In cosmology, the Infinite Universe theory is a model developed in 1948 by Fred Hoyle along with Thomas Gold, Hermann Bondi and others as an alternative to the Big Bang theory.
According to this model, as the Universe expands, new matter is constantly created between expanding galaxies, so believed the supporters of the Infinite Universe theory (also known as Steady State theory), which was popular in the 1950-60s. Thus, though the Universe has always existed in an unchanged state, the cosmological principle is respected.
The oscillating universe theory (also known as the cyclic model) was introduced by a Russian scientist A. Friedmann in his seminal papers of 1922 and 1924. Three years after Friedmann’s paper in the Zeitschrift für Physik, an article on the same subject by the Hungarian physicist Cornelius Lanczos appeared in the same journal.
The oscillation theory correlates with the model of an expanding universe and is based on the general relativity equations for a universe with positive curvature (spherical space), which results in the universe expanding for a time and then contracting due to the pull of its gravity, in a perpetual cycle of a Big Bang followed by a Big Crunch. This is then followed by a new cycle of existence.