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The accelerating expansion of the un...

Upadhye, Amol Ravindra.

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The accelerating expansion of the universe.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	The accelerating expansion of the universe./
Author:	Upadhye, Amol Ravindra.
Description:	154 p.
Notes:	Source: Dissertation Abstracts International, Volume: 68-10, Section: B, page: 6713.
Contained By:	Dissertation Abstracts International68-10B.
Subject:	Physics, Astronomy and Astrophysics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3286135
ISBN:	9780549284987

The accelerating expansion of the universe.
Upadhye, Amol Ravindra.

The accelerating expansion of the universe. - 154 p.

Source: Dissertation Abstracts International, Volume: 68-10, Section: B, page: 6713.

Thesis (Ph.D.)--Princeton University, 2007.

Nearly a decade after the discovery of the cosmic acceleration, its cause remains a mystery. We present a broad range of theoretical models which could explain the acceleration, confronting them with experimental data whenever possible. We begin by studying the possibility that the cosmic acceleration is caused by a dark energy with a dynamical equation of state w( z). Current data from WMAP, supernova probes, and the SDSS are shown to allow a broad range of dark energy models, including the cosmological constant, tracker quintessence, and a dark energy whose equation of state drops rapidly from zero at z ≈ 1 to less than -1 today. We forecast the dark energy constraints achievable over the next several years, assuming eight years of WMAP data, approximately 2000 supernovae, and realistic projections for ground-based measurements of weak lensing. At the 2sigma level, the constraint on the current value of w is Deltaw 0(2sigma) = 0:20, and the constraint on its derivative is Deltaw1(2sigma) = 0:37. Although these constraints are tight enough to rule out rapidly evolving equations of state as well as tracker quintessence, we find that a large range of dynamical dark energy models remains allowed.

ISBN: 9780549284987Subjects--Topical Terms:

1019521
Physics, Astronomy and Astrophysics.

The accelerating expansion of the universe.
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020 $a 9780549284987
035 $a (UMI)AAI3286135
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100 1 $a Upadhye, Amol Ravindra. $3 1266251
245 1 4 $a The accelerating expansion of the universe.
300 $a 154 p.
500 $a Source: Dissertation Abstracts International, Volume: 68-10, Section: B, page: 6713.
502 $a Thesis (Ph.D.)--Princeton University, 2007.
520 $a Nearly a decade after the discovery of the cosmic acceleration, its cause remains a mystery. We present a broad range of theoretical models which could explain the acceleration, confronting them with experimental data whenever possible. We begin by studying the possibility that the cosmic acceleration is caused by a dark energy with a dynamical equation of state w( z). Current data from WMAP, supernova probes, and the SDSS are shown to allow a broad range of dark energy models, including the cosmological constant, tracker quintessence, and a dark energy whose equation of state drops rapidly from zero at z ≈ 1 to less than -1 today. We forecast the dark energy constraints achievable over the next several years, assuming eight years of WMAP data, approximately 2000 supernovae, and realistic projections for ground-based measurements of weak lensing. At the 2sigma level, the constraint on the current value of w is Deltaw 0(2sigma) = 0:20, and the constraint on its derivative is Deltaw1(2sigma) = 0:37. Although these constraints are tight enough to rule out rapidly evolving equations of state as well as tracker quintessence, we find that a large range of dynamical dark energy models remains allowed.
520 $a Next, we investigate the brane world model of Dvali, Gabadadze, and Porrati, in which the cosmic acceleration is caused by a horizon-scale modification to gravity, rather than a dark energy. A signature of such a modification to gravity is the apparent inconsistency between probes of the homogeneous expansion and inhomogeneous growth. We find that the measurements forecast above are insufficient to distinguish between dark energy and modified gravity. However, a more ambitious set of experiments will be able to probe modified gravity.
520 $a If the dark energy is a scalar field coupled to matter at the Planck scale, then its interactions with matter may be detectable, independently of its cosmological effects. A matter-coupled scalar theory, with a quartic self interaction, results in a fifth force at length scales relevant to the dark energy. We show that the Eot-Wash Experiment rules out such theories with unit values of the matter coupling and the quartic self coupling, although a small region of parameter space around these values remains.
520 $a Finally, we study the physics of energy landscape models. If our universe is in a vacuum of an energy landscape, then the vacuum energy will be equivalent to a cosmological constant. Examining several landscape models, we compute the probability that a given landscape will give rise to a spacetime region such as ours. We find that, if tunneling to adjacent vacua is gravitationally suppressed, and if each vacuum bubble periodically regenerates matter, then the observed cosmological constant will be of the order of the mean spacing between energy levels in the landscape.
590 $a School code: 0181.
650 4 $a Physics, Astronomy and Astrophysics. $3 1019521
650 4 $a Physics, Theory. $3 1019422
690 $a 0606
690 $a 0753
710 2 $a Princeton University. $3 645579
773 0 $t Dissertation Abstracts International $g 68-10B.
790 $a 0181
791 $a Ph.D.
792 $a 2007
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3286135