Yes, quantum gravity is generally regarded as an extension or a proposed theory that aims to reconcile the principles of general relativity with those of quantum mechanics. General relativity is Einstein's theory of gravity, which describes the gravitational force as the curvature of spacetime caused by mass and energy. It provides a classical description of gravity that has been tremendously successful in explaining a wide range of phenomena, such as the motion of planets, the bending of light, and the expansion of the universe.
However, at very small scales, such as the Planck scale (approximately 10^-35 meters), both general relativity and quantum mechanics are expected to play important roles. In these extreme regimes, the effects of quantum mechanics become significant, and the curvature of spacetime predicted by general relativity is expected to be influenced by quantum phenomena. The combination of general relativity and quantum mechanics is known as quantum gravity.
The primary goal of quantum gravity is to construct a consistent and mathematically rigorous theory that can describe the behavior of gravity at the quantum level. Several approaches have been proposed, such as string theory, loop quantum gravity, and causal dynamical triangulation, among others. These approaches attempt to reconcile the seemingly incompatible frameworks of general relativity and quantum mechanics by addressing questions related to the quantization of gravity, the nature of spacetime at small scales, and the behavior of black holes and singularities.
However, it is important to note that quantum gravity is still an active area of research, and a complete and universally accepted theory of quantum gravity has not yet been established. The extreme conditions where quantum gravity becomes relevant are not yet accessible through current experimental or observational capabilities. Nonetheless, physicists continue to explore different avenues in the pursuit of a comprehensive theory that unifies gravity with quantum mechanics.