Granted, I haven't seen the film, but my understanding (as per wikipedia) is that the Earth's core is melted by neutrinos generated by a massive solar flare.
Neutrinos. Really.
A neutrino has a 50/50 chance of penetrating a light-year of lead. It's practically a ghost particle. Of all the things in the universe, there isn't anything more harmless.
This as bad as the time someone on a Star Trek episode announced that the ship had been cleansed of baryonic matter. 10 brownie points to the first person to point out why that would be bad.
Removing baryonic material would mean all matter and dark matter are removed. Fundamentally a bad thing to lose all your protons, among assorted other atomic elements ;-)
In the movie, unprecedented solar activity accompanied by huge solar flares bombard the earth with multiple orders of magnitude more neutrinos than ever before. In the movie they are referred to as “mutated neutrinos” (snicker) because they are behaving like no neutrino has ever before. [ this is the Deus est Machina/ ‘magic occurs here’ of the movie ]. These “mutated neutrinos” act like microwaves to heat and liquify the earth’s core to the point where tectonic plates shift and portions of the earth crust liquefy — with predictable disaster porn results.
As you wrote, “normal” neutrinos are deomnstrably harmless, but these Mayan calendar neutrinos have mutated ... zombie neutrinos ;-)
Aside from that, the movie is ‘true’ enough to be enjoyable as science fiction drama.
announced that the ship had been cleansed of baryonic matter. 10 brownie points to the first person to point out why that would be bad.
Duh. That would be, uhh, us. And everything else we can see, hear and touch.
There wouldn't have been a ship left, or a crew, since all the protons and neutrons (atomic nuclei) would have been “cleansed.” Electrons would be left. Also, since the antimatter they use for fuel is antibaryonic matter, it would still be there. If any of the antimatter collided with electrons - boom!
“Cleansing” the ship of non-baryonic matter would have been just as bad. If all electrons disappeared, all the molecules in the ship and crew would break apart. (With no electrons, what would remain are positively charged atomic nuclei, which would repel each other.) At least there’d be no boom, since the antimatter would also have been “cleansed.”