How close to invisible can a mirror be?

Credit: US Environmental Protection Agency (Phys.org)—In 2011, mathematicians Alexander Plakhov and Vera Roshchina proved that objects with mirror surfaces cannot be perfectly invisible. Now in a new study, Plakhov has returned to the problem, asking just how close to invisible a mirror-surfaced object can be. Using concepts from billiards and optics, he has shown that…