Results 41 to 50 of about 3,462 (164)
Classification of teleparallel Horndeski cosmology via Noether symmetries
European Physical Journal C: Particles and Fields, 2022 Teleparallel Horndeski theory offers an avenue through which to circumvent the speed constraint of gravitational waves in an efficient manner. However, this provides an even larger plethora of models due to the increase in action terms.
Konstantinos F. Dialektopoulos +2 more
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Generating Gowdy cosmological models [PDF]
Journal of Mathematical Physics, 2004 Using the analogy with stationary axisymmetric solutions, we present a method to generate new analytic cosmological solutions of Einstein’s equation belonging to the class of T3 Gowdy cosmological models. We show that the solutions can be generated from their data at the initial singularity and present the formal general solution for arbitrary initial ...
Sanchez, A, Macias, A, Quevedo, Hernando
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METAPHYSICS AND EPISTEMOLOGY IN STEPHEN HAWKING'S THEORY OF THE CREATION OF THE UNIVERSE
Zygon, 1996 . In 1981 S. W. Hawking and J. Hartle presented a quantum mechanical description of the early stages of possible cosmological evolution. Their proposal was interpreted by many authors as a pattern of cosmic creation from nothing in which no divine ...
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Inferring Cosmological Parameters with Evidential Physics-Informed Neural Networks
UniverseWe examine the use of a novel variant of Physics-Informed Neural Networks to predict cosmological parameters from recent supernovae and baryon acoustic oscillations (BAO) datasets. Our machine learning framework generates uncertainty estimates for target
Hai Siong Tan
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Cosmological consequences of a variable cosmological constant model [PDF]
International Journal of Modern Physics D, 2016 We derive a model of dark energy which evolves with time via the scale factor. The equation-of-state is studied as a function of a parameter [Formula: see text] introduced in this model as [Formula: see text]. In addition to the recent accelerated expansion, the model predicts another decelerated phase.
Azri, Hemza, Bounames, A.
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The standard cosmological model [PDF]
Canadian Journal of Physics, 2006 The Standard Model of Particle Physics (SMPP) is an enormously successful description of high-energy physics, driving ever more precise measurements to find "physics beyond the standard model", as well as providing motivation for developing more fundamental ideas that might explain the values of its parameters.
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On nonlocal cosmological equations on half-line
Vestnik Samarskogo Gosudarstvennogo Tehničeskogo Universiteta. Seriâ: Fiziko-Matematičeskie Nauki, 2011 A system of nonlocal cosmological equations where the time variable runs over a half-line is considered. These equations are more suitable for description of the Universe than the previously discussed cosmological equations on the whole line since the ...
Irina Ya Aref'eva, Igor' V Volovich
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COSMOLOGICAL PERTURBATIONS AND THE RUNNING COSMOLOGICAL CONSTANT MODEL [PDF]
International Journal of Modern Physics D, 2012 We study the matter density fluctuations in the running cosmological constant (RCC) model using linear perturbations in the longitudinal gauge. Using this observable, we calculate the growth rate of structures and the matter power spectrum, and compare these results to SDSS data and the available data for linear growth rate.
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Neutrinos in Cosmological Models [PDF]
Progress of Theoretical Physics, 1980 Observations show that the Universe is very nearly homogeneous and isotropic on a large scale. It follows, that on a large scale, the Universe may be approximately described by one of the Robertson-Walker models. These models have the property o£ possessing exact spatial homogeneity and isotropy about each event.
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Use of Redshifts as Evidence of Dark Energy
PhysicsThe large-scale dynamics of the universe is generally described in terms of the time-dependent scale factor a(t). To make contact with observational data, the a(t) function needs to be related to the observable z(r) function, redshift versus distance ...
Jan Stenflo
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