  In this short review, we discuss how Earth's climatological and geological
history and also how the shadows of galactic black holes might reveal our
Universe's past evolution. Specifically we point out that a pressure
singularity that occurred in our Universe's past might have left its imprint on
Earth's geological and climatological history and on the shadows of
cosmological 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 occurred
in our Universe $70-150\,$Myrs ago, an abrupt change that deeply affected the
Cepheid parameters. We review how such an abrupt physics change might have been
caused in our Universe by a smooth passage of it through a pressure finite-time
singularity. Such finite-time singularities might occur in modified gravity and
specifically in $F(R)$ gravity, so we show how modified gravity might drive
this type of evolution, without resorting to peculiar cosmic fluids or scalar
fields. The presence of such a pressure singularity can distort the elliptic
trajectories of bound objects in the Universe, causing possible geological and
climatological changes on Earth, if its elliptic trajectory around the Sun
might have changed. Also, such a pressure singularity affects directly the
circular photon orbits around supermassive galactic black holes existing at
cosmological redshift distances, thus the shadows of some cosmological black
holes at redshifts $z\leq 0.01$, might look different in shape, compared with
the SgrA* and M87* supermassive black holes. This feature however can be
checked experimentally in the very far future.
