These supercomputers are awesome. Beyond all the numbers, they can do things like accurately model otherwise impossible scenarios, like weather, atomic bombs and physics, fluid computations, astrophysics, etc. One of the better examples I saw was a simulation of a galaxy being formed... they programmed in some unholy number of dust and gas particles, and each of these has gravity with respect to each other. They are all set in motion, so now each particle has a vector as well. Then, the computer does the math, and each particle moves according to physical laws relative to all the others. Gas and dust coalesce into stars, stars coalesce into galaxies, and the shape and motion of the galaxy is noted.
They used this model to predict the quantity of dark matter out there. By changing that, the model eventually produced beautiful spirals just like our Milky way. Without the correct dark matter, the model simply fell apart and no galaxy was formed.
