Emergent perspective of Gravity and Dark Energy
  There is sufficient amount of internal evidence in the nature of
gravitational theories to indicate that gravity is an emergent phenomenon like,
e.g, elasticity. Such an emergent nature is most apparent in the structure of
gravitational dynamics. It is, however, possible to go beyond the field
equations and study the space itself as emergent in a well-defined manner in
(and possibly only in) the context of cosmology. In the first part of this
review, I describe various pieces of evidence which show that gravitational
field equations are emergent. In the second part, I describe a novel way of
studying cosmology in which I interpret the expansion of the universe as
equivalent to the emergence of space itself. In such an approach, the dynamics
evolves towards a state of holographic equipartition, characterized by the
equality of number of bulk and surface degrees of freedom in a region bounded
by the Hubble radius. This principle correctly reproduces the standard
evolution of a Friedmann universe. Further, (a) it demands the existence of an
early inflationary phase as well as late time acceleration for its successful
implementation and (b) allows us to link the value of late time cosmological
constant to the e-folding factor during inflation.
