Re-FractalsAllison PenleyAward: Top 100
School: glenbard west high school Most objects are isotopic, meaning that their index of refraction (a value that determines how much light bends when entering a material) is equal in all directions. This means that light rays passing through them behave the same regardless of their direction or their "polarization"-- when light waves' oscillations occur in a plane, or the same direction. Some transparent materials, however, are birefringent, having the optical property which causes them to refract (bend) light at two different indices. For these materials, their indices depend in part on the polarization of their light. This property can be found in some crystals, like calcite, but also in other materials like cellophane, or even certain plastics when put under stress. Because cellophane is made up of long chains of aligned glucose molecules, light waves travel through the cellophane at a different speed when its polarization is parallel to the chains versus when it's perpendicular. The resulting birefringence can be seen when cellophane is placed between two polarizers (materials that only let through light that vibrates in the same direction)-- in my case, the polarizing light source of my computer screen and polarized sunglasses. As the polarized light rays from my computer screen pass through the cellophane, they're doubly refracted, meaning they travel in two different directions. These rays then pass through the second polarizer, my glasses, interfering with each other, either adding (constructive interference) or canceling each other (destructive interference), larger amplitudes of light causing the bright shocks of color observed. 
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