Hi,
You have to take a look at the work of Sir Roger Penrose (Oxford, UK). No need quantum mechanics machinery, just based on the Weyl Curvature and conformal geometry which is more fondamental than the metric one needed in Einstein General Relativity.
This is in a sense "classical", no need quantum gravity to treat the big bang problem.
I admire Roger Penrose for several years!
Experiments could be done by observing at the CMB. And more precisely, looking for some circle patterns in it. These circles could come from gravitational radiation emitted in an previous universe, existing before the big bang of our present Universe.
Penrose calls these various Universe (previous one, future one, present one...): AEONs
These circles could be seen as the circles made by the raindrops on a puddle...
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Adam Raki
"What I cannot create, I do not understand." R.P. Feynman (1988)