Where was past low-entropy?

Carlo Rovelli (1)

1 CPT - Centre de Physique Théorique - UMR 7332

Where was the past low-entropy of the early universe located? Contrary to some popular answers, I argue that that the dominant source of low-entropy is the fact that a single degree of freedom, the scale factor, was not at equilibrium. I also discuss possible interpretations of the “improbability” of this early low-entropy.

Mots clés: arrow of time; entropy in cosmology; past hypothesis

Domaines: Relativité Générale et Cosmologie Quantique [gr-qc]; Physique [physics]

Carlo Rovelli. Where was past low-entropy?. Entropy, 2019, 21 (5), pp.466. ⟨10.3390/e21050466⟩. ⟨hal-01965335⟩