It's easy to forget it, but much of the world is invisible to us. I do not mean that in the sense that things are really small or metaphorically. No, most of the world is literally invisible.
This is because what we call visible light is in fact a much larger filament of the electromagnetic spectrum. The rainbow that we see is situated in the middle of a broad continuous wave length, which includes everything from high energy radiation and ultraviolet radiation to lower radio and infrared waves.
There's a lot we're losing. But a group of researchers from the United States and China found a way to let other eyes see other near-infrared wavelengths that are not invisible, neither glasses nor bulky equipment needed. Using nanoparticles injected into their eyes that translate infrared photons into the visible ones, they say they gave mice the ability to see beyond the visible spectrum that the rest of us are confined.
Beyond the rainbow
The concept is quite simple. Scientists used nanoparticles to combine two photons of infrared light into a single photon that mammalian eyes could collect. The result is that incoming infrared photons with wavelengths (readings, energies) of 980 nanometers translate into photons with 535-nanometer wavelengths that feel directly around the green part of the visible spectrum. In fact, it turned the infrared light into a visible light within its eyes. Greening the planet, in fact.
Nanoparticles were coated with a protein that helps them bind to photoreceptors and injected below the retinas of mice, where they clutched on the rods and cones that converted the photons into neurals in the eyes.
Once the mice were updated, the researchers put them through a series of tests to see how they would react to their new and broader perspective on the world. The first test was to simply control their pupilar contractions in the presence of infrared light, which confirmed that their photoreceptors actually collected nanoparticles.
Then, put us in a simple configuration of two boxes connected by a door. A box was dark, the other was illuminated by infrared light. Like the normal preference of a mouse, mice with nanoparticles constantly choose the dark box. However, mice with no nanoparticles did not care about the box in which they were kept; As the infrared was the only light available, both boxes were dark.
Other tests found that not only mice could see the infrared light, and their perception was sufficient so that they could distinguish the illuminated forms by infrared ones. To do this, the researchers relied on a simple water maze test that challenged mice to find a hidden platform to stop. The location of the platform was given by a circle or an illuminated triangle in infrared, and the mice were able to discern specific ways to find it.
They also confirmed that nanoparticles did not interfere with the ability of the mouse to see normal light and that they could see infrared along with normal lighting conditions. In addition, researchers did not find unpleasant side effects in nanoparticles injections. The vision of the mice did not change, the inflammation was insignificant, and nanoparticles finally washed their eyes after a period of weeks.
The researchers report their results in the journal Cell.
Infrared ink lenses
So, probably, all of us are thinking exactly the same. They made Predator mice!
Holders have thermal vision and heat vision is the infrared, right? Well, kind of. While the Gang Han paper co-author of the Massachusetts Faculty of Medicine says the comparison is accurate, there is a functional problem. In fact, two of them. One of the nanoparticles that injected the researchers only collected infrared photons of a specific wavelength, in a very near infrared. The thermal signatures emit photons of very low energies, very low so that nanoparticles can be incorporated. They say nanoparticles that can collect heat signatures are technically possible, but they have not yet developed them.
The other problem with the thermal vision is that we are mammals of hot blood. Although we had the ability to incorporate infrared photons at these wavelengths, our eyes would be flooded with photons of our own body heat. The resulting noise means that we could not see anything at all in the static infrared. Sorry about that, the pirates of the body.
The dreams of science fiction, in addition, there are some real applications for technology like this, says Han. The nanoparticles that stick to our photoreceptors could be used someday to treat vision problems, he says, as well as to deliver drugs in the eyes. He also thinks that a technique similar to the photons of higher energies than we could see can be applied, which also allows to see the light in the ultraviolet spectrum.
The mouse and human eyes are quite similar, so nanoparticles will probably work in humans without modifications, he says. The procedure was not approved by the FDA, of course, but the type of injection they used is already common and the nanoparticles themselves do not cause any damage in the mice. (Han himself responds that he would "if my husband says yes …")
An enhanced vision with near-infrared capabilities would not allow us to cross the prey through the forest, but potentially it could open our world in other ways. Seeing new wavelengths of light can add shades to common views, for example, or may reveal things that previously wrapped in invisible wavelengths.
Stargazing, on the one hand, would never be the same. There are infrared photons that transmit us from the stars all the time: astronomers, in fact, often use infrared light to observe the universe.
Turning your eyes to the night sky would be a completely new experience. Invisible stars and galaxies previously glowed, their electromagnetic transmissions were revealed to our naked eyes. It would be a new perspective on the universe, a step, by very small, besides the limitations of our biological senses.