Olivia Thirlby embraces her inner freegan

American Repertory Theater’s latest show is the world premiere of playwright Eve Ensler’s (“The Vagina Monologues”) new play, “O.P.C,” which explores ideas of how best to affect change in the world. The mother/daughter duo of Smith and Romi are ostensibly both liberal people interested in protecting the environment, but they go about it in different ways. Smith is running for the Senate, while Romi has no interest in the system, and embraces freeganism and dumpster diving. The play seems likely to create debate, particularly in liberal Cambridge. Even the actors have had their issues with it, with Oscar-winner Melissa Leo leaving the play only a few weeks ago. But Olivia Thirlby (“Juno”), who plays Romi, seems pretty passionate about it.

How would you describe Romi?

Romi defies description. (laughs) She is an anomaly of existence. She’s incredibly awakened, mentally, emotionally and spiritually. She is wild, sparkling. She is an informer, an enlightener, a seducer, a mad, passionate, twinkling star.

What would you say is the central conflict between Romi and her mother?

The central conflict between Smith and Romi is the central conflict of the play, which is we know that we need to change the world that we live in and the structure that we’re all encased in. The question is, do we do it by changing the structure from within, or do we do it by changing from outside of it, as in from not participating in it, which is quite radical, and very difficult to do.

Did you end up feeling sympathy with for both sides?

I sympathized much more with Romi’s side, which is, the system is broken, it can’t be fixed, it’s inherently flawed, and it needs to change.

What’s it been like working with Eve Ensler?

Working with Eve has been a dream come true. It’s such an exciting dream I’m not sure I ever dreamed it before. She’s incredible. She’s my personal hero. She’s everything. She’s the real life Romi. She’s the most courageous, inspiring person that I’ve ever met.

Since this is a premiere, has the play changed much as you were working on it?

The play changes every single day. It’s part of the process when you’re mounting a new play. If the writer is present, which they often are, then they’re also hearing their play for the first time and wanting to make changes to it. We have lots of cuts and additions and tweaks every single day. Sometimes, whole new scenes. (Laughs)

Did you try any freeganism?

I have. I’ve done a good deal of research and had some experience doing freegan dives and trash turns.

Did you get anything good?

Yeah, I got tons of good stuff. Tons of citrus and cucumbers, flowers, and basil, ginger, couple Caesar salads.

And did you end up becoming an advocate for freeganism?

Yes, absolutely. It was inspiring to me to see just how easy it is to get beautiful fresh food for free.

If you go

“O.P.C.”

Nov. 28-Jan. 4

Loeb Drama Center

64 Brattle St., Cambridge

$25-$75, 617-547-8300