A Sound of Thunder by Ray Bradbury was first published in Collier’s magazine in the June 28th, 1952 edition, and subsequently included in Bradbury’s collection, The Golden Apples of the Sun in 1953. As my fellow Time Travel Nexus contributor, Michael Main, has pointed out in his own column (see At the Mercy of Rama-Tut! and Baby Dinosaur vs. Zombies! from earlier this year), the story was also presented in comic form in the pages of Weird Science-Fantasy #25 in 1954.

In the year 2055 travelling backwards in time has become a physical reality and a company, Time Safari Inc is organizing hunting trips for wealthy adventurers and they are paying to kill extinct dinosaurs. On the eve of the American presidential election an expedition is about to take place. On this particular trip back 66 million years to the Late Cretaceous Period to kill a Tyrannosaurus Rex, a hunter named Eckels after being warned by Travis, the guide, not to deviate from the path, panics and falls from the path. This encounter with a Tyrannosaurus forms the heart of the story with Bradbury’s eloquent prose transporting the reader along with the hunting expedition sixty-million years into the past:

It came on great oiled, resilient, striding legs. It towered thirty feet above half of the trees, a great evil god, folding its delicate watchmaker’s claws close to its oily reptilian chest. Each lower leg was a piston, a thousand pounds of white bone, sunk in thick ropes of muscle, sheathed over in a gleam of pebbled skin like the mail of a terrible warrior. Each thigh was a tone of meat, ivory, and steel mesh. And from the great breathing cage of the upper body those two delicate arms dangles out front, arms with hands which might pick up and examine men like toys, while the snake neck coiled. And the head itself, a ton of sculptured stone, lifted easily upon the sky. Its mouth gaped, exposing a fence of teeth like daggers. Its eyes rolled, ostrich eggs, empty of all expression save hunger. It closed its mouth in a death grin. It ran, pelvic bones crushing aside trees and bushes, its taloned feet clawing damp earth, leaving prints six inches deep wherever it settled its weight. It ran with a gliding ballet step, far too poised and balanced for its ten tons.

On their return home in the time machine, Eckels notices subtle changes to 2055 – English words are now spelled and spoken strangely, people behave differently, and Eckels discovers more importantly that the fascist candidate Deutscher has now won the American presidential election instead of the more moderate Keith:

But the immediate thing was the sign painted on the office wall, the same sign he had read earlier today on first entering. Somehow, the sign had changed:

TYME SEFARI INC.

SEFARIS TU ANY YEER EN THE PAST.

YU NAIM THE ANIMALL.

WEE TAEK YU THAIR.

YU SHOOT ITT.

Eckels looks at the mud on his boots and finds a crushed butterfly. Apparently, the death of this single creature has set in motion a string of consequences that have rippled through time and changed the timeline. They are now in an alternative present. Eckels pleads with Travis to return to the past to undo the events but Travis cannot as he has previously explained to Eckels about returning to the same time and the problem with paradoxes. Travis is so angry that he raises his gun and there is ‘‘a sound of thunder’’.

Bradbury’s classic tale serves not only to entertain but also to speculate on the dangers of time travel. His brilliant illustration of a ripple effect upon the timeline caused by seemingly unrelated events over an extended period of time is not only revealed by the shocking climax of the story but is also explained in the story when Travis and Eckles discuss the dramatic potential repercussions of killing just a single mouse:

“So what?” Travis snorted quietly. “Well, what about the foxes that’ll need those mice to survive? For want of ten mice, a fox dies. For want of ten foxes a lion starves. For want of a lion, all manner of insects, vultures, infinite billions of life forms are thrown into chaos and destruction. Eventually it all boils down to this: fifty-nine million years later, a caveman, one of a dozen on the entire world, goes hunting wild boar or saber-toothed tiger for food. But you, friend, have stepped on all the tigers in that region. By stepping on one single mouse. So the caveman starves. And the caveman, please note, is not just any expendable man, no! He is an entire future nation. From his loins would have sprung ten sons. From their loins one hundred sons, and thus onward to a civilization. Destroy this one man, and you destroy a race, a people, an entire history of life. It is comparable to slaying some of Adam’s grandchildren. The stomp of your foot, on one mouse, could start an earthquake, the effects of which could shake our earth and destinies down through Time, to their very foundations. With the death of that one caveman, a billion others yet unborn are throttled in the womb. Perhaps Rome never rises on its seven hills. Perhaps Europe is forever a dark forest, and only Asia waxes healthy and teeming. Step on a mouse and you crush the Pyramids. Step on a mouse and you leave your print, like a Grand Canyon, across Eternity. Queen Elizabeth might never be born, Washington might not cross the Delaware, there might never be a United States at all. So be careful. Stay on the Path. Never step off!”

It’s an interesting coincidence that Bradbury decided to use a butterfly to symbolize this chaotic, multiplied effect over time. The term, ‘‘The Butterfly Effect’’ is often (erroneously) connected to Bradbury’s story. However, the phrase originated with MIT research meteorologist Edward Lorenz who discovered in the early 1960’s that minor variations in his computer model caused wildly divergent results. This popularized the idea that the beat of a butterfly’s wings on one side of the world could lead to a storm on the other side. The research carried out by Lorenz led to him writing a seminal paper on Chaos Theory. Lorenz’s use of the butterfly metaphor (it was initially a sea-gull) when explaining the theory was designed to illustrate how inherently limited are the predictability of outcomes.

Yet in Bradbury’s story we have two completely divergent versions of reality after Eckels has stepped on and killed the butterfly. While dramatically powerful, the ending does seem very limited in the effects that this ripple is responsible for. All of the main players are the same and it is only the evolution of language which has been drastically altered. Although of course at the time Bradbury wrote his story, the idea that a fascist tyrant could become President of the United States was almost unthinkable and seriously shocking; yet here we truly are. Another thing which struck me was the rapidity with which Travis shoots Eckels. Does Travis not risk changing even this new timeline for an even worse outcome, by killing Eckels? Or could it be that he believed this act might just reverse the event that caused the first ripple in time and restore their original timeline?

Bradbury’s story is undoubtedly a warning. What was meant to be an adventure for Eckels has cost him his life and has irrevocably changed the future of mankind as a fascist tyrant has now become President of the United States. One simple incident can cause a chain of catastrophic events to occur. Eckels initially was excited by the prospect of hunting the Tyrannosaurus Rex but when the reality hit him he panicked and ignored all the warnings given and put his safety first. This may be the point that Bradbury is trying to make the reader aware of and suggesting that an individual should think hard, before they choose a course of action which may have serious unforeseen consequences. This must also apply to the very act of using a time machine. It is all very well that Travis explains the explicit dangers inherent in time travel to Eckels but is this wealthy businessman really interested in these hypotheticals? Eckels wants the thrill ride. He doesn’t want to know about what might happen to time if things go wrong. It isn’t just how mans selfishness and lack of concern for humanity as a whole is detrimental to others (we are all aware of that), but, Bradbury is clearly warning us that once the time machine is built, it really is by then too late, as you cannot predict the consequences for every ripple from every event, no matter how seemingly insignificant that event might be in the present. The Butterfly Effect will always be there. We should think twice before even considering building a time machine, for the sake of all humanity.