SE Gyges

The Argument in Brief Sandberg, Drexler, and Ord (2018) showed that the Fermi paradox dissolves once we take our uncertainty about the Drake equation's parameters seriously: the silence of the cosmos is unsurprising given what we actually know. This essay argues that their result is not a contingent fact about our particular universe but a generic prediction. Under a simple multiverse model, most sentient observers in most possible worlds should expect to find themselves alone. The argument runs as follows. Assume a multiverse in which every possible physical configuration is instantiated, weighted roughly uniformly. From the fine-tuning literature, we know that the fraction of configurations capable of producing complex chemistry, stable stars, and long-lived planets is extraordinarily small. The fraction capable of producing sentient technological civilizations is smaller still. This gives us a distribution of expected civilizations per configuration that is overwhelmingly concentrated at zero, with a thin tail of configurations that produce any sentience at all. Observation selection guarantees that we find ourselves somewhere in that tail, but it does not guarantee that we find ourselves deep in it. If the tail thins faster than linearly (that is, if configurations producing N civilizations become rarer faster than N grows), then even under observer-weighted reasoning, the typical observer inhabits a universe where sentience is rare. The expected number of technological civilizations in such a universe is small, is probably exactly one. The silence of the cosmos, on this account, is not a puzzle to be solved but a generic prediction of the model. This argument depends on several assumptions, which should be stated plainly. (A1) A multiverse of the relevant kind exists. (A2) Physical configurations within it are weighted approximately uniformly, or at least not in a way that overwhelmingly favors sentience-producing configurations. (A3) The fine-tuning resu