[tel]

Am I the only one absolutely terrified by that number?

Malthus wasn't wrong in principle, just in timescale. It's clear that technologies have improved Earth's human carrying capacity, but I don't know any method to claim that an S-shaped curve isn't inevitable.

It's sounds science fiction-ey, but I don't understand how you can see data like this and then defund NASA.

[reasonattlm]

Malthus was wrong in principle. He didn't understand human action or economics, and that misunderstanding remains very common. See:

http://www.fightaging.org/archives/2006/09/overpopulation.ph...

"Common Malthusianism - the idea that a given resource (such as living space or food) will run out in the future based upon extrapolation of present trends - stems from fundamental misunderstandings about economics, human action and change. We create change in response to our environment; our self-interest leads us to constantly strive at the creation of new resources where old resources are becoming scarce and expensive. This is the path to profit for the individual - and progress for all. One needs a certain amount of willful blindness to avoid seeing the process in action now and in recent history."

[yummyfajitas]

"Common Malthusianism" is a strange name to apply to a claim Malthus didn't make. Malthus didn't attempt to extrapolate current trends, he merely pointed out (correctly) that there will eventually be a limit to productivity. From "An Essay on the Principles of Population":

We may be quite sure that among plants, as well as among animals, there is a limit to improvement, though we do not exactly know where it is. It is probable that the gardeners who contend for flower prizes have often applied stronger dressing without success. At the same time, it would be highly presumptuous in any man to say, that he had seen the finest carnation or anemone that could ever be made to grow. He might however assert without the smallest chance of being contradicted by a future fact, that no carnation or anemone could ever by cultivation be increased to the size of a large cabbage; and yet there are assignable quantities much greater than a cabbage. No man can say that he has seen the largest ear of wheat, or the largest oak that could ever grow; but he might easily, and with perfect certainty, name a point of magnitude, at which they would not arrive. In all these cases therefore, a careful distinction should be made, between an unlimited progress, and a progress where the limit is merely undefined.

He then observed the tendency of humans to reproduce until the limits of their environment are reached and concluded that poverty will be the terminal state of humanity.

Malthus was merely wrong on this empirical point - humans are willing to voluntarily stop reproducing under certain cultural and economic circumstances. These circumstances involve modern levels of economic productivity, technologies (birth control) invented 100 years after his death, and western cultures. He wasn't wrong on principle, he merely lacked the data we have today.

[spindritf]

> he merely pointed out (correctly) that there will eventually be a limit to productivity

I don't understand this point. Why would there be a limit to productivity, especially with machines and computers to leverage our efforts thousandfold and more?

And how could anyone know that such limit exists, even if it is actually reached one day? That would require predicting any possible innovation of the future.

[brazzy]

As long as the measure of productivity corresponds to something physical (which even bits on a harddisk are), then an exponential increase in productivity (as we have seen in the past) would eventually require humanity and its products to form a sphere whose radius grows faster than the speed of light.

Do you agree that that is a pretty hard limit?

[TheSOB88]

I think you may have skipped some steps... Could you fill in the middle a bit? I'm confused.

[Retric]

Let's suppose the amount of physical goods produced increases 1% each year. Let's add that as physical objects they take up some space minimum amount of time. Now let's add that humanity is spreading out in all directions at the speed of light. If humans cover 1 light year of space they can expand faster than the new amount of stuff. However Volume = 4/3 pi * radius ^ 3 so what happens when humanity covers 1,000 light years. Well, next year they need to put 1% more stuff into 1002^3 / 1000^3 = 0.6% more space which means they need to increase the density which at some point means you have a black hole.

PS: 1% growth per year seems slow and sustainable but in 20,000 years your talking about 2.7 with 86 zeros after it. Start with 1 atom for one second and compare it with every atom in the earth for a year and your only at 4.2 with 57 zeros. So if the total economic output of humanity was 1 atom we could not sustain 1% economic growth per year for 30,000 years.

Edit: This assumes that the economy is based on physical goods, if we assume intangibles can take up 99.99...9% of the economy then 1% growth is possible for long periods of time even if it's somewhat meaningless.

[brazzy]

In out three-dimensional space, volume grows with radius at r^3. If something physical grows exponentially (2^t), then the radius of its volume needs to increase over time at an accelerating rate, which means the growth of that radius will eventually surpass c.

[barry-cotter]

I don't understand this point. Why would there be a limit to productivity, especially with machines and computers to leverage our efforts thousandfold and more?

There are limits to what you can do with matter. It's unlikely the economy (our productive capacity) will continue to grow much for 100,000 years after all mass we can get at is weird ass artificial quark composite computronium.

[6ren]

Yes, I think a limit on productivity amounts to a limit on knowledge. Does knowledge have a limit? There's no evidence for it; all our present mathematics of complexity suggests not (but it's possible one will be discovered...)

However, energy needs do seem to increase with productivity, and there's limit on how much energy we can get from the sun (a dyson sphere encloses the sun, capturing all its energy). But there's some assumptions here: that we can't discover ways of being productive that require less energy (and wouldn't that enhancement itself be "productive"?); that we can't discover other sources of energy (e.g. room temperature fusion micro-suns - or something better).

Once you factor in the unknown (i.e. knowledge that we don't yet have) it's hard to know what the limits are. I guess the entire universe is a limit on matter... if we can't discover a way to make more matter... or more universes.

[Symmetry]

There are actually mathematical limits to the amount of information that can be stored within a given volume, the Bekenstein bound, which is a lot like a limit to knowledge.

[6ren]

Well... if we can make new universes, the volume isn't limited.

[G_Morgan]

Actually we know for a fact such a limit exists. There are physical limits on how much energy can be extracted from a certain mass.

[mlinsey]

Of course Earth must have some finite carrying capacity, but that's only terrifying if you assume that "The Crunch" is the only way to bring population growth to a halt.

Population growth is already zero or negative in most developed countries if you remove the effects of immigration. If this becomes a consistent rule for all countries once they become fully developed, the real question is not whether we can sustain infinite population growth, but whether we have the resources to support a developed lifestyle for the entire world. Given current technologies and energy sources, the answer is almost certainly "no", but this is a much more tractable problem.

[tel]

I agree that such a state doesn't (a) seem impossible or (b) seem untenable if we have sufficient technological advances (solving fusion ignition, perhaps).

What kind of trajectory takes us from here to there (or to a place dense with similar stable solutions) without going through war and famine? Or, how does a developed nation survive in relative bounty surrounded by nations undergoing severe war and famine?

[Unseelie]

The first question is very difficult to answer..the second?

>Or, how does a developed nation survive in relative bounty surrounded by nations undergoing severe war and famine?

Brutality and self interest.

[Unseelie]

That currently developed nations currently have a negative growth rate only makes sense in terms of our current medical situation. If it were a hundred years ago, they'd all have collapsed by now, and if life expectancy doubled, or if people could halt their aging, population would once again explode, simply because couples like to raise children.

[davidhollander]

>Am I the only one absolutely terrified by that number?

No, unfortunately there are plenty of other irrational sensationalists.

>Malthus wasn't wrong in principle, just in timescale.

He has been horribly wrong in principle, as has every other pessimist who cried wolf for the past 3000 years. Saying 'the timescale was just wrong' is not an adequate defense by any means. Timescale is what matters and is the essence of all predictions.

Ask a trader: a prediction that oil will go up in the long run is completely useless if you don't define when that event will occur, and subsequently loose everything on a big short term dip that you were blind to.

Additionally, if your prediction is allowed to take "infinity" duration to come true, then it can never be disproven. And what can't be disproven is usually categorically not worth the thought.

To discuss particulars, the current evidence is technology allows us to produce TOO much food TOO cheaply, which is compounded further by domestic farm subsidies. Efficiency gains are so successful in keeping up with demand, that in Mexico City they buy corn from Iowa, even though they have cheaper farmland and local labor that could be utilized.

Additionally, many economists are currently considering the possibility of efficiency gains being so strong a factor that they lead to structural unemployment. This picture of runaway efficiency gains is the exact opposite of what Malthus had envisioned (constant\linear resource utilization massively outstripped by population growth rate)

>It's sounds science fiction-ey, but I don't understand how you can see data like this and then defund NASA.

All the nations economically developed enough to have a space program are rapidly decreasing in population. China, Russia, Japan are all on the decline, the US is only increasing due to immigration. It's economics 101: wealthy people have more economic freedom to invest in birth control and their time in things other than family. Additional children switch from being an asset into a liability when you have to pay substantial amounts for them to be educated and the opportunity cost of taking time to raise a child becomes higher. The S shaped curve has been in full swing in developed countries like the US and Russia where the vast majority of the land is deserted, without anything resembling a Malthusian scenario.

[michaelfairley]

I'm putting much more faith in commercial spaceflight programs (Scaled Composites, SpaceX, Armadillo) for advancing space exploration/colonization than I do in NASA. Even their early work shows that their marginal costs are many orders of magnitude less than NASA's funding. This is one of those areas where market forces will beat out the government hands down.

[scott_s]

Historically, colonization has had little impact on the size of the population that sent them. And even if it improved the lives of the people who left, it had no impact the lives of the people who stayed.

[jgorham]

One interesting fact regarding population growth is that worldwide, having children on aggregate is a inferior good: if parts of Africa and Southeast Asia can make some significant gains in the next few decades, we will likely see population peak sometime this century.

[Unseelie]

Children can't be compared to goods. There's biological things at worth beyond self interest. That is to say, people want children, even though its not in their self interest.

I'd posit, if you were to try to assign children a status as a good in a wealthy culture, they'd be a luxury good. They cost a great deal, are effectively useless, but still desired.

[koningrobot]

<i>That is to say, people want children, even though its not in their self interest.</i> It certainly isn't in the children's interest either, because they can't be benefited by being brought into existence (they are not waiting in some pre-existence limbo wishing to become existent).

[cousin_it]

It's in the "interest" of our genes, like many other things we do.

[lotharbot]

The vast majority of natural populations that I've looked into have s-shaped population growth without any particular unpleasantness; as population nears its carrying capacity, birth rate naturally tapers off, leading to near-zero population growth. Humanity appears to be in the tapering-off stage of this already (since around 1980), and I don't see any reason to presume there will be unusually high levels of conflict or tragedy as that tapering-off process continues.

The typical Mathusian "overpopulation" argument (based on a shallow misreading of Malthus) is not that we'll have an S-shaped population growth curve, but an A-shaped one -- that we'll have population grow out of control, and then come crashing back down through some massive tragedy (akin to the Kaibab Deer population [0]). The A-shaped scenario is reasonably unlikely for humans.

[0] http://depts.alverno.edu/nsmt/youngcc/research/kaibab/story3...

[btilly]

You are not alone. If you want to get more scared, read http://www.amazon.com/Collapse-Societies-Choose-Fail-Succeed....

Interestingly from the population statistics alone it is possible to make an argument about the total likely future number of humans that will live. There is debate about whether the reasoning is correct, but it is at least suggestive. See http://en.wikipedia.org/wiki/Doomsday_argument for more.

[ellyagg]

I don't think the Doomsday Argument is that interesting. It may be trivially true, but it doesn't tell us anything interesting or predictive. All it says is that the chronology of human existence is too complicated for us to calculate. That being the case, our working assumption can only be that we're at the midpoint of our species population line. But, keep in mind that this estimate is really, really horrible, it's only virtue being that it's better than all the others.

If someone gave you a trick coin, and you didn't know which side was favored, you'd have to assume 50/50, even knowing that you were certainly wrong. Knowing that one side is weighted doesn't give you any interesting information for one toss.

If you follow the arguments for and against the DA, it's clear this isn't about a well-defined statistical argument, but immediately devolves into qualitative arguments about our survivability. The optimists say, well, based on the average extinction rate it's extremely unlikely we'll die in <100 million years. The pessimists counter that we're creating technologies with extinction level capacities very rapidly. Either way, we don't have a way of gauging the predictive power of these claims. We can't run a controlled study of 100 human species spans.

And that's fine, because we need to argue about and introspect on the longevity of species, but brainteasers like the DA don't further it in any meaningful way.

[btilly]

I don't think the Doomsday Argument is that interesting. It may be trivially true, but it doesn't tell us anything interesting or predictive.

If it is true, it can let us put probabilistic upper bounds on the future of the human race. For instance with 99.99999% likelihood I can tell you that the human race will fail to succeed in expanding colonization of other stars. As much as we may dream of the stars, we will never reach them.

Similarly the odds of our maintaining our current population levels for the next thousand years is something like 40%. That is both interesting and predictive. Its meaning, however, is highly debatable.

[michaelchisari]

And maybe once you're done with that, you can read a rebuttal of sorts:

http://www.amazon.com/Coming-Population-Crash-Planets-Surpri...

[btilly]

I am familiar with the arguments suggesting that population growth is self-limiting. I am also aware that the spread of birth control is breeding people whose will fail to use it. They may be a small portion of the overall population, but any portion that is on an exponential curve when the rest are not is bound to eventually dominate the population.

Malthus has been postponed for centuries. And may well be postponed for more centuries. But unless resources grow exponentially, Malthus eventually will have the last laugh.

[radu_floricica]

Scared? I remember distinctly the book ended with a "cautious optimism".

Yes, it points out a lot of potential problems, and makes it obvious that societies _do_ fail, and that we're not yet above that rule, but I wouldn't call it scary.

[dasil003]

> It's sounds science fiction-ey, but I don't understand how you can see data like this and then defund NASA.

The politicians who authorized the current pension structures for California state employees undoubtedly had similar data, so I imagine defunding NASA would be comparatively trivial short-term thinking.

[eoghan]

Nature will find far less technical solutions to this problem. War, poverty, disease will provide a ceiling to this growth.