How do you make things invisible?

Scientists have long been working on technologies to hide objects from view. Recently researchers at the University of Rochester have succeeded, using inexpensive and readily available materials. Physics professor John Howell and graduate student Joseph Choi used four standard lenses to make an object seem invisible against a background, even if the viewer moves by several degrees. “This cloak bends light and sends it through the center of the device, so the on-axis region behind it cannot be blocked,” explains Choi.