Universe without a cause: a reply to David Lu

Abstract David Lu has recently argued that denying the Modified Causal Principle (MCP)—that if the universe began to exist, then it has a cause—leads to the conclusion that we likely inhabit an Omphalos universe, one that began recently with the appearance of age. Lu goes on to argue that if the universe is likely Omphalos, then independent measurements of the universe’s age are unlikely to agree. I offer three families of objections. First, Lu’s probabilistic reasoning faces technical challenges and, even if those challenges are overcome, cannot rule out an Omphalos universe. Second, I propose an alternative hypothesis that does so. Third, I argue—drawing on a standard argument in the foundations of statistical mechanics—that no ordinary scientific inference can be used to rule out our living in an Omphalos universe. Instead, we must either presuppose that we do not inhabit one or else be stuck in a skeptical scenario tolerable to no one.