Entertainment

SIGH-FI

UNLESS you’ve seen Robert Wise’s original semi-documentary “The Day the Earth Stood Still” (1951), you’d never suspect the utterly generic remake was based on a seminal sci-fi classic.

This version stars a somnolent Keanu Reeves (is that redundant?) as an alien visitor and Jennifer Connelly – essentially reprising her role from “The Hulk” – as a hot scientist who helps Reeves make mankind realize the dangers of global warming.

Why would extraterrestrials care about global warming, anyway? In the original, the more credible threat was nuclear proliferation, and the arrival of the alien and his giant robot, Gort, was a clear metaphor for McCarthy-era paranoia.

Moving the action to the present after a pointless prologue set in 1927, the undistinguished script attributed to David Scarpa (“The Last Castle”) removes the context from a story rooted in a very specific era, as well leaving out almost every memorable scene from the original.

Yes, even “Gort! Klaatu barada nikto!” Were the filmmakers afraid of comparison, or worried that if the affectless Reeves were killed and brought back to life, audiences couldn’t tell the difference?

The only improvement in this edition, directed without noticeable enthusiasm by Scott Derrickson (“The Exorcism of Emily Rose”), is the new CGI Gort. He’s a lot more imposing than the original, played in a robot suit by a doorman at Grauman’s Chinese Theatre.

The flying saucer in the original has been replaced by a CGI globe that lands not in Washington but an unrecognizable version of Central Park.

Much of the movie – a patchwork of scenes from, among many other movies, “Independence Day” and “The Day After Tomorrow” – takes place in a geographically challenged New Jersey where Princeton seems to be right next to Newark.

A good part of the first 45 minutes takes place in one of the state’s fictional military installations, the first of many tiresome clichés.

When Reeves’ alien, Klaatu, escapes with Dr. Helen (Connelly) and her annoying stepson (Jaden Smith), the first stop is McDonald’s for a risible rendezvous with another extraterrestrial.

Another is the home of a learned scientist who has won a Nobel Prize for “biological altruism.” He is played by John Cleese, who used to routinely make fun of stuff like this during his Monty Python days.

Meanwhile, Secretary of Defense Kathy Bates – complete with a Sarah Palin ‘do – is barking out military assaults on Klaatu and Gort, when she isn’t asking Dr. Helen, “Do you really think you can persuade him?”

One of the big problems here is that, despite much exposition, the nature of Klaatu’s mission on Earth isn’t at all clear.

And his powers seem to change from scene to scene: If he can paralyze military cops to escape, then why is it necessary to elude a state trooper by crushing him to death with a car, then bringing him back to life?

By that point, “The Day the Earth Stood Still” is in serious need of resuscitation.

The title more or less forces the filmmakers to re-create the earlier movie’s riveting climax, but it’s as half-heartedly rendered as their CGI version of Manhattan.

lou.lumenick@nypost.com