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

TL;DR

This paper explores how Earth's geological history and black hole shadows could reveal past cosmic events, especially a pressure singularity, potentially explaining the H0 tension and affecting celestial trajectories.

Contribution

It proposes that a pressure finite-time singularity in the universe's past, modeled via modified gravity, could explain cosmological tensions and leave observable imprints on Earth and black hole shadows.

Findings

Pressure singularity may have influenced Earth's geology and climate.

Black hole shadows at certain redshifts could differ due to past singularities.

Modified gravity models can produce such singularities without exotic matter.

Abstract

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.