Steady State Theory

Steady state theory holds that the universe has always looked roughly the same on the largest scales and always will, expanding forever while new matter continuously appears to keep its average density constant, rather than having a beginning as the rival big bang theory claimed. Its proponents tried to explain the microwave radiation as light scattered by ancient dust and stars, but that explanation failed: the radiation is the same in every direction and matches the spectrum of an ideal hot body far more closely than scattered light from many separate sources ever could. Once the cosmic microwave background was confirmed as genuine leftover heat from a hot, dense early universe, exactly what the big bang theory predicted, steady state theory was abandoned by nearly all cosmologists. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/