Everything is possible except that which is deemed impossible by the nature of things

"... it would halt the expansion of the universe to collapse into itself, until it compressed down to something so infinitesimal, so spatially unassuming, that it almost ceased to exist. Or if for simply an instant it lessened, a momentary fault like an unexpectedly dropped glass, the universe would race away from itself.

It would become inert, endless, essentially empty. Pitched perfectly, our current gravitational pull holds our natural world together at precisely the right values. Still, if nature has taught us anything it is that there are anomalies through which we find exception to rules.

As such, we are reminded time and time again that nothing is too extraordinary to be true. This is the tension between what works and what appears to suspend our understanding of how the world works – the mystery and the power of the unknown."