Coronavirus Math of the Path and the Beach
CNN keeps showing pictures of people jogging by the side of the San Francisco Bay, and using the Florida beaches, and going tsk, tsk about the separation of the joggers or beach goers. They apparently have never heard of the math of dimensionality.
The six feet or die math that I did before was for typical height and confined small rooms. That could apply to spring breakers who are parting hard in crowded and confined bars or restaurants.
But look how different the above activity sites are. The jogging path looked like fifteen feet wide, so no problem there. The people together were mainly live together or date together couples. Mathematically, however, the path was a line in a three dimensional world. Since it is by the bay, their exhalations horizontally were first swept out to the enormous bay, and then out to the 6,000 mile sea. But vertically, infinity to the universe is a bit of exaggeration. The air may only circulate effectively five miles high or so. The real one dimensional tubes to worry about are buses, trains, and airplanes, which are already empty.
Now for the beach. The crowding at the beach was not the shoulder to shoulder European summer beach, where people from a two dimensional country try to crowd onto an essentially one dimensional beach. People tend to be polite and spread out on a beach, anyway. But again, the air is usually moving horizontally, spreading out over two dimensions. By convection, turbulence, and diffusion, it is also spreading vertically and far into the third dimension.
There is also the fourth, time dimension. While in an enclosed space the airborne viruses might last a half hour or more, the air motion outdoors and at the beach wafts it away in a second or two. So, CNN, get off your high horse, which is also a great way lose the virus. Math triumphs.