Game logic

How the fuck do they code games so that everything moves smoothly and at a consistent rate regardless of the speed of the machine you run it on, and still have tons of shit interacting with each other somehow?
Maybe I need to find a good open-source candidate to have a look at.

Also, I wish I knew the correct terms to describe what I'm talking about.

>>9
if delta time ends up getting too high intersection testing will fail
Most good physics engines should calculate intersections at increasing granularity, preferring vector intersection equations over if x1+vx1 >= x2 as collisions become more likely (e.g. after bounding-box tests, pythagorean distance tests and simple directional vector tests have all returned true).
Even with high deltas, logic should say that if one object ended up on the other side of another after an update, it's pretty likely that they should have collided.