Pepper's ghost

Pepper's ghost is an illusion technique, used in theatre, cinema, amusement parks, museums, television, and concerts, in which an image of an object offstage is projected so that it appears to be in front of the audience.

The technique is named after the English scientist John Henry Pepper, who popularised the effect during an 1862 Christmas Eve theatrical production of the Charles Dickens novella The Haunted Man and the Ghost's Bargain, which caused a sensation among those in attendance at the Regent Street theatre in London. An instant success, the production was moved to a larger theatre and continued to be performed throughout the whole of 1863, with the Prince of Wales (future King Edward VII) bringing his new bride (later Queen Alexandra) to see the illusion, and it launched an international vogue for ghost-themed plays that used this novel stage effect during the 1860s and subsequent decades.

The illusion is widely used for entertainment and publicity purposes. These include the Girl-to-Gorilla trick found in old carnival sideshows and the appearance of "ghosts" at the Haunted Mansion and the "Blue Fairy" in Pinocchio's Daring Journey, both at Disneyland in California. Teleprompters are a modern implementation of Pepper's ghost. The technique was used to display a life-size illusion of Kate Moss at the 2006 runway show for the Alexander McQueen collection The Widows of Culloden.

In the 2010s, the technique was used to make virtual artists appear onstage in apparent "live" concerts, with examples including Tupac Shakur and Michael Jackson. It is often wrongly described as "holographic". Such setups can involve custom projection media server software and specialized stretched films. The installation may be a site-specific one-off, or a use of a commercial system such as the Cheoptics360 or Musion Eyeliner.

Products have been designed using a clear plastic pyramid and a smartphone screen to generate the illusion of a 3D object.

Effect

The core illusion involves a stage specially arranged into two rooms or areas, one into which audience members can see, and a second (sometimes referred to as the "blue room") that is hidden to the side. A sheet of plate glass, acrylic glass or plastic film is placed somewhere in the main room at an angle that reflects the view of the blue room towards the audience. Generally, this is arranged with the blue room to one side of the stage and the plate on the stage rotated around its vertical axis at 45 degrees. Care must be taken to make the glass as invisible as possible, normally hiding the lower edge in patterning on the floor and ensuring lights do not reflect off it. The plate catches a reflection from a brightly lit actor in an area hidden from the audience. Not noticing the glass screen, the audience mistakenly perceive this reflection as a ghostly figure located among the actors on the main stage. The lighting of the actor in the hidden area can be gradually brightened or dimmed to make the ghost image fade in and out of visibility.

When the lights are bright in the main room and dark in the blue room, the reflected image cannot be seen. When the lighting in the blue room is increased, often with the main room lights dimming to make the effect more pronounced, the reflection becomes visible and the objects within the blue/hidden room seem to appear, from thin air, in the space visible to the audience. A common variation uses two blue/hidden rooms, one behind the glass in the main room, and one to the side, the contents of which can be switched between "visible" and "invisible" states by manipulating the lighting therein.

The hidden room may be an identical mirror-image of the main room, so that its reflected image exactly matches the layout of the main room; this approach is useful in making objects seem to appear or disappear. This illusion can also be used to make an object, or person—reflected in, say, a mirror—appear to morph into another (or vice versa). This is the principle behind the Girl-to-Gorilla trick found in old carnival sideshows. Another variation: the hidden room may itself be painted black, with only light-coloured objects in it. In this case, when light is cast on the room, only the light objects strongly reflect that light, and therefore appear as ghostly, translucent images on the (invisible) pane of glass in the room visible to the audience. This can be used to make objects appear to float in space.

The type of theatre use of the illusion which John Henry Pepper pioneered and repeatedly staged in the 1860s were short plays featuring a ghostly apparition which interacts with other actors. An early favourite showed an actor attempting to use a sword against an ethereal ghost, as in the illustration. To choreograph other actors' dealings with the ghost, Pepper used concealed markings on the stage floor for where they should place their feet, since they could not see the ghost image's apparent location. Pepper's 1890 book includes such detailed explanation of his stagecraft secrets, disclosed in his 1863 joint application with co-inventor Henry Dircks to patent this ghost illusion technique.

The hidden area is typically below the visible stage but in other Pepper's ghost set-ups it can be above or, quite commonly, adjacent to the area visible to the viewers. The scale can be very much smaller, for instance small peepshows, even hand-held toys. The illustration shows Pepper's initial arrangement for making a ghost image visible anywhere throughout a theatre.

Many effects can be produced via Pepper's ghost. Since glass screens are less reflective than mirrors, they do not reflect matte black objects in the area hidden from the audience. Thus Pepper's ghost showmen sometimes used an invisible black-clad actor in the hidden area to manipulate brightly lit, light-coloured objects, which can thus appear to float in air. Pepper's very first public ghost show used a seated skeleton in a white shroud which was being manipulated by an unseen actor in black velvet robes. Hidden actors, whose heads were powdered white for reflection but whose clothes were matte black, could appear as disembodied heads when strongly lit and reflected by the angled glass screen.

Pepper's ghost can be adapted to make performers apparently materialise from nowhere or disappear into empty space. Pepper would sometimes greet an audience by suddenly materialising in the middle of the stage. The illusion can also apparently transform one object or person into another. For instance, Pepper sometimes suspended on stage a basket of oranges which then "transformed" into jars of marmalade.

Another 19th century Pepper's ghost entertainment featured a figure flying around a theatre backcloth painted as the sky. The hidden actor, lying under bright lights on a rotating, matte black table, wore a costume with metallic spangles to maximise reflection on the hidden glass screen. This foreshadows some 20th century cinema special effects.

History

Precursors

Giambattista della Porta was a 16th-century Neapolitan scientist and scholar who is credited with a number of scientific innovations. His 1589 work Magia Naturalis (Natural Magic) includes a description of an illusion, titled "How we may see in a Chamber things that are not" that is the first known description of the Pepper's ghost effect.

Porta's description, from the 1658 English language translation (page 370), is as follows.

Let there be a chamber wherein no other light comes, unless by the door or window where the spectator looks in. Let the whole window or part of it be of glass, as we used to do to keep out the cold. But let one part be polished, that there may be a Looking-glass on bothe sides, whence the spectator must look in. For the rest do nothing. Let pictures be set over against this window, marble statues and suchlike. For what is without will seem to be within, and what is behind the spectator's back, he will think to be in the middle of the house, as far from the glass inward, as they stand from it outwardly, and clearly and certainly, that he will think he sees nothing but truth. But lest the skill should be known, let the part be made so where the ornament is, that the spectator may not see it, as above his head, that a pavement may come between above his head. And if an ingenious man do this, it is impossible that he should suppose that he is deceived.

From the mid-19th century, the illusion, today known as Pepper's ghost, became widely developed for money-making stage entertainments, amid bitter argument, patent disputes, and legal action concerning the technique's authorship. A popular genre of entertainment was stage demonstrations of scientific novelties. Simulations of ghostly phenomena through innovative optical technology fitted these well. Phantasmagoria shows, which simulated supernatural effects, were also familiar public entertainments. Previously, these had made much use of complex magic lantern techniques, like the multiple projectors, mobile projectors, and projection on mirrors and smoke, which had been perfected by Étienne-Gaspard Robert/Robertson in Paris early in the century. The new illusion, soon to be labelled Pepper's ghost, offered a completely different and more convincing way to produce ghost effects, using reflections not projection.