scholarly journals Coarse Graining Spin Foam Quantum Gravity—A Review

2020 ◽  
Vol 8 ◽  
Author(s):  
Sebastian Steinhaus
Keyword(s):  
Quantum Gravity ◽  
Coarse Graining ◽  
Spin Foam

scholarly journals MEASUREMENTS AND INFORMATION IN SPIN FOAM MODELS

2012 ◽  
Vol 27 (28) ◽  
pp. 1250164
Author(s):  
J. MANUEL GARCÍA-ISLAS
Keyword(s):  
Information Theory ◽  
Quantum Gravity ◽  
Cosmological Constant ◽  
Shannon Entropy ◽  
Three Dimensional ◽  
Spin Network ◽  
Spin Foam Models ◽  
Foam Model ◽  
Spin Foam Model ◽  
Spin Foam

In the three-dimensional spin foam model of quantum gravity with a cosmological constant, there exists a set of observables associated with spin network graphs. A set of probabilities is calculated from these observables, and hence the associated Shannon entropy can be defined. We present the Shannon entropy associated with these observables and find some interesting bounded inequalities. The problem relates measurements, entropy and information theory in a simple way which we explain.

scholarly journals POLYMER GEOMETRY AT PLANCK SCALE AND QUANTUM EINSTEIN EQUATIONS

1996 ◽  
Vol 05 (06) ◽  
pp. 629-648 ◽  
Author(s):  
ABHAY ASHTEKAR
Keyword(s):  
Quantum Gravity ◽  
Planck Scale ◽  
Coarse Graining ◽  
Space Structure ◽  
Einstein Equations ◽  
Hamiltonian Constraint ◽  
Recent Approach ◽  
Canonical Approach ◽  
Background Fields ◽  
Discrete Spectra

Over the last two years, the canonical approach to quantum gravity based on connections and triads has been put on a firm mathematical footing through the development and application of a new functional calculus on the space of gauge equivalent connections. This calculus does not use any background fields (such as a metric) and thus well-suited to a fully non-perturbative treatment of quantum gravity. Using this framework, quantum geometry is examined. Fundamental excitations turn out to be one-dimensional, rather like polymers. Geometrical observables such as areas of surfaces and volumes of regions are purely discrete spectra. Continuum picture arises only upon coarse graining of suitable semi-classical states. Next, regulated quantum diffeomorphism constraints can be imposed in an anomaly-free fashion and the space of solutions can be given a natural Hilbert space structure. Progress has also been made on the quantum Hamiltonian constraint in a number of directions. In particular, there is a recent approach based on a generalized .Wick transformation which maps solutions to the Euclidean quantum constraints to those of the Lorentzian theory. These developments are summarized. Emphasis is on conveying the underlying ideas and overall pictures rather than technical details.

scholarly journals Coarse graining in spin foam models

2003 ◽  
Vol 20 (5) ◽  
pp. 777-799 ◽  
Author(s):  
Fotini Markopoulou
Keyword(s):  
Coarse Graining ◽  
Spin Foam Models ◽  
Spin Foam

scholarly journals Towards a cosmological subsector of spin foam quantum gravity

2017 ◽  
Vol 96 (8) ◽  
Author(s):  
Benjamin Bahr ◽  
Sebastian Klöser ◽  
Giovanni Rabuffo
Keyword(s):  
Quantum Gravity ◽  
Spin Foam

scholarly journals Hamiltonian Renormalization V: Free Vector Bosons

2021 ◽  
Vol 7 ◽  
Author(s):  
K. Liegener ◽  
T. Thiemann
Keyword(s):  
Quantum Gravity ◽  
Coarse Graining ◽  
Scalar Fields ◽  
Recent Proposal ◽  
Fock Representation ◽  
Vector Bosons ◽  
Free Scalar ◽  
Fock Representations ◽  
Canonical Quantum Gravity ◽  
Canonical Quantum

In a recent proposal we applied methods from constructive QFT to derive a Hamiltonian Renormalization Group in order to employ it ultimately for canonical quantum gravity. The proposal was successfully tested for free scalar fields and thus a natural next step is to test it for free gauge theories. This can be done in the framework of reduced phase space quantization which allows using techniques developed earlier for scalar field theories. In addition, in canonical quantum gravity one works in representations that support holonomy operators which are ill defined in the Fock representation of say Maxwell or Proca theory. Thus, we consider toy models that have both features, i.e. which employ Fock representations in which holonomy operators are well-defined. We adapt the coarse graining maps considered for scalar fields to those theories for free vector bosons. It turns out that the corresponding fixed pointed theories can be found analytically.

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