EA - [Linkpost] Can we confidently dismiss the existence of near aliens? Probabilities and implications by Magnus Vinding

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: [Linkpost] Can we confidently dismiss the existence of near aliens? Probabilities and implications, published by Magnus Vinding on July 25, 2023 on The Effective Altruism Forum.An earlier post of mine reviewed the most credible evidence I have managed to find regarding seemingly anomalous UFOs. My aim in this post is to mostly set aside the purported UFO evidence and to instead explore whether we can justify placing an extremely low probability on the existence of near aliens, irrespective of the alleged UFO evidence. (By "near aliens", I mean advanced aliens on or around Earth.)Specifically, after getting some initial clarifications out of the way, I proceed to do the following:I explore three potential justifications for a high level of confidence (>99.99 percent) regarding the absence of near aliens: (I) an extremely low prior, (II) technological impossibility, and (III) expectations about what we should observe conditional on advanced aliens being here.I review various considerations that suggest that these potential justifications, while they each have some merit, are often overstated.For example, in terms of what we should expect to observe conditional on advanced aliens having reached Earth, I argue that it might not look so different from what we in fact observe.In particular, I argue that near aliens who are entirely silent or only occasionally visible are more plausible than commonly acknowledged. The motive of gathering information about the evolution of life on Earth makes strategic sense relative to a wide range of goals, and this info gain motive is not only compatible with a lack of clear visibility, but arguably predicts it.I try to give some specific probability estimates - priors and likelihoods on the existence of near aliens - that seem reasonable to me in light of the foregoing considerations.Based on these probability estimates, I present Bayesian updates of the probability of advanced aliens around Earth under different assumptions about our evidence.I argue that, regardless of what we make of the purported UFO evidence, the probability of near aliens seems high enough to be relevant to many of our decisions, especially those relating to large-scale impact and risks.Lastly, I consider the implications that a non-negligible probability of near aliens might have for our future decisions, including the possibility that our main influence on the future might be through our influence on near aliens.Thanks for listening. To help us out with The Nonlinear Library or to learn more, please visit nonlinear.org