Why would it be confirmation of Great Filter? It's quite possible that life is abundant in the galaxy but that intelligent life is not common and especially industrialized civilizations.
I don't understand with this fascination with the Great Filter. I am sure there are many filters out there, from having a Sun that lives long enough, that doesn't throw off flares very often, need for a magnetic field to shield advanced organisms, water, fossil fuel creation, gravity that can be beaten with fossil fuel rockets, big moon to reduce number of asteroid hits to the planet, just enough water to have continents yet plenty to reduce temperature differences, no tidal locking, ...
Essentially it's the fermi paradox. If life is out there, why aren't there signs? The universe should be teaming with life but isn't. There's a few reasons why... the Great Filter is a hypothesis that basically means almost all life hits a wall where it dies out no matter what. No life so far that we know has ever made it past this filter.
For the same reason the large dinosaurs died out. Life as we know it operates best within fairly narrow mass scales and energy level ranges. Those are both several orders of magnitude away from the quantities needed to produce effects observable at interstellar distances.
The universe should be teeming with life but isn't.
We currently have no good evidence that it is. That doesn't mean it isn't, just that our detection methods aren't yet up to the challenge. Basic information theory suggests that they may never be. Advanced civilizations will use coherent EM radiation for a limited time only. The radiation they do generate in the long term probably won't be wasted by letting it escape isotropically into space.
Also, at some point they may come to understand that drawing attention to themselves isn't a good survival strategy. A civilization that is advanced enough for us to observe is also advanced enough to hide from us.
> Those are both several orders of magnitude away from the quantities needed to produce effects observable at interstellar distances. (...) our detection methods aren't yet up to the challenge. Basic information theory suggests that they may never be.
Not really true. There are more signs of life than just radio waves. One - like in the article - is chemistry. Planets that seem to be very far from chemical equilibrium are objects of interest, as this may imply there is a complex system that's actively fighting entropy. I.e. life. For instance, aliens with powerful telescopes and good understanding of geology could conclude Earth has life on it by observing it keeps a surprising amount of oxygen in the atmosphere, where it should have already oxidized everything instead.
Yes, really true. Look at how hard it was to establish the presence of the PH3 absorption line on the planet right next door. We are not able to make that kind of observation on extrasolar planets yet, at least not beyond very rudimentary levels. Hopefully someday, but certainly not now.
Admittedly Earth's oxygen signature would be a lot easier to detect than a minute quantity of PH3 on Venus. But we wouldn't have been able to look for that either until just a few years ago. Even to a seasoned RF engineer, ALMA and JCMT are indistinguishable from magic.
Fair enough. What I'm saying is that detecting anomalous chemical composition of exoplanet atmospheres seems almost reachable with our current capabilities, and - unlike radio signals - is an indicator we can't really hide. So aliens slightly more advanced than us could be looking at that.
Life, as we know it, only exists in one single known location in the Universe: Earth.
If we assume life is abundant in the Universe, then we should be able to pick up signs of others, such as radio signals, or bio-indicators in other planets' atmospheres, and so, we ask where the aliens are.
Since we don't find any, we then assume that there is something preventing this abundance of life from developing into something we can detect, and something's called the Great Filter.
As of yet, we only have a single point of data, and since we're still here there's some speculation that we've allready passed through the filter. Another data point would mess up the math a bit and we could, statistically speaking, end up with a scenario meaning we still haven't passed the filter, and that we might still have an apocalyptic event wiping us out.
Life on Venus would give us a better idea of what to look for in other places, and that might help us narrow down the search a bit and find other places with life.
Intelligent life is a different matter. We don't know how common it is for
1) a planet to have formed around a star with the right composition of materials
2) have the exact right conditions for life to form early
3) for that life to survive for billions of years while
4) building up large reserves of substances that can
5) be used as fuel by a tool using bunch of talking apes
6) propel their civilization's technology far enough to match ours
7) send a signal that can reach our specific little dot
8) for that signal to be reach us during the miniscule time-frame that we've been able to pick it up.
I mean, what if the glory days of the Milky Way was 500 million years ago and we're developed just a little to late to be able to see the last remnants of galactic civilization crumble to dust? What if we just happen to be the first, and we develop past such technology before anyone else develops it?
Intelligent life doesn't need to be very common before you should expect to be pervasive.
We're a matter of years from originating von Neumann machines ourselves, so any civilization with thousands or millions of years head start should have incredible galactic spread.
> so any civilization with thousands or millions of years head start should have incredible galactic spread.
No, we're saying that that life didn't even reach "civilization". Humans are a blip in time compared to the dinosaurs, for example - we may well be the anomaly, but life still be abundant.
