Application of the Theory of General Relativity to the large-scale structure
of the Universe leads to various cosmological theories. Of these, the most
important are a class of solutions called Friedmann cosmologies that
lead to what is termed the hot big bang. The starting point for these theories
is what is termed cosmological
Stated simply, this principle means that averaged over large
enough distances, one part of the Universe looks approximately like any other
- Viewed on sufficiently large distance scales,
there are no preferred
directions or preferred places in the Universe.
This clearly is not true on short distance scales: your classroom probably
looks rather different from your dormitory room, and we certainly see
distinguishing structure like galactic superclusters
and the Great
Wall up to at least 100-200 Mpc scales. However, well beyond those distance
scales there is strong observational evidence for the cosmological principle.