So lets start by looking at the assumptions the paradox makes. They are: We've got 13 Billion years of history, and our system is only 4 Billion years old, so everyone else has a head start. There are not only lots of planets, there are lots of habitable planets. We'd see the signs of civilizations that are more advanced than us.
So let's tackle the head start one. At the start of the universe there was just hydrogen. Heavier elements are made in the center of stars, and get included in planets when those stars explode and their remnants eventually make it into new systems. As a result the chemistry of the universe is constantly changing. Solar Systems formed significantly before ours won't have the same proportion of elements. Yes in the planets we can see, we see complicated elements, but a lot of the time we're just seeing things on the lower part of the periodic table. Being sure that there is a head start for planets like ours is a stretch. So at worst we passed a filter, but I think it's more accurate to say that we don't know when life should have started to start, yet.
What about all the habitable planets? Well as noted above a lot of them may not have our complicated chemistry, and might be ok to colonize if we can bring the trace elements we need, but may not be complicated enough to give rise to life. Beyond that, let's look at our solar system. Mars is in the habitable range, but if it's home to anything now it's only extremophiles. What went wrong for Mars?
It's magnetic field went belly up. That cost it most of it's atmosphere as well as protection from radiation. It's speculated that our magnetic field is the result of the motion of our planets ferrous liquid core. We think that martian vulcanism is dead. So maybe is the mojo in the core that once generated the field. So some would be habitable planets just haver a limited lifetime, after which only extremophiles can hang on. Then there's Venus. Venus has a very slow rotation and no magnetic field. Why is the rotation so slow did it ever have a magnetic field? Venus also has another problem. A runaway greenhouse effect. What did this, the lack of a magnetic field, the long days leading to less localized thermal regulation to begin with. There's so much wrong with Venus, that we don't know where to begin. But of our 3 planet sample, one has life, one could have had life but not anymore, and one had at best a much shorter period of habitability. Again planets like these might be useful to us in the long run but don't serve as sources for the civilizations that we think that we should see. And that's not counting other benefits we have like our moon to give us tides and wind, or the moon and Jupiter to reduce the number of strikes our planet takes. We don't know what portion of planets out there have all these favorable factors but it's far fewer than 100% It would be weird if the majority of potentially habitable planets in our solar system weren't habitable but nearly all others were. So compared to others in our own system we passed the filters. But finding life on Mars doesn't tell us more than we already know, that Mars isn't habitable. But in the big picture it's just that we need to refine our estimates of habitable worlds. To produce civilization they probably need magnetic fields, and maybe a few other things.
Finally there is the notion that we'd see signs of civilizations more advanced than us. Our use of radio waves has been a blip. Who knows what our future holds, but if we abandon broad spectrum radio waves within a hundred years than that it's just a blip and the notion that we'd be where we are and be at the perfect distance to catch another civilizations radio blip is highly unlikely. And it's really arrogant to project on what we'll be capable of in the future, and thus what another civilization would be capable of. This is the most baseless of the assumptions. We have reason to believe the universe is much older than us, we have reason to believe that there are lots of planets, but until we spot one we have no reason to believe that a remote civilization would be detectable by us for all but a brief window. Finding the ruins of one of these civilizations wouldn't necessarily be ominous. We keep finding remnants of pockets of our own civilization that have been lost and forgotten. If we never quite terraform Mars or the moon, it would be logical for us to abandon them if we end up with easier access to terraformed worlds. So this isn't a sign of a greater doom for us.
So where does this leave us? With shrinking the time and the candidates for habitable planets, I think we've taken the advanced civilizations should be out there to advanced civilizations may be out there. And by being honest with notion that we would see them, I think we've taken the sails out of it completely. And without there Paradox where is the doomsday of finding alien life? It's potentially largely gone too. If we find extremophile primitive life, it's a good sign that even on inhabitable worlds we may find important compounds for a colony (also potentially dangerous ones). If we find life on a scale relatable to the progress of life on earth, we can tweak our sense of where we are on the timeframe of life. And if we find a thriving inter-sellar society than hooray no filter. And if we find ruins, until we find that they really are all gone it doesn't necessarily mean anything in particular because it could pretty much mean anything. Plus if we do find that they were done in by a filter, we can learn from that (what humans are good at) and maybe avoid it.
In conclusion I would say the Fermi paradox can be ignored, for being perhaps too baseless. The doomsday of finding life in light of the Fermi paradox, more so. Don't be afraid. The universe is beautiful, and it's mysteries, no matter what they are, are worth exploring.
In conclusion I would say the Fermi paradox can be ignored, for being perhaps too baseless. The doomsday of finding life in light of the Fermi paradox, more so. Don't be afraid. The universe is beautiful, and it's mysteries, no matter what they are, are worth exploring.
