Samah Nabil Abuelhamd Osman <br/><br/>
f(R) or  f(T)-Theories :   Unification Priciple and Problems of Standard Cosmology /  
 نظريات الانحناء أم الالتواء :   قاعدة التوحيد  و مشكلات علم الكون العياري 
Samah Nabil Abu-Elhamd Osman ; Supervised Mamdouh Isaac Wanas 
 - Cairo :   Samah Nabil Abuelhamd Osman ,   2017 
 - 145 P. ;   25cm 
<br/><br/>Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Astronomy and Meteorology 
<br/><br/> It is known that standard cosmology suers from some problems. Among suggested solutions are f(R) and f(T) theories in which energy-momentum distri- bution is described by a phenomenological second order tensor. In a version of absolute parallelism (AP-) geometry, a pure geometric eld theory is constructed in the context of the Unication Principle. This principle guarantees writing every quantity in the theory using the building blocks (BB) of the AP-geometry only. Physical analysis of the theory shows that the theory represents a unied gravity and electromagnetic eld. Geometric expressions for Poisson equation for gravity and electromagnetic elds are obtained. Also, we show that the suggested theory has a successful GR-limit. A general dierential identity is derived in a modied version of AP-geometry. The importance of this dierential identity is its relation to conservation in the context of geometrization philosophy. Applications of the suggested theory in the domain of cosmology, satisfying the cosmological principle, solve atness and particle horizons problems 
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<br/><br/><label>Subjects--Index Terms: </label>f(R) or  f(T)-Theories Standard cosmology problems Unification Priciple