Buoyancy turned inside out: a clear shallow mountain stream running over pale pebbles, seen from a low side angle at water level. First 2 seconds: a hand-sized grey river stone is dropped from above and, instead of sinking, bobs up and floats on the surface like a cork, drifting slowly downstream. Next 2 seconds: a single yellow ginkgo leaf lands on the water and sinks straight to the bottom like a coin, settling flat on the pebbles. Final second: the floating stone turns gently in the current. The water, the light and everything else behave normally. Bright autumn daylight, static locked-off camera. No text
