Aside

Vampire Selfie: A Curious Case of an Absent Reflection

Top view of a person standing in an elevator while facing the door. (a) Rays originating from a point (O) on an object, reflected from a plane surface, form a virtual image at the apparent point of origin (I) of the reflected rays. (b) Rays originating from a point on an object, reflected from many irregularly oriented small facets, cannot be traced back to an apparent common point of origin, so no image forms. (c) If many points (O1, O2, O3, etc.) along the object are approximately the same color and shape, then the randomly reflected rays from these various points can appear to have a common origin (I) and form an image.

Top view of a person standing in an elevator while facing the door. (a) Rays originating from a point (O) on an object, reflected from a plane surface, form a virtual image at the apparent point of origin (I) of the reflected rays. (b) Rays originating from a point on an object, reflected from many irregularly oriented small facets, cannot be traced back to an apparent common point of origin, so no image forms. (c) If many points (O1, O2, O3, etc.) along the object are approximately the same color and shape, then the randomly reflected rays from these various points can appear to have a common origin (I) and form an image.

Joshua M. Grossman
During a recent ride in an elevator, I was startled by an observation. Once the door closed, the features on the back wall of the elevator were evident in a reflection on the door; however, my own reflection appeared absent . How could that be? What physics caused this curious phenomenon? The elevator had wooden molding, including horizontal strips that ran all the way around the back and sides . These horizontal strips were what showed up most clearly in the reflection. The door’s surface was brushed metal with the brush marks all running vertically. Therein lay the solution…
…Read more at scitation.aip.org

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