If the "bounce" is perfectly "elastic" then the explosion should not eject matter fast enough to reach escape velocity from the local system. The explosion would then collapses back onto itself into a black hole, and the whole thing would repeat over and over. Kind of like the old theories of the eternally recurring Big Crunch --> Big Bang.
I'm can buy that the bounce it's not a classic bounce, but that doesn't answer the parent comment. If the ejected matter has sufficient energy to reach escape velocity, where does the additional energy come from? Does the theory hypothesize that some of the matter is converted to energy?
I cannot speak to the theory. But, if one starts out with the classical "bounce" intution, one then arrives at the escape velocity issue you and the OP are noting. I was trying to point out that the escape velocity argument may not be relevant, because of the assumption/intuition which went into framing the problem, as stated by the OP.
In general, yes, the escape velocity would need to be overcome. But because it would need to be a quantum and general relativistic phenomenon, there are quantum and curved spacetime effects which make framing the problem as simply "escape velocity", a potentially problematic approach.
I don't think QM or GR really change anything here. Matter and energy in must equal matter and energy out. So if the "bounce" produces the same amount of matter that went in, then it seems in general to lack the energy to reach escape velocity. If some (significant?) amount of matter is converted to energy, then maybe it works.
I glanced over the paper and I don't see anything that specifically addresses this, but I might be missing it, because I only skimmed, and I'm not particularly knowledgeable about physics.
I think we are mostly agreeing with each other. I was not saying energy and momentum conservation are no longer important. Rather, I was merely noting one should use caution when trying to intuit how energy and momentum conservation manifest themselves in non-classical systems such as was proposed in the Nature article.
