The Science of Star Wars: The Scientific Facts Behind the Force, Space Travel, and More!

by Mark Brake

Many companies claim to create 3D images but really they are just 2D images reflected off a mirror or transparent solid surface. These “holograms” make use of an effect known as Pepper’s ghost. Pepper’s ghost is a reflection-based holographic effect developed in the mid 1800s by scientists John Pepper and Henry Dircks. It was more recently used to make rapper Tupac Shakur appear on stage at Coachella Valley Music & Arts Festival in 2012—sixteen years after Tupac’s death. Other “holographic” techniques involve the use of a curved mirror to give the illusion that an image is suspended in mid-air in front of us. Sometimes referred to as a “reflecting hologram,” this virtual image is due to the way the light rays from an original image reflect off of a concave mirror. This creates a three-dimensional real image, if the object being viewed is actually 3D. OPTI-GONE International has been using this technique since 1977 to create their popular Mirage toys. In 1991, a concave mirror was also used in an arcade game called Time Traveler, advertised by Sega as a hologram. A similar method has also been used in Realview’s interactive live holography, which they describe as “probably the most advanced 3D interactive visualization system.” They say that “it accurately reconstructs points of light in mid-air.”