The four fundamental forces of nature are extremely important because they dominate the formation and evolution of the universe. However, until now, their physical origins and essential qualities have not been explained with wide acceptance. This paper provides new explanations for the origins and essences of these four forces based on different understandings, suggesting that all four fundamental forces originate from the electric force and can therefore be unified as one force. First, the gravitational force is a synthetic electric force produced by a huge number of electric charges via non-uniform charge distribution. Based on a novel inference of nuclear structure, which is strongly supported by observed phenomena, the strong and weak forces are also deduced to be electric forces. These newly introduced understandings can explain observed confusing phenomena simply and effectively, such as “dark matter,” “dark energy,” “flat galaxies,” “filamentary nebulae,” and “gamma-ray bursts” in nuclear fission or fusion and from black holes, and so on. The author presents these new understandings in an effort to find the natural truth sooner.