PBT: Light

$A beam of light bending gently through a glowing medium of fine particles, refracting rather than traveling through empty space.$

Light in PBT bends via refraction through density gradients in the medium, rather than spacetime curvature — deliberately built to match GR’s weak-field prediction ($\theta \approx 4GM/(c^2b) \approx 1.75’’$ for the Sun) rather than diverge from it. More fundamentally, PBT holds that this particle medium is the substance light (and radio waves) actually propagate through — not empty space carrying a wave with no medium at all — see Pressure for the fuller point of understanding.

Covered in: Paper 2 (light bending derivation), Paper 12 (summary equation), Pressure (the medium light travels through). See also What Would Actually Distinguish PBT From General Relativity, which notes this specific prediction is a consistency check with GR, not a point of difference.