Globular clusters are distributed in the halos around the Milky Way and other galaxies. Grand Unified Theories Theories which describe the behavior of the single force that results from unification of the strong, weak, and electromagentic forces in the early universe. The strength of the gravitational field decreases as the square of the distance. Light from the distant object is bent into two or more separate images. A prediction of Einstein's general theory of relativity.
Photons lose energy as they escape the graviational field of a massive object.
Because a photon's energy is proportional to its frequency, a photon that loses energy suffers a decrease in frequency, or redshift, in wavelength. The attractive effect that any massive object has on all other massive objects. The greater the mass of the object, the stronger is its gravitational pull. The lowest energy state that an electron can have within an atom.