Disentagling the Cosmic/Comoving Duality: The Cognitive Stability and Typicality Tests

Cosmological scenarios wherein the cumulative number of spontaneously-formed, cognitively im-paired, disembodied transient observers is vastly larger than the corresponding number of atypical ‘ordinary observers’ (OO’s) formed in the conventional way – essentially via cosmic evolution and gravitational instability – are disqualified in modern cosmology on the grounds of Cognitive Instability, let alone the atypicality of OO’s like us. According to the concordance ΛCDM cosmological model –when described in the (expanding) ‘cosmic frame’ – the cosmological expansion is future-eternal, and we are atypical OO’s, who just happen to observe the future-eternal Universe at a finite time after its beginning – before dark energy (DE) completely takes over the expansion – and vastly outnumbered by typical Boltzmann Brains (BB’s) that spontaneously form via sheer thermal fluctuations in the future-eternal asymptotic de Sitter spacetime. In case that DE ultimately decays a finite time after the Big Bang and the Universe empties out the cumulative number of transient ‘Freak Observers’ (FO’s) formed and destroyed spontaneously by virtue of the quantum uncertainty principle ultimately over-whelms that of OO’s. Either possibility is unacceptable. We argue that these unsettling conclusions are artifacts of employing the (default) cosmic frame description in which space expands; when analyzed in the comoving frame, OO’s overwhelmingly outnumber both BB’s and FO’s. This suggests that the dual comoving description where space is globally static, masses monotonically increase, and the space describing gravitationally bounded objects contracts, is the cognitively stable preferred framework for describing our evolving Universe, assuming that the latter is indeed future-eternal.