“There is no branch of detective science that is so important and so much neglected as the art of tracing footsteps,” says the fictional detective Sherlock Holmes. Now, UK researchers have developed a ...

Waves close wavesVibrations that transfer energy from place to place without the transference of matter. - including sound and light - can be reflected at the boundary between two different materials.

Refraction close refractionProcess by which a wave changes speed and sometimes direction upon entering a denser or less dense medium, eg a light ray changes direction when refracted by a lens. from a ...