Amid the scientific questions raised by considering a duplicate, parallel Earth with mirror images of ourselves, the film exudes raw emotions of joy, rage, sorrow, regret and love.

What is it that makes us human?

What if we had made different choices here and there?

Rhoda Williams, played by screenplay co-writer Brit Marling, is a smart young woman growing up in Connecticut who has been accepted into the Massachusetts Institute of Technology's astrophysics program.

But she doesn't make it there.

The night the duplicate Earth is discovered, Williams makes what she calls her "unforgivable mistake" -- she drives drunk, collides with another vehicle and kills a pregnant woman and a young child.

The pregnant woman's husband, John Burroughs, is a talented music composer and college professor.

He survives the crash, but spirals downward into an alcohol- and pill-induced haze.

When Williams is released from prison four years later, she goes to Burroughs' home to apologize, but she loses her nerve and pretends she's there to clean his house as a trial offer for a cleaning company.

Williams keeps returning to put the shattered widower's house in order and nurse him, as well as herself, back to health.

She does not reveal her true identity and each week the two become closer and eventually fall in love.

It's then that Williams is notified she has won a contest to travel to the duplicate Earth.

Williams and people around the world had already watched and listened as a scientist established communication with her duplicate, also a scientist, on Earth II.

In her contest essay, Williams had reflected on the very first explorers, who were sometimes criminals and others seeking a new beginning.

"As a felon, I'm an unlikely candidate for most things ... (but for this) ... perhaps I'm the most likely," she wrote.

When Williams excitedly tells Burroughs that she is going to Earth II, he pleads with her to stay.

"We're so close to something here," he says.

It's then Williams tells Burroughs that she needs to share a story with him and, after hearing it, if he wants her to stay with him, she will.

Williams reveals that she was the drunk driver who killed his family and tells him that she kept cleaning for him because "in the smallest ways" she thought it made his life a little bit better.

The final scenes of "Another Earth" provide more questions that answers, including, "What would we like to see if we could stand outside ourselves and look at ourselves?"