Paper 1: Hypothesis of the Ground State Particle Sea —— The Nature of Fluctuation and the Principle of Unobservability of the Ground State

Traditional physics provides separate explanations for the wave and particle properties of light, failing to unify them from the underlying material structure. Starting from the discrete particle nature of water waves, this paper demonstrates the necessity of discrete waves, and combines the objective fact that light waves lack an observable medium with rest mass to logically deduce the hypothesis of a universal "Ground State Particle Sea" —— a hypothetical quantum field composed of fundamental particles in their lowest energy state —— existing throughout the universe. This hypothesis states that the essence of light waves is the in-situ perturbation transmission of ground state particles after excitation, and photons are only a phenomenon of energy transfer rather than independent physical particles. This naturally explains the wave-particle unity of light (wave as the intrinsic state, particle property as the interaction manifestation), and proposes that the speed of light may depend on the local energy density of the Ground State Particle Sea. This paper also establishes a unified fundamental medium basis for subsequent series of studies.