compared to other books. I've got too many softbacks already with loose pages beeing a disgrace to my bookshelf. However you got a great point that the software is a new print, I didn't see this until you pointed it out!

/Fredrik

 

[marcus]

... However you got a great point that the software is a new print,..

I don't know how much revision, if any! The paperback may be no advantage of that sort.
I have the hardbound edition you ordered---one of my favorite books.

 

[Fra]

I've started to skim the old paper until I get the book. I think this will be enlightning! I hope the book will come soon. The official delivery time was claimed as 2-5 days from where I ordered it.

The first think that strikes me from the old reasonings is the logic of reasoning that is applied to the decision process of "picking the observables" so to speak. This should IMO have a connection to statistical physics and measurement issues, I think this particular focus is a key and will ve very interesting

/Fredrik

 

[Fra]

I finally received the book! Due to time constraints the reading will be slow. There are some interesting key styles of thinking that reveal themselves already during the first chapter. I hope to get back to these issues, and hear if my reflections on these things coincide with the others who read this.

The two things that strike me first is the view of "background independence" and what is means, and the decomposition of "configuration space" into spacetime and "other things". Would knowledge about "spacetime" be treated differently than information about anything? I'll read on a little more before I'll start a discussion on this, since the following, increasinly more technical discussions rely on this, it seems crucial to question these things as they first appear.

/Fredrik

 

[Fra]

I've started to read the book, but so far I've been unusually busy so I've only been able to read a few pages only per night before I fall asleep. His first conceptual overview is nice but also ambigous to me beucase I like some parts, but some other parts are unclear. So either I don't like his reasoning, or I don't understand his reasoning yet.

To tell I need to make more progress in the book. I'll jump in the book to try to find out Rovelli's idea of QM and quantization in general, to me that is a key. Because to just pull out a hilbert space, doesn't seem to comply with my view of background independence as I think of it. It seems his view of background independence is concentrated in the metric only. But I like to think that background indepedence applied to any non-trivial "structure". Be it a probability space or anything. But I hope it's beceuase his informal overview is too brief, and that he will explain that in the QM section. I read breifly about rovelli's elephant ideas before but never analyzed that in depth. So I'm excited to review his view of that part.

/Fredrik