The universe is a conglomerate, a collection of things created in time due to the Big Bang around 13.8 billion years ago. Aside from being a conglomerate, it also acts as a single coherent structure expanding in time. Therefore, we can study the universe as a whole, it is the ultimate Astronomical Object of study.

Gravity is the most fundamental force for the universe as a whole because only the gravitational and electromagnetic forces can act over large distances, but electromagnetic forces are negligible as most matter in the universe are electrically neutral.

Gravity is explained by Einstein’s Theory of General Relativity (1915) as curvatures of spacetime.