Study Says Eyes Evolved For X-Ray Vision

The advantage of using two eyes to see the world around us has long been associated solely with our capacity to see in 3-D. Now, a new study from a scientist at Rensselaer Polytechnic Institute has uncovered a truly eye-opening advantage to binocular vision: our ability to see through things.

Most animals — fish, insects, reptiles, birds, rabbits, and horses, for example — exist in non-cluttered environments like fields or plains, and they have eyes located on either side of their head. These sideways-facing eyes allow an animal to see in front of and behind itself, an ability also known as panoramic vision.

Humans and other large mammals — primates and large carnivores like tigers, for example — exist in cluttered environments like forests or jungles, and their eyes have evolved to point in the same direction. While animals with forward-facing eyes lose the ability to see what's behind them, they gain X-ray vision, according to Mark Changizi, assistant professor of cognitive science at Rensselaer, who says eyes facing the same direction have been selected for maximizing our ability to see in leafy environments like forests.

All animals have a binocular region — parts of the world that both eyes can see simultaneously — which allows for X-ray vision and grows as eyes become more forward facing.

Demonstrating this X-ray ability is fairly simple, the researcher says: hold a pen vertically and look at something far beyond it. If you first close one eye, and then the other, you'll see that in each case the pen blocks your view. If you open both eyes, however, you can see through the pen to the world behind it.

To demonstrate how eyes allow us to see through clutter, hold up all of your fingers in random directions, and note how much of the world you can see beyond them when only one eye is open compared to both. You miss out on a lot with only one eye open, but can see nearly everything behind the clutter with both.

"Our binocular region is a kind of 'spotlight' shining through the clutter, allowing us to visually sweep out a cluttered region to recognize the objects beyond it," says Changizi, who is principal investigator on the project. "As long as the separation between our eyes is wider than the width of the objects causing clutter — as is the case with our fingers, or would be the case with the leaves in the forest — then we can tend to see through it."

To identify which animals have this impressive power, Changizi studied 319 species across 17 mammalian orders and discovered that eye position depends on two variables: the clutter, or lack thereof in an animal's environment, and the animal's body size relative to the objects creating the clutter.

Changizi discovered that animals in non-cluttered environments — which he described as either "non-leafy surroundings, or surroundings where the cluttering objects are bigger in size than the separation between the animal's eyes" (think a tiny mouse trying to see through 6-inch wide leaves in the forest) — tended to have sideways-facing eyes.

Watch more breaking news now on our video feed:



Bookmark http://universeeverything.blogspot.com/ and drop back in sometime.

New Coating Is Virtual Black Hole for Reflections

Researchers have created an anti-reflective coating that allows light to travel through it, but lets almost none bounce off its surface. At least 10 times more effective than the coating on sunglasses or computer monitors, the material, which is made of silica nanorods, may be used to channel light into solar cells or allow more photons to surge through the surface of a light-emitting diode (LED).

Publishing in the March 1, Nature Photonics, lead author Jong Kyu Kim and a team from Rensselaer Polytechnic Institute in Troy, N.Y., reveal how they crafted the coating, which reflects almost as little light as do molecules of air.

Guided by National Science Foundation-supported electrical engineer Fred Schubert, the researchers developed a process based on an already common method for depositing layers of silica, the building block of quartz, onto computer chips and other surfaces.

The method grows ranks of nanoscale rods that lie at the same angle. That degree of the angle is determined by temperature. Under a microscope, the films look like tiny slices of shag carpet.
By laying down multiple layers, each at a different angle, the researchers created thin films that are uniquely capable of controlling light. With the right layers in the right configuration, the researchers believe they can even create a film that will reflect no light at all.

One critical application for the material is in the development of next-generation solar cells. By preventing reflections, the coating would allow more light, and more wavelengths of light, to transmit through the protective finish on a solar cell surface and into the cell itself. Engineers may be able to use such a technique to boost the amount of energy a cell can collect, bypassing current efficiency limits.

Another application would involve coating LEDs to eliminate reflections that cut down the amount of light the LED can emit. The researchers hope the efficiency gains could allow the light sources to compete more effectively with fluorescent and incandescent bulbs. So, they will next focus their attention on solid state lighting.

Bookmark http://universeeverything.blogspot.com/ and drop back in sometime.