I am not claiming I know for sure (it’s confusing) but I saw an interview with Hanson where he explained the gist of it was, that they are expanding at the speed of light (or close to it) so therefor we won’t see them until they are here.
This is the post that I was responding to:
So you were speaking about 1) Humans, or species at a similar cognitive level might 2) Reach a limit in what they can achieve due to some kind of evolutionary plateau / limit on how intelligent creatures can get.
My response was therefore that Homo sapiens show that such a limit, if it exists, is “too high” to function usefully for the Fermi paradox. Humans accumulate and pass on knowledge and we use various tools to improve our rate of acquiring new knowledge, none of which requires evolving greater intelligence. And, as I say, we’re virtually at the point of being able to synthesize and augment intelligence anyway.
In my post 596 I misspoke saying “sentient species” instead of “sapient” or “technological” (frustratingly, I opened an edit window but never hit submit), because I suspected a red herring like chimps still being chimps might come up.
But why would they be grabby? Our solar system almost certainly doesn’t contain anything scarce that they would actually need. Elements are widely distributed throughout the universe, and given elements, energy and sufficient technology they can make anything they want anywhere.
Maybe we’re just not very interesting?
Barring faster-than-light travel (a pretty good bet) all interstellar travel would presumably be expansionist/ colonial, with systems by necessity being self-sufficient. So unique resources wouldn’t be a motivator, it would just be the quest for independence or breathing room.
As far as we know anyway; maybe there are technologies we can only speculate about that would require mega- or giga-scale engineering to implement. Things that would require an accelerator the size of a solar system and need the output of a star to run.
Politics and/or population pressure, right.
There are quite a few SF stories about aliens who are unwilling (or even unable) to refrain from breeding exponentially. Mote in God’s Eye, for example.
I disagree. This is not known. We currently do not have the technology to colonize the galaxy. Your assumption that we will one day we will is just that, an assumption. Alien societies’ inability to travel a portion of the speed of light, build generation ships and self-replicating probes could very well be an answer to the Fermi Paradox. I believe it is.
The basic premise of TMiGE is that the Moties are doomed by the inexorable logic of selection to always attempt to outbreed other Moties because anyone who doesn’t will lose; thereby trapping the Moties in endless cycles of Malthusian collapse. But isn’t this evolutionary presumption contradicted by what we actually see in island species? Species that live on isolated islands seem to evolve to avoid overrunning their limited habitat: they’re less prolific and tend to be smaller to need less resources. And without access to the novel’s FTL technology, the Motie’s home system effectively is an island. So why haven’t the Moties become an “island” species?
Darned if I know? Better ask Larry… 
It’s been used as a plot driver quite a few times of course, but it seems to me that a very technologically advanced species would understand enough biology to invent contraception?
AIUI, it wasn’t that contraception wasn’t possible, it’s that those who used it lost out in the long run: selection favored the breeders; or so the novel postulates. What I’d be interested to know is how do island species evolve reduced fecundity? It seems like a teleological outcome that’s hard to explain by individual generations maximizing reproductive success.
IIRC the Moties were in essence born adults in terms of development; they might develop physically but there was no notion of schooling to learn how to perform tasks, that knowledge was inborn.
Which meant that in terms of r/K selection theory, there was little that K-strategy could do to improve survivability of offspring, thus the Moties all focused on the r-strategy of producing as many offspring as possible. But this requires the deus ex machina of genetically reproduced culture and skills, while ignoring all the issues that such a rather static reproduction would have created in the past (though I guess some “Crazy Eddies” would have reproduced their genes more successfully at some time in the past).
Inability to travel makes METI (Messaging to Extra Terrestrials) safe and practical.
I’ve been googling to try to find out how much energy it would take to send radio/TV signals so that civilizations a bit more advanced than ours, in this part of the galaxy, could detect them. And I’m reading that not only would sending those kind of signals be practical, we may already be inadvertently be sending some.
So – inability to visit other stars in person, or even robotically – sounds correct. But lack of interstellar communications – that’s where I find the Fermi paradox real.
I made no such assumption. All I have said is that there is no known physical barrier, and if the rate of progress is even 1% as high as it currently is, then we will likely be sending craft interstellar distances in millenia, let alone millions of years. Whether it will happen for Homo sapiens largely depends on if we destroy ourselves first.
In any case, this is a deflection from the point being put to you. You were suggesting that there may be an evolutionary barrier; a limit to how intelligent species can evolve to be. And I (and others) were explaining why this doesn’t work in the context of the Fermi paradox; if there’s a limit, it’s at or beyond humans’ current intellectual level, which is already enough to send probes out of our star system and makes progress by accumulating knowledge and building tools to aid in accumulating knowledge.
Right – so it is you that is making assumptions. You’re assuming unbeatable barrier(s) that we have no knowledge of today.
I’ve tried debating with Hanson, but he does tend to suffer from idée fixe syndrome; if you argue against the hypothesis, you are rejecting the premise in his eyes. I think this means he is simply arguing from a philosophical or hypothetical standpoint, rather than trying to determine the facts, which I suppose is normal in this kind of debate.
In my assessment, the problems with interstellar travel are great, but they increase exponentially as your ship gets faster. The interstellar medium (dust, gas, cosmic radiation) presents an impassible obstacle at speeds faster than about 0.5c, and is very problematic after 0.2c. No matter how advanced your technology, the interstellar medium becomes a deluge of particles at very high speeds.
So the idea of ‘grabby aliens’ following close behind their own detectability is nonsense, as far as I can see. A wave of aliens approaching at 0.2c from many tens, or hundreds, of light years away should give us adequate warning.
Excellent post.
Here is an interesting bit of observational science that might greatly affect the habitability of a lot of stars currently thought to be decent candidates for hosting ETIs:
I am not sure how decent candidates they ever really were though. Even aside the issue of flare stars, things like tidal locking and how variable the output of even peaceful red dwarfs is, are reasons to be pessimistic, or at least would require a very different route to habitability than happened to earth.
A big part of the reason that we speculate so much about life around red dwarfs is because a large proportion of discovered exoplanets orbit them. This is both because it’s easier to detect planets orbiting closer to dimmer stars, but also because problems with projects like kepler mean the data on G type stars’ exoplanets has been slower coming.
Once we’re detecting more small, rocky worlds in the habitable zone of sun-like stars, M stars probably won’t get talked about much.
Finally, I feel I need to again add the disclaimer: I think it would be great if there’s life around M type stars. And I am not claiming to know that there is or isn’t.
They may indeed be life around a fraction of red dwarfs, but the ability to have a technological civilization arise on a planet orbiting one seems many orders of magnitude beyond minimal even as compared to a star more along the middle of the HR diagram.
There may be a pernicious catch-22 on the HR diagram as well: too massive and the star goes into the giant phase before life can evolve, but not massive enough and the zone of habitability is too narrow, meaning the planet may not exist within said zone long enough for life + civilization to arise.
Another factor is the sheer number of M-class stars, roughly ten times as many as G-class stars. Quantity potentially making up for poor quality.
Thanks everyone for the additional background on M stars and current exoplanet thinking. Not a topic where I’ve got much useful to say.
I found this thread a couple weeks ago and it was quite a slog reading all 600 posts to get to the current end of thread. But I learned a bunch along the way. Which is sorta the point of threads like this. Bravo everyone! Even the testy ones.
Here’s a graphic showing how far away Voyager will be in a million years. I realize we will probably build faster crafts in the future, but, to me, the vastness of the universe is the main solution to Fermi’s ‘paradox’.