The steady state theory is a cosmological model proposed in the 20th century as an alternative to the Big Bang theory. According to this theory, the universe has no beginning or end and is continuously expanding while maintaining a constant average density as new matter is created. It suggests that the universe looks the same at all times and in all directions due to a continuous creation of matter to replace the expansion. However, the steady state theory has been largely abandoned in favor of the Big Bang theory, which is supported by extensive evidence such as the cosmic microwave background radiation.
