Origin of Gravitational Force—Model of Inductively Oriented Electric Dipole with Dynamically Self-Calibrating Constant Attraction

Gravitational force is extremely important because it dominates the formation and evolution of the universe. However, its physical origin and intrinsic qualities have not been clearly understood for a long time. Certain observed phenomena, along with those newly discovered by the Hubble and James Webb telescopes, cannot be well explained by existing theories. Furthermore, general relativity and quantum mechanics, which are the current mainstream theories explaining gravitational force, are incompatible with each other. This situation strongly points to the need for a better or even novel theory of gravitational force. Here, based on the classical space-time perspective, a different yet robust understanding of gravitational force is introduced. The author has realized that gravitational force originates from none other than the electric force. But it is a synthetic electric force produced by a large number of electric charges, including both of positive and negative charges, and thus shows very different characteristics from a simple electric force caused by either positive or negative charges. In any object, there are a large number of free and inducible net electric charges. Due to various macroscopic and microscopic reasons, the electric charge distribution in any object is non-uniform and directional, since in most cases, the centers of positive and negative charges of this non-uniform distribution cannot be exactly at the same point. Thus, almost any object becomes an electric dipole inherently. When an object exists independently, its dipole direction is randomly oriented, resulting in its overall electrical neutrality statistically. However, when two objects interact, their charge distributions change under the influence of the electric field generated by the opposing object's internal charges. This change intensifies through continuous interactions, eventually aligning dipole directions of two objects along a line. Furthermore, through a dynamically self-calibrating process, the directions of two objects’ dipoles can always point toward each other, regardless of whether the two objects are stationary, moving, or orbiting each other. Therefore, although the force direction of an electric dipole is anisotropic, because the dipole direction, determined by directional non-uniform charge distribution, can change dynamically and quickly, an object’s dipole can always maintain attraction to other object’s dipole, similar to an object exhibiting isotropic attraction to another object. The multiple electric dipoles, or even multiple groups of electric dipoles can mutually attract each other too, since multiple dipoles or multiple dipole groups can have a combined directional non-uniform charge distribution too. This is the true origin of gravitational force. Calculations have shown that, under certain conditions, the strength change rate of gravitational force deduced from the dipole model theory closely follows the law of inverse square of distance. This understanding can effectively explain observed phenomena, including confusing ones, such as flat galaxies, filamentary nebulae, the formation of the Solar System and the Milky Way galaxy, the unusual trajectories of ‘Oumuamua and 3I/ATLAS, as well as dark matter and dark energy. This understanding also naturally unifies gravitational and electromagnetic forces and opens a key door for the final unification of the four fundamental forces of nature.