Ray Bradbury is usually regarded as one of the greatest SF authors of the twentieth century. Indeed, his fiction moves the reader in quite an unconventional way: Unlike most SF prose, Bradbury's prose does not depend largely on action, suspense or violence. It appears to be much more subtle, and builds its infrastucture on multiple levels of metaphors and symbols. He could be regarded as a science fiction poet, although poetry as a literary form is not his forte. His stories, however, stay with the reader long after the reading is over, as is the case with any worthwhile poem.

One of Bradbury's best stories deals with the dangers of time travel. A Sound of Thunder!, first published in his short story collection The Golden Apples in 1953, tells of a time travel far into the past. The traveller accidentally kills a butterfly and returns to the future to see it drastically altered. The most fascinating aspect of the story is its somewhat veiled reference to Chaos Theory. A famous example to illustrate the thory, which holds that the magnitude of causes and events have no visible correlation, is that of a butterfly flapping its wings somewhere in southern Africa. The air currents that are created by this phenomenon may well end up causing a storm in Florida. In the same way, Bradbury suggests that time travel, if ever achieved, would have to be used responsibly since causal links across different quantum branches could turn out to be incredibly complex and delicate, which makes sense when one considers that causality in our own quantum branch is proving to be enough of a challenge for contemporary physicists and philosophers.

Of course, the specifics of any voyage in time is defined both by the traveler's departure and destination points. As Einstein pointed out with his theory of relativity, the speed of an object one observes depends both on one's own velocity (that of the observer) as well as the object's (the observed event). This phenomenon is illustrated quite clearly by the The Asimov-Clarke Treaty of Park Avenue:

This treaty, which was put together as Asimov and Clarke were travelling down Park Avenue in New York while sharing a cab ride, stated that Asimov was required to insist that Arthur C. Clarke was the best science fiction writer in the world (reserving second best for himself), while Clarke was required to insist that Isaac Asimov was the best science writer in the world (reserving second best for himself). Thus the dedication in Clarke's book Report on Planet Three reads:

In accordance with the terms of the Clarke-Asimov treaty, the second-best science writer dedicates this book to the second-best science-fiction writer.