This paper re-examines the fundamental physical connotation of the speed of light under the framework of Time Field Theory (TFT). Contrary to classical physics that regards light as a material entity moving at constant c, this paper ontologically proves that light is a geodesic satisfying the first-order vanishing variation condition of Fermat’s principle: ds / =0. The zero intrinsic time of photons vₓ=0 is not a negative physical feature of light, but a precondition that legitimizes the calculus of variations for physical research. This paper constructs a closed logical chain: metric self-consistency flux conservation () =0 Fermat’s principle ds / =0 vanishing first variation zero intrinsic time of photons locally unique constant speed of light differential relation ds=c dt calculus as a valid language for physical description. If any link in this chain breaks (variable light speed or non-zero intrinsic time for photons), the underlying logic supporting calculus and variational calculus as physical tools will fully collapse. The speed of light is not an inherent property of moving substances; it is the mathematical signature of metric self-consistency in path space. Metric Self-Consistency → ∇· (γ∇γ) =0 → δ∫ (ds/γ) =0 → Vanishing First Variation → Zero Intrinsic Time of Photons (vₜ=0) → uniquely defined local γ → Constant Speed of Light ds = cγ dt well-defined → Calculus Valid for Physical Analysis
Huowang Huang (Fri,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: