Re: Intelligence <> sense @Arnaut the less
"If (or perhaps when) we suffer a new Mesolithic-style population crash, our descendants won't have an industrial revolution; they won't find enough cheap fuel to get it started." - I actually agree with this. Let's call it a "Situation C"
"...a way to live sustainably on this planet,..." - that I would call a "Situation B"
"...social pressure will drive us to other planets..." - and this is a "Situation A"
Now I put it to you that unless A happens before B we will end up in C.
We must expand before we find a way to live comfortably ever after here on Earth or we will die because the expansion will never happen. But, thankfully, I don't think that B is possible before A - the laws of nature will prohibit it, somehow.
"falls at the embarrassing hurdle of the Earth's gravity well and the amount of stuff we need to burn to get out of it." - do you mean we have a shortage of hydrazine and nitrogen tet?
We're reproducing like there was no tomorrow, - that is a delusion. It only happens until the energy consumption reaches the developed world's level. After that we are not reproducing enough.
"We are not taking things at all seriously." - we will begin soon enough. The economic war with Russia is only the beginning. Things are changing in a profound way. Key players in the world will soon turn their attention outwards and compete in space because it is becoming impossible to compete on Earth without destroying each other.