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MODIFIED f(R) THEORY OF GRAVITY: AN ALTERNATIVE GRAVITY THEORY
 Date Issued:
 2022
 Abstract/Description:
 Through the variational principle, we review the gravitational field equations in Einstein gravity and modified f(R) gravity theories. Metric and Palatini formalisms are two different approaches that are employed to obtain the field equations in the context of f(R) theory of gravity. In this framework, we attempt to investigate the energy conditions in FriedmannLemaitreRobertsonWalker (FLRW) metric using the Raychaudhuri equation. Then, we focus on wormhole geometries and their thermodynamics behavior in Palatini and metric versions of modified f(R) gravity, separately. To violate the null and the weak energy conditions, wormhole spacetimes need an exotic matter. It has been shown that in f(R) gravity the matter threading the wormholes serves the energy conditions, and it is the derivative terms of the higher order curvature that may be explained as a gravitational fluid, that supports these geometries. Therefore, in f(R) gravity theory it is not required to introduce exotic matter in order to have traversable wormholes. In the framework of metric and Palatini f(R) gravity, we investigate the thermodynamic properties of evolving wormholes. We obtain an expression for the variation of the total entropy to discuss the thermodynamic behavior of wormhole spacetimes. The investigation has been extended to the apparent and event horizons. Eventually, we apply the radius of these horizons to determine the validity of the generalized second law of thermodynamics. This law states that the rate of change of total entropy is positive.
Title:  MODIFIED f(R) THEORY OF GRAVITY: AN ALTERNATIVE GRAVITY THEORY. 
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Name(s): 
Saiedi, Hamidreza, author Wille, Luc T. , Thesis advisor Florida Atlantic University, Degree grantor Department of Physics Charles E. Schmidt College of Science 

Type of Resource:  text  
Genre:  Electronic Thesis Or Dissertation  
Date Created:  2022  
Date Issued:  2022  
Publisher:  Florida Atlantic University  
Place of Publication:  Boca Raton, Fla.  
Physical Form:  application/pdf  
Extent:  84 P.  
Language(s):  English  
Abstract/Description:  Through the variational principle, we review the gravitational field equations in Einstein gravity and modified f(R) gravity theories. Metric and Palatini formalisms are two different approaches that are employed to obtain the field equations in the context of f(R) theory of gravity. In this framework, we attempt to investigate the energy conditions in FriedmannLemaitreRobertsonWalker (FLRW) metric using the Raychaudhuri equation. Then, we focus on wormhole geometries and their thermodynamics behavior in Palatini and metric versions of modified f(R) gravity, separately. To violate the null and the weak energy conditions, wormhole spacetimes need an exotic matter. It has been shown that in f(R) gravity the matter threading the wormholes serves the energy conditions, and it is the derivative terms of the higher order curvature that may be explained as a gravitational fluid, that supports these geometries. Therefore, in f(R) gravity theory it is not required to introduce exotic matter in order to have traversable wormholes. In the framework of metric and Palatini f(R) gravity, we investigate the thermodynamic properties of evolving wormholes. We obtain an expression for the variation of the total entropy to discuss the thermodynamic behavior of wormhole spacetimes. The investigation has been extended to the apparent and event horizons. Eventually, we apply the radius of these horizons to determine the validity of the generalized second law of thermodynamics. This law states that the rate of change of total entropy is positive.  
Identifier:  FA00013879 (IID)  
Degree granted:  Dissertation (Ph.D.)Florida Atlantic University, 2022.  
Collection:  FAU Electronic Theses and Dissertations Collection  
Note(s):  Includes bibliography.  
Subject(s): 
Gravity Gravitational fieldsMathematics Wormholes (Physics) 

Persistent Link to This Record:  http://purl.flvc.org/fau/fd/FA00013879  
Use and Reproduction:  Copyright © is held by the author with permission granted to Florida Atlantic University to digitize, archive and distribute this item for nonprofit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.  
Use and Reproduction:  http://rightsstatements.org/vocab/InC/1.0/  
Host Institution:  FAU  
Is Part of Series:  Florida Atlantic University Digital Library Collections. 