So many of Bradbury's narratives contain technology that had not yet been created--huge, flat-screen televisions, thimble radios much like earbuds; always attached to this technology is his warning of the disassociation it causes, the dehumanizing of emotions, the conformity, and the alienation from the human and natural world as in "The Pedestrian." In others of his works, Bradbury demonstrates how technology controls and even oppresses as in Farenheit 451; certainly it can "run amuck" at times, as it does in his short stories "The Veldt" and "There Will Come Soft Rains."
In "A Sound of Thunder," when Eckels arrives for his safari back in time, he notices wires tangled and
an aurora that flickered now orange, now silver, now blue. There was a sound like a gigantic bonfire burning all of Time, all the years and all the parchment calendars, all the hours piled high and set aflame.
Then, he is told that six Safari leaders were killed last year, and he must sign a release. When the ship finally lands Eckels is told that he is in a time before Moses. Mr. Travis instructs him about the "Path" that has been placed in position by the company for Eckels's use,
“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 any way. Stay on the Path. Don’t go off it....For any reason! If you fall off, there’s a penalty. And don’t shoot any animal we don’t okay.
Obviously, the anti-gravity path is the most important item on this hunt. Because of this technological device, there is nothing that touches the earth, nothing to disturb the smallest insect, nothing to upset the natural world as it existed in this prehistoric time. But, if there is an misuse or neglect involved, the repercussions can be monumental.
Along with the Time-travel ship, the anti-gravity Path makes this adventure to pre-historic times possible. If the ship were to not function, the men could not return, or if the path were to be destroyed, the chaos theory would go into effect. That is, a series of changes in nature would take effect, mostly harmful. Travis provides examples, such as this one:
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.
So, when Eckels slips off the Path and inadvertently smashes a butterfly, he effects the chaos about which Travis has warned him. As he discovers this Travis cries out, "Who knows what he’s done to Time, to History!” For, when Eckels returns to the Present, he does not recognize the words on the sign he has read the day before. He learns the meaning of Travis's words, “messing around in Time can make a big roar or a little rustle in history.” For, the President of the country is not Mr. Keith, but his radical opponent, "Deutscher, of course! Who else?" the clerk tells Eckels. "Not that fool weakling Keith. We got an iron man now, a man with guts!” the clerk says.