For the experiment, a high-power green laser was directed through ruby cube and illuminated with a blue laser from the side. The green laser increases the optical absorption of the blue illuminating laser beam, creating a matching region in the illuminating light and creating a darker area that appears as a shadow of the green laser beam. Credit: R. A. Abrahao, H. P. N. Morin, J. T. R. Pagé, A. Safari, R. W. Boyd, J. S. Lundeen Can light itself cast a shadow? It may sound like a philosophical ri...