Can light itself cast a shadow? It may sound like a philosophical riddle, but researchers have found that under certain conditions, a laser beam can act like an opaque object and cast a shadow. The discovery challenges the traditional understanding of shadows and opens new possibilities for technologies that could use a laser beam to control another laser beam.

After discussing the quirks in 3D modeling software, where a laser beam is treated as a solid object that can cast a shadow, scientists decided to experiment in real life — and found that laser beams can indeed cast a shadow under the right conditions.

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.

Shadows are a natural consequence of opaque walls in an illuminated Universe. Light shines; photons travel until they hit an object through which they cannot pass; this blockage creates a shadow, a little piece of darkness where the light has been impeded.

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