Have you ever sat on the bottom of a swimming pool and pondered your watery ceiling? Most of the surface is a sheet of light blue, and you can't see through it, even though the water is clear. But ...

We are surrounded by waves. tiny vibrational waves transport sound to our ears. Light waves stimulate the retinas of our eyes. Electromagnetic waves bring radio, television and endless streaming ...

Researchers have constructed a 'meta-mirror' device capable of perfectly reflecting sound waves in any direction. The proof-of-principle demonstration is analogous to looking directly into a mirror ...