Thoughts while watching the Olympics …
My car gets about 30 miles per gallon of gasoline. Miles per gallon has the dimensions of inverse length squared, and the reciprocal of 30 miles per gallon is roughly the area of a circle whose diameter is 0.3 mm, or about 1/100 of an inch.
That means that when I drive my car, the fuel I consume has the same volume as a thin thread stretched along the road over the distance I travel, with a thickness just a few times the width of a human hair.*
That skinny little thread of gasoline is enough to keep my car going! Thinking about it reinforces one’s appreciation for the internal combustion engine.
Okay, let’s compare with another admirable machine — the human athlete. How many calories a runner burns depends on the runner’s weight, pace, and other things, but a typical male runner burns between 100 and 150 kilocalories per mile. Over a 26 mile marathon, that comes to about 3500 kcal, roughly equivalent to a pound of fat.
The human stomach holds about a gallon. I don’t recommend this, but if the marathon runner goes to McDonald’s after the race and scarfs down a few Big Macs, orders of fries, and Cokes, he’ll fill his stomach with about as many calories as he burned during his run.
So the marathon runner also gets about 30 miles per gallon. A skinny little thread of fuel, about 0.3 mm thick, is enough to keep you and me going, too! Is that a universal constant of Nature?
Wait ’til I tell my car!
* I heard this nugget from Charlie Bennett, who, appropriately, told it to me while we were sharing a taxicab.