Analysis and Research on the Expansion of the Universe and the Calculation of the Distance to Distant Galaxies Based on Doppler's Law

As a basic physical law widely used in various wave phenomena, Doppler's law is often used in the study of the emission distance of light waves in the universe and the movement speed of celestial bodies, and has been frequently mentioned and used in the development of physics and cosmology in recent years. This paper mainly reviews how Doppler's law is applied to the absorption lines (Franhofer lines) of different elements and uses this to explain the appearance and role of redshift and blueshift, and then deduce the fact that the universe is expanding based on the redshift, and use data analysis to calculate the distance between distant galaxies on this basis. Finally, through the movement phenomenon between different galaxies in the universe due to the expansion of the universe, the relative motion of the galaxies moving away from each other and the increasing actual distance between them are determined, providing a simple basis for astronomical calculations. This paper finds that the redshift phenomenon caused by the Doppler effect can deduce the state of motion of the universe that is constantly expanding, and can help calculate the relative distance between stars.