@niconiconi @puniko lemme tell you about a little thing called molecular dynamics

So imagine you wanted to simulate how a protein or something moves over time. Nuclei and electrons interact with each other with a bunch of quantum fuckery, but the problem with calculating that quantum fuckery is that it's computationally expensive (gotta calculate eigenvalues for stupidly big matrices) and that's not feasible for big proteins.

On the other hand... you could just pretend every atom is a massed ball, and every bond is a spring, and have them apply forces to each other very, very cheaply. The worst part about all this is that it's surprisingly accurate, too.