“The world is blue at its edges and in its depths,” writes Rebecca Solnit in A Field Guide to Getting Lost (Penguin Books, 2005). “This blue is the light that got lost.” That comment is, on the one hand, a pithy statement about the physics of color: The ocean and sky are blue because they preferentially scatter blue light. On the other hand, it is a metaphor, and an apt one for us. While studying the physics of color, especially blue, we’ve found that it’s easy to get lost. And that is not a bad thing.
Consider the blue jay, a common sight in our home state, Massachusetts. Is it blue like the ocean or blue like the sky? In the ocean, red light is absorbed, leaving blue to be scattered back to us. In the sky, blue light is scattered more than red by the atmosphere, a process known...