Movies do not exist in a vacuum. There are things which influence them and things which they influence. Nowhere, perhaps, is the front half of that more clear than when a movie is made based upon a book, as with “Divergent” coming from Veronica Roth’s novel of the same name.

The book is the first in a trilogy, and when Gregory Ellwood sat down with two of the movie’s stars, Ashley Judd and Tony Goldwyn, the first thing he asked was whether or not they had read it. Goldwyn’s answer was straightforward, “It’s part of your homework, really, isn’t it?” while Judd offered up the more playful, “I’d feel pretty lame standing around on set, ‘No, I didn’t read that, no, been busy.’”

The upshot is that both actors were able to bring some of the background from the book that isn’t in the movie to their characters. This was only enhanced when they sat down with Roth to talk about the series, including the third novel, which hadn’t been published at that time.

As for the other end of things, the movie then influencing something else, Goldwyn takes some time in the interview to talk about how being cast in the film led to a growth in followers on Twitter, “Literally the day I was cast in this movie, I got flooded with tweets,” and that the new followers have remained with him to this point. Judd points out during the talk that fans and world of “Divergent” is something of a “social movement,” which certainly fits with Goldwyn’s added followers.

“Divergent,” which also stars Shailene Woodley, Theo James, Miles Teller, and many others, opens today. It will be interesting now that the film is out to see what Goldwyn’s new followers and other members of the movement have to say.