Cosmology since the first Astro/Cosmo Moriond meeting// The emergence of the Big Bang 2.0

TL;DR

This review traces the evolution of cosmology from the classical Big Bang to the modern $\\Lambda$CDM model, highlighting key discoveries, current tensions, and future prospects in understanding the universe's dynamics.

Contribution

It provides a comprehensive overview of cosmological developments since 1981, emphasizing paradigm shifts and unresolved tensions in current models.

Findings

Discovery of CMB fluctuations by COBE

Measurement of a flat universe by CMB experiments

Detection of cosmic acceleration via Type Ia supernovae

Abstract

This paper presents a necessarily incomplete review of the evolution of cosmology since the first Astro/Cosmo Moriond meeting in 1981. I trace the journey from the classical Big Bang model based on three pillars -- universe expansion, primordial nucleosynthesis, and the cosmic microwave background -- to the modern $\Lambda$CDM paradigm and the discovery of cosmic acceleration. I discuss major observational milestones: the COBE discovery of CMB fluctuations, the CMB measurements of the flat universe, the pivotal discovery of accelerated expansion through Type Ia supernovae and the emergence of precision cosmology with Planck. I review current tensions in cosmological parameters, particularly the Hubble tension and $\s8$ discrepancies, and discuss future prospects from large-scale structure surveys like DESI. The emergence of ``Big Bang 2.0'' reflects the profound paradigm shift from a model based on standard physics to a dynamical cosmos dominated by dark matter and dark energy, the description of which requires a physics that has yet to be developed and validated.