Philosophical thought of the day

Cheer up: even if you didn't have a good day today, someone indistinguishable from you did, somewhere.

Philosophical Implications of Inflationary Cosmology

It is said that the ancient Greek philosopher Diodorus Cronos once put forth a powerful argument for a peculiar view about the relationship between the possible and the actual. Diodorus claimed that everything that could possibly happen is either occurring right now or will occur at some point in the future. His claim, in other words, was that there are no unrealized possibilities. Unfortunately, the works of Diodorus have been lost, and although a number of modern philosophers have tried valiantly to reconstruct his argument, no one really knows exactly how it was supposed to go.

Nonetheless, we think that Diodorus's conclusion was essentially correct, and we will here provide a new, entirely modern argument for it. Unlike the orignal argument of Diodorus, however, our argument draws on inflationary cosmology and quantum mechanics. It follows from inflationary cosmology that the universe is infinite and can therefore be divided into an infinite number of regions of any given size. But it follows from quantum theory that the total number of histories can occur in any one of these regions in a finite time is finite. We draw on these two premises to argue for our central conclusion: that all possible histories are realized in some region of the universe.