Physics - and arguably all of science changed forever in 1687 when Isaac Newton published his Principia. Within it were equations of motion and gravity that transformed our erratic-seeming cosmos into a perfectly tuned machine of clockwork predictability.

Given the current positions and velocities of the bodies of the solar system, Newton’s equations could be used in principle be used to calculate their locations at any distant time, future or past. I say “in principle” because the reality isn’t so simple. Despite the beauty of Newton’s equations, they lead to a simple solution for planetary motion in only one case - when two and only two bodies orbit each other sans any other gravitational influence in the universe. Add just one more body and in most cases all motion becomes fundamentally chaotic - there exists no simple solution. This is the three-body problem, and we’ve been trying to solve it for over 300 years.