Galactic Evolution Showing a Constant Circulating Speed of Stars in a Galactic Disc without Requiring Dark Matter

It is an unsolved mystery that the rotation velocity of a galactic disc is same at any radial distances. The presence of dark matter is expected, but not observed. Here we propose a novel scheme for the evolution of the initial cosmic energy to current galaxies. According to the energy circulation theory, which we previously reported, the fundamental force works based on momentums. Antiparallel movements of energy pieces form a circulation. Due to the space expansion, the initial energy circulations separate and decompose to smaller level circulations; to galactic seeds, stellar seeds, and smallest energy circulations. The internal circulating velocity of a galactic seed is inherited to the circulating speed of stellar seeds in a ring. The intra-circulation interaction by the fundamental force keeps the stellar seeds to circulate at the initial speed, which does not alter by the space expansion. The new scheme meets the galaxy rotation curve without requiring dark matter.