CHAPTER 9

ASOUND OF THUNDER: THE SHAKESPEAREAN CAUSE

In 1972 Edward Lorenz delivered a paper with the evocative if somewhat unwieldy title “Predictability: Does the Flap of a Butterfly’s Wings in Brazil Set off a Tornado in Texas?”, in which he addressed the issue of how seemingly negligible perturbations in complex dynamic systems such as that of the terrestrial atmosphere might have vast but completely unforeseeable consequences in the long term.1 As a meteorologist Lorenz was specifically concerned to demonstrate that long-range weather forecasts can never attain to perfect accuracy, since it is not possible to take account of all the factors that might potentially bring about significant alterations in the state of the atmosphere over extended periods of time. Even marginal variations in the data used to generate predictions concerning the evo- lution of the weather system might be sufficient to lead, in a wider temporal perspective, to radically different results. What this means is that, at least in principle, something as seemingly insignificant as a single flap of a butterfly’s wings might produce infinitesimal changes in the atmosphere that contribute, however minimally, to determining the onset of a tornado and the trajectory it pursues. While the movements of the butterfly’s wings obviously do not cause the tornado in any direct or immediate sense, they do constitute an element in the initial conditions of the system which ultimately give rise to the tornado, and in the absence of that element it is theoretically possible that the tornado will not occur. The “butterfly effect” posited in Lorenz’s paper has subsequently come to be associated with what would eventually be known as chaos theory, and the image of the butterfly itself used to represent the idea

1 Reprinted as an appendix entitled “The Butterfly Effect”, in Edward Lorenz, The Essence of Chaos, London: UCL Press, 1993, 181-84. 198 Making Sense in Shakespeare that events apparently trivial in themselves might have momentous but totally unpredictable repercussions in the future. In many iterations of the notion it is not so much the flapping of the butterfly’s wings as the premature demise of the butterfly that might have flapped those wings which is responsible for differences in the way history evolves. This version of the idea, which in a multitude of guises has become a per- vasive topos of popular culture, does not however originate with Lo- renz’s work as such. It derives instead from one of the most frequently reprinted of all science fiction stories, “A Sound of Thunder” (1952) by Ray Bradbury, which describes the effects produced in human his- tory by the inadvertent killing of a butterfly on the part of a man who travels back in time in order to shoot a dinosaur. After returning from his adventure the hunter observes that the world is subtly different from that he left, and discovers the reason when he inspects his boots:

Embedded in the mud, glistening green and gold and black, was a butterfly, very beautiful and very dead. .... It fell to the floor, an exquisite thing, a small thing that could upset balances and knock down a line of small dominoes and then big dominoes and then gigantic dominoes, all down the years across Time.2

This is one of those occasions in which literature appears to have stolen a march on science, propounding as a fictive speculation a conception that would later be reformulated in the more stringent terms of technical and academic language. It is not without interest that in the particular case in point the work of literature has generated something resembling a butterfly effect of its own, spawning an exponentially proliferating multitude of stories, films, and television programmes which pivot on what is essentially the same idea, and thus enacting in its own history the imaginative postulate from which it takes its point of departure. There are few butterflies in Shakespeare’s works, 3 and none that can be said to exercise any determining influence either on the unfold-

2 Ray Bradbury, “The Golden Apples of the Sun” and Other Stories (1990), rpt. New York: HarperCollins Perennial, 2001, 215. 3 Of a total of six such references in the canon, interestingly enough, three are concentrated in a single play, Coriolanus.