Pepper’s Ghost – a fun optical illusion

Miss Chu has enjoyed taking part in the annual Singapore Science Busking festival over the past two years, managing to bag a couple of prizes by performing street-entertainer style routines with bubbles and spinning tops to engage the general public’s interest in science. But this month has just been too busy to go for the auditions. Now she’s midway through P4, it’s no exaggeration to say her school workload has moved up a gear. However, despite not having the time to participate, we’ve put together a fun little science-themed video on an intriguing optical illusion which she considered presenting had she entered the competition.

Commonly known as Pepper’s Ghost, the idea for this technique was conceived in the nineteenth century by Henry Dircks, but developed and popularized by John Pepper. In recent years, with improved technology and materials, the setup has been refined in theatres to “resurrect” deceased stars back to the stage in “hologram” form – well known examples being Tupac’s appearance at the 2012 Coachella and a collaboration between Cirque de Soleil and Michael Jackson in Vegas. Japan has its own “hologram popstar” – Hatsune Miku – an anime character whose hologram concerts can draw thousands of fans. The term “hologram” here is actually a misnomer as the visuals are actually just cleverly aligned projections which give the audience the illusion of the artiste on stage. 

Nevertheless, it’s an illusion which can be easily replicated at home on a smaller scale using a DIY plastic pyramid and a mobile phone or tablet to project the image. We tried it, and the kids were amazed! Miss Chu demonstrates and explains how it all works in this month’s video.