Covid-19 is now widely regarded by many as the greatest illustration of the ‘butterfly effect’ in our lifetime. This metaphor is borrowed from the concept of ‘Chaos Theory’ and was propagated by MIT mathematician Edward Lorenz. The theory says some systems, highly sensitive to initial conditions, are simply too complex to be predictable over the long term. The ‘butterfly effect’, widely known after a lecture delivered by Lorenz entitled “Predictability: Does the Flap of a Butterfly’s Wings in Brazil Set Off a Tornado in Texas?” at a meeting of the American Association for the Advancement of Science in 1972, indicates that tiny changes might result in unpredictable effects.
A 1952 short story A Sound of Thunder by Ray Bradbury about time travel is often credited as the origin of the term butterfly effect. Bradbury illustrated how the death of a butterfly in the past could have drastic changes in the future. In fact, Lorenz himself first realised this phenomenon in 1961 when he was using a computer program to simulate weather. He was astonished to observe that a tiny alteration in the input value like rounding off a number representing atmospheric conditions from 0.506127 to 0.506 utterly transformed his long-term forecast of the weather. “The initial round-off errors were the culprits; they were steadily amplifying until they dominated the solution,” Lorenz later commented in his 1993 book The Essence of Chaos.
In addition to severe health effects, the pandemic is certainly an acute shock to the world economy, its education system, job market, social stability, process of globalisation, international trade, the global supply chain model and international politics. However, was the global spread of Covid-19 orchestrated by a Chinese butterfly (or Chinese pangolin or bat) alone? People grossly overlook some aspects inherent in the philosophy of the ‘butterfly effect’. A big phenomenon comprises a long chain of successive small events. Lorenz provided an ‘input’ in his simulation exercise. A tiny alteration or approximation in the ‘input’ may be interpreted as a flap of a butterfly.
However, there are innumerable conditions thereafter, mostly random, in the process, beyond the input provider’s control, which would eventually yield some ‘output’. At the ‘input’ stage, you have no other way than to average out all the future ‘random’ events, and thus the ‘butterfly effect’ seems the only dominating issue to you. It’s essentially a perspective look. It thus prevents us from isolating specific causes of later conditions. However, “we shall never know what would have happened if we had not disturbed it” due to numerous subsequent random events—most of which are flaps of other butterflies. How the event unfolds, thus, depends very sensitively upon its present state, so that, even though it is not random, it seems to be.
However, in reality, we usually look at any event in a retrospective angle—after it has already occurred. Innumerable butterfly flaps in the complex path of the event have already happened by then. These are realisations of different random variables, each of which had potential to change the course of the event as well. It’s certainly a reflection of the ‘domino effect’ or ‘chain reaction’—the cumulative effect produced when one event sets off a faraway change.
However, the chain can completely be broken or directed differently by shifting just one domino a bit. For example, in late February, when the US President Donald Trump was on a state visit to India, Dr Nancy Messonnier, the director of the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention of the US, publicly sounded an alarm about the severity of the coronavirus outbreak, warning that the outbreak would soon become a pandemic. And an angry Trump, in denial, threatened to fire her. Had Trump paid attention to her warning instead, the US might have averted the present situation—who knows! Again, the World Health Organization is under fire with the allegation that it ignored a crucial December email from Taiwan inquiring about the person-to-person spread of Covid-19.
A timely action could have possibly reduced the intensity of the pandemic drastically. Did the initial reliance on ‘herd immunity’ prove to be too costly for the UK? Were the countries of Europe late to close their respective borders? There are innumerable such butterflies in the complex route from the wet market of Wuhan in China to Italy, Europe, America and other parts of Asia—many of them had the potential to drastically cut the severity of the pandemic in different countries.
Our usual instinct is to attach a specific cause to an event, and we cannot easily accept the randomness of the world. In the 2004 Hollywood movie The Butterfly Effect, the character played by Ashton Kutcher travels back in time and alters his troubled childhood so that the present could be altered. The results were dismal though. It clearly indicates that our ability to analyse and predict the functioning of the world is inherently limited.
This pandemic, initiated by a Wuhan ‘butterfly’, is likely to be a combination of a lot more butterfly effects over time across the globe, and it might cause hurricanes that are longer and much more severe than we can currently predict.
Atanu Biswas
Professor of Statistics, Indian Statistical Institute, Kolkata
(Email: appubabale@gmail.com)