Pepper's Ghost

museumvictoria.com.au

Pepper's Ghost is an illusionary technique, which directly connects to how light and reflection behave. By utilizing special lighting teqniques and plate glass, it makes viewers see objects that are not physically there. In that sense, this method has been frequently used for theater, haunted house, magic tricks and special effects in movies.

The first known description of the effect is found in a 16th century Naepolitan scientist and scholar, Giambattista della Porta's work Magia Nuturalis (Natural Magic) from 1584. 

Later in the 19th century, the tequnique was developed by inventor Henry Dircks as the Dircksian Phantasmagoria, in which a ghost appears on-stage during theater performances. Consequently, the effect was named after John Henry Pepper, who modified Dircks's concept and demonstrated it during a scene of Charle's Dickens's The Haunted Man in 1860, which led him to a great success.

Currently, Pepper's ghost effects can be found in various museum exhibitions, amusement attractions and onstage live performances. 3D holographic projection technology is also based on this illusionary technique. 

Reference: Pre Cinema History 1980 , How 2pac Hologram Pepper's Ghost Worked, The Enduring Illusion of Pepper's Ghost