Some Consequences of Dual Nature of Ricci Scalar in the Early Universe

Einstein’s theory of gravity is very much successful at low energy level (large distance scales). But the same theory has two very serious problems at high energy (small distance scales). The first problem is the singularity problem. It is established that Einstein’s field equations exhibit solutions having point-like singularities, where physical laws collapse. Non-renormalizability of the theory is the second problem. So a modified version of theory of gravity is needed which matches with Einstein's theory at low energy but significantly differs from it at high energy. In this context, there have been efforts to study higher-derivative gravity, which incorporates basic principle of Einstein’s theory i.e. the principle of general covariance [1-9].