[Loquebantur]

It is precisely the point that in reality, the system under consideration is finite.

Consequently, you cannot find "economic substitutes" forever, as they are finite and limited themselves.

One central restriction here is the limit to pollution, which you cannot help by polluting with different stuff.

So long as the economy depends on physical objects, these restrictions apply. And they aren't "in the distance" either, but right around the corner.

[cornholio]

> the economy depends on physical objects

That's entirely the point, the economy is quickly dematerializing. As the smartphone example shows, we can provide the same service (and in fact, a far superior one) using a tiny fraction of physical resources. Electronic mail and newspapers, online marketplaces, real time video-communication are in every way better, cheaper and environmentally friendlier than their traditional counterparts.

So we can generate far more economic output (defined as transactions people are willing to make, for example software licenses, apps etc) using the same physical input.

[Loquebantur]

No, it's not. The "virtualizable" part of the economy is limited. While it gets digitized, the remaining part continues to grow exponentially, rendering the former irrelevant.

The primary problem here is the generation of energy and pollution in general. The entire economy is oil-based and all those material products have a very limited lifespan, ending as pollution.

What you need is complete recycling, which necessitates to incorporate that goal in the design phase already.

[cornholio]

> generation of energy and pollution in general. The entire economy is oil-based

The current system is unscalable, sure, but are these fundamental limits that preclude growth?

The total amount of recovereable uranium in the oceans is in the billions of tons. Orders of magnitude more U and Th in the crust. Fusion energy seems possible and the total solar irradiance is astronomical. Self replicating solar system probes, that would turn us into a Kardashev type 2 civilisation, are also conceptually possible, and could use only resources from other planets.

So we are many, many doublings away from hitting the physical limits on growth, and we can barely comprehend how our society would look like in such a scenario.

[tzs]

> The total amount of recovereable uranium in the oceans is in the billions of tons. Orders of magnitude more U and Th in the crust. Fusion energy seems possible and the total solar irradiance is astronomical. Self replicating solar system probes, that would turn us into a Kardashev type 2 civilisation, are also conceptually possible, and could use only resources from other planets.

You are greatly underestimating how fast exponential growth gets out of hand.

At 1% annual growth in human energy use starting from where we are now, in around 9300 years our annual energy use would equal all the energy in the Milky Way galaxy. By "all the energy" I mean all the energy including the energy we'd get from converting all the mass into energy (E=mc^2).

12000 years from now, so a mere 2700 years after we are consuming an entire Milky Way per year, our annual consumption would equal all the energy in the entire observable universe.

There are similar limits if we look at population growth. At 1% annual population growth we would need the mass of the observable universe to make all the living humans in about 12300 years.

For population growth another limit 1% hits in 12000 years is space. Assuming no FTL, since every human is close to Earth now in 12000 years every human has to be within 12000 light years of Earth. The volume of a sphere of radius 12000 light years divided by the population after 12000 years of 1% growth gives a volume available per human that is about equal to the volume of one person.

One I've not calculated is what the limit is when you combine 1% energy growth and the speed of light limit on how fast we can expand human space. Long before the earlier limit of 12000 years to needing all the energy in the universe we'd reach a point where the energy density in human occupied space is enough to turn human space into a black hole.

If anyone wants to calculate that limit I'd love to see the results.

[Geisterde]

You are treating the economics of growth like paperclip simulator.

[tzs]

How so?

I believe I'm treating the physics of growth, not the economics of growth.

If you need to use 1% more energy each year starting from what we use now per year, our universe does not contain enough energy to do that for more than 12000 consecutive years.

[fluoridation]

The question however, is a) whether what's conceptually possible is actually possible, and b) whether what's possible will become factual before we hit a hard limit. It's small consolation that having a Dyson sphere around the Sun would solve our energy problems if we've already run out of fossil fuels to run our logistics networks, and maybe we should have scaled back on the growth-seeking wasteful expenses and focused more on the bare essentials.

[defrost]

To be more specific the person you replied to has confused total amount present (of U, etc), with total amount recoverable (at any cost), and not even addressed total amount that is economically feasible (a cost that can be afforded).

WRT: "total amount"

Elements in suspension in ocean water become increasingly dilute as more of them are removed .. so "in theory" 'all you need to do' is move the entire ocean from one bucket to another and remove what you need as you do so ... (otherwise you are constamtly circling back for diminishing returns).

WRT: "recoverable"

Then there is the no small matter of exactly how uranium (or other elements) are extracted, by what means and at what efficiency - today it's unclear what the answer for that is at scale.

WRT: "economically feasible"

Once you have a method, how much can be recovered at a sensible cost .. for less energy than the energy expended for the recovery task, how much gold can you mine for lesss than the value of the gold recovered, etc.

It's not feasible to mine all the roadways on the planet to recover all the valuable minerals burnt away in catalytic converter.

[cornholio]

You might want to read up on this topic. The total amount of Uranium in the oceans is estimated at 4.5 billion tonnes, constantly replenishing at a rate much higher than we could currently imagine consuming.

Feasibility studies were done since the 70s assessing the opportunity to exploit this resource, and found a that Titanium oxide hydrate adsorption bed could be able to extract the resource at a cost of a few thousand $ per pound, one order of magnitude over traditional mining. Since we are talking about exponential economic growth, the notion of economic viability has only a tenuous connection to present day reality, as such growth would drastically cheapen machine labor, even to the point of deploying a software command to build the factory.

It stands to reason that such factories could still recover uranium even if the concentration in the oceans dropped, say, by 20%, so the "recoverable" quantity - in this scenario of exponential growth - is indeed, in the billions of tons. Each cubic meter of ocean water contains 3 mg of Uranium or something like 100 kWh of energy, far more than the energy required to circulate ocean water to the surface to get at it. Of course, there could be ecological reasons why you would not want to do that, as well as an enormous source of energy to solve them.

[wait_a_minute]

Another example is how modern farming yields far more produce than in the past, with less inputs. For example, vertical farming can yield 240x more produce despite using 99% less land and 99% water versus a regular farm. That technology is in its infancy and will innovate rapidly.

[cornholio]

Or we might do away with farming entirely. Photosynthesis is less than 1% efficient while a solar cell can exceed 40%; so direct chemical synthesis of starch could become the primary source of calories in our food chain, further processed into proteins, fats etc. by appropriate bioreactors down the chain.

[fluoridation]

Does that figure include the cost of manufacturing and installing the photovoltaic cells? Plants may waste sunlight, but they're very cheap to produce. Also, plants produce sugars from sunlight almost directly. Intuitively, producing electricity from sunlight and then using that electricity to produce sugars could not possibly be more efficient. It could very well be that storing energy in carbon-hydrogen bonds is intrinsically inefficient.

[cornholio]

> producing electricity from sunlight and then using that electricity to produce sugars could not possibly be more efficient.

Per photon, no. Per area of sunlit land, yes, orders of magnitude more.

Also, the photosynthesis efficiency generally refers to the entire chemical energy stored in things like the leaves, stem etc., often useless in the food chain. Solar to food efficiency is abysmal.

Then, there is the question of fertilizer and pesticide use, runoffs and accumulation in groundwater and soil, destruction of soils by intensive agriculture, water use, substantial energy required to transport the large masses involved, the subtraction of that land from the natural habitat etc. Modern agriculture is a necessary evil.

[fluoridation]

>Per photon, no. Per area of sunlit land, yes, orders of magnitude more.

That's contradictory. The Solar flux for a given region at a given time is basically constant.

I don't think fertilizer (or something analogous) would be avoidable in such a scenario, since one way or another you need a source of nitrogen.

[wait_a_minute]

Let's get to advanced vertical farming first since it's yummier and see if we need to get beyond that, but I like how you think. ;)

[omnimus]

Having worked for two vertical farming startups… people have been saying the same thing for 20 years.

Turns out when somebody actually tries this in practice its not so feasible. Considering both of the startups failed in quite rapid fashion i would say it might not be so surefire like you seem it to be.

[wait_a_minute]

The most recent examples I've seen from the last few years are very promising. Big investors are moving in, too. Even if the attempts failed in the past, they'll keep getting better. Just like with anything else - renewables, fusion, etc.