Electron Orbitals as 4-D Rotor Projections: A Geometric Basis for Hydrogenic Structure and Chemical Bonding
Stephen Euin Cobb
Abstract
The hydrogen atom exhibits an exact SO(4) symmetry that has long been recognized but seldom explained. Conventional quantum mechanics reproduces the spectrum through algebraic methods, yet leaves unanswered why spin-½, orbital degeneracies, and the Pauli exclusion principle exist. In this work, we show that these features arise naturally if the electron is modeled as a four-dimensional rotor constrained to the three-sphere, S 3 . The two independent spin modes of the rotor generate the SU(2) + × SU(2) - structure, whose balanced irreducible representations project into three-dimensional orbitals with the familiar quantum numbers n, l, and m. The radial equation reduces to the associated Laguerre form, yielding exact hydrogenic wavefunctions and energies. Orbital filling, exclusion, and hybridization emerge as geometric necessities rather than axioms. The model also predicts small but definite deviations from ideal quantum mechanics, including corrections from finite rotor inertia, spin–spin couplings, and symmetry-breaking effects. These deviations are accessible to precision spectroscopy and condensed matter experiments, providing falsifiable tests. By grounding quantum mechanics in four-dimensional geometry, the rotor framework preserves all known successes while offering new explanatory clarity and predictive power.