Tidal, Spin, and Obliquity Dynamics in Exoplanetary Systems: Dissipation, Spin–Orbit Resonance, and Long-Term Rotational Evolution

Second report in a series begun with Orbital Stability in Exoplanetary Systems (Da Silva 2026, doi:10.5281/zenodo.21132194). This graduate-level, self-contained review develops the finite-body physics excluded from Paper I: the tide-raising potential and Love-number response; the constant-Q and constant-time-lag dissipation models and their mutual inconsistencies; the Hut (1981) evolution equations, pseudo-synchronization, circularization timescales, and the a^(13/2) orbital-decay law; spin–orbit resonance theory and Mercury's 3:2 state; obliquity dynamics, Cassini states and their saddle-node bifurcation, and obliquity chaos; dynamical tides and resonance locking; and the coupling of tidal dissipation to multi-planet dynamics (resonant repulsion, resonantly maintained heating). Theory is anchored to observations — the measured orbital decay of WASP-12 b, satellite-astrometry calibrations of giant-planet dissipation, the Rossiter–McLaughlin obliquity demographics — with case studies of Mercury, Venus, the Earth–Moon system, Io–Jupiter, WASP-12 b, and TRAPPIST-1. Includes four illustrative computations by the author (with complete Python source in Appendix C and in the accompanying archive), a catalog of open problems, and one explicitly flagged falsifiable exploratory hypothesis on the demographics of measured orbital-decay rates. No new observational data are presented; all illustrative figures are labeled as such.