Quantum gravity Definition and 482 Threads

https://www.physicsforums.com/showpost.php?p=847769&postcount=426 what is wrong with Wang's approach? or even simpler, what IS Wang's approach, what is the essential, what makes it different? how can one even consider using conformal diffeomorphisms instead of ordinary? Is this what he...

QG '05 was held in September, on the island of Sardinia Here is the program http://www.phy.olemiss.edu/GR/qg05/program.html There is a sampling of the abstracts here: https://www.physicsforums.com/showthread.php?p=842631#post842631 and a little discussion, comparing this conference with Loops...

In the canonical quantum gravity, Hamiltonian equal zero, why? Since the split is space, the time is a constant? or the space-time is Ricci-flat? In other words, if the space-time is Ricci-flat whether time supersurface, Hamiltonian equal zero?

http://arxiv.org/abs/hep-th/0510270 Authors: Michael A. Ivanov Comments: 20 pages, 3 figures, LaTeX. Contribution to the VII Asia-Pacific International Conference on Gravitation and Astrophysics (ICGA7), which will be held in Jhongli, Taiwan, 23 - 26 November 2005 If gravitons are...

Do We Observe Quantum Gravity Effects at Galactic Scales? http://www.arxiv.org/abs/astro-ph/0509163 Do we Observe Quantum Gravity Effects at Galactic Scales? M. Reuter, H. Weyer 6 pages, 1 figure. Talk given by M.R. at the 21st IAP meeting "Mass Profiles and Shapes of Cosmological...

Could somebody here tell me how somebody gets into Loop Quantum Gravity. I've seen that the CASM and Glasgow and a lot of other universities have String Theory courses, but I've never seen a LQG module. Is it simply a matter of applying to some group after your Ph.D.? Just curious...

http://math.ucr.edu/home/baez/this.week.html brief, on the whole pessimistic, comment on the current situation of string and loop/foam. no discussion of other approaches currently being researched. post conveys the strong attraction of pure math. Baez cites a Rovelli paper that came out...

i know what it is, and why its searched for...but i have brought myself to a fairly simple answer, and would like to know why it is not a correct one. could quantum gravity not merely state that the reason for the distortion of particles into the qm description (partial-wave) is because of the...

Stephen Hawking's latest preprint on Arxiv uses "Euclidean Quantum Gravity". In fact, he says: "I adopt the Euclidean approach [5], the only sane way to do quantum gravity nonperturbatively." http://www.arxiv.org/abs/hep-th/0507171 Any comments? Carl

here is a fairly simple question... is the purpose of quantum gravity to relate gravitation/relativity to our understanding of quantum machanics as is? I am not entirely sure on this, could someone explain

http://arxiv.org/PS_cache/hep-th/pdf/0506/0506189.pdf Title: Gravitons as super-strong interacting particles, and low-energy quantum gravity Authors: Michael A. Ivanov Comments: 38 pages, 9 figures, Latex. Will be published in 2005 It is shown by the author that if gravitons are...

Hi, I have been reading the paper "Quantum Gravity with a Positive Cosmological Constant" by Lee Smolin (http://arxiv.org/abs/hep-th/0209079), and am having some trouble making the constants in Part I, Sections 2, 3, and 4 match with what I would calculate them to be when I try to go through...

I think in LQG matter has only been tentatively considered, but if matter is reduced to a," field", or wave function, could one transform into the other?

I happen to think it does. I will try to say why in this thread. Other people may very likely disagree, so it is possible to have discussion about this. you can get most of CDT out of two basic papers "Dynamically..." and "Reconstructing..." the links are in my signature. I will copy them...

The question I am going to ask here lies on a thin line between quantum gravity research and philosophy, but I'd thought I'd post it in this forum here to get insights in line with the research on quantum gravity. Basically, in quantum gravity approaches, LQG is background-independent but...

http://arxiv.org/abs/gr-qc/0505052 Authors: Rodolfo Gambini, Jorge Pullin Comments: 8 pages, one figure, fifth prize of the Gravity Research Foundation 2005 essay competition Report-no: LSU-REL-051105 We argue that recent developments in discretizations of classical and quantum...

Is it correct to think that, in QG at a fundamental level there is no time evolution , and 10-40 seconds is the smallest measurable time period? I have looked at various papers, and it seems that even though 10-40 seconds is the smallest time unit ,many "Timeless events", can occure beyond...

Short question: is the concept of length meaningful in LQG?

http://arxiv.org/pdf/gr-qc/0502110 Has anyone a reason to believe that gravity is" quanta sizable", or quantum in nature? The above paper has little to say on the subject its more an over view of QG, but it does state in the first few lines that there is no reason. And is Plank a...

Does anyone know how in LQG they avoid the contradiction of a smallest unit of quantized space and Lorentz contraction?

The "Third Road" to Quantum Gravity I have been thinking lately about where the search for Quantum Gravity may be headed in the near future and it has struck me that the LHC is going to be a major pivot point in the future of research- if they are able to observe micro black-holes with the LHC-...

Phenomenological Qunatum Gravity: the birth of a new frontier? http://arxiv.org/abs/astro-ph/0501581 If you can overlook the spelling error in the title, it is otherwise an entertaining read.

http://xyz.lanl.gov/pdf/gr-qc/0501053 The search for quantum gravity signals jan 2005 an overview of ongoing searches for quantum gravity effects.

This paper by Mohammed Ansari and Lee Smolin, http://arxiv.org/abs/hep-th/0412307, seems to have been overlooked here. The authors argue that for any quantum theory of gravity (they mention LQG and causal triangulations) to produce macroscopic physics - which would be necessary for it to have...

Since the link came up... http://arxiv.org/PS_cache/hep-th/pdf/0106/0106109.pdf

Reading around Sommerfeld, I noticed a suppossedly very well known result: that orbits in the relativistic kepler problem have a minimum momentum. It is a special relativity result, and I do not know if it is related with the problem of the existence of stable orbits in GR; the later are orbits...

In the forward to rovelli's new book "Quantum Gravity", james bjorken states quite plainly that the effective field theory approach to quantum gravity correctly taught us that GR must be viewed as just an effective field theory, and in fact this is the universally shared view. The problem for...

INTRODUCTION TO LOOP QUANTUM GRAVITY, everything you ever wanted to know... In Loop Quantum Gravity, also referred to as LQG, the attempt is made to introduce the concept of quantum gravity. This is the unification of the General Theory of Relativity and the Quantummechanics. It is a very...

In a recent post in his blog, Woit comments on a philosophy of science article by a philosopher who claims that the dualities in string theory imply the "dissolution of the ontological object". His claim is that because the dualities in string theory can describe two different sorts of...

This quantum gravity workshop at the Perimeter Institute was really cool: http://www.perimeterinstitute.ca/activities/scientific/PI-WORK-2/ It was their first conference in the new building. I'm writing an issue of This Week's Finds about some things I learned that made me much more...

i have the elegant universe and am about half way through. after this, i would like to read about string theory's rival, loop quantum gravity. does anyone know of a good intro book to loop quantum gravity?

want to read together this recent Bojowald paper? Time Dependence in Quantum Gravity http://arxiv.org/gr-qc/0408094 Bojo is at Albert Einstein Institute (AEI-Gölm) one of the premier places for QG. It looks like not too hard and it clarifies things about time in QG. So could be useful...

What exactly is 2D quantum gravity? Is it just a simplification of 3D quantum gravity i.e. to get results easier?

let be e>0 but small so quantum gravity is renormalizable then what would be the calculation of mass and charge of it depending on e,now let,s take the limit e--->0 what would we have?...

I was wondering once a consistent quantum gravity theory would be devised (I have in mind especially string theory or loop quantum gravity) what would happen to quantum mechanics interpretations. Would these all be abandoned? Would a new interpretation come up? I mean by this for example...

I decided to start this thread and it can be moved to wherever people might feel it appropriate, under the heading of Relativity or quantum Mechanics, or New Forum. I decided to started http://wc0.worldcrossing.com/WebX?14@2.gNrQc8lGC5Y.43@.1de0f3cf in the event such an idea was to begin...

It would be nice if there were a Quantum Gravity Forum at PF It's rather a separate business from string and in a combined forum with string the buzz of interest in other matters is a mite distracting Dividing might make it more convenient to both pursuits and interested parties (btw...

When do you people think an actual quantum gravity theory will become falsifiable? I know that a big criticism of string theory right now is that it can't make any experimental predictions, but as far as I know, loop quantum gravity can't either. I was wondering what your guesses are for when...

hello, can anyone give me some introductory notions of what loop quantum gravity (i hope it is in the right order) and what are the differences with string theory. I know my QFT and i have some introductory notions on strings, so i don't mind a deeply elaborated physical answer. Feel free...

Third scale QG that Smolin and others are working on attempts to incorporate 3 invariant scales (the speed c, the Planck mass kappa, and the length L = Lambda-1/2) and to have 3SR---triply special relativity---as its flat limit. this research direction has been attracting more people lately...

i found this in my wandering in google: http://pdg.cecm.sfu.ca/~warp/papers/essay/essay.html can someone explain to me this approach of quantum gravity in simple terms? i think it has to do with simulations of quantum gravity at the Planck level, am i correct?

quantum gravity research seems to be undergoing some changes so just because this function comes up today doesn't mean it will be around for eternity, but that said, look at this function L(x) = \sum_{p = semi-integer > 0}\frac{1}{x^\sqrt{p(p+1)}} It comes up in connection with Black...

http://arxiv.org/physics/0401128 Beyond Space And Time Ruediger Vaas 7 pages, English translation by Amitabha Sen of the German article "Jenseits von Raum und Zeit" http://arxiv.org/physics/0403112 The Duel: Strings versus Loops Ruediger Vaas 10 pages, English translation by...

Apart from C, P and T violation in weak interaction, do the same violations occur for the other three forces, in particular, the quantum gravity force?

There’s a consensus among many physicists that the universe did not emerge from nothing, if fact stating that nothing simply cannot exist. However while reading Carlo Rovelli book Quantum Gravity, the following on page 25 states: So if we continue with this interpretation of fields...

I would like to hear comments from anyone concerning the below. Honest and critical feedback from qualified individuals is most welcome. Thanks for your reviews! This simple calculation bases the quantum effects of gravity on the electromagnetic frequency across ½ the Compton wavelength of...

In the following discussion we will use an equation which is a possible candidate for quantum gravity to demonstrate that the size of the universe at the time of the Big Bang could have been much greater than is currently thought by the majority of physicists. Using mvr = nh/2pi from Bohr’s...

april 2004 paper http://arxiv.org/abs/hep-ph/0404014 Decoherence has the potential to explain all existing neutrino data including LSND results, without enlarging the neutrino sector. This particular form of CPT violation can preserve the equality of masses and mixing angles between...

Not sure where to put this, so I'll drop it here. It seems that both NASA and ESA are committed to performing tests that may show deviations from GR. NASA has LATOR http://science.nasa.gov/headlines/y2004/26mar_einstein.htm And ESA has LISA...

This seems like an important issue. In his recent talk (reported on Woit's blog) David Gross said yes: Gross:"String theory is a consistent, finite quantum theory of gravity" However Woit says not: "Simply not true. Peturbative string theory is a divergent expansion, non-perturbative...