As we now know, there are indeed at least two major difficulties with General
Relativity (GR). The first one is related with its incompatibility with quantum
mechanics, in the absence of a widely accepted consistent theory that combines
the two theories. The second problem is related with the requirement of the
dark sectors - inflaton, dark matter and dark energy by the energy-stress
tensor, which are needed to explain a variety of astronomical and cosmological
observations. While, these dark sectors themselves do not have any
non-gravitational or laboratory evidence, the dark energy poses, in addition, a
serious confrontation between fundamental physics and cosmology.
Guided by the theoretical and the observational evidences, we are led to a
slight modification in the notion of the existence of the source of gravitation
and its manifestation in GR, which is in striking agreement with not only the
theory, but also the observations without requiring the dark sectors of the
standard approach. Additionally, it provides natural explanations to some
unexplained puzzles.Comment: Expanded version (added with new findings) of the essay
(arXiv:1206.2795) awarded `Honorable Mention' of the year 2012 by the Gravity
Research Foundation; v3: Published Versio