For the first time, I'm watching the movie 2012. A friend asked me to and to tell him what I thought. So I thought, I'll tell everyone instead, and then send him the link.
Very quickly, for those who don't know, the gist of 2012 is that neutrinos from the sun heat the core of the Earth which results in extreme tectonic activity. Then the planets line up and electromagnetic fields go crazy and everything explodes. It looks great, but is the science even close to reality? No.
Neutrinos, at least many, do come from the sun. They are weakly interacting, neutrally charged particles. They don't do much, if anything, for us to be concerned about- though they are very interesting to particle physicists for reasons I won't pretend to fully understand. As far as heating up the Earth's core, that's about as laughable as saying that doing push-ups will knock Earth out of its orbit, though at least the push-ups hypothesis is somewhat realistic.
Neutrinos simply don't have the energy necessary to do so, and even if they did, since only about 1 in a 100 million actually collide with some atom in the planet, never mind in the core, it would take a truly astronomical amount to actually heat the planet. Let's explain the terms before we go on, though.
First, lets start with what "weakly interacting" means. There are 4 forces, gravity, electromagnetism, and the strong and weak forces. Gravity affects objects with mass, electromagnetism affects those with a charge, and the strong forces interact with particles such as protons and neutrons. The Weak Force only interacts with leptons, which includes neutrinos (and a handful of others), but it's extremely weak- it's quite a bit stronger than gravity, but with such tiny range it has been described as contact only.
Contact isn't as common as you might think, though- when we touch solid objects, we are really interacting with the electromagnetic force. Solid to us is actually almost entirely empty space. We "feel" solidity because both we and the objects we're touching are electrically charged- either positive or negative. Because neutrinos are neutrally charged, they can't interact with the electromagnetic force, so they pass right through.
Here goes- tedious (but fascinating, if you're into that sort of thing!) math ahead.
If they do interact, they've got a minuscule amount of energy anyway- between 2.2 eV and 15 or so MeV (Electron Volts and Mega Electron Volts, at 1 million each). An eV is an incredibly small amount of energy- 1 eV is equal to about 3.83 × 10^-20 calories. Even 15 MeV is only enough to make 0.0000000000006 calories. So, if the most energetic neutrinos were to hit the core, it would take 1.7 Trillion of them to raise the temperature 1 degree per cubic cm. However, since only 1 in 100000 actually interact with anything (contact only), we would need 17000 Trillion per cubic cm for 1 degree. To put that number in perspective, if it were in dollars, we could pay a half billion dollars to every US citizen (Man, woman and child) and still have money left over- 20000 Trillion dollars (which is still enough to pay for the country to run for the next 5000 years or more!). And that is just to raise 1 milliliter of the Earth 1 degree Celsius.
We must also realize that the Earth is cooling at the rate of 4.42 * 10^13 W, or about 10 Trillion Calories. Per Second. Which means, that, for the neutrinos just to equal our rate of heat loss, we would need 17 Trillion Trillion. Right- enough to pay every person on earth 200 times our entire national budget and run our country for 3 and a half billion millennia!
So, just to break even we need about 10^24 neutrinos coming at us.
Let's look at planetary alignment, supposed to worsen the neutrinos (already dispatched as an even likely form of trouble). The trouble with planetary alignment is gravity- all the planets line up, somehow magnifying their gravitational pull. While in the room with you (well outside your territorial bubble, at about 1 meter) I have about 0.2 % the gravitational pull of the moon on you. Not much, granted, but the moon is very massive. Jupiter, though, only has 5 times as much pull as me (about 1 percent of the moon)! And besides Venus (at 3 times my pull), none of the other planets can match my gravitational effect on you. And my pull is eclipsed by your car or your office! The point here is that gravity is a very weak force- and that distance matters ALOT. So, Earth and the moon are much closer to the sun than any of the other planets (except for Venus and Mercury), and their pull is negligible in comparison. Regardless of that fact, there's no reason for a planetary alignment to do anything more than cause a high tide on earth (it probably wouldn't, but at best that's all it'd do) and do absolutely nothing to the Sun- much less cause a solar flare, because solar flares are electromagnetic emissions- not gravitic ones!
The only thing in the movie even remotely possible was the solar ejections/flares becoming worse. This is problematic. Potentially, electrical grids could collapse as a massive electromagnetic field induces a current in every wire on Earth. We'd live through the initial hit, but without electricity (and without the possibility to restore it for years) we'd be devastated. That's scary- because it could actually happen. But we could recover. However, that would require an enormous solar flare (which has happened before) and a weakened magnetosphere on Earth's part. Possible, but not too likely.
There was one realistic point: Yellowstone is the site of the worlds largest inactive volcano. A very serious problem, and one we can do nothing about. A meteor coming for us, we can shoot down (or more likely, move out of the way). A gamma ray burst, we'll never see and will fry everything on the planet before we can scream. Besides, I'm handy with a handgun and a baseball bat if my kids or I get hungry (ain't nobody taking my food first), if we get to fight back to survive.
Yellowstone. The volcano- that will be an inevitable experience, worsened by being dragged out. We'll know it's coming and can't stop it. If we get a chance to escape, we'll die in the coming winter, or feast on the misfortune of our fellow men. It will be a terrifying and tormented death, which scares the piss out of me. But what can I do? It would obliterate everything from the Dakotas to the Mississippi river and beyond, crush the Rockies to dust and throw them into the Pacific, taking a chunk out of much of Canada and Mexico as well. The ashes would cover the planet, blocking the sun (and mitigating global warming!) and devastating all life. Cows (hell, cockroaches) would be lucky if they made it, and they'd be luckier than us. There's no way of preparing for such destruction on a global level- we're going to die or dramatically reduce global population, and we're talking 1 in 1000 if they're lucky. It's over, if Yellowstone blows. There's no way to prepare. All terrestrial life could end.
2012 was, as far as the science is concerned, a joke at best, and exploiting the conspiratorial among us at worst, taking advantage of the ones who don't understand the science. It reminds me of the Core, a movie from a few years back which boasted some of the most awful science in all of Hollywood history, actually provoking nightmares in yours truly (which I was still able to logic my way out of). Whenever you watch a movie that makes you question the future of the planet, grab a science geek and ask them what they think. We're usually thinking about the death of human society, when we aren't worried about getting laid (or leveling our D&D characters). My favorite (by which I mean "think most likely") is without a doubt the Yellowstone volcano.
Anyway, if only I had a nickel for every neutrino...