For many of us, there have been a few characters in our past who have have made a deep and lasting impact. For me as a chemist, I have to report that one of those people was a physicist at a school I only went to part time.

Many years ago I was lucky to have taken a class at CU Boulder by Professor Albert A. Bartlett, or “A-squared” as he was affectionately known by a few. I recall that in true Boulder fashion, he was fond of wearing flannel shirts with a Bolo tie and heavy boots.  It was an elective class in the Physics & Society vein. Professor Bartlett was (and is) skilled in the art of back-of-the-envelope calculations to help people think about problems, even when you are lacking exact numbers- what science folk call “order of magnitude” estimates. He was good at looking at a problem, estimating key quantities, and sketching approximate trends and consequences.  This is a mark of a skilled scientist- peeling away the unnecessary details and deriving estimates from core phenomena or just F=ma.  

Professor Bartlett had written a paper called “The Forgotten Fundamentals of the Energy Crsis“.  Recently I happened to find it on the web while following another vein.  

Bartlett was fond of saying that one of our biggest downfalls as a society was the failure to appreciate the exponential function.  He reminded people that Malthus had already shown that the use of arithmetic was crucial to the understanding of population growth and by extension, the consumption of natural resources. 

To scientists, this is quite obvious.  But his audience was the general public. During his talks he would give the audience a small take-home gift. The ability to calculate doubling times by the “rule of 70” as some call it. By simply dividing the number 70 (approximately 100 x ln2) by a constant growth rate, say 5 % population growth in a municipality, you would easily compute a doubling time of 70/5=14 years to double the population.

This handly little calculation helps one think critically about the consequences of growth when you hear a town council member state that some particular growth rate is desirable. In the above example, a 5 % annual growth rate will require the doubling of many city services in 14 years- a fact that often goes unnoticed by the council and public.

Professor Bartlett is a true crusader in the campaign against innumeracy.  His personal example of the use of basic math to reason his way through the consequences of unchecked consumption of natural resources and to make persuasive arguments to local government was an inspiration to many of us.