The "Big Bang" Model
Cosmology deals with the origin, evolution, large-scale structure and possible end of the cosmos. In 1929 it was discovered that the universe is not of a fixed size but is expanding. Since then a gradually more and more profound understanding of the cosmos has evolved. The present consensus among physicists is expressed in terms of a cosmological model bearing the misleading name "Big Bang" Model - despite the circumstance that Tiny Puff Model would be more adequate.
The theoretical foundations of the "Big Bang" Model are General Relativity, which deals with the gravitational force on the macroscopic level, together with Quantum Field Theory, which deals with the electromagnetic, the weak and the strong forces on the microscopic level. Empirically, the "Big Bang" Model is based on observational astronomy as well as on the outcome of experiments carried out in other branches of physics - most noticeably in high-energy particle physics. According to the "Big Bang" Model the universe originated from a singularity of pure energy. As time went by, the universe expanded and cooled. As it cooled, more and more of the initial energy became confined as matter.
At the ultimate beginning the energy was so high and dense that all known physical laws break down. However, the not so ultimate beginning can be explored by simple extrapolations of results obtained at the frontiers of quantum physics. Later on this tour we shall return to the question of where it all did come from but first we shall have a look at the cosmic evolution from a tiny fraction of a second after the origin until the present day.
(If you are unfamiliar with the physics of elementary particles or the field concept you may prefer to take the introductory tour on Quantum Field Theory before proceeding).
