The Great Happiness Filter
I.
The universe is full of wandering celestial bodies covered in complex, superintelligent lifeforms who engage in eternal masturbation.
That's it. That's the Great Happiness Filter.
II.
This idea has been discussed before, but it strikes me that people still struggle to find other solutions to the Fermi paradox, as if the Great Happiness Filter was not already explaining everything. Sure, synthetic biology going out of control, AI going out of control, cosmic superpredators going out of control, Earth-is-a-zoo, all make great film plots. But that is what they are: great film plots. We hear about them because they are on display in sci-fi films and books. You know what Great Filter hypothesis would make a terribly boring film? Aliens sitting in the dark with a wire plugged straight to the happiness center of their brains, doing nothing, while a combination of robots and nuclear fusion takes care of all the logisticsAn earlier version of this post was about stimulating the pleasure centers of the brain. But stimulating happiness should work just as well (just replace dopamine with serotonine, something along this line). It also makes the idea a bit scarier, for some reason.. All they have to do is figure out which neurotransmitters and which parts of the brain are involved in the "I'm happy" sensation, and find a way to stimulate it. Save your philosophical arguments about whether they are really happy or if they just have the illusion of being happy, it does not matter for the following.
You might object, this is not optimal, eventually they will run out of whatever fuel they are using, or their sun will turn into a red giant, so they should still try to expand and obtain more energy. As Robin Hanson puts it:
After all, even navel-gazing virtual reality addicts will likely want more and more mass and energy (really negentropy) to build and run better computers, and should want to spread out to mitigate local disasters.
This rests on the assumption that intelligent civilizations will necessarily try to fully optimize masturbation. They won't. Compare this to heroin addiction: all things considered, heroin addiction is far from being the ultimate hedonistic experience (quite the opposite), yet many people still get trapped into it. You don't see heroin-addicts building Dyson spheres to make sure they have a sustainable feed of high-quality heroin forever in the future. This also applies to masturbation. For the Great Happiness Filter to occur, you don't need a perfect self-sustaining planetary masturbation system. You just need to reach the threshold were masturbation is just the right amount of good, so it's not worth working to fix the flaws of your current masturbation scheme, because you would need to stop masturbating in order to do that. Past this threshold, intelligent lifeforms will not try to improve their masturbatory experience anymore, and will just chose to masturbate instead. Maybe there will be a warning, like as little red icon on the lifeform's internal brainscreen that will say “warning: your fusion reactors have almost turned everything into iron already, please plug the system to a new planet", but who cares at that point? You can just ignore the warning and enjoy maximal sensation of fulfillment and satisfaction. This is basically a sink point.
III.
The real difficulty with the Great Happiness Filter is the order in which the relevant technologies are discovered. If robotic servants and artificial general intelligence are developed before happiness-pods, then there is a chance that we get to stay in the pod while a robotic butler continues to improve the experience on our behalf. In that case, we are back to the Fermi paradox and space colonialism, because our butlers will try to maximize the energy we can spend on happiness-pods. Eventually, our civilization's masturbation-maximizers might conflict with other civilizations' paperclips-maximizers (not all civilizations can be as wise as ours), leading to cosmic-scale battles. On the other end, it is likely that happiness-pods are available to everyone before we get the appropriate energy source to sustain them. In that case, the intelligent lifeform will quickly go broke and possibly go extinct (as if the entire humanity got addicted to heroin at once). But between these two extremes, there is a large sweet stable spot where there is enough automation to power the happiness-pods and make sure everything is running well, but not enough to expand and reach for new planets. As a result, we get plenty of silent planets covered in happy masturbating lifeforms, traveling through space at speeds beyond imagination. Remember this when you look at the stars.