The Wave Function as an Energy-Quantum Density Amplitude
Qiang Huang
The mathematical and physical foundations of the Born rule remain open questions, largely because the wave function lacks a mathematical identity and a physical origin. Here we uncover a mathematical structure of the wave function by treating the phase as a circular variable. This structure reveals that the wave function is the pullback of the phase probability-density amplitude to position space via the phase field. Because the phase probability distribution forms an equal-area contour in the complex plane, its probability-area element yields the modulus squared as the position probability density, revealing the Born rule as a geometric relation rooted in the circular topology of the phase variable. The same structure governs the phase-energy distribution of electromagnetic waves. By quantizing phase energy into energy quanta, in the single-quantum limit the energy-quantum density reduces to the probability density, and its amplitude becomes the probability-density amplitude. This therefore identifies the energy-quantum density amplitude in the single-quantum limit as the physical origin of the wave function. To verify this, we derive the time-evolution equation for the energy-quantum density amplitude from five physical principles. This yields the Gross-Pitaevskii equation for many-body systems and, in the single-quantum limit, the Schrödinger equation. The framework also recovers Maxwell's equations in the classical limit. Overall, this study introduces the energy-quantum density amplitude from the classical phase-energy distribution, and derives the three core postulates of quantum mechanics: the wave function, the Born rule, and the Schrödinger equation, thereby identifying the position probability density as the energy-quantum density in the single-quantum limit.
•Sep 5, 2026•0 citations