An industrial and expansionary civilisation which came into existence anywhere in the Milky Way 10 Mya, and whose interstellar travel was limited to 0.01c, would’ve colonised Earth while we were still in the process of losing our body fur and interbreeding with Neanderthals.
This is fairly recent compared to the age of the universe, and the speeds can be achieved with know (albeit expensive) human technology.
If the aliens had self replicating probes (of the robotic kind, not the organics-in-factories kind), the known rules of physics suggest that a Dyson swarm can be built in less than a century, at which point (0) now you have to ask why there are stars to see, and (1) 0.9c is easy, as is going intergalactic, so such a civilisation can’t have been that recent in half the Council of Giants either.
That we can see stars and that we exist, says that expanding industrial intelligences like us, either never got to this stage, or are filtered in what currently looks like a small gap between here and there.
Misaligned AGI that doesn’t want to expand could be one, so could in-fighting necessarily becoming too easy at the same time as any tech for interstellar expansion.
Personally, I think there’s dozens to hundreds of small-ish (think factors of 0.95-0.10) filters, some ahead, some behind.
Why does everything you imagine look like dust? Shouldn't civs advanced enough to build Dyson Spheres have figured out building materials better than those in the Titanic? That pressure is similar to or stronger than those found in outer space.
They should at least be strong enough to withstand an asteroid hit, and those don't just disintegrate into space dust quickly.
Space Junk is already a problem for us in our present state of advancement. There's space debris from the 50s out there. Why isn't that dust?
Just like evolution doesn't happen suddenly, civilizations don't just disappear. And if the universe is so vast and old, we should be seeing civs in transition, like ours.
There's the argument of the dark forest that everyone is in hiding, but accidents happen, right?t Karma. Why don't these UFOs ever make mistakes? Why don't we see the predator civs? Where's all the noise in the universe? Shouldn't there be massive explosions from all the space wars?
I think it's more interesting and a lot creepier that we are alone in the material universe. Of course, this line of thinking leads to God, and that's poison for the "open-minded".
I think your sense of scale for time and distance needs recalibration.
Billions of years for structures of old to break, not just for civilisations to arrive. It's enough time for planetary atmospheres to boil off into space.
> Shouldn't civs advanced enough to build Dyson Spheres
Kessler cascade.
But, once they're actually that big, I think their only possible downfalls are fratricidal conflicts; so my thinking and comments here are mainly regarding pre-Dyson civilisations.
Further aside: on this scale, one thing I want to find out but don't know who to ask, is "how fast do iron and aluminium sublimate in a vacuum at 300 K?"
> They should at least be strong enough to withstand an asteroid hit, and those don't just disintegrate into space dust quickly.
Asteroids come in many sizes, up to "moon"; moons also disintegrate under gravity when they pass the Roche limit, and for other reasons; the rings of Saturn are young on such timescales, 10 million to 100 million years old.
Now I think about it (in favour of your position, but again I'm assuming filters other than fratricide have to happen before Dyson swarms) an expansive civilisation that Dysoned up 10 Mya inside the Milky Way should've turned the galaxy into one of red dwarfs even if the spheres have since disintegrated.
> Space Junk is already a problem for us in our present state of advancement. There's space debris from the 50s out there. Why isn't that dust?
Remember this is in the context of what we can see looking out into the cosmos.
Our space junk is indistinguishable from dust at lunar distance, let alone interstellar.
And 50 years? Every beat of your heart is to your lifetime what 8 Earth years is to the lifetime of Sol.
> civilizations don't just disappear
Yeah they do. Heck, entire species disappear.
> And if the universe is so vast and old, we should be seeing civs in transition, like ours.
Only with sufficiently good telescopes. The actual ones we've got? It's noteworthy when they've got the capacity to resolve stars as more than single pixels.
I don't ned to recalibrate anything. What I need to do is stop arguing about UFOs and electric cars in this forum. The Fermi Paradox is based precisely on the time and scale of the universe.
"he Fermi paradox can be asked in two ways.[note 1] The first is, "Why are no aliens or their artifacts found on Earth, or in the Solar System?". If interstellar travel is possible, even the "slow" kind nearly within the reach of Earth technology, then it would only take from 5 million to 50 million years to colonize the galaxy.[26] This is relatively brief on a geological scale, let alone a cosmological one. Since there are many stars older than the Sun, and since intelligent life might have evolved earlier elsewhere, the question then becomes why the galaxy has not been colonized already. Even if colonization is impractical or undesirable to all alien civilizations, large-scale exploration of the galaxy could be possible by probes. These might leave detectable artifacts in the Solar System, such as old probes or evidence of mining activity, but none of these have been observed.
The second form of the question is "Why are there no signs of intelligence elsewhere in the universe?". This version does not assume interstellar travel, but includes other galaxies as well. For distant galaxies, travel times may well explain the lack of alien visits to Earth, but a sufficiently advanced civilization could potentially be observable over a significant fraction of the size of the observable universe.[27] Even if such civilizations are rare, the scale argument indicates they should exist somewhere at some point during the history of the universe, and since they could be detected from far away over a considerable period of time, many more potential sites for their origin are within range of human observation. It is unknown whether the paradox is stronger for the Milky Way galaxy or for the universe as a whole.[28]"
The biggest of the past: the relatively thin crust that allows non-catastrophic volcanism, the dual composition of the crust so we have both oceanic and continental plates and the right amount of water to get both massive oceans and not so much as to be a water world, surviving the oxygenation catastrophe, evolution of multicellular life/Cambrian explosion, that the various inorganic carbon sinks and sources are balanced well enough for billion year evolutionary history, that we’re cooperative enough to work together while being competitive enough to develop new tech for “our side” (too little competition and we’d have stopped in c. 1860 tech and communism; too much competition and we’d be at each other’s throats and not be able to sustain global supply chains needed for modern computers).
Arguably the Moon is a big part of many of these things.
My best guess for the future: as we get more tech, it gets easier for individual insane people to blow up important things and/or kill lots of people. AI (never mind AGI/ASI) is just one of many such technologies that make this risk bigger, but even just sufficiently cheap electricity and manufacturing makes it (relatively) simple to use a cyclotron to enrich uranium.
The only way I can see past that is a ridiculous and unpleasant level of surveillance that you need some kind of AI to be able to achieve in the first place, with all the downsides that come with that surveillance, and that’s still the case even if you’re “only using the surveillance AI to find and section dangerously insane people, honest”.
> My best guess for the future: as we get more tech, it gets easier for individual insane people to blow up important things and/or kill lots of people.
I've been saying this recently. I think EM or similar could potentially take and defend a big area with the massive number of drones he could buy or build companies to produce. And that's without inventing any new tech, just mass producing specialized drones.
That's scary enough, but then imagine some small nation-state you've never thought much about, that has all that manpower and collective wealth, and maybe some ambition...
Tech is able to concentrate a big amount of power into a very small number of hands.
Sounds like we’re on the same page. As I’ve thought about this, I can’t escape the disorienting feeling that many more filters are in the past than in the future (and ones with worse probabilities are in the past too). Do you perceive the same? And does the cumulative probability of future filters seem smaller than the cumulative probability of past filters?
Given all the exoplanets with no signs of life, either abiogenesis is probably very hard or life is very fragile (~1e-3 or fewer planets will both develop life and retain it for long enough to pass through an oxygenation catastrophe, but that's squished several filters together).
Difficult to do more than guess past filters beyond oxygenation given the sample size of n=1.
Future? All unknown-unknowns. Even if you rule out paper-clipping-AI-gone-wrong scenarios by assuming only weak and narrow AI slightly less than we have today, the mere ability to get a million colonists to Mars, even with just SpaceX's Starship, requires enough space industry to be a direct military threat to Earth.
This is fairly recent compared to the age of the universe, and the speeds can be achieved with know (albeit expensive) human technology.
If the aliens had self replicating probes (of the robotic kind, not the organics-in-factories kind), the known rules of physics suggest that a Dyson swarm can be built in less than a century, at which point (0) now you have to ask why there are stars to see, and (1) 0.9c is easy, as is going intergalactic, so such a civilisation can’t have been that recent in half the Council of Giants either.
That we can see stars and that we exist, says that expanding industrial intelligences like us, either never got to this stage, or are filtered in what currently looks like a small gap between here and there.
Misaligned AGI that doesn’t want to expand could be one, so could in-fighting necessarily becoming too easy at the same time as any tech for interstellar expansion.
Personally, I think there’s dozens to hundreds of small-ish (think factors of 0.95-0.10) filters, some ahead, some behind.