Invisibility is a prevalent theme in popular culture, more commonly in science fiction and fantasy genres. In folklore and fairy tales, wizards concoct potions, or procure mystical rings or use a spell to grant themselves invisibility. In science fiction, a person is often rendered invisible by some advanced scientific experiment or technology. Invisibility by the means of scientific experimentation is usually not reversible.
Invisibility in Pop-culture
There are countless videogames, TV shows, films and comic books which make use of this plot device. There are several works of fiction that employ this trope as well. The Invisible Man by H.G Wells, Harry Potter by J.K Rowling and The Hobbit and The Lord of the Rings series you might be familiar with.
In the realms of science fiction, being able to make things invisible is often taken for granted and is the ultimate fantasy for us regular folk. So, is it scientifically possible to achieve it in the real world? And if so, how close are we to materializing this fantasy?
How do we see?
Before you can understand how it’s possible to render things impossible, it is important that you understand how vision works. Light behaves as a wave. Like all waves, its wavelength changes when it hits a surface and is reflected off it. We perceive different wavelengths of light as different colors. So, when light bounces off something, enters your eyes and stimulates your retinas, an image of the said object is formed in your brain. This is how you see things. So, to make something completely invisible, all you have to do is to keep any light from bouncing off its surface.
Invisibility in Nature
Invisibility already exists in nature in the form of transparency. Many natural materials don’t give off light, don’t reflect or absorb visible light rendering them invisible to the viewer’s eye. That said, the process of transmitting light isn’t perfect. Some light is inevitably reflected off any naturally occurring surface, making it impossible for an object in nature to be 100% transparent.
What are the current limitations?
Scientists have been experimenting and researching for years and thanks to that invisible technology now exists. Sort of. Invisible science is a study that examines whether not the phenomenon known as invisibility can become a reality. Scientists are aware that everything we see concerns the reflection of light. You could say that at night everything is invisible as it is black and light is not able to reflect back from the objects.
Magicians have for several years been able to give the illusion of making various objects invisible by using a variety of tricks. There are various types of invisibility and as such you could see that it is possible to make things invisible. If we stand in front of a solid object, we can clearly see it and the prospect of being able to make that invisible is relatively far-fetched. However, invisible technology can make things invisible to radar. Although ships are incredibly large solid objects there are ways to make them invisible from radar. It is not as incredible as it may seem at first glance because as mentioned previously everything we see is as a result of light being bounced back from it.
Being able to give certain objects the impression of being invisible would be something of tremendous value to the military. This is really what invisible science and invisible technology are trying to investigate. It is purely a matter of physics and examining the way the light can be bent around objects that can give the impression of invisibility. Scientists are currently carrying out experiments using different types of metals at various temperatures to explore this possibility further.
For the time being, we will have to content ourselves with knowing that although invisibility is not impossible it is highly unlikely that we as individuals would ever be able to make ourselves invisible to each other. As previously stated, the closest we will ever get to this would appear to be by implementing the same methods that David Copperfield uses. Optical illusions can sometimes give the impression of invisibility but again this is just a trick of the light.
Modern innovations pertaining to making things invisible
Modern technology can render real-world objects invisible, in theoretical and at least some practical capacity.
One technology that can render things invisible is called Active or Adaptive camouflage. The idea is to conceal the target by projecting images from a real-time feed onto an adaptive display. Several sea creatures and reptiles use a similar process to blend into their environment perfectly, making them impossible to detect visually.
Rochester Cloak was the first cloaking device ever developed. It uses an intricate arrangement of lenses that make something appear invisible when viewed from certain angles. It is limited to concealing smaller targets and doesn’t work for larger objects. Developments in this technology have made it possible to cloak objects for viewing angles up to 30 degrees. Upgraded designs use cameras to scan the object’s background and map it on the screen pixel by pixel from a number of different angles. Practical applications for this technology include digital windows for homes and use in surgery to get a view without the surgeon’s hands in the way.
Another advancement for rendering things invisible is known as the “invisibility cloak”. It conceals objects by manipulating light so that it never interacts with the object. Since light will never hit the object and reach our eyes, it is impossible to see it. When the cloak is placed in front of an object, it bends light away from it, rendering it invisible to the viewer’s eyes.
Another technology that has the potential for making this sci-fi dream a reality, is plasmons. On some metallic surfaces, electrons can be excited by supplying the energy, this excitability can cancel the electromagnetic radiation, including visible light leaving the object. These minute electronic excitations are called plasmons. Unfortunately, this concept is limited to objects far too small to be seen with the naked eye. However, humans or human-sized objects can be made undetectable to electromagnetic radiation with longer wavelengths such as microwaves, at least in theory. This could find potential applications in radar stealth technology.
Using a sheet of carbon nanotubes, and heating them to several thousand degrees Fahrenheit, an object behind them is rendered invisible. Carbon nanotubes are one molecule thick cylinders whose diameters are only a few nanometers. This technology harnesses the phenomenon of mirages but it only works underwater. Theoretically, it could be used to make submarines invisible to observers.
Invisible technology and invisible science will continue to strive to find an answer to the question can we make things invisible? However, the reality of the situation is that objects being looked at by humans will not be invisible, but huge objects like ships and tanks may well become invisible to radar.