Ever since I was old enough to spell “science”, I have carefully evaluated many of the world's most unbelievable proposals in theoretical-physics, including Einstein's. The only time I slammed into the brick-wall of disbelief was at the mention of singularities. There's no such thing as a Singularity, or to state it in terms of a quote I might be remembered for, "A Singularity is the detectable part of a cyclical-process that is viewed over too short a time-frame". A significant example of a singularity, in most minds, would be the Big-Bang. Much of my adult-life has been spent seeking a model for the Big-Bang that would fit with this claim regarding singularities.
For a model to have any credibility at all, it needs to incorporate some containment-mechanism capable of causing the collapse of the current universe. Without this, there could be no traction for the idea that anything might exist outside the current Big-Bang and its end-game [ whatever that might be ].
One of the unbroken rules of Nature is that nothing exists without a reason. A most fundamental driver in science is the search for these 'reasons'. Without question, the biggest of the unexplained in our observable world are dark-matter and dark-energy. In a sense, this is convenient because it allows the 'darks' to participate in modelling various explanations for other phenomena.
Most models of our universe make an implicit coupling between the few percent of visible universe and the darks. If it was conceivable that the darks were uncoupled, then I could build an almost Newtonian model of the current universe, where the visible part was being dragged outwards. This would satisfy the relatively recent observation that the rate of universe-expansion is increasing. But if, overall, the dark component was actually contracting at the same time, that could provide the essential element that would lead to eventual collapse and the start of the next Big-Bang cycle.
To take this further, I am going to need a huge amount of support to cobble together a mathematical model where the visible and the darks can actually be decoupled [ this is obviously the non-Newtonian bit ]. The next giant step will be into territory we are forever unable to visit – “What exists outside our current universe?”.
I am very willing to accept that time and everything in our physical-world was created at the instant of the Big-Bang. This could be accommodated by a rearrangement of the matter/energy equilibrium [ can't get away from that 'conservation of mass/energy' concept ]. What is much harder to accept is that all the RULES that govern our existence were also crafted in that same instant. These rules are way too beautifully formulated and mind-bogglingly complex to be just a one-off shot at the equations and parameters of creation. There is also a complete absence of evidence that there has been even the minutest change to any of these rules since time began. In any case, the intricate relationships involved would basically preclude any isolated variations, no matter how subtle.
A comfortable explanation [ for me, at least ] is that the Big-Bang cycles occur in a constant background where the 'rules' are steady-state. Sadly, the proof for this hypothesis is quite likely to occur well outside my life-span.