posted on May, 31 2009 @ 02:36 PM
reply to post by GreenBicMan
Point taken.. I guess you place accent on the rule of 72 because a lot of people do not seem to grasp exponential growth and it provides an easy way
to do. Pardon me if I came off a bit harsh, throwing logarithms and powers around as if all of us use them daily. So here goes, a story about growth,
When seen in a larger scale, the population growth rate has almost always been above 0.0% since 0 AD. In the dark ages and the earlier centuries were
brief moments of a declining population; all other times the growth rate was between 0.0% and 0.5% - until the industrial revolution came along. Right
around the 1900's was the first time since at least 2000 years that the barrier of 0.5% (doubling time 138.9 year) was crossed, and mere decades
later the barrier of 1.0% (doubling time 69.66 year) was crossed. This increase of growth rate meant that individuals now witnessed a doubling or more
of the entire world-population within their life-span, for the first time
in known history.
The growth rate continued to rise untill the second half of the 20th century, were it declined to the point we are at now - 1.2% in 2008, predicted to
0.5% in 2050. Bear in mind that this will be the first time in a century that we will see a rate of 0.5% - if we will indeed see it (there are more
gruesome projections out there!). It would be a real struggle to get there.
As long as the growth rate stays above 1%, most of us will witness a doubling of the entire world population in their lives - it takes 69.66 years
with a growth rate of 1% - and we haven't seen that since the 20th century to begin with. So we're pretty much in a new area of growth.
Bear in mind that this new area in growth is exponential to population size. With every passing year, a growth rate of 1% will mean more people than
the previous 1% - and we have to keep up with production of food, shelter, education, etc.