Nope. You do talk about population having an “exponential growth rate”, but that is the growth rate of the exponential curve that has been chosen to match an infinitesimally small segment of the actual population curve. It does not imply that the curve is itself exponential, and in fact no population curve in all of history will ever have been exponential for anything other than an infinitesimally small segment. And this is true of any curve at all. Population curves can sometimes be approximated by exponential curves over reasonable lengths of time, but that is certainly not the same thing as saying they are exponential, and also, “sometimes”.

(Plus you have the fact that using a smooth curve of any kind to model a discrete rather than continuous variable is also a statistical approximation, but at least this one is often a good approximation).

That’s probably what will happen to humanity. I’m not looking forward to it.

However, as noted, humans, unlike other species, can manipulate their environment to enlarge its carrying capacity. This postpones the saturation. But it can’t avoid it.

The alternative is a singularity, which transforms humanity into something that doesn’t grow.

I don’t know how Samizdata stays so relevant to my life. I must be very important.

In the U.S., the birth rate fell by 1/3 from 1800 to 1850. It declined continuously up to 1940, revived somewhat in 1945-1965 (the “Baby Boom”, and then declined further.

In the last 25 years or so, birth rates have declined substantially all over the world. The exceptions are Europe (where rates were already low) and a few African and Middle Eastern countries. East Asia, South Asia, Latin America, and even most of the Middle East and Africa have seen declines of 30% to 70% (Iran, believe it or not).

I don’t know where this is going. Eventually, some combination of cultural and technological change will create a society with a higher birth rate, and that society will inherit the earth.

In the short term, societies with currently and recently higher birth rates will dominate the near future, and that means Moslem and African societies. Unfortunately.

In the very long term, Malthus will have the last laugh, because his ultimate point cannot be refuted. Population grows exponentially, and will inevitably exhaust the resources available to support it.

Suppose the human population grew at only 0.7% a year. In 2,000 years, there would be six quadrillion people – 11 for every square meter of the Earth’s surface, including oceans.

Expansion into space? Fine. There are 100,000,000,000 stars in our galaxy, and 10% may have earthlike planets. In another 3,000 years they would all be covered with people. In another 21,000 years (a very short time, geologically and astronomically), the entire visible universe would be solid human flesh.

As the Blogfather is fond of writing, what can’t go on, won’t go on.

Most likely, there will be some sort of singularity first; but it will have the effect of ending exponential growth. The alternative is a calamity (or series of calamities) in which most of humanity dies.

I don’t understand your argument. You say we lack enough fissile material, but then admit that we have plenty if we use breeder reactors, except they are a “proliferation risk”.

If you say they are a “proliferation risk”, that does not mean that we don’t have enough fissile material. I understand your point from your link about the proliferation risk, but that doesn’t change McCarthy’s point about the sustainability of nuclear power.

You are describing a political/security issue, not a resource issue.

The link stands.

An intractable problem (barring certain speculative technologies) is the scarcity of nuclear fuel. If we were to start using the planet’s fissile stocks in modern light water single cycle reactors at a level that provided say a significant share of US electricity usage (not energy usage, just electricity) means we run out of fuel in about a century, far shorter than a billion years.

There are some options- you can eke out some more years by using a two cycle reactor. You can get a LOT more by using a breeder reactor, but breeder reactors are huge proliferation risks. If Uranium from seawater ever pans out we’ll have tons of fuel. Similarly if thorium based reactors ever really work in an economic way also have tons of fuel. But neither of those technologies has panned out as of yet.

Here’s a blog post I wrote on the matter some years ago: http://swordscrossed.org/diary/20081202/nuclear-fuels
it has all the numbers and sources in it. So now you can sop showing that link around, right?

He who refuses to do arithmetic is doomed to talk nonsense.

PROGRESS AND ITS SUSTAINABILITY