The Dark Side of Ghost Imaging

Displays of candy corn and costumes may soon be replacing sunscreen and beach towels, but this post isn't meant to detract from what's left of the summer. Ghost imaging is a technique for imaging something that you can't see directly. It does seem a bit spooky--imagine getting detailed images of the ground from a satellite-based optical system even when clouds or smoke obscure the line-of-sight. However, ghost imaging isn't a supernatural feat. It's just another strange and mind-bending applicat...