The steady state theory is the cosmological theory that the universe has no beginning or end and is expanding at a uniform rate. It also states that the universe continues to expand while having a constant density and is even with the distribution of old and new objects.
According to Dictionary.com, the steady state theory was abandoned for the big bang theory due to the discovery of quasars and other entities that only appear at great distance. This suggests an absolute relationship between the distances of objects and age. The steady state theory was also discredited when cosmic background radiation was discovered, as it was not predicted by steady state theory but was predicted by the big bang theory.