A new experiment has demonstrated something that sounds physically impossible – light itself casting a shadow. It turns out that if you manipulate a laser just right, then hit it side-on with another light source,

The technique works because the green laser (wavelength 532 nanometers) changes the way the crystal responds to some other wavelengths of light, including the 450 nm of the blue laser. Consequently, the crystal now serves to block the blue laser’s path, creating a shadow on a nearby screen.

With the help of a ruby cube and two laser beams, researchers made one ray of light cast a shadow when illuminated by the other