The first experiment involves measuring the time it takes for light to travel a known distance in air, utilizing a parabolic mirror and an oscilloscope for precision.

Parabolic reflectors are pretty handy devices. Whether you’re building a microwave antenna or a long-distance directional microphone, suitable commercial dishes aren’t that hard to come by.

A light rigid structure (of aluminum or other material) which reflects sound to a focus at which a MICROPHONE is placed. This focussing effect is very strong with WAVELENGTHs less than the aperture of ...