|January 7, 2002|
Without light, there would no vision, no color, no food to eat. Without light, there could be no life on Earth as we know it. How does a shortage of light affect people in winter, and how can they compensate?
The Old Testament begins: "In the beginning God created heaven and earth. The earth was unformed and void, with darkness over the face of the deep and a wind from God sweeping over the water. God said, 'Let there be light'; and there was light." (Genesis 1:1-3) By the Biblical account, the creation of light was one of God's first acts. Light is at the very foundation of life on Earth as we know it.
In Greek mythology, Apollo was the god of the Sun, logic, and reason. The Greeks had already made a connection between light and the workings of the mind. This concept exists today in phrases like "Let's shed some light on the subject" and "I see!" A standard convention in cartoons is to represent someone who has an idea as having a lightbulb go on over their head.
In Celtic mythology, there is a dark Holly King, disguised as a wren, and his twin, the light Oak King, disguised as a robin. At the summer solstice the Holly King kills his twin and begins a half-year reign. At the winter solstice, the robin slays the wren and he reigns for the next six months. There is an eternal duel of light and darkness.
It is easy to imagine how ancient peoples may have feared the darkness of night, not knowing if light would return. The passing of summer into autumn and the increasingly short days of winter must have also caused concern over whether spring would really arrive as in past years.
Light is such a central component of human life that it is probably no coincidence that many religious and mythological texts try to explain it. Also some of the earliest scientific work by cultures such as the Egyptians and the Babylonians dealt with light in the context of astronomy.
Bring on the Light
Many ancient cultures instinctively felt the need to bring light into their lives during the winter months, close to the winter solstice when days are short.
In addition to the psychological need for light throughout the winter, modern science has taught us that there is a physical need as well. When people say they have the "winter blues," they are not just making excuses for their behavior. Seasonal Affective Disorder (SAD) is a recognized form of depression that affects 10 million Americans, while 25 million more suffer a mild version.
The symptoms of SAD are:
Individuals most susceptible to SAD are women, people who live in northern latitudes, people with a family history of mood disorders, and people who work or study in windowless rooms. SAD victims usually feel the onset of symptoms in the fall and feel relief setting in by the spring.
Light therapy has become a standard treatment for SAD. Doctors prescribe exposure to a light box in the morning. "It's not the kind of light, it's the intensity," explains Dr. Norman Rosenthal of the National Institute of Mental Health.
Generally the light boxes use a bright light with a frequency spectrum closely simulating the frequencies of natural sunlight. The required length of exposure depends on the severity of the winter depression. While no one is certain why this helps, scientists hypothesize that it has to do with shifting the body's internal clock. And there are many testimonials to the success of light therapy.
A Modern Light Celebration
Laser light shows are a balance of technology and art. They combine lasers, colored filters, mirrors, oscillators, projectors, and computers. These elements are the tools of a laser light show; how they are used is the artistry.
Laser shows depend on a phenomenon called "persistence of vision." Think for a moment of how a movie is projected. An individual frame is run quickly over a light source and projected onto a screen. The light-sensitive cells of the eye's retina transmit signals to the brain, which interprets the signals into an image. While this is occurring, the next frame already appears on the screen. The brain merges the various signals into one continuous image, smoothing the motion from one frame to the next. This phenomenon is also the basis of many optical illusions.
There are two major types of laser light show effects:
Laser animation may be traditional character animation, where each frame is digitized from drawings prepared by an animator. Laser shows can also use object animation, in which the images are created by the movement or rotation of a projected object. Computers can also add depth to a laser light show by dimming parts of a projected object that should be perceived as being "farther" away.
You can find out more about lasers from these Web sites: