The loop-quantum-gravity tag has no wiki summary.
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2answers
174 views
Coherent $U(N)$ intertwiners in Loop Quantum Gravity (LQG) and a measure on the Grassmannian
This is a detailed question about $U(N)$ intertwiners in LQG, and it comes from the the paper by Freidel and Livine (2011 - archive). It is very specific but related to finding a measure on a quotient ...
9
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0answers
156 views
How is Matter Modelled in Loop Quantum Gravity?
I have a basic understanding of how gravitational degrees of freedom are modelled in loop quantum gravity, but as far as I know, the main machinery - spin network states and observables, does not ...
1
vote
1answer
169 views
Is Space-Time Quantisation necessary or even meaningful?
It is believed among people working on Quantum Gravity, that space-time must be quantised at the Planck scale. Although it is very hard to verify such proposition, it is interesting from a ...
1
vote
1answer
96 views
What are all the approaches that have been tried for a theory of quantum gravity? [closed]
I am aware that that the most researched approach is that of string theory. I have also heard about quantum loop gravity. What other approaches are there to unify gravity and QFT? Also, please include ...
0
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1answer
89 views
Entropy, Mass and Brane gravity
Does string theory state as vibrational entropy increases, mass increases?
Related: What is a D-brane?
Reference: Cambridge Relativity
7
votes
1answer
202 views
Area law for Entropy in Loop Quantum Gravity
In connection with the long saga of the (claimed) microscopic
calculations of the Hawking-Bekenstein entropy in (3+1) Loop Quantum Gravity (LQG) and related approaches I have the following question: ...
10
votes
3answers
438 views
Space-time in String Theory
I would like to understand how Physicists think of space-time in the context of String Theory. I understand that there are $3$ large space dimensions, a time dimension, and $6$ or $7$ (or $22$) extra ...
1
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1answer
336 views
How is the expansion of space itself explained in LQG?
To explain the expansion of space I have often heard people saying that space is continuously created. This picture is usually applied to cosmological scales but I`m nevertheless curious if some ...
2
votes
3answers
504 views
Does the Opera result hint to a discrete spacetime?
Could the Opera result be interpreted as some kind of hint to a discrete spacetime that is only seen for high enough energy neutrinos?
I think I`ve read (some time ago) something like this in a ...
3
votes
1answer
241 views
LQG Demystified Book?
Does a similar easy to read introduction like David Mc Mohan s Demystified books exist for LQG? I d like something easier to start with than a paper but deeper than a popular book...
3
votes
1answer
196 views
A loop quantum gravity toy inspired by an Aharonov-Bohm ring
Comparing my question to Give a description of Loop Quantum Gravity your grandmother could understand what I'm looking for here is a toy for a toddler ($\approx$ a pre-QFT graduate student).
I seek ...
2
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1answer
131 views
If the graph isomorphism problem can't be solved in polynomial time, do spin-networks in loop quantum gravity violate the Church-Turing thesis?
If the graph isomorphism problem can't be solved in polynomial time, do spin-networks in loop quantum gravity violate the Church-Turing thesis? To determine whether or not two graphs are isomorphic ...
4
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1answer
706 views
What do “tachionic” neutrinos mean for QG?
Reading about the spectacular Opera claim, I`m (again ;-P) wondering if a confirmation of superliminous neutrinos could help settle some still open quantum gravity issues ...?
In this post, Lumo ...
3
votes
4answers
449 views
Question regarding the validity of the big bounce
I have several questions regarding the "big bounce" theory. It appears to be popular among LQG researchers. My questions are as as follows.
1) How one reconciles it with the fact that it is now ...
6
votes
1answer
304 views
Are there any versions of LQG that claim to not violate Lorentz symmetry?
LQG formulations have a minimum length/area. Since say, a Planck area can always
be boosted, any minimum area in space can be shrunk. Do LQG proponents worry about local Lorentz invariance violation, ...
7
votes
4answers
1k views
Can Loop Quantum Gravity connect in any way with string theory?
The one difficulty I see with LQG is that it requires an enormous number of degrees of freedom, e.g. these spin variables in the net. This is in contrast to stringy holographic theory where the ...
9
votes
7answers
652 views
Does the discreteness of spacetime in canonical approaches imply good bye to STR?
In all the canonical approaches to the problem of quantum gravity, (eg. loop variable) spacetime is thought to have a discrete structure. One question immediately comes naively to an outsider of this ...
7
votes
2answers
314 views
Is taking the “square root” of the densitized inverse triad irregular in loop quantum gravity?
In loop quantum gravity, the canonical (Ashtekar) variables are chosen to be the densitized inverse triad $\mathbf{E}$ and some rotation connection field $\mathbf{A}$. To get the ordinary triad from ...
9
votes
4answers
870 views
Discussion of the Rovelli's paper on the black hole entropy in Loop Quantum Gravity
In a recent discussion about black holes, space_cadet provided me with the following paper of Rovelli: Black Hole Entropy from Loop Quantum Gravity which claims to derive the Bekenstein-Hawking ...
9
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5answers
611 views
What is the role spin-networks play in Loop Quantum Gravity?
This is a second question (in what will probably become a series) in my attempt to understand LQG a little. In the previous question I asked about the general concepts behind LQG to which space_cadet ...
14
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4answers
2k views
Give a description of Loop Quantum Gravity your grandmother could understand
Of course, assuming your grandmother is not a theoretical physicist.
I'd like to hear the basics concepts that make LQG tick and the way it relates to the GR. I heard about spin-networks where one ...
