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In this short review, we discuss how Earth's climatological and geologicalhistory and also how the shadows of galactic black holes might reveal ourUniverse's past evolution. Specifically we point out that a pressuresingularity that occurred in our Universe's past might have left its imprint onEarth's geological and climatological history and on the shadows ofcosmological black holes. Our approach is based on the fact that the $H_0$tension problem may be resolved if some sort of abrupt physics change occurredin our Universe $70-150\,$Myrs ago, an abrupt change that deeply affected theCepheid parameters. We review how such an abrupt physics change might have beencaused in our Universe by a smooth passage of it through a pressure finite-timesingularity. Such finite-time singularities might occur in modified gravity andspecifically in $F(R)$ gravity, so we show how modified gravity might drivethis type of evolution, without resorting to peculiar cosmic fluids or scalarfields. The presence of such a pressure singularity can distort the elliptictrajectories of bound objects in the Universe, causing possible geological andclimatological changes on Earth, if its elliptic trajectory around the Sunmight have changed. Also, such a pressure singularity affects directly thecircular photon orbits around supermassive galactic black holes existing atcosmological redshift distances, thus the shadows of some cosmological blackholes at redshifts $z\leq 0.01$, might look different in shape, compared withthe SgrA* and M87* supermassive black holes. This feature however can bechecked experimentally in the very far future.

Probing our Universe's Past Using Earth's Geological and Climatological History and Shadows of Galactic Black Holes