Energy conditions in the epoch of galaxy formation

TL;DR

This paper discusses how energy conditions in general relativity can constrain the universe's evolution during galaxy formation, revealing violations of the strong energy condition that challenge normal matter models.

Contribution

It demonstrates that energy conditions provide model-independent bounds on cosmic evolution and shows observational evidence of strong energy condition violations during galaxy formation.

Findings

Strong energy condition is violated between galaxy formation and now

Normal matter cannot fully explain observational data

Energy conditions offer robust bounds on cosmological behavior

Abstract

The energy conditions of Einstein gravity (classical general relativity) do not require one to fix a specific equation of state. In a Friedmann-Robertson-Walker universe where the equation of state for the cosmological fluid is uncertain, the energy conditions provide simple, model-independent, and robust bounds on the behaviour of the density and look-back time as a function of red-shift. Current observations suggest that the "strong energy condition" is violated sometime between the epoch of galaxy formation and the present. This implies that no possible combination of "normal" matter is capable of fitting the observational data.