3rd July 2015
Port Life
Oh say, can you see?
Making Sense of Medicine
Bob Keller
Tomorrow, the Fourth of July, we’ll celebrate our country’s colors: red, white and blue. We’ll be
dazzled, as well, by millions of bright and dark hues streaming from falling fireworks in the evening.
And the flowers of summer, having come into their own, treat us to a symphony of rainbows beyond
imagining.
But how do we see these colors? Do we all see them the same way? How does color feel or taste?
How can we use light?
Let’s start with light.
Light is energy. In fact, it’s the same kind of energy as radio and TV signals, X-rays, gamma rays, and
many others. We can think of light and the others being made up of unimaginably small individual
packets or particles of energy that we call photons. One of the ways that light photons differ from the
other photons is in the amount of energy each photon contains. Radio waves are relatively lowenergy, light is in the middle and X-rays are very high-energy. This is why usually we can stand in the
way of light without being harmed, except for sunburn, but we can be badly injured by getting a
relatively small amount of X-ray energy.
In addition to behaving like a long stream of particles, light acts also as though it were a wave. While
light waves are of a nature different from sound waves, you can see some similarity.
For example, if you strike a high note and a low note on the piano and watch the struck strings
vibrate, you will see that the high note string is vibrating more rapidly than the low note string.
Frequency is the name we give to the speed of vibration. That is, the high note is of a higher
frequency than the low note.
We can observe also that there is a recurrence of waves that go the length of each string, and that
the distance between waves on the high note string is shorter than on the low-note string.
Wavelength is what we call the distance between waves.
Light waves, too, have frequency and wavelength. For these waves, the lower frequency, longerwavelength waves appear toward the color red on the scale from red to violet, and higher-frequency,
shorter-wavelength waves appear toward the violet.
How do you see?
Obviously, you see with your eyes, don’t you? Well, yes, at least partly, but the parts of the eyeball
you notice — the pupil, white and colored iris— are only the beginning of a complex mechanism.
When you look at something, the light enters your eyeball through the pupil, and the lens then
focuses the image on the back of your eye on an area called the retina. This contains cells that are
receptive to light, photo receptors, of which there are two types: rods and cones. Rods, about 120
million of them, are spread over most of the retina and are very sensitive to light. They provide night
vision, motion perception and peripheral vision. Alas, however, rods don’t respond to color.
Cones, on the other hand, are concentrated near the center of the retina in an area called the fovea.
Although less sensitive to light, cones can detect color, and there are three types of cones based on
color sensitivity: red, green and blue. These are called primary colors, meaning that in proper
combination, they will yield white, and any color we can see is made up of different intensities of
stimulating the red, green and blue cones.
When the rods and cones are stimulated by light, they send electrical signals through the optic nerve
to a part of your brain called the thalamus, which is your brain’s primary switching center. That is, the
thalamus decides where in your brain to send whatever signals it receives. It is involved primarily in
directing sensory input, but also the signals that control movement. For light, the thalamus sends the
signals to various parts of an area at the back of your brain called the visual cortex. There, the color,
shape, movement and depth of an object is analyzed simultaneously to put together a complete
picture of the object.
Is your red my red?
Up until the 1950s, science would have said that yes, the red that you see is the same as the red I
see. Since then, however, researchers have found differences in color perception. For example, men
generally perceive shades as being lighter than do women, and men can’t seem to distinguish shades
as precisely.
Actually, rather than calling the cone types red, green and blue, we should call them long, medium
and short wavelength receptors. That is, the physical properties of your cones are somewhat different
from mine, and so it could be, for example, that the color you call red is the same frequency as the
color I would call orange. In some way, this makes little difference culturally because you and Iwill
have both been taught that the light at the top of a traffic light is called red even though we are
responding to it differently in our eyes.
Are you crazy!?
Very many of us associate a color with a particular letter. When I’m angry, I say I’m seeing red, or I
may be green with envy or even feeling blue today. But what if, when you encountered a letter, you
actually saw it in a particular color? Or how about seeing a part of your body as orange when it’s in
pain?
It used to be that if you told us you could see or hear or feel or smell colors, we’d say you were crazy
and send you to a shrink. Relatively recently, however, neuroscience has discovered that there are
people who do indeed see letters in color and more. This is a relatively rare— 1 percent of us— but
very real condition in which any pair of your senses get mixed together. That is, you may experience
sounds as colors, colors as smells or smells as colors. The condition is called synaesthesia, which
means working together (syn) and senses (aesthesia). The most common form is seeing a certain
color when you hear a particular sound.
Taming light
We use light in very many ways from just finding our way around to projecting movies on a screen to
generating electricity from sunlight. There is intense research all over the world trying to efficiently
transform light energy into electrical energy because, theoretically, it should be possible to get
enough energy out of sunlight to make solar cells our primary source of electricity.
Nanotechnology is that area of science and engineering that is working with materials at the level of
manipulating their individual atoms and molecules. Although practical application is someway in the
future, researchers at the University of Pennsylvania, my alma mater, have recently (March 2015)
published their success in creating the first 3-D nanoparticles they call raspberries because of their
shape. The importance of this is monumental in that with these structures, scientists can now
manipulate light in ways never before possible.
What is being called “the taming of light” has far reaching potential not only in solar energy, but in
medical diagnostics and treatment and countless other areas.
Bob Keller maintains a holistic practice in Newburyport. He offers medical massage therapy for pain relief
and advice on muscular balance and diet, as well as psychological counseling, dream work and spiritual
direction. He can be reached at 978-465-5111 or [email protected].