This movie gets a downcheck from most reviewers, I gather — but, I think, for the wrong reasons.

Oh, don’t get me wrong. This is not, repeat definitely not, academy award material. On the other hand, the acting is as good as one can expect in a disaster movie of this type, the pacing is not bad, and the special effects are — if not up to the level expected from the advance hype — fairly decent even by current standards.

Strange things are happening. In Boston, thirty-some people with pacemakers all drop dead at once. In London, a flock of pigeons at Trafalgar Square go crazy, in a scene right out of Hitchcock’s “The Birds”. A space shuttle lands in the bed of the Los Angeles River (shades of Blue Thunder!) instead of at Edwards because there’s been a glitch in the nation’s navigation satellite system. And people at low altitudes are treated to a magnificent (and ongoing) display of the aurora borealis.

Josh Keyes (Aaron Eckhart), a geophysicist from the University of Chicago, figures out that something is going wrong with the earth’s magnetic field because the outer core of the earth has stopped rotating, with the result that in a year the field will fail and everybody on earth will be roasted alive by cosmic radiation from distant galaxies and by the radioactive solar wind and solar microwaves. He brings this to the attention of the Sagan-esque Dr. Conrad Zimsky, a charismatic figure with many contacts in government; Zimsky pooh-poohs the idea, but in fact realizes that it must be true and what must have caused the core to stop. Ultimately, the government decides to start the core rotating again by sending an untried borer to the center of the earth and triggering off a bunch of multi-hundred-megaton nuclear devices. I suppose I give nothing away here if I state that the plan ultimately works, though with the loss of life of everyone in the expedition except the romantic leads (Eckhart and Hilary Swank, who plays an Air Force major training to be a NASA shuttle pilot). There is also a subplot involving a phenomenally competent hacker named “Rat” (D. J. Qualls).

The science in the film is, as usual, … unscientific. The disappearance of the earth’s magnetic field would, indeed, cause severe long-term problems, and perhaps species extinctions, but the sun’s output of microwave energy is not such that, within moments, every car on the Golden Gate bridge would have its tires melted down, its passengers cooked, and the bridge itself disintegrating. Nice special effects, though — even better than the near collapse of the bridge in Superman the movie 25 years ago.

Worse, to me, is the idea that nobody would notice the core stoppage except through its effects on the geomagnetic field. Even assuming that the core was so decoupled from the mantle and the crust that those would not in turn come to a stop (and presumably somebody would notice that the sun had stopped rising and setting), the amount of rotational kinetic energy converted into heat would be such that, likely, the atmosphere, the seas, and probably the crust itself would be boiled off into space — an effect that someone would certainly notice. It’s a freshman physics problem, to calculate the amount of heat that would be released. Luckily, the average movie-goer is likely not to think about such scientific esoterica.

Again, the special effects — to complete which the film was, according to rumor, delayed for the better part of a year — were generally good, with a few glitches (the explosion of the Colosseum in Rome was poorly done, in my opinion), but nothing out of the ordinary.

Ultimately, a pleasant way to pass an afternoon, if disaster flicks are your cup of tea.