- Education and Science
In Search of Invisibility, between magic and high tech
Is it possible to become invisible? Most people will say no and they are right because they never had the proof (Is God invisible?). But others, a minority, will say yes. Why? From medieval witches to magicians and scientists, and even governments, they all have searched for a way to invisibility, using either potions, either magic mirrors or cloak technology. And what did they find? I’m not so sure. But I know the search just got a bigger dose of hope.
In October 19 2006 the scientists at Duke University have announced that they made a device that could hide objects from our sight. The thing was called an “invisibility cloak” and was only five inch big and could only be used in two dimensions. When tested, they said it worked as panned. The news went unnoticed by the public but not by the scientists and fans of invisibility. As today, scientists are still working to perfect this cloaking device and who knows, maybe prove, one more time, that everything we can dream of is, in fact, possible.
To begin, I will try to explain, for me and for you, what is visibility and how it works, in my own words.
For our case, visibility has two meanings. First is our ability to see things. But that’s too easy. We see objects, people, birds, trees, surroundings and we see them because they exists. What we do not see, it does not exist. But what if they do exists? What if we just don’t see them? And here comes the second meaning of visibility which is the nature of things to be seen by human eyes. But if some things are missing this property then we don’t see them. But they still exist. So, they are invisible.
Our sight or vision is also called visibility. It works like this: the light enter the eye and hits a membrane called retina. This membrane is part of our brain and its role is to transmit information to the visual system, which is part of central nervous system. Then the visual system form images in color and shape and transmit them to the brain as sight. Through our experience and education we know what these images are and how to behave when we see them. But what if some of this light does not rich our eyes and consequently, does not transmit information to the brain. Then we do not see them. They are not visible to our eyes.
Objects reflect light. Light is that part of electromagnetic spectrum that human eye can see. Electromagnetic radiation (which is a form of energy) behave different in contact with different materials. The light is transmitted in waves and our eye only sees certain length of waves, not all of them. This band of waves is very narrow for humans. Some animals can see more of the electromagnetic spectrum.
So, in this light, so to speak, there are some waves we do not see. Some of them we may not even be aware of, but others, like infrared and ultraviolet waves, have been discovered and studied. We know they exist and if we use the right machines we could see things. Infrared are used to see in the dark or at distance. Ultraviolet waves and radiation have application in medicine.
Now, that we know some things about visibility we can assume the opposite is true about invisibility. To resume, invisibility is the quality of things to be unreachable by our sight, because:
1. they can not be seen with our eyes (it is an attribute of the object)
2. our eyes cannot see them (it is an attribute of our eye).
Is this the same thing? No. Some objects (or beings) could be hidden from our sight by optical illusions, tricks or high engineering, or simply they may not reflect light. On the other hand, we already know that we don’t have access to all the waves of the electromagnetic spectrum. So, in between these two attributes, lies invisibility.
Religions and myths, witches and magicians
If we look at major religions and religious systems of the world we will see that all of them have deities that cannot be seen by ordinary people. Some of these Gods were once alive, like Jesus. They died but then they revived and are now living but they are invisible for us. Only few fortunate people have said they saw God (and some of us still don’t believe them). Jesus, Buddha, God, Allah, they are all present but in a state of invisibility. At least this is what majority of people think. So, why a deity could be hidden from the sight and other things or beings cannot? Or maybe is like this: we believe that only gods could be invisible but other things can not?
Not everybody is sceptical about invisibility. Witches don’t. As a matter of fact they were (and maybe are) the most active group of searchers. They used wands, potions and spells, and later, on modern days, some sophisticated machines to make things invisible and/or disappear (Disappearing is different then being invisible. It means that something is not present, or not in existence.)
In the old literature, some well known authors speak about the proprieties of some plants to make one invisible. In this regard, at great respect were the fern seeds. Writers like Hans Christian Anderson, Grimm brothers and even Shakespeare were using fern or other materials to narrate scenes were people were, or were thinking to become, invisible. Other mythical materials were plants like hazel nuts, mistletoe, luck flower, heliotrope or stones like agate.
Later, magicians did the same thing as witches did but using different methods. Without having to hide their practice or having to endure a bad reputation as witches, magicians performed in front of an audience, sometime an elite one, and got applauded when they worked their magic. The little bunny pulled out of the hat is a perfect example of invisibility. Jim Steinmeyer remembers the first time he became invisible on a show performed in 1970 in front of people selling retail fixtures. How did he do it? Well, you have to read his book called Hiding the Elephant.
Magician have put a great amount of work into the tricks that make things and people disappear and reappear, or invisible. They worked with optical illusions and with the willingness of their audience to be “blinded” by their magic. By whatever power or science they use, magicians are the only ones that achieved some sort of invisibility. But not for long. High tech magicians, called scientists, are fast catching up.
The cloak of invisibility
According with The Free Dictionary, a cloak is something that covers or conceal and cloaking is the action of covering. The science fiction genre has been using cloaking since, at least, the last part of the 20th century. The most famous movie who used it is Star Trek and the most recent one is Harry Potter. But the cloak of invisibility is not only a fiction device, it is a reality.
The way the scientists want to achieve invisibility is by manipulating the light. Light is responsible for making something visible as well as making the same thing invisible.
At this time there are more then one method to hide objects from our sight. Aside from Duke in the US, other universities in Japan and England are researching the subject. They may come up with different or slightly different ways to make things invisible but they are all working with electromagnetic waves and radiations. Duke University used a cylinder made out of a so called “metamaterial” to make light bend around this object.
Others are using “dielectrics” or retroreflecting projection technology to make you see through things. And who knows what will bring tomorrow.
Another idea that is being experimented is not only to make things invisible but to make events invisible. This technology, experimented in England, would use a “spacetime cloak” to hide the sequence of time and is based on a stream of photons to separate light waves. This specetime cloak should work wonder for thieves. Here is how they describe invisible event “ it pulls apart the light ray in time, as if opening a theatre curtain - creating a temporary corridor through which energy, information and matter can be manipulated and transported undetected”.
All this cloaking devices, ideas and technologies have been around for a while but is just in the 21st century that physicists have been making small steps to accomplish invisibility. It may not be long until they perfect a way to hide things, people and events from our eyes. Then Harry Potter won’t hold any mystery anymore.