Light is essential to vision, at least the kind we perform with our naked eyes. This is why we can see through a glass lens but not through a brick wall (though we're working on that). But what about materials that let some light pass while scattering it in seemingly chaotic ways?
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.