منابع مشابه
Stealth Acceleration and Modified Gravity
We show how to construct consistent braneworld models which exhibit late time acceleration. Unlike self-acceleration, which has a de Sitter vacuum state, our models have the standard Minkowski vacuum and accelerate only in the presence of matter, which we dub “stealth-acceleration”. We use an effective action for the brane which includes an induced gravity term, and allow for an asymmetric set-...
متن کاملCosmic Acceleration and Modified Gravity
Abstract I briefly discuss some attempts to construct a consistent modification to General Relativity (GR) that might explain the observed late-time acceleration of the universe and provide an alternative to dark energy. I mention the issues facing extensions to GR, illustrate these with two specific examples, and discuss the resulting observational and theoretical obstacles. This article compr...
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The recently observed accelerating cosmological expansion or ”dark energy” may be either a negative pressure constituent in General Relativity (Dark Energy) or modified gravity (Dark Gravity) without any constituent Dark Energy. Lowor high-curvature modifications of Einstein gravity are distinguished by the spacetime (Ricci) curvature of their vacua. If constituent Dark Energy does not exist, s...
متن کاملAcceleration from Modified Gravity: Lessons from Worked Examples
I examine how two specific examples of modified gravity explanations of cosmic acceleration help us understand some general problems confronting cosmological tests of gravity: how do we distinguish modified gravity from dark energy if they can be made formally equivalent? how do we parameterize deviations according to physical principles with sufficient generality, yet focus cosmological tests ...
متن کاملThe Dynamics Driving Cosmological Acceleration: Dark Energy or Modified Gravity?
This phenomenological review stresses the distinction between kinematics), the description of the recently inflationary universe (cosmography), and dynamics, the mechanism driving this accelerating expansion. Because the homogeneous expansion history H(z) of the universe measures only kinematic variables, it cannot fix the underlying dynamics: cosmographic measurements of the homogeneous univer...
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ژورنال
عنوان ژورنال: Journal of Cosmology and Astroparticle Physics
سال: 2007
ISSN: 1475-7516
DOI: 10.1088/1475-7516/2007/10/006