Physics
Celestial Mechanics and the Three-Body Problem
Quick fact
Despite centuries of effort, astronomers have found no general closed-form solution to the three-body problem—the motion of three point masses under mutual gravity is generally chaotic, amplifying tiny differences in initial conditions into vastly different outcomes.
Why this is interesting
From the dance of Jupiter's moons to the orbits of spacecraft, celestial mechanics predicts motion in the heavens. But add a third body, and the once-reliable math becomes a puzzle that has stumped scholars for centuries.