by joewp » Sun 27 Nov 2005, 01:52:37
$this->bbcode_second_pass_quote('Lokutus', 'I') just finished watching the one hour video with Dr Bartlett explaining how exponential growth operates and its consequences.
Recall his early example of bacteria placed in a bottle at 11:00 AM. Their population doubles every minute leading to the bottle being full by noon. So he asks "when was the bottle half-full?". Answer: at 11:59, not at 11:30.
He keeps echoing this example throughout the next hour.
I'm a poor mathematician so this may sound like a dumb question. A 100% growth rate is very high. Would his example of the bacteria been as dramatic if he had used say a 5% growth rate?
Did he cherry-pick an improbable growth rate to drive his point home that we only see the danger after it's too late?
Could someone shoot down Bartlett's argument with, "Hey nothing grows at 100%".
Well all growing populations double, it's just a matter of when. He could have used 60 seconds or 60 millenium to illustrate. 60 minutes is just something everyone can relate to.
For instance, a 5% growth rate per minute would equate to a doubling every 14 minutes. (70/5 = 14). 60 minutes X 14 is 14 hours instead of one hour. Instead of the last minute, it would be the last 14 minutes till doubling. The big point is that in 70 years (a human lifetime) one can project the population by raising 2 to the power of the growth percent. A 5% per year growth rate means the population will be 2^5 or 32 times larger in 70 years.
Hope this helps.
