According to the leading hypothesis in primordial cosmology, the very early universe underwent a rapid phase of accelerated expansion known as cosmological inflation. Inflation ended approximately 10^{−34} s after the expansion began, through a process called reheating, during which the inflaton field decayed into the particles of the Standard Model. In this paper, we do not address questions concerning the empirical adequacy of this cosmological scenario. Instead, we focus on two following questions: 1. According to inflationary cosmology, can we argue (...) that the particles of the Standard Model emerged from the inflaton field, and in what sense? 2. If we claim that the interaction carriers of the Standard Model (e.g., gluons) emerged during reheating, does this imply that the laws governing these interactions (e.g., the strong nuclear force) emerged at the same time? We argue that current models of reheating already provide a clear answer to the first question when interpreted through a diachronic account of emergence. However, the second question may not have a definitive answer, as it depends on one’s metaphysical conception of physical laws. We propose that a powers ontology, according to which laws are based on the causal profile of fundamental dispositional properties, could elegantly accommodate the claim that physical laws emerged in the wake of inflation. (shrink)

Among physicists and cosmologists, it is common practice to refer to the "cosmic laboratory" to describe how the study of the universe others important insights into the inner constitution of matter. Yakov Zel'dovich, for instance, famously claimed that the "universe is the poor man's accelerator." The goal of this paper is to clarify the relationship between cosmology and particle physics by examining a case of crucial importance in connecting these fields: how cosmologists of the 1970s were able to limit the (...) number of lepton families from the measure of the cosmic abundance of helium-4 . My claim is that knowledge of the primordial universe enables cosmologists to conceive it as a natural experiment for testing hypotheses of particle physics, thereby supporting the analogy between the universe and particle colliders. (shrink)