Researchers discover that light can cast a shadow. It may sound like a riddle, but a uottawa and brookhavenlab team proved that a laser beam can act like an opaque object to cast a shadow under certain conditions. To create the shadow, the team directed a high-power green laser through a cube made of standard ruby crystal and illuminated it with a blue laser from the side. When the green laser enters the ruby, it changes the material response locally to the blue wavelength. The effect is visible to the naked eye, with the laser's shadow following the object beam without an observable delay. Read more in our newsroom! #lightscience #photonics #scienceandtechnology #lasers #laserscience #OPG_Optica