[palata]

We are living a mass extinction right now (that's not a prediction for a future risk, that's a fact that we can observe now). The reason of this mass extinction is cheap, abundant energy: habitat loss comes from there.

Fusion would be great to finish making life on Earth look like surviving on Mars. Is that what you want?

What we need (and will most likely face anyway) is to do less with less. Organise society to live the forced degrowth that is coming, and survive the climate changes that we started and cannot possibly change anymore.

[damascus]

I'm not sure I follow. The mass extinction event is mostly due to habitat destruction AFAIK right? The reason for that is seeking new resources aka energy. You don't need to cut down the rainforest to plant low yield crops if you can more profitably grow higher yield crops vertically with grow lamps and powered watering systems.. no? 'Cheap energy' is very different from 'basically free energy' in terms of what you can do.

[palata]

I get what you are saying, but... yeah I guess I need to elaborate on why I believe fusion is not a solution (and get more downvotes from techno-solutionists, yay \o/).

First, let me say that I usually start by mentioning the mass extinction, because technical people (myself included) have a tendency to believe that "the problem is CO2 emissions, and we can find new technology to reduce that". So I find it important to note that we humans are already responsible for the loss of essentially 2/3 of trees, 2/3 of animals and 2/3 of insects on Earth, and this is before the consequences of climate change. It is easy to say "if we had more energy, we would grow crop vertically and leave biodiversity alone", but sadly I don't think it works like this. Crops are not the only factor (population raises because of cheap energy, so we transform more wild spaces, also for tourism, and I am not even talking about hunting and industrial fishing, etc). But even for crops, we already know a simple way to use them more efficiently: eat crops, not meat. But we don't do that, because with cheap energy (and ignoring the fact that we are killing the planet) we don't need to. If you think about it, we used to eat the crops (and not the meat) in the past, when we did not have access to cheap energy :-). Why would we suddenly avoid rebound effects with fusion, when history shows that it has never happened for any technology before?

Then, if we put the biodiversity problem aside, there is the energy problem. Modern society fundamentally relies on fossil energy, which is limited by definition (this is very important to realize!). We passed the production peak for conventional oil in ~2008 (Europe has been feeling it since then), the global peak is predicted to be around now (I remember the predictions for the peak of conventional oil from when I was studying in 2004, and retrospectively they were very accurate, so I could imagine that the new ones may be reasonable as well), and for natural gas it may be in the next decade. So fossil energy will become a problem in the next few decades. Building a nuclear plant today, with technology we know (i.e. fission) takes what... 15 years? Fusion is most likely already too late for the party (and anyway it is not clear to me that it fundamentally solves the problem better than fission, except that people are afraid of fission for some reason). But nuclear plants make electricity, and that's only part of our society. Planes don't fly with electricity, plastic is not made of electricity, and we can't store electricity in big jars like we do with oil. So we are facing an energy problem, and we don't know technology today that could remotely solve it (I know, it's hard to accept for engineers, but please try to seriously think about it and don't stop at "many VCs put a ton of money on startups that try to find solutions, it will work out in the end").

Finally, and on top of all that, climate change is coming (again in Europe we have been feeling it strongly every summer in the last few years, and it won't go back to "normal" ever again). From what we can observe, it seems like the IPCC predictions are systematically optimistic; in other words, it seems like climate change is going faster than predicted. So it's not that we can count on 60-80 years to solve the energy problem anymore: now it seems like we may be playing the "survivability" (if that is a word in English? :-)) on many places on Earth in the next 10-20 years (maybe less). As a reminder, 10-20 years is the time we need to build a nuclear plant. If we continue in the next two decades the way we have in the last two decades (which we are clearly doing, if not worse), it is very likely that we will have screwed up many places on Earth for the next centuries. That means mass immigration, famines, wars, general world instability... not very good conditions to develop new non-military tech to solve a problem we haven't solved in decades of peace (globally).

Those are all problems with huge inertia (i.e. once you realize it is very bad, then there is no coming back), each with major consequences if they were taken individually. But they are not happening individually, they are happening together! Essentially for the same reason: our society is based on abundant energy. So the solution is not to "make a small step in one of those problems with a major technological change (like fusion)", because (and ignoring rebound effects with new technologies) even if we solve one of them, the other two problems will screw us big time.

All that not to say that we are already screwed anyway: maybe it's too late already (that's possible), but maybe not. And in case it is not, the highest chances of survival IMHO come from degrowth. Degrowth is a huge technological challenge. It's maybe not as fun as throwing Python scripts using ChatGPT in piles of docker containers running on hundreds of machines on the cloud, but it is not less challenging: how do we do less with less, while keeping our society from collapsing?

[ianai]

Energy is not a bad thing in itself. Fossil fuels are problematic precisely because they’re slightly more energy dense than previous forms of energy while having huge, dispersed externalities not reflected in their upfront costs. Fusion and nuclear in general put the power densities of fossil fuels and all other previous forms of power to shame. It’s not a single order of magnitude more dense, it’s very many. And there are high costs up front which can thus be reflected in costs and price. Thus the market can more accurately use them.

Energy is not an evil. We are not “screwed already” as you put it. But thinking we’re past some fundamental point that makes any progress futile absolutely negates the possibility of improvement by keeping us from searching and exploring options. It’s saying we can’t row ashore because we refuse to row the boat despite being fully capable of rowing the boat.

All the rest of us not convinced of the futility need from those people unwilling to figuratively row is for those unwilling to simply let the rest of us row, figuratively, instead of them. That’s all your side needs to do-stop obstructing the rest of us.

[palata]

> Energy is not a bad thing in itself.

I did not mean to say that. My intention was to say that our society fundamentally relies on fossil energy, and it seems more and more clear that we won't manage to solve that without degrowth before our society collapses.

> But thinking we’re past some fundamental point that makes any progress futile

Who said progress is futile? I say infinite growth is bad. I find it much more elegant to build a sustainable society with clever use of technology than to rush for productivity. Since we're on HN, look at software: we as an industry mostly write bad software, because all we care about is growth. We could probably write better, more sustainable software, for more sustainable products. To keep with the software comparison, my feeling is that I am saying "guys, please stop piling up crap code and hacks just to release a bad product tomorrow; let's go slower, but write good code that solves actual problems". And you're telling me "stop obstructing the rest of us, we like piling up hacks and releasing crappy software, and it makes good money".

Degrowth does not mean "go back to how people lived 300 years ago", but rather "be clever and do sustainable stuff". Or "instead of optimizing for productivity (which is killing us), what about trying to optimize for something that would be sustainable?". I, for one, would call that progress.