Who propouse the pulsating theory?

The pulsating theory of the universe, which suggests that the universe undergoes cycles of expansion and contraction, was notably proposed by the Indian physicist Jayant Narlikar in the 1960s. He, along with other cosmologists, developed this idea as an alternative to the Big Bang theory. The concept posits that after each expansion phase, the universe could collapse back into a singular state, potentially leading to a new expansion phase.