“Either extraterrestrial civilizations (ETCs) are incredibly rare (or non-existent), or they are deliberately avoiding contact with us (aka. the “Zoo Hypothesis“).”
There is a 3rd possibility - it may not be deliberate.
Our position in the Milky Way is really out on the ass-end of it. We are nowhere near galactic central. If our current understanding of slower than light travel is correct, it just may not be possible for other civilizations to reach us.
When it comes to communications, and our radio sweeps of the galaxy turning up nothing, well, we’re assuming any advanced civilization is still using radio transmissions.
Look at our recent experiment with laser based communication:
100 or so years after radio communication was widespread, we have the technology to eliminate it. There may be other methods orders of magnitude beyond that. We could be awash in alien communication streams we just can’t percieve because ours are too primitive.
There are also hundreds of other theories that can potentially explain it. Like, 100 years really isn’t a long time on cosmic scales. Maybe we’re late to the party and intelligent life wiped itself out already. Maybe we’re early, and we will wipe ourselves out before a new intelligence even figures out where the copy paper is.
We don’t want to be near the galactic center, there’s too much radiation. A quiet spot out on one of the arms away from supernovae and active objects is a much better place for life to evolve.
At this point our own radio is even too advanced for an alien civilization to detect. An interesting thing about radio is that aside from a few lingering powerful analog signals (AM/FM radio, active radar) our modern spread-spectrum radio is hard to distinguish from background noise. It’s an interesting consequence of information theory, as bandwidth and noise tolerance grow, if you aren’t looking for a signal it becomes almost invisible. We also do a lot with very little power now due to these amazing encoding methods, when I was a kid and the analog cell phone was novel we would have outright said that a phone could never communicate directly with satellites. Not enough power or antenna in your pocket. Yet here we are.
So any civilization that develops radio is only likely to send out a short burst of detectable radio before disappearing within 100 years, even without switching to an alternate technology. This makes radio an almost impossible thing to search for in a vast galaxy where time can separate us even more than space.
All this time? What like less than 100 years looking only? That’s a blip on the cosmic scale. 100 lightyear sphere of our galaxy is what, less than 1%? With all the theories and possibilities of what’s going on out there, it’s way too rash to start theorizing like this in my opinion.
No, rare intelligence and to a lesser extent rare earth remain as convincing as ever. Potentially habitable does not mean life sustaining, and given the lack of strong biosignatures on any of the examined near earth exoplanets, I’d say that there is indeed increasing evidence that life of any kind really is that rare, much less intelligence.
It is just absurdly hard to get conditions right for microbes to form on a reasonable timeframe is a solution after all.
given the age of the Universe and the relatively short time it would take for an advanced civilization to spread across the Milky Way Galaxy (650,000 years, by Hart’s estimate), Earth should have been visited by an extraterrestrial civilization (ETC) by now.
It took humans 30,000 years to cross the Atlantic. Using modem propolsion systems, it takes us two years to get to Mars and 40 to reach the edge of the solar system. This seems like an extremely generous estimate considering the Milky Way has a 50,000 light year radius.
I’m as bullish about extraterrestrial life as anyone, and I think a fuller survey of even just the current Solar System has potential. But I have no idea how you get a full galactic survey in so short a time, given what we know about the soft limits on speed of travel and communication.
By Tipler’s refined estimate, an ETC would be able to explore the entire galaxy in “less than 300 million years.”
That definitely feels like it’s more in the ballpark. But, again, it presumes a certain amount of steady cartography by the hypothetical fleet of Von Neuman probes.
There’s a Sci-fi series called The Bobverse that explores the idea of a sentiment fleet of Von Neumans exploring the galaxy, and the various trial and tribulations involved. One point it discusses is that even with a saturation of probes, you don’t get real time communication. So even in a hypothetical universe where alien life did exist and survey earth, what are they odds they’d be watching us at the moment of our development. What would an alien AI be looking for and what would it do when it was discovered?
We could still be too primitive to bare noticing. Or we could be living in between blinks of an alien camera that only reports back every 1000 years.
As we look out at the cosmos, we could be looking at things we don’t understand. After all, what does a star surrounded by a Dyson Sphere look like to a telescope that is searching for glimmers of light, heat, and gravity? SETI is operating purely on conjecture. That’s assuming alien civilizations are even capable of creating these hypothetical superstructures. Or that the structures would function as we intuit.
At some level, I have to question if we know what we’re looking for. Because so much of this feels like we’re searching for humans deep in space. Perhaps the reason we can’t find aliens is that they are simply… too alien.
My theory is that if any ETI exists, our species is under quarantine until we have either grown up or burned ourselves out. They will have seen violent, self-destructive beings in the past and know it is dangerous to let them spread and destroy peaceful society. If they can travel between the stars, they would have to be able to communicate to keep cohesion, this communication could very well include the warning “Avoid this system, there are killer apes on that planet”.
Well the vampires are on the nightly news reports about Wall Street, and zombies are shown in attendance at every tRump rally… so yeah the ETs would certainly know they are quite prevalent here. Don’t see as many werewolves in the news, but they interview a shit ton of ghouls.
My personal take is that there’s some kind of anthropomorphic fallacy in thinking life should tend towards “civilization”.
Life will tend towards reproductive success and it seems entirely plausible to me that reproductive success doesn’t at all imply the use of radio waves.
The dinosaurs were a very intelligent life form that never tended towards civilization and some of their bird ancestors can be smarter than most mammals etc. Expecting the trait of civilization to emerge seems unfounded and against available evidence.
Space travel seems impossible. I realize you can back of the envelope it in a way that makes it seem within grasp but there’s no economic benefit in colonizing another star and only some marginal mining benefit in even visiting the nearby planets so I don’t think it will ever happen.
If an extraterrestrial civilization has a SETI project similar to our own, could they detect signals from Earth?
In general, no. Most earthly transmissions are too weak to be found by equipment similar to ours at the distance of even the nearest star. But there are some important exceptions. High-powered radars and the Arecibo broadcast of 1974 (which lasted for only three minutes) could be detected at distances of tens to hundreds of light-years with a setup similar to our best SETI experiments.
Every moment adds to our data of course, but the idea that we're at some sort of tipping point in how we should perceive the odds of extraterrestrial civilization is silly. Some of this feels like sour grapes from aging nerds who come to believe that it won't happen in their lifetimes, so it is obviously never gonna happen.
To be fair, the odds of an intelligent civilization arising at the exact same time as us are rather absurdly remote on astronomical timelines. Aliens should be somewhere between a billion years old to at least a few million, and that is plenty of time to colonize vast reaches of space and build telescope arrays in the scale of small galaxies with only known tech.
I agree though, it is rather silly to think that we’ve passed any point of significance in our search recently.
True, and I suppose that's a certain filter of its own. I suppose the main thing that makes me roll my eyes is that having done SETI by half measures for a handful of decades, the article is asking if it's time to assume that the rather presumptuous (though not absurd) zoo hypothesis is "the answer".
This all is what it is. The results so far imply virtually nothing about anything, except I suppose that there is not a very close civilization intentionally listening for our types of signals and eager to communicate back.
I mean i’d argue that the lack of any big sphere of space which is largely dark, save absolutely glowing in IR, does indicate that there is likely no one millions of years more advanced than us anywhere nearby. A K2 or K3 civilization millions of years more advanced than us should absolutely be visible to even our current telescopes if they were out there, and an absence of any massive otherwise explainable waste heat signatures seems to imply that they arn’t.
That is a result which tells us a lot about the Fermi Paradox, but hardly one that proves one solution over another. Similarly, we’ve recently found habitable zone exoplanets are not rare, but have yet to find any with a strong biosigniture. This does indicate to us that the odds of abiogenesis may actually just be that rare.
Negative results are still results, and indeed contrary to what the article thinks complex life being common around us while still lacking signs of intelligence would seem to be a lot stronger evidence of the Zoological Hypothesis than just a lot of dead rocks.
We’d need a sample size large enough to contain a bunch of positive signs of spacefaring intelligent aliens to ‘solve’ the Fermi Paradox though, so until and unless that comes along it’s all just idle speculation around the fact that we just don’t have the data to know.
The commenter who identified that we’re now able to eliminate radiowave-broadcast communications, via lasers ( & fiberoptics, etc ), is spot-on.
There is another angle, though.
Imagine a simplified-model of civilization…
a batch of 7 newborn-babies, instead of hundreds of genetically-distinct populations in Africa…
those 7 babies live in “eden”.
they learn that they can consume everything they want, that doesn’t harm them.
they learn that they have to be somewhat self-moderating, because others fight them when one crowds the other, too much.
etc.
they move away from each-other, & some lose their skin-pigment, others change it…
an empire forms, in-which industry is the rule ( the Roman empire ).
Now a momentum is set in-place, that is making the sequence of the Industrial-Revolutions inevitable…
at the time of the Roman Empire, the children are, say, 11yo.
at the time of the Industrial Revolutions, they are in puberty, their brains forced into chaos, & ALL sorts of new force-multiplying technologies landing in their hands…
So, what is The Great Filter?
What happens when it is unconscious-toddler-mind, or unconscious-adolescent-who-never-got-challenged, who has all the world-snuffing technologies that we now have, but who has the global-responsiblity-level of … drunk & drugged narcissistic children…
Say you have 7 kids going into The Great Filter, representing the whole populations-sea of our world…
Say only 1 of them survives The Great Filter…
Are they going to be CAREFUL in what they do, technologically, from then on??
Obviously.
I don’t expect more than about 1.5% of this planet’s population to survive this century’s TANTRUM/POGROM that has narcissism-roots, politics-roots, religion-roots, food-insecurity-roots ( like total collapse of the terrestrial & marine food-webs, later this century ), etc.
Will the remnant who survive this century, if any do, be as careless with technology as we currently are??
How could they be?
If The Great Filter is an automatic force-growing-up consequence of EVERY world-overwhelming-species, who mixes accommodated-immaturity with ecosphere-destroying technology, then whatever portion of worlds who reach The Great Filter have survivors of it, … it’d be inherent in the survivors’ experience that they have been made careful.
Same as you don’t find incapable-of-self-discipline in career-military-officers, you don’t find our murderous carelessness/ideological-rabies in any survivor of The Great Filter:
Universe automatically force-extinguishes populations who won’t grow up, who gain the technological-leverage that we’ve gained.
So, silence depicts a lack-of-carelessness AND an absence-of-need to be throwing-away-energy through radiowave broadcast, both.
When combined, galactic silence makes much fundamental sense.
We’re in our species’ “puberty” stage, and haven’t survived our force-growing-up Great Filter, yet.
If we do, well, then finding others who also did, will make sense.
If we won’t, … then our epitaph will be that we wouldn’t grow-up, at ANY cost.
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