Infinity is another issue
The infinity of the universe is the Sun. Although, illuminating, the sun does not light the universe, the universe illuminates itself. Chemical reactions cause the light as the light in the clouds. If you understand the physics of light you would understand the clouds. Understanding clouds is not easy as they have always been there and probably have not always been there in the history of Earth. Clouds are a culmination of gases with rain and water absorbed by the Earth but like the Sun are predominately like helium and hydrogen. A theory of the Sun being the Earth in a different stage of development either before or after Earth or somewhere in-between is the theory of spacetime but not a common theory. The stages of Earth viewed in other planets could illuminate an understanding of the development of planets but perhaps not the understanding of Earth we are needing. The variable is needed and the variable is the Sun. Light and matter are therefore, infinite. Infinity is another issue.