EA - Silent cosmic rulers 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: Silent cosmic rulers, published by Magnus Vinding on July 17, 2024 on The Effective Altruism Forum.
In this post, I wish to outline an alternative picture to the grabby aliens model proposed by Hanson et al. (2021). The grabby aliens model assumes that "grabby aliens" expand far and wide in the universe, make clearly visible changes to their colonized volumes, and immediately prevent life from emerging in those volumes.
In contrast, the picture I explore here involves what we may call "quiet expansionist aliens". This model also involves expansion far and wide, but unlike in the grabby aliens model, the expansionist aliens in this model do not make clearly visible changes to their colonized volumes, and they do not immediately prevent life from emerging in those volumes - although they do prevent emerging civilizations from developing to the point of rivaling the quiet expansionists' technology and power.
The reason I explore this alternative picture is that I think it is a neglected possible model for hypothetical alien expansion. I am not claiming that it is the most plausible model a priori, but I think it is too plausible for it to be altogether dismissed, as it generally seems to be.
1. What changes in the quiet expansionist model?
The most obvious change in this model compared to the grabby aliens model is that we would not be able to see a colonized volume from afar, and perhaps not even from up close. Likewise, the quiet expansionist model implies that there would be more instances of evolved life, including observers like us, since the expansionist aliens would not immediately prevent such observers from emerging within their colonized volumes; they could instead stay around and observe.
Taken together, this means that quiet expansionist aliens could in theory be here already, and they could even have a lot of experience interacting with civilizations at our stage of development.
Note that the grabby aliens model and the quiet expansionist model need not be mutually exclusive, as they could in principle be combined. That is, one could have a model in which there are both grabby (i.e. clearly visible) and quiet expansionist aliens that each rule their respective volumes, and different versions of the model could vary the relative proportion of these different colonization styles.
(The original grabby aliens model only involves clearly visible expansionist aliens, not quiet expansionist ones; that is a helpful simplifying assumption, but it is worth being clear that it may be wrong.)
2. Arguments against the quiet expansionist model
A reason the quiet expansionist model is rarely taken seriously is that there seem to be some compelling arguments against it. Let us therefore try to explore a couple of these arguments, to see how compelling they are and what they should lead us to conclude.
2.1 "Implausible motive"
One argument is that it is implausible that an expansionist civilization would not visibly change its colonized volume. In particular, it is difficult to see what kind of underlying motive could make sense of such cosmic silence. The default expectation appears to be that we should instead see overt signs of colonization.
How convincing is this as an argument against the plausibility of quiet expansionist aliens? In order to evaluate that, it seems helpful to first outline what could, speculatively, be some motives behind quiet expansion. For example, it is conceivable that quiet expansion could aid internal coordination and alignment in a civilization that spans numerous star systems and perhaps even countless galaxies.
By staying minimally concentrated and diversified across its colonization volume, a civilization might minimize risks of internal drift and conflict.
Another potential reason to stay silent is to try to learn about emerging civilizati...