What the Classical Problem States
- Given three masses interacting pairwise
- Predict their future positions exactly
- Using force-based equations of motion
For two bodies, analytic solutions exist. For three, they generically do not.
Why the Two-Body Case Closes
In a two-body system:
- The center of mass frame is fixed
- Transport loops close
- Phase residue averages out
This closure is what allows Keplerian orbits and integrability.
What Changes with Three Bodies
- The effective center frame moves
- Transport loops become nested
- Loop order matters
Transport around one body is carried by transport around the others.
Path A — Transport Geometry (Nested Non-Closure)
Primitive: Motion preserved under evolving frames
Each body defines a local transport frame.
In a three-body system, no frame is inertial for all bodies simultaneously.
Transport loops fail to close at every scale.
This produces:
- energy exchange between modes
- secular drift
- sensitive dependence on initial phase
Path B — Phase Accounting (Mode Coupling)
Primitive: Phase conservation under transport
Each orbital motion has a phase $\theta_i$.
In two bodies, phases decouple.
In three bodies, phases are coupled:
No global phase coordinate exists.
This prevents closed-form integration.
Agreement Condition
Both views predict chaos, resonances, and escape.
Why Numerical Solutions Work
- Numerics track transport incrementally
- No assumption of closure is made
- Local frames are updated continuously
Connection to Earlier Principles
- Kepler’s Second Law → non-uniform transport
- mc = ma → constrained motion leaks into unbound motion
- Orbits do not close when the center moves
Transport-First Summary
- The three-body problem is a transport problem
- Forces obscure the moving frame
- Chaos is phase bookkeeping failure
- No closed form exists because no closure exists