Nästa gång du ställs inför påståendet att någon viss procentuell årlig tillväxt är en förutsättning för att ekonomin och samhället skall fungera,1 betänk då att sådan tillväxt innebär en exponentiell ökning, och fråga dig hur länge den rimligtvis kan tänkas pågå. Om ditt svar blir "i obegränsad tid", tag då del av sagan om vetekornen och schackbrädet, eller av astronomen Geogre Abells moderna variant från boken Exploration of the Universe (fjärde upplagan, 1982, s 594), och tag dig en funderare till. Så här skriver Abell:
- The world population [is] at present doubling about every 35 years (2 precent [increase] per year).2
In New York City there are a little more than 100 square meters of land area for every person living in that city. Suppose we imagine New York to be more than 100 times as crowded as it is now, so that there is only one square meter per person. Moreover, let us suppose the same crowding applies over the entire land area of the earth. At the present rate of population growth, the land area of our planet would be filled to this density in about 550 years.
Perhaps one can argue about how crowded the earth can be. An uncontested ultimate limit to the number of people, however, is set by the fact that we are made of atoms of matter, and matter is conserved; that which comprises our bodies has had to come from the earth itself. Most of the matter in our bodies is in the form of water. [...] At a doubling time of 35 years, the oceans would be entirely converted to people in about 1200 years (never mind about water to wash with, drink, and water our fields with, or even for fish). At the same doubling rate, in 1600 years the mass of people would be equal to the mass of the earth, and in 2300 years to that of the solar system. If we could create matter from nothing (to create people), after about 5300 years a great sphere of humanity 150 light years in radius would be expanding at its surface at the speed of light!
Fotnoter
1) Eller påståendet om obevekligheten i Moores lag.
2) Tillväxttakten i Jordens befolkning har avtagit sedan Abell skrev dessa rader, och var 2009 nere i en årlig ökning om 1,1%. Detta förtar naturligtvis på intet vis kraften ur Abells demonstration av det absurda i oupphörlig exponentiell tillväxt.
