The Origin of Gravitation and Electromagnetism

Assuming that protons and electrons are three-dimensional body particles that have only mass and volume, the volume repulsion can ensure the finiteness of particle density. A scalar potential and a vector potential are constructed respectively with the mass density and the momentum density. A set of particle field equations is derived from the scalar and vector potentials with the help of vector calculus. The equation set is general field equations in three-dimensional flat space, instead of that in four-dimensional curved spacetime. It is shown that the particle field includes gradient field, divergence field and curl field. The gradient field predicts both attraction and repulsion between particles, the divergence field represents the undulation of particles, and the curl field describes the vortex motion of the particles. It is proven that gravitation and electromagnetism both originate from the interaction of body particles. The undulation of pure electronic system represents both gravitational waves and electromagnetic waves. If graviton and photon are regarded as body particles identical to electron, the electrons are the dark matter in the background of the universe.