The Eyes Have It
(for the science geeks among us)
I’ve always liked that expression about the eyes being the windows of the soul. They are holes in our heads out of which the light of the spirit shines. When you look into someone’s eyes, a connection is made. I feel it when I make eye contact with one of the cats, or any other animal. I think it’s confirmation that all of us, everywhere, are in fact the same One. Epistemology aside, though, the human eye is truly a magnificent instrument.
Keeping things simple, light enters the eye through a double convex lens, similar to that of a magnifying glass. It’s focused to a point on the retina, at the back of the eye. On the retina are two types of light receptors, rods and cones. The cones are sensitive to color and natural light, and are concentrated near the focal point. We humans are diurnal, we evolved to function in daylight, to be able to focus on objects at the center of our vision. The rods are sensitive to faint light, and don’t register color. That’s why when we look at a faint nebula in the telescope, it appears gray. Long exposure photographs bring out the colors we don’t see. You can try this little experiment yourself. On a clear night, pick out a faint star. Look directly at it. Then look just to one side, and you’ll see it’s brighter. Now you’re using your rods.
The fluid of the eye contains proteins called opsins. There are three different types, sensitive to blue, red, and green. Occasionally someone is born without one of these opsins; that person is colorblind. Glaucoma and cataracts are diseases of the eye, and with age, we become near or farsighted, or develop astigmatism.
Nocturnal animals have more rods near the point of focus, so they can see clearly in the dark. An owl’s eyes gather fifty times the amount of light as a human’s. I would love to look up at a starry sky through the eyes of an owl. The eagle has 8X vision, or eight times the magnification of our eyes. They fly at over a hundred feet, so they need to be able to spot a tasty field mouse, much in the same way that a drone spots a potential assassination target.
Nearly all animals have two eyes, rather than one. Each eye sees from a slightly different angle, which provides depth perception — what we call binocular vision. It’s the principle behind 3D movies. It’s interesting to note that predators, like us, have the eyes together at the front of the head. Prey animals, like cute little bunny rabbits, have the eyes on either side of the head, all the better to watch for the predators.
The electromagnetic spectrum measures all forms of radiation, from Gamma and X-rays at one end, to microwave and radio waves at the other. Somewhere around the middle is the visible light portion, what humans can see. Other animals can see a little further into the infared or ultraviolet. So, yes, if there are ghosts or other spectral beings, cats and dogs may be able to see them.
How far can we see? We have a pair of 1X, or one power, telescopes. What is the most distant object we can discern? Well, that depends on atmospheric conditions. I can remember when I was in high school, in Newcastle, Wyoming. One clear day my friend Ron and I drove to the top of Watertank Hill, just North of town. Looking to the South, we could pretty easily make out the top of Laramie Peak, which is 130 miles away. Then again, that was some forty years ago; I doubt those conditions exist today. To see further, we must look outward, into deep space. Now what’s the most distant object we can see with the naked eye — or the unaided eye, if nudity bothers you? That would be M 31, the Andromeda Galaxy. It is the nearest galaxy to our own Milky Way, and it can easily be seen in a dark sky as a faint, elongated smudge. Andromeda galaxy is just over two million light years away. In highway miles, that’s a 12 followed by 18 zeroes, and it would look like this: 12,000,000,000,000,000,000 miles. That’s how far your eyes can see, and I think that’s pretty impressive.
There’s a wealth of imagery and metaphor concerning the eye, and seeing. Mystics talk about the difference between looking and seeing. In the film “Avatar” the expression “I see you” goes far beyond looking, to an affirmation of awareness and appreciation of another’s presence. We say that someone with exceptional eyesight and attention to detail as having an eagle eye. People who claim to sense ghosts or other supernatural beings are said to have second sight. People who are dating are “seeing each other.” They ain’t seen nothin’ yet. Wait till they get married, then they’ll really see each other.
A “vision” describes a transformative experience, like that of Paul on the road to Damascus, or apparitions of the Virgin Mary. Entrepreneurs may outline the vision of a company or business they hope to create. We may refer to such people as being far-sighted. The sense of sight becomes a metaphor of understanding. See what I mean? Beauty is in the eyes of the beholder. Does that slightly imply that in the absence of a beholder, beauty does not exist? Then there’s the mind’s eye; I really like that one.
Here is a wonder. Did you know that when you see a rainbow, that is your own individual rainbow? Actually, each eye sees its own rainbow, and our binocular vision makes it into a single image. But it is your eye that views the refraction of light through droplets of water vapor, and that begs the same question we asked about beauty — without observers, do rainbows exist? I can think of no better way to end our lesson than to note that the Greek goddess of the rainbow was named Iris.
Take care of your eyes. They’re one of your best assets. Whether you can believe your eyes is a discussion for another time. See ya later.