Density Duration Overshoot

As part of my plan to “get sick later” => ideally much later => we’ve been discussing what activities to add back.

Our kids are the most connected people in our family.

Two concepts have been guiding our thinking: density of the environment and duration of exposure.

  • Walking past someone, while wearing a mask (low density, low duration)
  • Grappling for an hour, face-to-face (high density, high duration)

Using this framework is helpful but I catch myself trying to rationalize exposures that are convenient for me => i.e. anything that gets my kids out of the house!

Now that low-density pools are open, we decided to replace BJJ/Grappling with cycling and swimming.

This week, I caught myself ignoring the density and telling myself that current community spread was low. I’m a sucker for things I want to believe.

The trouble with going down a line of thinking (low risk right now) is I’m not qualified to judge when community spread is high again. I’m also not qualified to judge what constitutes low community spread!

My thinking was a form of market-timing for COVID infection. I’m sure we’re all doing some version right now.

In addition to leaning away from density/duration, we have a family policy that no kid can be in a group of more than three people, outside of the family unit. This rules out other “groups of three” where the kids are in close proximity all day. It’s a simple heuristic that greatly reduces the connectivity of each of my kids.

I’m more isolated than anyone I know. However, I’m one step away from the cumulative exposure of my wife and kids.

Little bit of math => 1% chance of infection in a given period, what’s my chance of not getting infected for 50 periods? (1 – .01) ^ 50 = 61% not infected, 39% infected

For 100 periods? (1 – .01) ^ 100 = 37% not infected, 63% infected

Consider the math for workers in meatpacking plants, farm workers in dormitory housing and airline workers.

I don’t know the infection probability or the number of periods I will have to endure. This does not matter because, in a process repeated over time, the math to “stay healthy” is compelling.

We need to greatly reduce our household risk and limit our collective number of exposure events.

Stay the hell away from high density / high duration. Wear a mask.

Businesses and smart people, in all political parties, are going to figure this out.

NNT got me thinking about this with a tweet (linked above).

Related to Monday’s post, I can get everything I need by studying smart people from a distance.


I read a lot of non-fiction. Stories from believable people can be useful to find my way in the world.

There are a lot of useful stories in The Alchemy of Finance. They are relevant to what we are seeing right now.

Three areas:

  • Overshoot => human systems always overshoot
  • Regulation => political life moves between under, and over, regulation
  • Reflexivity => circular relationships between cause and effect

The difficulties inherent in our political systems can be useful. They reduce our capacity to overreact.