Dark energy and dark gravity: theory overview
نویسندگان
چکیده
منابع مشابه
Dark Energy and Dark Gravity : Theory Overview
Observations provide increasingly strong evidence that the universe is accelerating. This revolutionary advance in cosmological observations confronts theoretical cosmology with a tremendous challenge, which it has so far failed to meet. Explanations of cosmic acceleration within the framework of general relativity are plagued by difficulties. General relativistic models are nearly all based on...
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Observations provide increasingly strong evidence that the universe is accelerating. This revolutionary advance in cosmological observations confronts theoretical cosmology with a tremendous challenge, which it has so far failed to meet. Explanations of cosmic acceleration within the framework of general relativity are plagued by difficulties. General relativistic models are nearly all based on...
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Given the expansion rate of the universe in terms of the Hubble constant H0 = (ȧ/a)0, one can define a critical energy density ρc = 3H 2 0/8πG which is required to make the spatial sections of the universe compact. It is convenient to measure the energy densities of the different species, which drive the expansion of the universe, in terms of this critical density using the dimensionless parame...
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Explanations of the late-time cosmic acceleration within the framework of general relativity are plagued by difficulties. General relativistic models are mostly based on a dark energy field with fine-tuned, unnatural properties. There is a great variety of models, but all share one feature in common – an inability to account for the gravitational properties of the vacuum energy, and a failure t...
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ژورنال
عنوان ژورنال: General Relativity and Gravitation
سال: 2007
ISSN: 0001-7701,1572-9532
DOI: 10.1007/s10714-007-0549-5