India's population "problem" if it can be called that is in only 3-4 states out of 28 - Uttar Pradesh (230M), Bihar (120M), Maharashtra (120M). Most states in India have population densities comparable to countries in Europe.
Suitable is a question of idealogy and choices , one is cultural and other is ecological.
Whether you are comfortable living in a 700sq foot apartment or you need a sprawling 10 acre property is really about culture, europe is okay with smaller cars, more public transport , dense cities , US is not .
Sustainable density really then, Looking at the crazy limits in the bay area is funny to me, but perhaps it is right for people here they don't want higher density housing.
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Earth itself quite capable of supporting multiple ten of billions but it would come at the expense of reduced bio diviserty
Most people would think that is bad, but there is case that it isn't . Earth has gone through multiple extinction events before us, however this is chance for life to become multi planetary for the first time, for life itself it is probably worth the risk.
Theoretically ofcourse we all cooperate and work in sync, we could achieve that without destroying the planet. However we aren't wired that way , evolution is not efficient.
If you can live on Mars you can live on Earth, the problem is that nobody wants to live on Mars or a Mars like Earth.
You are also underestimating the time it takes to colonize Mars. There aren't any plans right now, all we get is more rovers. Nobody is sending space manufacturing equipment to Mars nor is anyone sending an autonomous outpost ahead of time ready for people to move into it. As it is right now, if we were to send people to Mars we would send them there to die there.
If you are going to talk about Elon Musk, I'm going to remind you that he planned a Mars mission for 2018, he can't be trusted with anything.
Just Going to mars is not really multi planetary. The difference of few years when the first attempt takes place is not going to change much.
I am talking about a self sustaining significant colony. That is going be realistic probably only after 2150-2200.
Climate change and other problems will have huge impact but the humanity isn't going die from it.
You are right nobody would want to go mars today to live and work. To be the first sure, further science, unique experience sure, but regular people will have no interest in living there permanently.
However in 2150 earth is going to be rough enough that mars or space won't look too bad. The economics will also have low enough by then.
My point is that's real goal for life. we can be all eco friendly today, all it will go anyway with one extinction type of event , super volcano/asteroid/earth quake/.. take your pick
We need to keep that in mind, sustainability is important but not if we don't become multi planetary.
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To me it like we are fixing bugs and improving code and efficiency instead of worrying about HA. For uptime that's most important damn thing.
Users(humans) care about the bugs and issues (sustainability) , system (life) should be worried about uptime /reliability. That is lot easier with HA.
As an engineer I would prioritize developing HA/fail over and DR over fixing the bugs if I had to choose, I would only fix bugs which make the application completly unusable and user leave (die?) Until I have a solid uptime solution
My own viewpoint is that, our mastery of technology has enabled us to overcome "natural" limitations in a given geographical area, human potentialities and thus our relationship with the "planet". Darwin's "survival of the fittest" is no longer simple but has become multidimensional. Modern urban centers are an interplay of complex systems sustained by marvels of technology each of which is quite "fragile" to external shocks. Thus when something like Covid happens you can imagine the devastation due to ripple effect and aftershocks.
> My own viewpoint is that, our mastery of technology has enabled us to overcome "natural" limitations in a given geographical area, human potentialities and thus our relationship with the "planet".
I don’t think this is borne out by the evidence and certainly not supported by Diamond. We inhabit all sorts of niches, but unsustainably so. We farm in places we can’t sustain by taking water from natural reservoirs that won’t refill for thousands of years or else from lakes or rivers. Similarly we farm in such a way as to promote erosion. If we have the technology to live sustainably, we aren’t using it to that end.
Your question was; Why do you suppose that European population density is sustainable all over the world? Presumably the sustainable population density is going to vary with climate and geography ?
"It is not" w.r.t. the first one and "Yes" w.r.t. the 2nd one. Diamond's books were pointed out because they were the most popular ones showing the influence of Geographical Latitudes on the spread/sustainability of Human Civilizations.
Coming to my point; our mastery of technology has enabled us to overcome "natural" limitations in a given geographical area, human potentialities and thus our relationship with the "planet"
What i meant was that ever since the start of the "Technological Age" i.e. the industrial revolution, we have gained power to drastically change our environments to sustain larger Human populations (eg. in the extreme northern latitudes, desert regions, megapolises in the already densely populated regions etc.) which Nature by herself would not have allowed. Now add the influence of Technology to extend Human lifespans and potentialities and you realize that our very "technological progress" is now our greatest danger to survival. Nature no longer has the upper hand (other than infrequent occurrences like natural disasters etc.) and our stewardship of Technology is not well thought out. Though https://en.wikipedia.org/wiki/Criticism_of_technology wikipedia page is not well written, it points to authors who have thought about the detrimental influence of Technology on Society.