Of all the things in the physical world we think we know a lot about, water is definitely among them. Nonetheless, by precisely shaking a shallow container of water, researchers have now observed two new types of waves that have never been observed before in water--and one that has never been observed in any other media either.
To conjure the waves, the researchers used what is known as a Hele-Shaw cell mounted on a small shake table. A Hele-Shaw cells is a container consisting of two parallel transparent plates separated by a small gap, much like an ant farm (see images above and .gifs below). In this case, the gap between them was 1.5 millimeters, or less than 6 hundredths of an inch.As they ratcheted up the oscillation amplitude of the shaker, a high-speed camera recorded the surface deformation of the water inside the Hele-Shaw, revealing two new kinds of strange waves (both known as Faraday waves). One has an even symmetry, the other an asymmetric appearance, with a larger upper half and a smaller lower half.