Results 41 to 50 of about 20,416 (75)

The cosmological implications of a fundamental length: a DSR inspired de-Sitter spacetime

, 2008
We study a de-Sitter model in the framework of a Deformed Special Relativity (DSR) inspired structure. The effects of this framework appear as the existence of a fundamental length which influences the behavior of the scale factor.
Amelino-Camelia G, Amelino-Camelia G, Ashtekar A, Brandenberger R H, Carmona J M, Cheng T-P, Connes A, Green M, H R Sepangi, Khosravi N, Khosravi N Sepangi H R, Kowalski-Glikman J, Liddle A R, Magueijo J, Majid S, N Khosravi, Nascimento J R, Perkins D, Polchinski J, Rovelli C, Rovelli C, Seiberg N, Susskind L, Zachos C K   +23 more
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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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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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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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Loop Quantum Cosmology, Boundary Proposals, and Inflation

, 2003
Loop quantum cosmology of the closed isotropic model is studied with a special emphasis on a comparison with traditional results obtained in the Wheeler-DeWitt approach.
A. Ashtekar, A. Vilenkin, A. Vilenkin, B.S. DeWitt, C. Rovelli, C.W. Misner, G. Immirzi, H.D. Conradi, J.B. Hartle, J.F. Barbero G., Kevin Vandersloot, M. Bojowald, M. Bojowald, M. Bojowald, M. Bojowald, M. Bojowald, M. Bojowald, M. Bojowald, M. Bojowald, M. Bojowald, M. Bojowald, M. Bojowald, M. Bojowald, Martin Bojowald, N. Kontoleon, T. Thiemann, T. Thiemann   +26 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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Past-directed scalar field gradients and scalar-tensor thermodynamics. [PDF]

Gen Relativ Gravit, 2023
Giusti A, Giardino S, Faraoni V.
europepmc   +1 more source

On the Physical Hilbert Space of Loop Quantum Cosmology

, 2004
In this paper we present a model of Riemannian loop quantum cosmology with a self-adjoint quantum scalar constraint. The physical Hilbert space is constructed using refined algebraic quantization.
A. Ashtekar, Abhay Ashtekar, Abhay Ashtekar, Alejandro Perez, C. Rovelli, C. Rovelli, Karim Noui, Kevin Vandersloot, L. Smolin, Martin Bojowald   +9 more
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More on the first-order thermodynamics of scalar-tensor and Horndeski gravity. [PDF]

Eur Phys J C Part Fields, 2023
Faraoni V, Houle J.
europepmc   +1 more source