Imagine a smartphone that remains "hidden" until its owner whispers a passphrase. It's an awesome concept, but could the latest smartphone security feature be stealth?
If you think that sounds crazy, how about making a car or spaceship invisible? Even crazier, it's fast becoming science fact instead of science fiction. And that's because not only has it been shown to be possible within the laws of physics, but scientists and researchers are working on it right now.
This was not always the case. Even 10 years ago, cloaking devices were still closely tied to the realm of science fiction and meant to defy the laws of optics.
But in 2006, scientists in the UK and US created an incredible new material that seemed to do just that.
And this week, researchers at the University of Cambridge announced the discovery of a new technique (opens in a new tab) that could one day be used to make anything from an iPhone to a space station invisible. .
So what techniques could we use to make objects invisible and when can we expect an invisible smartphone?
“The key to any 'invisibility' effect is how light interacts with a material. When light hits a surface, it is either absorbed or reflected, allowing us to see objects."
The most obvious method of making something invisible is to use what is often called optical or active camouflage.
By photographing the landscape behind an object and projecting that image onto its front, you'll make it partially invisible.
That was the concept behind James Bond's invisible Aston Martin in Die Another Day. But while this method can be quite effective from a certain angle, there are obvious weaknesses when it comes to viewing the "invisible object" from positions. However, the technology still finds great practical uses.
For example, you can potentially project the view from under an aircraft onto the cockpit floor - opens in a new tab - so a pilot can get a better idea of where the runway is. In the same way, you can project the ground under a car onto the hood so off-road drivers can navigate rough terrain more efficiently. The see-through cockpit idea could also be used to eliminate blind spots in the car (opens in a new tab).
The technology has already been put to practical use by companies such as Land Rover, which unveiled its Transparent Bonnet virtual imaging concept in April. Cameras located in the vehicle's grille capture data that is used to feed a heads-up display, creating a view of the terrain through the hood and engine compartment.
It's a realistic and promising way to see through objects, but almost totally useless for making things like an iPhone invisible. For this, you will need an understanding of quantum mechanics and the ability to manipulate materials on the smallest scale…
Cuando lo piensas, la invisibilidad no es realmente tan rara. ¿Alguna vez te has preguntado cómo es el aire? ¿Qué pasa con el vidrio u otros líquidos claros?
Many things are invisible to the human eye and it all depends on how their atoms are arranged. Many gases and liquids are invisible because their atoms are far enough apart that visible light wavelengths pass through them undisturbed.
The water is only visible because of the way it bends and distorts light as it passes through it, and it is this bend, or refraction, of light that holds the key to invisibility. Hold that thought.
If atoms hold the key to invisibility, it makes sense that we manipulate them in new and innovative ways. And we first developed the ability to do this in the early 1980s. Using the 1981 Nobel Prize-winning scanning tunneling microscope, scientists can not only take pictures, but also manipulate individual atoms. In 1990, this technology caused a stir and reached the international media when it was used to spell "IBM" using 35 individual xenon atoms, a watershed moment for nanotechnology.
Using this technique, scientists try to build materials and even machines using individual atoms as building blocks. And it's the research in this area that seems to be paying off when it comes to invisibility.
Perhaps the most promising application of nanotechnology for invisibility is the production of what scientists call metamaterials.
Considered prohibited by the laws of optics until less than a decade ago, metamaterials have properties not found anywhere in the natural world and have the potential to one day render objects completely invisible, even to the naked eye.
Los metamateriales se fabrican reorganizando los componentes básicos de un material en entramados sofisticados, de modo que su índice de refracción general (el grado en que la luz se desvía cuando pasa) sea negativo en lugar de positivo. Al hacer esto, puede doblar potencialmente la luz alrededor de un objeto y hacia el otro lado, una piedra angular en la búsqueda de una capa de invisibilidad.
In 2006, scientists in the United States and the United Kingdom created a material made of copper and other metals that could bend light around a cylinder in such a way that it made it almost completely invisible to microwaves. This amazing experiment proved the concept and sparked a new race to build metamaterials capable of manipulating different types of light.
Nathan Myhrvold, exdirector de tecnología de Microsoft, dijo (se abre en una ventana nueva) que los metamateriales “cambiarán por completo la forma en que abordamos la óptica y casi todos los aspectos de la electrónica. [They] puede lograr hazañas que habrían parecido milagrosas hace unas décadas».
So the laws of physics don't prohibit light from bending around an object, but how do you create a material that can make an iPhone invisible?
The problems stem from the fact that the crystals inside metamaterials have to be smaller than the wavelength of the light you're trying to deflect. With a wavelength of about 3 cm, creating a material that interacts with microwaves is quite simple. However, to play with visible light in the same way, you're talking about many different wavelengths between 380 and 800 nm, with a nanometer being one billionth of a meter, roughly the length of five atoms side by side. Quite a challenge.
