Steady State Theory16.7 - Understand how the expansion of the Universe supports both the Big Bang theory and the Steady State theory
Cosmological theories of the origins of the universe were not developed until the mid 20th century.
Until galaxies were observed to be shifting, the universe was presumed to have always existed and to always continue to.
Some astronomers reconciled the evidence with a 'quasi steady state' theory which proposed that although the universe appeared to expand, this was part of its nature and is continually changing to some extent. The matter and density of the existing universe stays constant but new formations take place to expand the universe.
Evidence of the big bang theory has changed scientific minds since then.