Dustin Hoffman (search) has been mulling over life, the universe and everything a lot lately - and not just because his latest film, the absurdist comedy "I Love Huckabees (search)," has him playing an "existential detective."

"I've never found it more relevant to think about what is real and what is absurd than I do today," the 67-year-old acting legend told The Post, after delivering a quick history lesson on the post-WWII birth of existentialism.

"It's such an absurd reality we live in.

"At one time it seemed like the streets had sidewalks, and children bounced balls and the beach was the beach and the sky was the sky - it was inconceivable when we were kids that the planet would have a limited life span.

"Now we think, 'S—-, we keep up the way we're going, the whole thing could collapse.' "

But let's not forget, "Huckabees" is a comedy, and that Hoffman appears in the film sporting Beatle-esque bangs that make him resemble, in the words of co-star Lily Tomlin (search), "a little dust mop."

Surprisingly, indie whiz David O. Russell's wacky farce marks the first time the veteran actors have starred together - and it's a match made in comedy heaven.

Hoffman and Tomlin play amorous husband-and-wife gumshoes, joining an eccentric all-star cast that includes Jude Law, Naomi Watts, Mark Wahlberg, Isabelle Huppert and Jason Schwartzman.

The married metaphysicians are called upon to help an environmentalist, who is locked in a heated battle with a preening Huckabees department-store exec, unlock the secrets of the universe after a series of coincidences involving a Sudanese doorman.

Much existential wackiness ensues, encompassing Zen philosophy, Jean-Paul Sartre, red rubber balls and Shania Twain.

Russell - who says Hoffman's 1967 classic "The Graduate" changed his life - describes the investigators as mixing elements of the priest, rabbi, analyst, philosopher and neurologist.

"They think their calling is somehow higher," says Tomlin. "It's about the whole cosmic universe, not just some psychological problem someone has.

"I think they see themselves as philosophers and interpreters of the entire universe in some way."

"Modest, huh?" Hoffman interjects with a laugh, before admitting he didn't fully understand Russell's mind-boggling "Huckabees" script at first and had to have the director come over and explain bits of it.

"I felt I didn't understand all of it, but I didn't think of it as strange," he says. "I thought of it as original."

The fact that the big-picture questions are sugar-coated in comedy helps make "Huckabees" accessible, too.

"It's like in boxing - the jab opens everything up, opens up the ability for the knockout punch," Hoffman says. "Maybe the comedy opens up the audience to receive it."

As for that hair, Hoffman says it's all the fault of Robert Thurman, the Indo-Tibetan philosopher, father of actress Uma, and Russell's mentor and friend.

"I think Thurman is probably the inspiration of the movie," Hoffman says. "[Russell] told me I'm basically playing Thurman, so he says grow your hair long. That's [really] my hair."