A Paper on Sean Carroll’s Multiverse model for explaining the low entropy initial condition
In his introductory post, Barry listed several questions that are central to this blog. The first three revolve around the question of whether anything explains the low entropy condition of the Universe at the Big Bang; and they are the subject of a paper I just published in Entropy. In the paper, “Bumps on the Road to Here (from Eternity)” (It’s open access!) I discuss Sean Carroll’s proposal which says that the world consists of an ever-growing set of universes that cleave off from each other in Big-Bang-like states. Like Barry, I’m uncertain if the proposal works even if the fundamental laws do the work that Sean hopes they do. I’m hoping to attract some comments on the paper here and to get the blog ball rolling!
Abstract: In his recent book, From Eternity to Here, and in other more technical papers, Sean Carroll (partly in collaboration with Jennifer Chen) has put forward an intriguing new way to think about the origin of the Universe. His approach, in a nutshell, is to raise certain worries about a standard Boltzmannian picture of statistical mechanics, and to present certain commitments that he thinks we ought to hold—commitments that the standard picture doesn’t share. He then proposes a cosmological model—one that purports to give us insight into what sort of process brought about the “initial state” of the universe—that can uniquely accommodate those commitments. The conclusion of Carroll’s argument is that statistical mechanical reasoning provides grounds for provisionally accepting that cosmological model. My goal in this paper is to reconstruct and critically assess this proposal. I argue that “statistical cosmology” requires a careful balance of philosophical intuitions and commitments against technical, scientific considerations; how much stock we ought to place in these intuitions and commitments should depend on where they lead us—those that lead us astray scientifically might well be in need of philosophical re‑examination.