Impossibly Huge Collisions

The universe is majestic in its complexity, size, and simplicity. At galactic scales, things tend to act in fairly straightforward Newtonian movements. None of that exotic quantum mechanics, matter acting as waves and/or particles.
Simplicity, albeit on a grand scale, with billions upon billions of what can be modeled as point masses.

The really interesting thing about galactic collisions is that stellar collisions are vanishingly rare. Hundreds of billions of stars flying around each other, yet none of them meet.