## 14 May 2015

### 1% growth is not sustainable long-term

I was recently startled to read this assertion*:
If our species had started with just two people at the time of the earliest agricultural practices some 10,000 years ago, and increased by 1 percent per year, today humanity would be a solid ball of flesh many thousand light years in diameter, and expanding with a radial velocity that, neglecting relativity, would be many times faster than the speed of light." - Gabor Zovanyi
That didn't seem possible - until I did a rough approximation.  An increase of 1% per year, according to the rule of 72 (which may be accurate for such a small number), would mean a doubling every 72 years.  Lets be conservative and translate 1% annual growth to the population doubling every 100 years [and thus avoid the nitpicking argument that two people can't increase by 1%].

10,000 years would allow for 100 doublings, which according to a QI comment... "You should end up with a figure of roughly 3.27 x 10^43. Which is quite a lot."  It is, of course, another variant of the ancient puzzle of placing doubling grains of rice on a chessboard.

I often weary of every politician, businessman, sports coach, guidance counselor etc. mindlessly repeating a mantra that something has to get bigger to be better. Buildings have to taller, cars faster, bandwidth wider, budgets increased, growth is inevitable and necessary to progress.

There are limits to growth.

*One of the forums at QI led me to the source of the quote: "his quote comes from the book The No-Growth Imperative by Gabor Zovanyi. In which he cites (141, p198) this example as taken from a calculation done by P C Putman taken from The Economic History of World Population by Carlo M. Cipolla."

1. Does his math take things into account like the Black Death killing 75 to 200 million people or 11 million people being killed in the Holocaust, or countless other things that killed people en masses? That would certainly affect population growth rates.

1. Math is math, and is correct. The things you mention are irrelevant to the math, just as is the concept of a "ball of flesh light-years in diameter."

2. Didn't you already post the mind-blowing TED talk that predicts that the earth's population will flatten at 8 or 9 billion?

1. I'm sure I did, but I can't find it right now.

2. That was the Hans Rosling, yes?
http://tywkiwdbi.blogspot.com/2015/03/hans-rosling-clarifies-world.html

3. It all depends on how much energy the human race can get it's hands on and how much of that energy can be used to feed people.

4. A great many problems would be solved if there were fewer people in the world. But it doesn't look like population growth is going to slow down sufficiently before we run out of resources to feed people. Then, I guess, the Malthusian Doctrine kicks in.

5. The Rule of 72 is all well and good, but the Rule of 69 would result in a much lower birth rate.

6. And then compare that to the evidence that suburbs require significant growth to be financially sustainable.
http://www.strongtowns.org/the-growth-ponzi-scheme/

Also the population video was Hans Rosling
http://www.gapminder.org/videos/population-growth-explained-with-ikea-boxes/

7. He is also assuming that no one dies which puts this with the classic science cartoon " first, we assume a square cow...."

8. When an economists talks about growth he is usually not talking about tons of some ressource or number of people or any discrete amount of something, but instead about wealth measured in monetary value.

As long as there is innovation there is the possibility for limitless growth without necessarily any growth at all in the use of limited ressources. At least up until we reach a unimaginable point in the future where wealth is as abundant as saltwater in the oceans - at which point the discussion about growth will have become obsolete anyway...

This is why one has to be really careful when using a word like growth that means very different things in different contexts. There is a lot of potential for misunderstanding...

9. I find that looking too far forward isn't very useful. Look to the human race 10,000 years ago - it had nothing. Stone age. People then could not even comprehend where we are now.

In 10,000 years, we surely will have developed an energy solution. We may have the technology to live on Mars or Venus. We may live under the oceans, or underground. We may agree on an economic model that doesn't require constant growth (as capitalism does). We may flatten out our birth rates, like Japan or Italy have. The point is, 10,000 years, although very short in the history of our planet, is a very long time in the history of our people.

1. Forget the 10,000 years, which is just there for a hyperbolic example. Is 5-6 generations of your family too far to look forward? Apply the multiple and consider...

10. "Let Me Take My Chances On The Ball Of Flesh" was the refrain of a Linda & Richard Thompson song if I recall correctly.

11. Oh wait...
https://youtu.be/GcFhyy2kgdo

12. The figure of 3.27 x 10^43 at year 10,000 is correct, but the statements about the the "solid ball of flesh being many thousands of light years in diameter" is way out.

Assuming the average human volume is 0.7 m^3, then the total volume at year 10,000 would be 2.29 x 10^43 m^3. The radius of this would be 1.76 x 10^14 m, which is 1.86% of a light year, since light travels at 3 x 10^8 m/s and there are 31,536,000 seconds in a year.

The difference in radius between year 9,999 and year 10,000 is 5.83 x 10^11 m, which equates to the radius expanding at an average velocity of 1.85 x 10^4 m/s or 18.5 km/s. Still fast, but nowhere near the speed of light.