Gravity, as described by the theory of general relativity, is not considered to be a particle or a wave in the same sense as particles or waves in quantum mechanics. Instead, gravity is understood as the curvature of spacetime caused by the presence of mass and energy.
According to general relativity, massive objects like planets, stars, and galaxies curve the fabric of spacetime, and this curvature influences the motion of other objects within that spacetime. This effect is what we experience as gravity. It is a fundamental force that acts over large distances and affects the behavior of matter and energy.
The mathematical framework of general relativity describes gravity through a set of equations that determine the curvature of spacetime based on the distribution of mass and energy. These equations involve the concept of gravitational waves, which are ripples in the curvature of spacetime that propagate outward at the speed of light. Gravitational waves are a prediction of general relativity and have been indirectly observed through their effects on spacetime.
While gravitational waves can exhibit wave-like behavior, it is important to note that they are not particles themselves but rather disturbances in the fabric of spacetime. The gravitational force itself, as described by general relativity, is not associated with particles in the way that electromagnetic forces are associated with photons.