In the new thriller Unstoppable, opening today, Denzel Washington desperately tries to stop a runaway train laden with combustible liquids and poisonous gas — which is hard because it is, paradoxically, unstoppable! Have you ever tried to stop something unstoppable? It’s impossible, of course yet it’s so damn tempting to be the one who proves the adjective wrong, isn’t it? Therefore, it’s no wonder that so many moviemakers are drawn to unstoppable objects or forces (buses, meteors, cyborgs) hurtling toward disaster, with only a superman or everyman trying to get the damn thing to put on the brakes, or at the very least slow up a bit. Here, Vulture provides a list of film’s most unstoppable forces, and their various degrees of unstoppability. Don’t stop now — read on!