Peter Bird

The Eternal Recurrence: Understanding Fine-tuning and Cyclical Universes through Nietzsche

Faculty Mentor: Dylan Sabo, Cognitive Science and Philosophy Department

Majors: Philosophy, Cognitive Science

Funding: Undergraduate Research Center Summer Research Fellowship


From as early as the 5th Century BCE, there are records of the hypothesis that there are an infinite number of universes, as well as parallel universes. In contemporary times, some physicists and philosophers have formalized the proposal that our observable universe is actually one of many universes existing within an infinite “multiverse”. Though there are various versions of the multiverse hypothesis, the typical notion is that these universes formed at different points in time after the Big Bang, and that we simply cannot see them because they are beyond the observable universe. Moreover, because the initial conditions of each universe are essentially randomized, universes evolve differently throughout their lifetime. The physicist Max Tegmark has proposed a 4-level multiverse, which increases in diversity with each level. This paper will focus solely on his Level I multiverse. Specifically, it will examine Tegmark’s proposal that parallel universes exist within the multiverse. This hypothesis is based upon the claim that particles of matter can only be arranged in so many ways before repetitions, or “duplicates”, occur. Parallel universes are generally similar to our universe, except with randomized variations. For instance, in a parallel universe, there could be a person who closely resembles someone currently living on earth, except for the fact that they have four hands instead of two. This would be because the initial conditions in that particular parallel universe differed from those in our universe in such a way that humans evolved to have four hands. Tegmark also postulates the existence of “identical parallel universes”, which are exactly the same as our universe, and even contain identical “doppelgängers”—in other words, exact duplicates—of all people who live on earth. In addition to analyzing Tegmark’s Level I multiverse, this paper will also assess the philosopher Friedrich Nietzsche’s doctrine of the eternal recurrence of the same. Nietzsche claims that if “energy” is constant and has a finite number of possible arrangements, then, given a universe which is infinite in terms of time and space, you will relive your exact same life an infinite number of times. Moreover, he argues, all things—including objects, events, decisions, organisms, and planet earth—will eternally recur in the exact same form or manner. In this paper, Nietzsche’s doctrine of the eternal recurrence will be understood as a claim about the nature of the universe—that is, a claim about the way the universe really is. First, this paper puts forth the argument that a very similar line of reasoning is offered in both Friedrich Nietzsche’s doctrine of the eternal recurrence and Max Tegmark’s claim that parallel universes exist. Second, it will argue that if we accept Tegmark’s reasoning about parallel universes and the possible arrangements of matter, then we are committed to accepting a version of Nietzsche’s doctrine of the eternal recurrence.


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