Results 31 to 40 of about 20,270 (72)

Isotropic Loop Quantum Cosmology [PDF]

, 2002
Isotropic models in loop quantum cosmology allow explicit calculations, thanks largely to a completely known volume spectrum, which is exploited in order to write down the evolution equation in a discrete internal time.
, Ames W F, Ashtekar A, Ashtekar A, Ashtekar A, Ashtekar A, Baez J C, Bahcall J N, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Bojowald M, Gurovich V Ts, Hawking S W, Immirzi G, Kuchar K V, Martin Bojowald, Rovelli C, Thiemann T, Thiemann T, Thiemann T, Veneziano G, Witten E   +25 more
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Quantum Gravity and Inflation [PDF]

, 2004
Using the Ashtekar-Sen variables of loop quantum gravity, a new class of exact solutions to the equations of quantum cosmology is found for gravity coupled to a scalar field, that corresponds to inflating universes.
A. D. Linde, A. D. Linde, A. Perez, A. Vilenkin, Carlo Rovelli, Chopin Soo, Chopin Soo, D. Oriti, G. A. M. Marugan, G. F. Mazenko, H. Kodama, H. Kodama, J. B. Hartle, J. Martin, Justin Malecki, L. Smolin, Lee Smolin, Stephon Alexander, T. Thiemann, T. Vachaspati, Takashi Sano, William H. Kinney   +21 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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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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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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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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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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Nonmetricity formulation of general relativity and its scalar-tensor extension

, 2018
Einstein's celebrated theory of gravitation can be presented in three forms: general relativity, teleparallel gravity, and the rarely considered before symmetric teleparallel gravity.
Järv, Laur, Rünkla, Mihkel, Saal, Margus, Vilson, Ott   +3 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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