Why is Arthur Dent a good choice for the protagonist?
Arthur might not seem like the best protagonist—after all, he's rather bumbling, quotidian, and occasionally hapless. However, the fact that he isn't a genius or a hero and is more of an Everyman (albeit a lackluster one) makes his encounters with Vogons, planet-builders, babel fish, and improbability drives all the more amusing and relatable. Like it or not, most of us would have the same reactions and emotions as Arthur, and it's much more effective for Adams to denote how absurd and fascinating the Universe is if we see it through the eyes of Arthur.
What might Adams' message be about science in this novel?
The novel engages with the disciplines of astronomy, physics, biology, and more in its depiction of interstellar travel, Improbability Drives, time travel, wormholes, etc. Adams is comfortable with these scientific elements; however, in the way the events of the novel unfold, it is clear that he is suggesting we have so much more to learn. The Universe is infinite and therefore unknowable; the history of science is a history of humans figuring out that they were wrong about something. Adams encourages exploration, curiosity, and openness to admitting one has to radically readjust one's conclusions.
What's the symbolic import of the towel in the story?
A towel is seemingly an unimpressive, quotidian item that no one would think would be useful in traversing the galaxy. However, in classic Adams fashion, he gets us to rethink what we know about science fiction and, perhaps more so, enjoys pulling out the rug from underneath readers just for fun. A towel is supposed to be both useful and indicative of something more important: that the traveler knows what they're doing. This latter fact calls attention to the arbitrary value we place on certain items and how we elevate such items in collective esteem.
What is the significance of Trillian as a character in the story?
Trillian initially seems like she is a classic female science fiction character: she is there as a love interest for the male hero. Indeed, she was introduced as a woman whom Arthur and Zaphod both pursued at a party. Despite this, Trillian is only somewhat interested in Zaphod and never develops any relationship with Arthur. She remains inscrutable in many respects, saying she chose to join Zaphod because her degrees on Earth weren't helping her get anywhere. We never learn anything else about her backstory or her motivations. She is cool-headed, logical, rational, and thoughtful, and she is largely on the fringes of Zaphod and Arthur's actions.
How has the radio show/novel been influential in the decades following their airing/publication?
Many of the lines and plot elements of the work entrenched themselves in popular culture. Many people know exactly what "42," Deep Thought, the importance of towels, the Babelfish, and more are. References to his work show up in pop culture icons such as "The Big Bang Theory," "Doctor Who," and "X-Files." The fusing of science fiction, fantasy, and humor are present in works such as Star Wars and Neil Gaiman and Terry Pratchett's Good Omens. And, of course, the Guide itself pretty much comes to life in the iPad and Wikipedia.