HYPERBOLIC GLASS For a fixed color of monochromatic light (e.g. as produced by a laser) and a given material, the Summary: HYPERBOLIC GLASS For a fixed color of monochromatic light (e.g. as produced by a laser) and a given material, the light will move through the material at a particular speed, satisfying the relation v = c/n, where n is the index of refraction of the material, and c is the speed of light in a vacuum. To make a chunk of hyperbolic glass sitting on a table, make the index of refraction of the glass so that the speed of light changes in proportion to the height of the table, i.e. the index of refraction changes inversely proportional to the height above the table. Thus, light moves much more slowly near the table. This could be done by doping the glass at different heights with some other material, so that the index of refraction changes, as is done in certain types of fiber optics cables. When a laser is shined on the glass, the rays of light will be bent, and will follow paths which are circles or lines which are perpendicular to the table, as in figure 1. These paths are called geodesics. This is because light follows the shortest path. Since it moves more quickly higher above the table, to connect get from one point to another at the same height it is quicker to move upwards first where it can move more quickly, then come back down. PSfrag replacements H3 n = 0 n = 1 n = 2 rays Collections: Mathematics