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Holography: The Curious Case Of Pepper's Ghost

Holo Ghost

Holo Ghost

A Holo Existence

When you think of holographic technology, sci fi movies come to mind; Star Wars, Star Trek even more recent films like Iron Man and Superman. In the Star Wars series one of the iconic scenes was of family favourite R2 D2 projecting a little 3D holographic image of princess Leia sending a distress signal that would play on a loop to the on looking Han Solo and Luke Skywalker, a holographic gif if you will.

Star Trek introduced audiences to the ever fantasised about 'holodeck' where a whole room was able to project full 3D holographic interactive environments. Throughout the series it was used for training simulations to full-on role play scenarios based in any historical era they wanted. In fact holograms have been showcased in lots of entertainment. But were these images really holographic, well obviously in a word, no!

Princess Leia Hologram Star Wars

Princess Leia Hologram Star Wars

Holograms have been used for decades, okay the types of holographics you see on credit cards, passports and security identifiers may not be as impressive as having a dynamic conversation with a 3D holographic representation of your long dead father like Superman. But these low budget holograms are very good security aids because they are cheap to produce and can be frustratingly difficult to copy without the master hologram.

The Origin Of Pepper's Ghost

Holographic technology harks back to the late 19th century do a bit more research and you will find the earliest roots of holograms in the late 1500's. His name was Giambattista Della Porta a Neapolitan scientist and scholar he was known for a number of inventions one of them being the Camera Obscura. (a precursor to later development) And in his 1584 work Magia Naturalis (Natural Magic) he describes an illusion titled "How we may see in a Chamber things that are not" this is the first known description of the pepper's ghost effect.

Della Porta & Camera Obscura

Della Porta & Camera Obscura

Henry Dircks

Henry Dircks

In 1862 inventor Henry Dircks developed the Dircksen phantasmagoria, it was an innovative technique used to make a ghost appear on-stage. Although this was a great invention Dircks tried to sell it on to theatres but they declined because the set-up proved too expensive for the theatres. Despite the knock backs Dircks set up a booth in The Royal Polytechnic Institute London,(now the University of Westminster Regent Street) a science-related institution where professor John Henry Pepper saw Dircks invention; was very impressed and saw scope to modify it for existing theatres.

They first tried the new modified technique in a scene of Charles Dickens's 'The Haunted Man' to great acclaim thus the term 'Pepper's Ghost' was coined even though Pepper constantly tried to credit Dircks for his invention the term stuck.

I can hear you thinking weren't you talking about holograms what have ghosts got to do with it. Well, yes and no, yes because the pepper's ghost effect paved the way to later advances in holographic technology and no because the pepper's ghost effect is just an optical illusion and NOT a hologram.

The pepper's ghost effect works by arranging a stage into two rooms; one viewable by the audience, and one that is hidden on the side known as a blue room, a plate of glass (plexiglas) is placed in the main room at an angle of 45 degrees that reflects the view of the blue room towards the audience. Care was taken to make the glass virtually invisible to the on-looking theatre goers.

Return To Pepper's Ghost

When lights are on in the main room and dark in the blue room, the reflected image cannot be seen. As lighting in the blue room is increased and lighting in the main room decreased this enhances the effect, and the reflection becomes visible giving the effect of an ethereal three dimensional object floating around in mid-air.

Pepper's Ghost was not a hologram but the technique is used throughout the world today for various entertainment one of the most recent events where this technique was used was at the 2012 coachella festival. Where rap legend Tupac Shakur was resurrected to perform with the very alive also legendary Snoop Dogg & Dr Dre.

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Tupac Pepper's Ghost

The Men Behind Real Holography

Actual holography dates back to 1947 scientist Dennis Gabor developed the theory of holography; while working to improve the resolution of an electron microscope. He coined the term Hologram from the greek holos (whole) and gramma (message).

By the 1960 russian scientists N Basov Prokhorov & American Scientist Charles Towns created the laser, ideal for hologram technology which overcame some of the problems that Gabor encountered.

Later that year Dr TH.Maiman developed the pulse-ruby laser which emits powerful bursts of light lasting only a few billionths of a second. This freezes movement and allows high speed event holograms to be produced.

In 1962 Emmett Leith and Juris Upatnieks realised from working on side reading radar that holography could be used as a 3D visual medium they duplicated gabors technique using the laser and an off-axis technique. This resulted in the first laser transmission hologram of 3D objects a toy train and bird.

In the same year Dr Yuri N. Denisyuk combined holography with Gabriel Lippmanns work in natural colour photography, resulting in a white light reflection hologram the first time a hologram could be seen from a lightbulb.

By 1968 Dr Stephen A. Benton invented white-light transmission holography this type of hologram could be seen in ordinary white light creating a rainbow image from seven colours which make up the white light.

In 1972 Lloyd Cross created the integral hologram by combining white-light transmission holography with conventional cinematography to produce moving 3D images.

Holograms A New Dawn

Recent Developments

In recent years hologram technology has made significant strides in getting closer to making what we see in the sci fi movies a reality.

We've seen this in Ironman and minority report the ability to be able to literally touch and manipulate 3D holographic images. And earlier this year a team of Japanese scientists showcased a machine called haptoclone that allows you to touch holograms by emitting ultrasonic radiation pressure. This is the first step in realising haptic (touch) holography, however it has its problems as it is limited to users lightly stroking the holograms because high level ultrasound can cause permanent nerve and tissue damage in humans.

Holographic data storage, a couple of years ago American and russian researchers have developed a new holographic memory that could dramatically increase data storage capabilities in electronics. Holographic storage also offers greater data transfer rates. This system uses spin waves ideal for electronic uses which could allow a laptop to store a terabyte of data in the space the size of an oxo cube.

Holographic Telepresence is a developing technology allowing full-motion 3D video conferences. These systems can project realistic 3D images of people with real-time audio communication. This is a acheived by the images being captured compressed, transmitted over a broadband network, decompressed and finally projected using laser beams, Much like how holographic technology works. Last year cisco systems showcased this technology by beaming Prof stephen hawking was to Australia's world famous Sydney Opera House where he gave a talk about his life however I'll point out that this is not holography just an advanced version of Pepper's ghost techniques.

Is The Universe A Hologram

We've all grown up in this world, a reality that is three dimensional where we use our 5 senses to navigate and interact with. But what if the life we live is a simulation, a hologram. I know it sounds crazy and matrix like but theoretical physicists have been trying to figure out for the last 20 years if indeed the universe is a hologram.

'The Holographic Principle' suggests that the universe has a 2D surface that we can't see and this surface contains all the information needed to project 3D objects. Equations have been used to show the holographic Principle could be true. This crazy theory was presented by physicist Juan Maldacena in 1997, the easiest way to explain this is by looking at the 2D holograms we have on credit cards which is two dimensional but appears to the human eye as 3D.

The latest study conducted at the Technology University of Vienna now suggests that the holographic principle holds in a flat space-time. It seems we are getting closer to finding out the answers to what the universe is and how it works. But once we have concrete evidence (which I guess would be redundant because we would realise the we are all holograms) would have profound existential implications as to what and where we are.

How would you deal with the revelation that you are indeed a hologram?

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