As we’ve learned, it only takes one person infected with Covid-19 to unleash chaos.
In Washington State, a person with the virus attended a choir practice, and more than half of the other singers subsequently fell ill. In South Korea, a 29-year-old man went to night clubs; he was Covid-19 positive, and has been ever since linked to at least 54 new cases. In China, nine people are on the path of air conditioning ventilation in one restaurant all got sick, probably from one person, because the channel blew viral particles across their faces.
Little things could have changed these outcomes. The clubber could have decided to watch TV instead of dancing. If the choir practice had been moved to the next day, the person might have felt sick and stayed at home. The air conditioning in the restaurant could have been turned off.
As Stephen Kissler, an infectious disease model, puts it, “Small shifts can have a disproportionately large impact” in a pandemic. And scientists have a name for systems that work like this: chaos.
What I’ve found talking to scientists like Kissler is that knowing that this pandemic is chaotic is one of the keys to understanding why the future is uncertain. But it can also help us understand why this uncertainty doesn’t have to be so debilitating.
The double pendulum teaches us about the nature of chaos
There is simple mechanics that help me understand the many possible futures we face with the Covid-19 pandemic.
It is the double pendulum and as a physical object it is very simple: one pendulum (a string and a weight) is attached to the bottom of another. The movement is explained by the laws of motion written by Isaac Newton hundreds of years ago.
But small changes in the initial state of the pendulum – suppose it starts to swing from a slightly higher height, or if the weight of the pendulum balls is slightly heavier, or one of the pendulum arms is slightly longer than the others – leads to vastly different outcomes that are very difficult to predict.
Is it too late for celebrations in 2020?
Here is a very colorful 20 second animation of 20 pendulums, starting from the exact same position, with only a 20 gram difference in mass. pic.twitter.com/Ue6aENsjeZ
– Double pendulum (@pendulum_bot) January 4, 2020
The double pendulum is chaotic because the movement of the first pendulum affects the movement of the second, which then affects the entire device. There is no simple scale or ratio to describe how the inputs relate to the outputs. A one gram change in the weight of a sling ball can result in a very different sling pattern than a two gram change.
It teaches us to understand the mechanics of a system – the science of how it works – without being able to accurately predict its future. It helps us visualize how something that looks like it should be linear and predictable isn’t.
The double pendulum shows us that simple systems are not simple at all. Complicated then? God knows.
The pandemic is chaos. We can still understand it.
An outbreak is not a double pendulum; it is much more complicated. Countless event chains, operating in overlapping networks, conspire to chart the course.
Therefore, when pressured, epidemiologists have to say they don’t know what’s going to happen.
Yet they know the effect of outbreaks. The chaos “doesn’t necessarily mean we don’t know anything,” says Kissler. They understand the conditions that aggravate an outbreak and the conditions that make it better.
There is a harsh tension of the present moment that we all have to work through: the future is cloudy, but we know the mechanics of this system. We know what is possible. Just as we know that when pushed, pendulums swing, we can sense the future of the Covid-19 pandemic.
Here are the mechanics. Scientists know that if we distance ourselves from social distance, without an alternative plan, the virus can infect more people. They know that this virus probably lasts for a few years without a vaccine. They know it is very contagious. That it is very deadly. They also know that pandemic potential is barely spent and that most of the population of the United States and the world is still vulnerable to it.
And so scientists are afraid of major revival of the virus in the coming months and years, and their fears are well-founded history and scientific analysis. Yet, they say, their outlook on the future is more closed than ever as the response to the pandemic becomes more varied.
“I think we have more uncertainty now than almost any other time,” Boston University epidemiologist Eleanor Murray recently told me. At the moment, some places are thinking about continuing the lock. Some places are thinking of opening. Opening means different things in different places. There are so many actions that different areas are taking that it is difficult to predict. “Our actions influence the results, which in turn influence our actions.
Will residents keep wearing masks and social distances even if their leaders relax the rules? In addition, there are scientific questions about the virus that are still not understood: will it reduce transmission according to a seasonal pattern? Do children make a huge contribution to its spread? How long does immunity last after an infection? Why do some people exhale more of the virus than others? The answers to these questions will influence the future and we don’t know the answers.
Scientists are still unraveling the difference between a sprawling outbreak in one city and a more manageable one in another. Some of it is the result of policy, some is the result of demographics, some is about structural inequality and racism, and another is about individual behavior. Part of it is just luck. That’s chaos to you.
Chaos rules our world. But that doesn’t mean we’re powerless.
“I don’t see uncertainty as a lack of knowledge,” said Philip Lorenz-Spreen, a physicist who studies the chaos of a different kind of viral dynamics. “I think it’s a fundamental part of how our world works. It’s not our fault that we don’t know where all this is going to go.”
Newton clearly told us what happens when an object falls from the sky. But follow his laws and discover that the path of a double pendulum is very difficult to predict. Climate scientists clearly tell us that adding CO2 to the air will raise global temperatures. Still, they discuss when the worst effects of climate change will be felt and how bad it will be. Epidemiologists clearly tell us what happens when you bring crowds together during a pandemic. But they cannot tell us exactly what form this outbreak will take.
Thinking about the future of the pandemic means struggling with uncertainty, both personally and as a wider community. It also means dealing with what is unlikely to happen: the virus will disappear in the coming months. If so, it will do this for reasons that scientists either don’t understand or can’t currently explain.
There is a lot in this chaotic pandemic system that we have no control over. Let’s be serious about the ones we can.