Results 21 to 30 of about 20,602 (71)

Brane-world gravity [PDF]

, 2003
The observable universe could be a 1+3-surface (the "brane") embedded in a 1+3+d-dimensional spacetime (the "bulk"), with standard-model particles and fields trapped on the brane while gravity is free to access the bulk.
Maartens, Roy
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Loop quantum gravity: the first twenty five years

, 2011
This is a review paper invited by the journal "Classical ad Quantum Gravity" for a "Cluster Issue" on approaches to quantum gravity. I give a synthetic presentation of loop gravity. I spell-out the aims of the theory and compare the results obtained with
Amelino-Camelia G, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Atiyah M, Baez J, Barrau A, Barrau A, Barrett J W Dowdall R J Fairbairn W J Hellmann F Pereira R, Bianchi E, Bianchi E, Bianchi E, Bianchi E Donà P Speziale S, Bianchi E Han M Magliaro E Perini C Rovelli C Wieland W, Bianchi E Han M Magliaro E Perini C Rovelli C Wieland W, Bianchi E Krajewski T Rovelli C Vidotto F, Bilson-Thompson S Markopoulou F Smolin L, Bojowald M, Calcagni G Gielen S Oriti D, Calmet X, Campiglia M Henderson A Nelson W, Carlo Rovelli, Ding Y, Ding Y Han M Rovelli C, Dittrich B, Dittrich B, Dittrich B, Dittrich B, Domagala M Giesel K Kaminski W Lewandowski J, Fairbairn W J Meusburger C, Fleischhack C, Freidel L, Freidel L Speziale S, Freidel L Speziale S, Geloun J B Gurau R Rivasseau V, Giesel K, Giesel K, Giesel K, Giesel K, Giesel K Tambornino J Thiemann T, Grain J Barrau A Cailleteau T Mielczarek J, Gurau R, Han M, Han M Rovelli C, Henderson A Rovelli C Vidotto F Wilson-Ewing E, Immirzi G, Immirzi G, Jacobson T, Kaminski W, Kaminski W, Krajewski T Magnen J Rivasseau V Tanasa A Vitale P, Livine E R, Livine E R, Major S, Major S A, Major S A, Martin-Benito M Garay L J Mena Marugan G A, Meissner K A, Mielczarek J, Minkowski H, Modesto L Premont-Schwarz I, Noui K, Oeckl R, Oriti D, Penrose R, Perez A, Ponzano G, Rivasseau V Wang Z, Rovelli C, Rovelli C, Rovelli C, Rovelli C, Rovelli C, Rovelli C, Rovelli C Smerlak M, Rovelli C Speziale S, Singh P, Singh P Vidotto F, Smolin L, Smolin L, Thiemann T, Thiemann T, Thiemann T, Thiemann T, Wieland W   +89 more
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Coherent states for FLRW space-times in loop quantum gravity

, 2011
We construct a class of coherent spin-network states that capture proprieties of curved space-times of the Friedmann-Lama\^itre-Robertson-Walker type on which they are peaked.
Abhay Ashtekar, Abhay Ashtekar, Antonino Marcianò, Carlo Rovelli, Claudio Perini, Elena Magliaro, Robert M. Wald, Thomas Thiemann   +7 more
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Unimodular Loop Quantum Cosmology

, 2010
Unimodular gravity is based on a modification of the usual Einstein-Hilbert action that allows one to recover general relativity with a dynamical cosmological constant.
A. Ashtekar, A. Ashtekar, A. Einstein, C. Rovelli, C. J. Isham, D. Marolf, Dah-Wei Chiou, M. Bojowald, Marc Geiller, P. A. M. Dirac, R. M. Wald, S. Hawking, T. Thiemann   +12 more
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The present moment in quantum cosmology: challenges to the arguments for the elimination of time [PDF]

, 2000
Barbour, Hawking, Misner and others have argued that time cannot play an essential role in the formulation of a quantum theory of cosmology. Here we present three challenges to their arguments, taken from works and remarks by Kauffman, Markopoulou and ...
Smolin, Lee
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On Higher Order Gravities, Their Analogy to GR, and Dimensional Dependent Version of Duff's Trace Anomaly Relation

, 2005
An almost brief, though lengthy, review introduction about the long history of higher order gravities and their applications, as employed in the literature, is provided.
A. Mardones, A. Salam, A.D. Dolgov, A.L. Berkin, B. Shahid-Saless, C. Romero, C.H. Brans, D.N. Vollick, E.S. Fradkin, F. Müller-Hoissen, G. Allemandi, G. Magnano, G. Stephenson, H.A. Buchdahl, H.A. Buchdahl, H.A. Buchdahl, I. Adler, I. Quant, J.A. Wheeler, J.C. Graves, J.D. Brown, J.T. Wheeler, J.Z. Simon, K.S. Stelle, K.S. Stelle, L. Amendola, L. Bonora, L. Bonora, M. Asorey, M. Farhoudi, M.E. Soussa, M.J. Duff, M.J. Duff, M.J. Duff, M.P. Ryan Jr., M.S. Madsen, Mehrdad Farhoudi, N. Deruelle, P. Teyssandier, P. Teyssandier, R. Bach, S. Carloni, S. Cecotti, S. Cnockaert, S. Deser, S. Deser, S. Gottlöber, S. Gottlöber, S. Nojiri, S. Nojiri, S. Nojiri, T. Chiba, T. Clifton, T. Fulton, V. Faraoni, W. Maluf   +55 more
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Observational Exclusion of a Consistent Quantum Cosmology Scenario

, 2015
It is often argued that inflation erases all the information about what took place before it started. Quantum gravity, relevant in the Planck era, seems therefore mostly impossible to probe with cosmological observations.
Barrau, Aurelien, Bolliet, Boris, Grain, Julien, Schander, Susanne   +3 more
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Modified Regge calculus as an explanation of dark energy

, 2012
Using Regge calculus, we construct a Regge differential equation for the time evolution of the scale factor $a(t)$ in the Einstein-de Sitter cosmology model (EdS).
McDevitt, T. J., Silberstein, M., Stuckey, W. M.   +2 more
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Spherically Symmetric Quantum Geometry: Hamiltonian Constraint

, 2005
Variables adapted to the quantum dynamics of spherically symmetric models are introduced, which further simplify the spherically symmetric volume operator and allow an explicit computation of all matrix elements of the Euclidean and Lorentzian ...
Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A Bojowald M Willis J, Ashtekar A Pawlowski T Singh P, Banerjee K, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M Hernández H H Morales-Técotl H A, Bojowald M Morales-Técotl H A, Bojowald M Skirzewski A, Brunnemann J, Cartin D, Date G, Fleischhack C, Giesel K Thiemann T, Hofmann S Winkler O, Hossain G M, Husain V, Husain V, Immirzi G, Lewandowski J Okołów A Sahlmann H Thiemann T, Martin Bojowald, Neville D E, Neville D E, Nicolai H, Perez A, Rafal Swiderski, Rovelli C, Rovelli C, Singh P, Smolin L, Thiemann T, Thiemann T, Thiemann T, Thiemann T, Tsujikawa S, Vereshchagin G V, Willis J   +61 more
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Planck-scale structure of spacetime and some implications for astrophysics and cosmology

, 2003
I briefly review some scenarios for the role of the Planck length in quantum gravity. In particular, I examine the differences between the schemes in which quantum gravity is expected to introduce a maximum acceleration and the schemes in which the ...
Amelino-Camelia, Giovanni
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