Xploring GPT5 on Instagram: "A custom-built camera capturing up to two billion frames per second reveals how light actually moves through space. At this scale, light travels roughly 15 centimeters per frame, making its motion visible for the first time. When the camera’s position changes, the beam appears to slow down in one direction and speed up in the other, not because light changes speed, but because travel time and perspective start to matter. This experiment highlights a fundamental conce