This is a linkpost for https://www.jehanazad.com/p/if-aliens-exist-we-should-expect
Because it's clearly possible to advance technology much further, there's no reason for aliens to wait for signs there's something interesting in a particular place instead of simply unconditionally colonizing everything that can be reached. Not taking over some of the things is a choice, but there's no reason for not already being here (for a very long time) if possible to reach, regardless of the signs there'd be life/civilization here. Such aliens can't be detected at all yet if they don't want to be.
A different possibility is a technologically bounding AGI takeover that enforces zones of thought (a permanent ban on superintelligence), so that the aliens are forced to engage in a retro space opera, not being allowed stronger tech for an absurdly long time. I'm positing AGIs as the enforcement authority since evolved life is probably insufficiently robust to maintain such a ban indefinitely, while it's probably feasible to make AGIs that maintain such a rule literally forever (when the AGIs don't have corrigibility, don't find feedback on this issue from their evolved builders compelling). In this case, not interfering is again a choice, and being here now even more strongly requires unconditional colonization rather than response to observations, because it would take the technologically stunted aliens too long to notice and respond (unless the overseeing AGIs provide digital transportation/reconstruction services and have already low-key colonized everything within reach).
The technologically capped aliens fit the poorly-hiding-spaceships stereotype, they could even mostly withdraw in response to ambiguous detection a few decades ago and thus get much harder to find even with better modern tech. The hypothesis of aliens being purely fictional is still much stronger, but I don't think the way the world works makes the technology-capping AGIs so impossible that it's not worth considering at all. AI companies being allowed to keep working towards superintelligence becomes evidence against as the work progresses further.
One reason could be that they were attracted by our 1900s radio broadcasts or nuclear tests, but I think it’s more likely they’ve always been around and we only recently had the technology to detect them.
A fairly general problem for UAP/UFO scenarios that I haven't seen discussed, and that kills a lot of hypotheses on UAPs/UFOs (and leaves the surviving hypotheses high-complexity/low-probability for other reasons) is the Dyson Dilemma, described by Isaac Arthur.
To simplify the issue here, if UAPs/UFOs were always in the solar system/galaxy or even further out, then we should not see what we currently see in the sky, and potentially we (and potentially all eukaryote life) don't exist at all, because the incentives for a spacefaring civilization is to do stuff to stars like collecting power from them/creating mega-computers out of materials in the solar system/starlift to lengthen star lifetimes/get hydrogen for artificial fusion or even just completely dismantle planets for the raw materials needed, and critically none of this is ever invisible, and unless civilizations end up universally caring about beings that they can trivially overpower, this maybe means the end of all eukaryote life as well once UAPs/UFOs are in a system, simply by stellar/planetary scale mining/unintentional habitat destruction.
(Even in the case where eukaryote life survives in it's ~entirety, it's far, far too easy for technological civilizations to spot UAPs/UFOs, since they'd have unmissable, vast heat signatures and depending on the civilization, it's easy to detect what they built in space, and this is especially true if they are in the non-grabby civilization's star system.
The main implication of this is that UAP/UFO hypotheses are pretty restricted, simply by the observed rate of technological/economic progress of humans and the fact that the planets/stars remain in their natural orbits, and that this has been verified out to billions and billions of years.
(And truth be told, I don't believe UAP/UFO hypotheses that much, for reasons relating to Dissolving the Fermi Paradox, and the one sentence summary is that when we properly model our uncertainty relating to the Drake Equation parameters, it's reasonably likely that there's at least 1 setting of parameters where aliens are simply astronomically unlikely to exist, and that this is concentrated around the early great filters like life existing. If you want a concrete mechanism, watch this video on The Phosphorus Problem by Isaac Arthur, and the one sentence summary is that phosphorus is rare on earth, even rarer in the solar system, and even rarer the earlier stars/planets formed, despite being essential for life, and it was so rare that scientists puzzled over how life could have begun on earth with such low phosphorus.)
A common question about UFOs is “why now?” As in, UFOs could have arrived at any point in Earth’s history; why would they happen to arrive in the 20th or 21st centuries?
One reason could be that they were attracted by our 1900s radio broadcasts or nuclear tests, but I think it’s more likely they’ve always been around and we only recently had the technology to detect them.
If you consider that for most of human history, “sensing” was limited to humans’ sensory organs, then it wouldn’t matter how long they’d been here if we couldn’t easily see or hear them. Telescopes emerging in the 1600s raised our detection capability, but in a pre-industrial, and more importantly, pre-digital world, the rate of improvement was slow.
However, in recent decades we’ve been developing exponentially, with sensing-relevant technologies like transistor density, memory capacity, and photon capture doubling every 1-2 years. As progress speeds upwards, the rate of improvement is proportional to the likelihood of detection, because each marginal advancement provides a new chance to detect ETs.
Compared to our stagnant past, we’re more likely than ever before to reach the technological level required for ET detection.
That said, indefinite exponential growth only means detecting the previously undetectable is more likely than in the past, but not necessarily more likely than in the future.
If it’s an S-Curve, not an Exponential
S-curves that eventually flatten can look like exponentials at first. Individual technologies will eventually plateau as they hit physical limits; for example, a camera can do no better than capturing every single photon that enters its aperture.
Overlapping S-curves of related technologies can keep progress going, but even when aggregated, a technological domain is likely to eventually slow. If sensor technology is really an S-curve, then where we are now, in the steep part, is the most likely time for us to find extraterrestrials ever.
The upshot of all this is that one planet’s inhabitants are most likely to detect another when:
It seems we are in this position now, so we should expect to find aliens around now, if ever.