Article Summary and/or Excerpt:
A rocket launch. Our nearest stellar neighbor. A Netflix show. All of these things have something in common: They must contend with the “three-body problem.” But exactly what is this thorny physics conundrum?
The three-body problem describes a system containing three bodies that exert gravitational forces on one another. While it may sound simple, it’s a notoriously tricky problem and “the first real worry of Newton,” Billy Quarles, a planetary dynamicist at Valdosta State University in Georgia, told Live Science.
In a system of only two bodies, like a planet and a star, calculating how they’ll move around each other is fairly straightforward: Most of the time, those two objects will orbit roughly in a circle around their center of mass, and they’ll come back to where they started each time. But add a third body, like another star, and things get a lot more complicated. The third body attracts the two orbiting each other, pulling them out of their predictable paths.
The motion of the three bodies depends on their starting state — their positions, velocities and masses. If even one of those variables changes, the resulting motion could be completely different.