Shukla Photonic Field Theory (SPFT 3) : SIPE as dark matter

The SIPE vacuum stiffness is K_SIPE = ρ_vac × c² ≈ 5.4 × 10⁷ Pa, with a corresponding effective mass density ρ_mass ≈ 6.7 × 10⁻²⁷ kg/m³, providing a first quantitative measure of vacuum elasticity in physics. Observations of galaxy rotation curves, gravitational lensing, and large-scale structure require a non-luminous gravitating component (dark matter), while cosmic acceleration is attributed to dark energy. We previously proposed that photons possess a Sub-Intrinsic Photon Energy (SIPE) — a finite internal energy persisting as frequency ν → 0 — and showed that a homogeneous SIPE background reproduces the observed dark-energy density (ρ_SIPE ≈ 6 × 10⁻¹⁰ J/m³). Under continued accelerated expansion, photon frequencies redshift exponentially from present-day values (~10⁻¹⁸ Hz) to ν ≲ 10⁻³⁰¹⁵ Hz, driving radiative energies below ~10⁻³⁰³⁰ eV and implying a non-radiative intrinsic energy floor consistent with SIPE. Here, we show that clustered SIPE, through its vacuum stiffness, provides a quantitative phenomenological mechanism capable of reproducing dark-matter-like gravitational effects and galaxy stability. Modeling the rotation curve of NGC 3198 with an Einasto-type SIPE halo yields an excellent fit (χ²_red ≈ 0.78), demonstrating that SIPE can simultaneously address dark energy and dark-matter-like gravity within a unified framework. The finite vacuum stiffness predicts environment-dependent halo structures, resolving core–cusp diversity in dwarf galaxies and matching cluster-scale observations such as the Bullet Cluster lensing offsets.