Modified Theories of Gravity and Cosmological Applications

<p>General relativity is a theory of gravity that describes with high accuracy some of the effects of gravity such as solar system tests gravitational lensing gravitational waves black holes etc. in a definite framework of homogeneous and isotropic space-time.</p><p>However considering the abundance and nature of dark energy and dark matter the nature of inflation cosmological tensions such as the H0 and S8 the possible values of local anisotropy in the evolution of the Universe as well as the theoretical problems of the cosmological constant and of non-renormalizability the validity range of general relativity might be restricted. Modified theories of gravity extend the form of general relativity through various methods leading to different field equations and thus to different cosmological implications. They play an essential role in and contribute to modern cosmology providing a foundation for the current understanding of physical phenomena of the Universe.</p>