WHAT MIGHT HAVE BEEN & WHAT HAD TO BE
IN RAY BRADBURY'S 1952 NOVELETTE, A Sound of Thunder, the story's hero, Mr. Eckels, arranges an unlikely itinerary through a most unusual travel company, whose wall advertisement declares:
TIME SAFARI, INC.
SAFARIS TO ANY YEAR IN THE PAST
YOU NAME THE ANIMAL
WE TAKE YOU THERE
YOU SHOOT IT
Time Safari, Inc. has studied the past so carefully that they know precisely when and where a certain animal is going to die. With the omniscience of Leibniz's demon, Time Safari, Inc. takes their customers back to just moments before the animal is about to meet its natural demise, at which time the hunter can nab his game.
There is, however, one critical stipulation--you must stay on a carefully chosen path that prevents any alteration of the past, as the guide explained: "It floats six inches above the earth. Doesn't touch so much as one grass blade, flower, or tree. It's an anti-gravity metal. Its purpose is to keep you from touching this world of the past in anyway. Stay on the path. Don't go off it. I repeat. Don't go off. For any reason! If you fall off, there's a penalty. And don't shoot any animal we don't okay." The consequences of violating this rule are dear: "We don't want to change the future. We don't belong here in the past. A Time Machine is finicky business. Not knowing it, we might kill an important animal, a small bird, a roach, a flower even, thus destroying an important link in a growing species."
Every hunter's favorite target, of course, are dinosaurs, and Eckels is no different as he heads for the Cretaceous, steps out of the time machine, meanders down the path, and prepares to bag his pre-selected Tyrannosaurus. Startled by the size and ferocity of the monstrous creature, Eckels stumbles off the path and into the moss. The other hunters shoot and kill the T-rex just moments before a giant tree limb was about to crush it in the original time sequence. The hunters pile back into the Time Machine and return to the present, bemoaning the fact that they are probably going to be fined for Eckels' breach. "Who knows what he's done to time, to history," the guide groans.
When Eckels departed, the country was in the midst of a political election in which the moderate candidate--Keith--won. Had the extremist candidate--Deutscher--won, he would have established a oppressive dictatorship. Exiting the machine Eckels and the others notice that things are not quite the same. The wall advertisement now reads:
TYME SEFARI INC.
SEFARIS TU ANY YEER EN THE PAST
YU NAIM THE ANIMALL
YU SHOOT ITT
As Eckels feared, Deutscher won. Predating chaos theory by decades, Bradbury took the butterfly effect--the sensitive dependence on initial conditions--quite literally, in his counterfactual denouement:
Eckels felt himself fall into a chair. He fumbled crazily at the thick slime on his boots. He held up a clod of dirt, trembling "No, it can't be. Not a little thing like that. No!" Embedded in the mud, glistening green and gold and black, was a butterfly, very beautiful and very dead. "Not a little thing like that! Not a butterfly!" cried Eckels. 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. Eckels' mind whirled. It couldn't change things. Killing one butterfly couldn't be that important! Could it?
Could it? Not likely, but if it did it would alter the historical sequence down a radically different path, tweaking the future a lot more than just alternative spellings and election outcomes. A more likely result would have been no English at all as a language, or no democratic elections, or even no Homo sapiens. More likely, however, large-scale necessities would have washed over and averaged out such relatively insignificant contingencies. …