Researchers have created the world's thinnest transparent screen using soap bubbles. The scientists used ultrasonic waves to alter the properties of the membrane screen. The flexible screen was created by a bidirectional reflectance distribution function, a four-dimensional function defining how light is reflected at an opaque surface. The transparency and reflective qualities were controlled by hitting the bubble's membrane with ultrasonic sound waves through speakers. When several bubble screens are put together, viewers get a 3D effect and even a holographic projection.