My favorite cyclic theory so far is probably Roger Penrose's conformal cyclic cosmology. In essence the universe keeps expanding exponentially which in the end

My favorite cyclic theory so far is probably Roger Penrose's conformal cyclic cosmology. In essence the universe keeps expanding exponentially which in the end becomes equivalent to a new big bang since the universe at that point will loose all notions of scale due to their being no more particles to drive scale. A much better explanation is given here https://youtu.be/FVDJJVoTx7s https://youtu.be/FVDJJVoTx7s