I always thought that universal expansion started unfolding in a fractal manner during the "Inflationary epoch" just after the big bang and continues to expand in a wavelike fashion that gives the appearance of alternately expanding and contracting but these are just caused by the greater universal Pilot wave function (Bohmian Mechanics).I believe the big bang theory is incorrect. The known universe is in a state of expansion and in time the expansion will slow and revert back to a state of contraction
https://openstax.org/books/physics/pages/13-1-types-of-wavesA wave is a disturbance that travels or propagates from the place where it was created. Waves transfer energy from one place to another, but they do not necessarily transfer any mass. Light, sound, and waves in the ocean are common examples of waves. Sound and water waves are mechanical waves; meaning, they require a medium to travel through. Read more.
There is evidence  that at large scales CDT approximates the familiar 4-dimensional spacetime, but shows spacetime to be 2-dimensional near the Planck scale, and reveals a fractal structure on slices of constant time. These interesting results agree with the findings of Lauscher and Reuter, who use an approach called Quantum Einstein Gravity, and with other recent theoretical work.