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Comment by gmuslera | Hacker News Reader

Reaching a conclusion with so many unknowns (specially unknown unknowns) is risky.

That life must evolve in enough number of planets doesn't mean that the next one is close. And that interplanetary travel is practical doesn't mean that interstellar or intergalactic travel must be. And considering the speed of our current technological development, vs the time needed to get to the next stage in colonization, something big may emerge in the middle. Or something different and unexpected.

In some way, we are like churches deciding what and how a god may think. We are not at the right stage to judge based on our lack of knowledge or perspective. It may not be just one road forward, and going galactic may be the wrong one.

I prefer to take one step at a time, and solve our current roadblocks, if we can. Maybe we have the great filter in front of us in plain view and we can't recognize it.

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Yes, maybe civilizations of social biological species that have a relativity low replication rate like us may find contentment with colonizing only a few close star systems. Create a few dense population clusters like our current cities on select planets and space platforms and leave the rest to 'nature'. We already have a declining population growth rate of 1.1 as more people are opting out of starting a family and children due to technological advances and better global socioeconomic conditions. And maybe our current power fantasies of galactic colonization may seem trivial and 'ignorant' to our future generations. One could also call this a great filter. The possibilities are endless and allows one to enjoy it as a bunch of inconsequential thought experiments. Actual problems that require solutions are usually not fun to think about.......

Low fertility among women is not due to desire but to demands of modern society [1]. Women typically desire 2-3 children each. In modern society they can't have them because of low marriage rates and increased employment among women.

1 - https://ifstudies.org/blog/how-many-kids-do-women-want

Interesting collection of stats, though I don't think the author's conclusions are the only possible interpretation. It's clear that the family size intentions really have been falling since the 60s, and that actual fertility is a fraction of that, which is unsurprising. The bigger sorry here, I think, is that the intended family size drops from 3.4 kids to 2.0. Possibly what's happening is that 'high producers' now make four kids instead of ten, bringing down the overall averages. Basically, it would be nice to see how the distributions of kids per woman change over the decades... I expect something at least bimodal, with a shrinking tail.

(Ed: fixed a couple stats, removed a bad statement about quotients. :P )

One problem with the data is that it's hard to know to what extent modern life changes how many kids you want. Meaning: if a woman knows she has to have a full time job, she may only want, or believe she can afford, two or three children. Conversely, I suppose a woman in agricultural setting might want 7-10 children knowing they could help on the farm. It's probably impossible to know what people would want "unconstrained" by reality, and maybe not even meaningful.

Two things I think are true though. First, women have fewer children than they want, even if what they want is declining over time. Second, women who don't want children, or who want children below replacement, won't ever become the majority of the population - at least not for any significant amount of time. Such women will be replaced by women who, genetically or memetically, want more children.

"Such women will be replaced by women who, genetically or memetically, want more children."

That's not necessarily true. The rural population has shrunk significantly, even as rural family sizes tend to be bigger. The kids largely move to cities (following the gigantic trend towards urbanisation, and in responses to economic realities), and then proceed to have fewer kids in the urban context.

If there's a context with high birthrates, you've got to account for replacement rate within the context: there's a tendency for the kids to find their way to other contexts and thus revert to the mean. Insane "quiverfull" people have lots of kids, but it's not clear to me that they manage to keep up the crazy across generations.

How often has low fertily held true in virgin-frontier, resource-rich scenarios though?

We've never had one where reliable birth control was available, so there is no data.

I agree and I’ve come to the conclusion that the highest moral purpose any intelligent beings can aspire to is to broadcast the information “You Are Not Alone!” by any means available.

At our current stage and philosophy, it may seem that way. That is the point. It may not be valid for most or all of civilizations (if they could be called that way) that are far from us in those and more points.

The same goes for some assumptions behind the great filter concept, like exponential growth and biological needs. Maybe the ideal goal is just a silent self-suficient culture in an small outpost far away from any galaxy.

Unless of course Dark Forest theory is correct.

The noun you're looking for is "hypothesis," and that's if we're being charitable.

https://en.wikipedia.org/wiki/BLC1 "DO NOT RESPOND TO THIS MESSAGE!" xD

> Maybe we have the great filter in front of us in plain view and we can't recognize it.

One candidate, if we take ourselves as the primary example, is biogeochemical crisis following rapid discovery and exploitation of environmental resources or energy reserves without sufficient consideration of the consequences

It seems a bit convenient that every species capable of interplanetary colonization manages to (a) possess world-climate-altering- industrial scale, (b) rest their industrial needs on a resource that threatens their ecosystem, & (c) remain ignorant of the threat until it's too late to do anything about it.

Comparatively speaking, asteroids and/or ice ages being more frequent than expected seems more plausible.

Curiously, the ability to alter biomes at a planetary scale is also one of the prerequisites for colonization. The trick then is having sufficient control of industrial processes to 'get it right,' which requires better global decision making than humans have thus far demonstrated.

(The alternative is extreme plasticity, allowing lifeforms to adapt to otherwise hostile atmospheres...)

> (The alternative is extreme plasticity, allowing lifeforms to adapt to otherwise hostile atmospheres...)

We meet that threshold, though. We are extremely adaptive to otherwise hostile environments by virtue of technology, particularly wearable one - from winter jackets to SCUBA gear.

(d) their previous activities have rendered it way harder to rebuild a technological society

There used to be iron deposits etc. on the surface. They were recovered by pre-industrial societies. Now we are digging deeper and deeper for resources, but once we lose that ability, it's possible we won't be able to regain it.

What do you do once the nuclear power plant's core has melted, the mine is full of water, and there is nobody around who knows what these things are even there for because all the people who did died years ago of old age. You can't read it up either once we've moved our stored knowledge from paper to machines in what the ancient texts refer to as the mythical "US-EAST-2 region".

Humans have deposited a lot of iron and other useful elements on the surface for the next civilization to start with though.

It's less of an issue with recraftable materials (like iron) and moreso with one-way ones (like petroleum, fissionable uranium isotopes, helium, or some plastics).

Of those, it feels like the only irreconcilable one is scale: e.g. something you need so much of, repeatedly, that no less-efficient substitute is viable.

And of those, geologically-created, carbon-based energy sources (coal, oil) are the primaries that come to mind.

(Also, nitrogen, but I imagine the Haber–Bosch process would survive)

Where did all that iron that we mined run off to? Is it not on the surface anymore?

1. it might be covered in sediments requiring expensive movement for little gain (and how do you know where the iron was/is?) and 2. the structures that don't get covered rust away and turn into dust that erosion distributes over large areas. Post apocalyptic societies will be able to salvage iron here and there for a long time, but will it be enough to cover our planet with railways and kick off a new industrial revolution?

Also, the iron was only an example. Coal and other fossil fuels we can only burn once, then they are gone.

Could be intelligence in any form is brought about by some kind of grand antagonistic pleiotropy. By this i mean the genes that develop intelligence in any species infancy, inevitably lead to the conditions for your (a)(b) and (c) later on.

We don’t have any evidence that there are any species capable of interplanetary travel. Maybe there are none.

Humans can do interplanetary travel already.

A species at a similar development level in some other solar system with slightly better societal goals or a need for a specific resource could already be colonizing other planets or asteroids.

Sure, I don't think there's necessarily a single filter, or that this is it. Just that it's a candidate. Your examples would presumably be much more common.

It doesn't have to be climate and it doesn't have to be industrial.

Any process which requires scaling intelligence from competitively local and tribal (or any equivalents) to integrated and planetary will do.

You either pass that test or you fail it. If you fail it, stagnation and eventually devolution beckon.

> stagnation and eventually devolution beckon

What was critical in parent's comment was the irrecoverability of the civilization, after such an action. Scaling intelligence is more of a repeatable "trial and error" step (as the article puts it, in a biology context).

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