During an early screening of Roland Emmerich's latest disaster flick 2012, which opens today, laughter erupted in the audience near the end of the film thanks to corny dialogue and maudlin scenes (among the biggest guffaw getters: a father tries to reconnect with his estranged son on the telephone, only to have the son's house destroyed just before he could say anything). Nobody wants to take anything seriously in a movie like this, in which digital mayhem is the draw. But if it were an audience of physicists, the laughter probably would have started in the first five minutes. You can't take any of the science seriously, although I give the filmmakers credit for creativity.
If you haven't heard, December 21, 2012, is supposed to be the day that the Mayan calendar ends (it doesn't really) and therefore somehow marks the end of civilization as we know it—notwithstanding the fact that the Mayan civilization ended centuries ago. (NASA has a good Q&A site that debunks the 2012 apocalypse nonsense.)
Thankfully, the movie 2012 doesn't dwell on ancient predictions. Instead, it takes us straight to the, er, science.
The premise: the sun's 11-year activity cycle reaches a peak in 2012. (A recent analysis led by the National Oceanic Atmospheric Administration actually pegs the peak to occur in May 2013, and it will be less intense than previous peaks.) For some reason, the neutrinos from the sun start behaving differently: they begin interacting frequently with matter, rather than largely passing through it harmlessly. The filmmakers could have easily invented entirely new particles for the job—call them bambinos, say—but perhaps that's too silly.
In the movie, the "neutrinos" heat up Earth's inner core, making it boil. That in turn destabilizes the overlying layers (outer core and mantle), making the crust buckle, rise and shift by thousands of kilometers.
As a result, skyscrapers topple, bridges crumble and runways fracture (always in the direction of take-off). People scream, puppies live, heroes escape, villains try to but die, and supporting cast members face their demise. (My favorite here: Danny Glover, famous for portraying a long-suffering cop in the Lethal Weapon movies, plays the U.S. president who decides to go down with the White House—and seemed to be on the verge of saying, "But I was only two days from retirement.")
If neutrinos behaved the way they are described in the film, then there wouldn't be much to film. Particles that can heat up the solid iron inner core by thousands of degrees should have cooked Earth's surface dry before Woody Harrelson gets the chance to steal all the scenes he's in. The inner core is under about 350 gigapascals of pressure (three million atmospheres), which is why it's solid. Just how hot the inner core must get to liquefy under that pressure is not known for sure, although Anneli Aitta of the University of Cambridge gives it a try in this paper (pdf).
Which is not to say there are no hazards from an overactive sun. Intense solar activity can disrupt satellite orbits and communications; in 1989, it triggered a widespread blackout around Quebec.
On the other hand, neutrinos might not be so harmless. Physicist Juan Collar, now at the University of Chicago, theorized in 1996 that the death of certain kinds of stars could produce so many high-energy neutrinos that they would interact with atoms in organic tissue and lead to mass deaths from cancer. The frequency of such stellar deaths, though exceedingly rare, is consistent with mass extinctions in Earth's history, he argued.
Alas, destroying civilization with slow deaths from tumor formation probably doesn't translate well to the big screen. All the puppies would die, too.
Scences from 2012 courtesy of Columbia Tristar Marketing Group