The Hubble eXtreme Deep Field (XDF) was completed in September 2012 and shows the farthest galaxies ever photographed. Except for the few stars in the foreground (which are bright and easily recognizable because only they have diffraction spikes ), every speck of light in the photo is an individual galaxy, some of them as old as 13.2 billion years; the observable universe is estimated to contain more than 2 trillion galaxies.[1]
Cosmology (from the Greek κόσμος,
kosmos "world" and -λογία, -logia "study of") is the study of the origin, evolution, and eventual fate of the universe .
Physical cosmology is the scholarly and scientific study of the origin, large-scale structures and dynamics, and ultimate fate of the universe , as well as the
scientific laws that govern these realities. [2]
The term cosmology was first used in English in 1656 in Thomas Blount 's
Glossographia , [3] and in 1731 taken up in Latin by German philosopher Christian Wolff, in Cosmologia Generalis .[4]
Religious or mythological cosmology is a body of beliefs based on mythological ,
religious, and esoteric literature and traditions of creation myths and
eschatology .
Physical cosmology is studied by scientists, such as astronomers and
physicists , as well as philosophers , such as metaphysicians , philosophers of physics, and philosophers of space and time. Because of this shared scope with
philosophy, theories in physical cosmology may include both scientific and non-scientific propositions, and may depend upon assumptions that cannot be tested . Cosmology differs from astronomy in that the former is concerned with the Universe as a whole while the latter deals with individual
celestial objects . Modern physical cosmology is dominated by the Big Bang theory, which attempts to bring together
observational astronomy and particle physics; [5] more specifically, a standard parameterization of the Big Bang with
dark matter and dark energy , known as the Lambda-CDM model.
Theoretical astrophysicist David N. Spergel has described cosmology as a "historical science" because "when we look out in space, we look back in time" due to the finite nature of the speed of light. [6]
Disci
