Deepglow May 2026

Approximately 380,000 years after the Big Bang, the universe cooled to roughly 3,000 K. Before this epoch, the universe was a "fog" of free electrons and protons (a plasma) that constantly scattered photons via Thomson scattering. As recombination occurred (electrons binding to protons to form neutral hydrogen), the mean free path of photons increased dramatically.

Deepglow: From Cosmic Photon Decoupling to Engineered Optical Uniformity deepglow

This moment—the —produced the CMB. In a poetic but accurate sense, the "Deepglow" is the visual echo of this phase transition. It is not a momentary flash but a last burst of thermal radiation that has since redshifted to microwave frequencies (today at 2.725 K). Observations by the Planck satellite reveal that this Deepglow is extraordinarily isotropic, with temperature fluctuations of only 1 part in 100,000, representing the oldest light in the universe. Approximately 380,000 years after the Big Bang, the

| Feature | Cosmological Deepglow (CMB) | Engineered Deepglow (Diffuser) | | :--- | :--- | :--- | | | Hydrogen-helium plasma | Glass, polymer, or fused silica | | Scattering mechanism | Thomson scattering (free electrons) | Mie scattering / diffraction from micro-structures | | Output spectrum | Blackbody (now microwave) | Homogenized laser linewidth (narrow) | | Isotropy | Natural, near-perfect | Engineered, angularly tailored | | Key parameter | Redshift (z ~ 1100) | Diffusion angle (e.g., 10° to 60° FWHM) | Observations by the Planck satellite reveal that this