Aug. 9 (Bloomberg) -- As the cast of ``Hair'' finished the musical's last song, ``Let the Sun Shine In,'' at the outdoor Delacorte Theater in Central Park last night, the rain came.

The downpour in New York did nothing to dampen the spirits of the young, ebullient ensemble on the show's opening night. During their curtain call, they sang an encore of ``Hair'' and invited a raucous audience to join them on stage.

Warren Spector, former co-president of Bear Stearns and chairman of the board of the Public Theater, which produced ``Hair,'' danced while drenched amid a crush of people.

``It's so enjoyable. It's so high energy,'' Spector said in an interview during intermission. ``We can't fill demand. We had a four-week run and we extended to six weeks.''

The crowd that turned out for the 1967 musical that protested the Vietnam War by celebrating hippies, free love, drugs and nudity included actresses Kathleen Turner and Marisa Tomei, actor Philip Seymour Hoffman, the writer Nora Ephron, the Public's artistic director, Oskar Eustis, and its new executive director, Andrew Hamingson.

Harvey Fierstein, 56, who recently starred on Broadway in the musical ``A Catered Affair,'' said in an interview during intermission that he feels young people today aren't as politically active as those from the 1960s.

Fight for Change

``Maybe my generation is doing it for them,'' he said. ``As we get older, we're supposed to turn right and become more conservative, but my generation hasn't. Maybe we need to turn right so they can turn left.''

The young cast members wouldn't be described an unconcerned.

``It's so obvious that this is material we can relate to today,'' Will Swenson, 34, who plays hippie leader Berger, said about ``Hair'' in an interview at the cast party after the show.

``It's easy for my generation to become passive, but it's important for us to form opinions and fight for change,'' 23- year-old Jonathan Groff, who plays drafted hippie Claude, said in an interview at the party.

If Groff had one disappointment about his venture into the '60s, it's that his character doesn't take off his clothes with the rest of the cast at the end of Act One.

``If there's a place to get naked on stage, it's in ``Hair.'' So I'm a little sad but my mother is happy,'' said Groff, a Tony nominee for 2006's ``Spring Awakening,'' in which he bared his backside.

To contact the writer responsible for this story: Mary Romano at mromano6@bloomberg.net.

Last Updated: August 8, 2008 12:57 EDT