Yesterday was my mother's birthday. She is in hospital in Shrewsbury recovering from surgery. I'm in San Diego heading for the airport.
My brother and I make a plan. He'll be visiting my mom and he will call me on his cellphone so I can wish her Happy Birthday.
It works... sort of. Communication over 5000 miles from California to England: no problem. But the cell signal drops out next to my mother's bed. To connect with me, my brother has to stand in the doorway - and my mom isn't yet mobile enough to walk over to him.
Technology connected us over 5000 miles - but it can't bridge the last couple of yards.
Later in the day I am heading back to State College on a much-delayed flight. The weather is foggy. As we glide in for our landing the lights below flicker in and out through the clouds.
Suddenly, there is the runway! Just a few yards below. The plane flares for the landing - but then the pilot decides that we are too high. The engines roar and we head back in to the clouds and to a diversion airport.
Nearly made it - but we couldn't cover the last few yards.
These stories make the point that distance is not always the best measure of impact. Those last few yards count for as much as all the previous miles.
I sometimes think of this when I hear about how many miles our food travels to get to us. It may be that the last mile or two (in a private car) are much more significant in terms of environmental impact than all the previous miles (traveling in bulk).
I'd like to include some quantification about this in my "sustainability math" course.
Photo of the Inaccessible Pinnacle, Skye, copyright Flickr user "Bocian", licensed under Creative Commons
A Bicategory of Decorated Cospans - My students are trying to piece together general theory of networks, inspired by many examples. A good general theory should clarify and unify these exampl...
2 weeks ago