What would the world look like if you could see cell phone radiation? Artist Nickolay Lamm has tried to answer that question. In July, Lamm released a series of illustrations imagining a Washington, D.C., where Wi-Fi was visible, bathing famous sites in a rainbow of colors. On Wednesday, he finished a sequel of sorts — a series of pictures of U.S. cities and landmarks, this time with cell phone radiation visible as a hazy, multicolored, strangely geometric overlay. …