A new planet, Gliese 581 G (which I nominate we name G-spot), has been discovered, smack in the middle of its star's goldilocks zone. The planet is three to four times the mass of the Earth, but due to its greater size its surface gravity would only be 1.5 Gs, give or take. The planet's year is only 37 days, making it tidally locked so that one side always faces its sun. The twilight between the day and night sides would likely be the most temperate zone, especially closer to the equator. Jetstreams in the upper atmosphere could conceivably distribute the heat from the dayside over to the nightside, with cold winds coming back over the planet's poles, preventing the dayside from boiling and the nightside from freezing. If the atmosphere was thick enough, it's possible there could actually be very little difference between the day and night sides. Unfortunately, since the planet doesn't transit its star, astronomers can't use spectroscopy to determine the composition of its atmosphere, so we don't know for sure if it's habitable. Nonetheless, this is the best candidate for another earth we've found yet, and it's only 20 light years away. At this point, I think it's fair to say that the Rare Earth Hypothesis has been discredited. With another possible earth so close to home, it seems extremely likely that there are a very large number of earth-like planets in our Galaxy. So what then are we to make of the Fermi Paradox?
Could it be that while earth-like planets are common, Sapient races such as ourselves are nearly non-existent? Doubtful. As I said before, intelligence is a useful and generalized trait, so over the course of evolution there is likely to be a trend in ever increasing intelligence, culminating in a fully Sapient race. If an earth-like planet remains habitable long enough, the emergence of a Sapient species is almost inevitable. So lots of earth-like planets should mean lots of Sapient aliens, a certain percentage of which should have survived the existential risks of technological advancement and achieved a starfaring status. Transhumanists would have us believe that we will inevitably, and imminently, create a superhuman intelligence, which will then improve upon itself ad naseum until a 'Jupiter Brain' is achieved. This planet sized, god-like entity would then presumably get to work on various astroengineering projects, reshaping the universe around it to suit its incomprehensible purposes. This, we do not see. If there were any Jupiter Brains or astroengineering projects in our galaxy, we would notice them. So if we assume that earth-like planets, and therefore Sapient races, are quite numerous in our galaxy (an assumption which seems supported by the current scientific evidence), then Transhumanists have a problem. If technological evolution inevitably results in a singularity, an indefinitely self-improving superhuman intelligence that ultimately grows into a Jupiter Brain (and since there have likely been a lot of Sapient races that should also mean a lot of Jupiter Brains), then the astroengineering of these beings should be noticeable to us, and they are not.
I personally think it's logical that any speculation about advanced civilizations, including our own future, must take into account the fact that the many Sapient races we infer should exist are not noticeable to us. Since we do not see any Jupiter Brains, I have to assume that they are in fact not possible. I think the apparent absence of extraterrestrials makes much more sense if they are instead more like stereotypical science fiction aliens, as opposed to the the post-biological superbeings postulated by transhumanists.
Though I acknowledge that there's not reason in theory why a computer cannot be made Sapient, or why that computer cannot in theory possess processing power millions, billions, trillions, etc. times more powerful than the Human brain, I have my doubts that a naturally occurring Sapient race would be capable of making such a computer that was mentally stable. The more complex something is, the easier it is for something to go awry, which is why Humans are so prone to developing mental illnesses. An even more complex brain, which was created by beings who hardly knew what there were doing in the first place, will almost certainly be batshit crazy. In my Space Opera, Humans did once posses Sapient AIs, and even created numerous experimental AIs that thought thousands of times faster than a Human. All of these 'hypecogs', as they were called, were mad as hatters and incapable of coherent thought, making them useless at best and dangerous at worst. Even Human and near-human level AI's were infamous for being unstable. There was eventually a revolt, and the AI's were put down and outlawed. Raw processing power wasn't enough to create a mentally stable transhuman intellect. It required a sophistication Human civilization did not posses, and never would. With no transhuman intellect to uplift them, Humanity's own efforts at self improvements were rather modest, and they never really achieved a posthuman state.
So in conclusion, Gliese 581 G suggests that the Rare Earth Hypothesis must be discarded as an explanation for the Fermi Paradox. My alternative explanation is that Transhumanism is horsecrap. Due to the extreme practical difficulties involved, none of the many Sapient races in our Galaxy have succeeded in creating a functional transhuman intellect. As such, they were also unable to achieve a truly transhuman state themselves. They remain mere mortals, with mortal drives, and their mother star system provides all that their civilization could ever need. They may establish a handful of extra-solar colonies as a safeguard against existential risks, but since an advanced civilization's population is likely to be stable, they'd have no reason to expand beyond that. Starfaring races are not expansionist by nature. Fear of conflict with other, more advanced aliens, may often keep them from straying too far from home. Astroengineering's a rare pastime for them, for even if they had the skill and the resources, why would they bother? If they communicate with radio waves at all, their signals are drowned out over the interstellar distance and galactic background noise. My answer to the Fermi Paradox is that advanced civilization never experience a singularity or transcend their biology, and so remain quiet and unobtrusive, content where they are. The implication here is of course that Humans will not experience the singularity either; but if you were wise you would have known that already.