Boundary Interface Theory: Universal Application to All Galaxies

As a supplementary study to the main work on the Milky Way galaxy, this paper shows that the Boundary Interface Theory (BIT) provides a universal dynamical framework for all types of galaxies, including spiral galaxies, elliptical galaxies, and irregular galaxies. Based on the same set of field equations, boundary potential, and interface structure used in the Milky Way model, the theory can consistently explain galactic rotation curves, spiral arm formation, mass distribution, and global morphology without introducing dark matter or additional assumptions. This confirms that the Boundary Interface Theory is not limited to the Milky Way, but represents a general and unified theory for galactic dynamics in the universe.