Every civilization has had a cosmology going as far back as is known. These cosmologies have usually taken the form of a philosophically based mythology. Now increased knowledge in Physics and Chemistry has resulted in a more scientific approach but philosophic assumptions still play a major role in Cosmology.
Edwin Hubble discovered the expansion of the Universe in 1929 by measuring the redshifts of distant galaxies. In 1998 it was discovered the expansion of the universe to be accelerating based on observations of type Ia supernovae.
Cosmic Background Radiation (CBR) is the thermal black body spectrum that is nearly uniform in every direction, It represents a temperature of 2.725 K in that it peaks in the microwave range a frequency of 160.2 GHz, with a wavelength of 1.9 mm. It was first observed in 1965 by Arno Penzias and Robert Wilson at the Bell Telephone Laboratories in
The Big Bang Cosmology is the current establishment Cosmology. The model starts with all mater and space squeezed into an infinitesimal dot called a singularity. This infinitesimal dot suddenly underwent an extremely energetic expansion commonly described as an explosion. Over time the heat of this expansion cooled eventually forming galaxies, stars, planets and eventually us. CBR is seen as residual heat from the Big Bang red shifted by the expansion of t he universe. The Big Bang is based on three main purely philosophical assumptions. First there is absolute naturalism with no intelligents or purpose being allowed in the process. The universe is considered to be unbounded with no edge that is no point beyond which there is no mater. Finally there is the cosmological principle which states that the universe looks the same from every place. The goal is to deal with the fact that we seem to be at the center of the universe by making every place look like the center
There Other Naturalistic Cosmologies such as the steady state cosmology which has no beginning or end to the universe but requires a continual source of new matter. There is a new Cosmology called the plasma universe which depicts much of the phenomenon in universe as being electrical in nature. It is not yet fully developed.
Creationist Cosmologies are based on three main purely philosophical assumptions. The first is God as the creative intelligents with purpose in the process. The universe viewed as bounded with an edge beyond which no mater is found. There is a center to the universe and the Earth is near it. Now this is not Geodetic because the universe does not rotate around the Earth Plugging these assumptions along with the observed expansion into relativity results in time dilation at the center where the Earth would have been producing a time line on Earth consistent with the Biblical account. CBR is seen as the light God created on day one red shifted by an expansion factor of about 3,300.
In conclusion Cosmology deals with the origin, structure, and relationships of the universe but is heavily dependent on philosophical assumptions since we only see the universe a one location that is the Earth. Evolutionary and Creationist Cosmologies are based on different assumptions producing different results for the same data.