Photon Structure

In quantum field theory, the photon is a massless spin-1 particle—an excitation of the electromagnetic field that carries energy, momentum, and mediates interactions.

In modal dynamics, there is no electromagnetic field. The photon is not a particle and not an excitation. It is a coherence-preserving mode—a self-sustaining bundle of phase that propagates without anchoring.

Latent Modes

A photon is a latent mode:

• It does not anchor into the surrounding coherence field
• It moves by preserving its own internal phase alignment
• It follows coherence gradients to avoid structural distortion

The defining property of a photon is that its anchoring cost is zero (or vanishingly small). This makes it the natural carrier of information and the limiting case for modal propagation speed.

Structure of the Photon

The photon’s coherence function ${\psi }_{\gamma }(x)$ is:

• Narrow in phase gradient (minimising distortion)
• Finely tuned to internal stability
• Propagating at the maximum coherence-preserving velocity, which emerges from the modal cost functional and defines the effective “speed of light” $c$.

Unlike other modes, the photon’s profile evolves primarily through coherence drift, not anchoring reconfiguration. It is the cleanest possible modal shape that can sustain itself while remaining unanchored.

Its velocity $c$ is not a postulate—it is the natural result of minimising decoherence cost under phase-preserving propagation:

Where $\alpha$ and $\beta$ are the modal stiffness constants in the coherence action.

Why Photons Curve

Even without anchoring, photons still respond to coherence gradients.

If the surrounding field $B(x)$ varies spatially, the photon’s internal phase will be distorted unless it adjusts its path. This deflection is not a force—it is bias avoidance. The photon curves to stay coherent.

This is the modal explanation of gravitational lensing—photon motion as a structural response to coherence field gradients, not spacetime curvature.

Polarisation and Phase

Photon polarisation corresponds to rotational degrees of freedom in its internal phase surface. It is not a vector field property—it is a structural symmetry of the mode.

• Linear, circular, and elliptical polarisations all emerge from how $\varphi (x)$ wraps across the coherence profile
• The photon’s phase alignment governs its ability to interfere, reflect, or be absorbed

(See Appendix O — Photon Structure and Appendix J — Casimir Pressure.)

The photon is not a messenger.
It is what coherence looks like when it moves without anchoring.