Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: The Fermi Paradox has not been dissolved , published by Fods12 on the Effective Altruism Forum. Introduction This article is a response to the 2018 paper ‘Dissolving the Fermi Paradox’ by Anders Sandberg, Eric Drexler, and Toby Ord. The Fermi Paradox is the apparent contradiction between the great size and age of the universe, which seem to imply a high probability of extra-terrestrial life, and the fact that no extra-terrestrial life has been definitively observed. In their paper, Sandberg et al. use the Drake equation to estimate the expected number of alien civilizations in the Milky Way galaxy and in the observable universe. What differentiates their approach from previous efforts to answer this question is that they do not simply make a point estimate for the number of alien civilizations. Instead, they estimate the uncertainty for each parameter in the Drake equation, and then take random draws from the distribution of each parameter to estimate the distribution for the end result. Using this technique, they find that, although the mean expected number of alien civilizations may be high, there is a large tail of very low expected values, which means that overall the probability of Earth being the only planet to harbour civilization in the Milky Way, and indeed even in the observable universe, is fairly high. On this basis, the authors argue that since it is quite likely given our existing knowledge that no other intelligent alien civilizations exist, the Fermi Paradox is not paradoxical at all, and is therefore dissolved. In this essay, I will argue that the analysis of Sandberg et al. is flawed in a number of key respects, and as a result the Fermi Paradox remains an open question. Here I briefly list the key problems with the Sandberg et al. paper, before proceeding to discuss each in more detail. The method used of multiplying uncertainties of many small numbers, most of which have an upper bound of one, is biased towards yielding a result of a high probability of Earth being unique, while also leading to various dubious results. The key result of the paper is driven largely by uncertainty in the parameter fl, which is modeled in an unusual way without clear justification. Adoption of slightly different (and I believe more plausible) modelling choices and parameter values yields totally different results, which do not result in the Fermi paradox being dissolved. I illustrate this by re-estimating the Sandberg et al. models using different parameters and modelling assumptions. Multiplying small numbers The very nature of the Drake equation, in which seven apparently-independent parameters (four of which are fractions) are multiplied together, means that it has the potential to give very low numbers. Indeed, since the rate of star formation is fairly well-established to be around 1-10, the average longevity of detectable civilizations is ultimately bounded by the age of the universe to around 10 years, and the number of Earth-like planets per star is generally set at one, it follows that the largest possible number detectable civilizations in the Milky Way galaxy is 10^11, or about the same as the number of stars in the galaxy. By contrast, there is no lower bound to any of these numbers, especially the four fractions, which can potentially be set to arbitrarily low non-zero values. The potential for abusing multiplication of fractions to give extremely low numbers is well known. A particularly egregious example of this can be found in the work of Christian apologist Tim McGrew, who estimates the prior probability of having the evidence we do pertaining to the resurrection of Jesus at less than 10^-40, on the basis of multiplying together supposedly independent probabilities of each of Jesus’ disciples separately experiencing a hallucination. The Drake equatio...