Longman Dictionary of Contemporary English
Wiktionary
n. (context astronomy English) A cosmological model of the universe in which matter is continuously created as the universe expands
Wikipedia
In cosmology, the Steady State theory is an alternative to the Big Bang model of the evolution of the universe. In the steady-state theory, the density of matter in the expanding universe remains unchanged due to a continuous creation of matter, thus adhering to the perfect cosmological principle, a principle that asserts that the observable universe is basically the same at any time as well as at any place.
While the steady state model enjoyed some popularity in the mid-20th century, it is now rejected by the vast majority of cosmologists, astrophysicists and astronomers, as the observational evidence points to a hot Big Bang cosmology with a finite age of the universe, which the Steady State model does not predict.
Usage examples of "steady state theory".
The proposal that gained widest support was called the steady state theory.
Theirs was known as the Steady State theory, in contrast to the Big Bang theory of creation.
That was a grave tactical error, because the three most ardent supporters of the Modified Steady State Theory were also members of the Council.
One is called the explosion theory, and the other is called the steady state theory.