The question of whether gravity is quantum is an active area of research in physics. Currently, there is no widely accepted theory of quantum gravity that successfully combines the principles of quantum mechanics with the theory of general relativity, which describes gravity on a classical (non-quantum) level.
General relativity, formulated by Albert Einstein, provides a classical description of gravity as the curvature of spacetime caused by the distribution of matter and energy. It is a highly successful theory that accurately describes the behavior of gravity in the macroscopic world.
On the other hand, quantum mechanics successfully describes the behavior of particles and forces at the microscopic scale, such as the behavior of subatomic particles. However, when attempts have been made to quantize gravity by treating it as a quantum field theory, fundamental difficulties arise, such as infinities in the calculations and the non-renormalizability of the theory.
Various approaches to quantum gravity have been proposed, including string theory, loop quantum gravity, and others. These approaches aim to reconcile quantum mechanics and gravity by providing a consistent framework for describing the quantum behavior of gravitational interactions. However, at present, these theories are still under development, and there is no definitive experimental evidence to confirm their validity.
In summary, while general relativity describes gravity as a classical theory, the quest for a complete and consistent theory of quantum gravity is ongoing. Researchers are actively investigating the nature of gravity at the quantum level to deepen our understanding of the fundamental workings of the universe.