The composite photo from the Hubble eXtreme Deep Field shows a speck of light that is an individual galaxy, some as old as 13.2 billion years. This image contains more than 2 trillion galaxies within the observable universe. Cosmology serves as the scientific study of this vast nature and origin of the cosmos. The term first appeared in English in 1656 within Thomas Blount's Glossographia with the meaning of speaking about the world. German philosopher Christian Wolff later used cosmologia in Latin during 1731 to describe a branch of metaphysics dealing with the physical world. Scientists including astronomers and physicists investigate these questions alongside philosophers such as metaphysicians and philosophers of space and time. Religious or mythological cosmology forms a separate body of beliefs based on creation myths and eschatology found in literature and traditions.
Ancient Philosophical Roots
Greek philosopher Anaximander proposed a model where the Earth floats very still in the center of the infinite without support from anything. Aristotle described a system of hollow concentric wheels filled with fire surrounding the Earth like bark on a tree. These early models placed the Earth at the center of the universe while stars moved through holes in the celestial spheres. Parmenides argued that the universe was unchanging, uniform, perfect, necessary, timeless, and neither generated nor perishable. Plato created a complex cosmogony where static Earth sat at the center surrounded by heavenly bodies moving in perfect circles. The Almagest written by Ptolemy in the second century CE became the most successful universe model due to its longevity. Ancient thinkers debated whether the cosmos had an infinite past or a finite beginning while constructing geometric-mathematical models to explain planetary motion.