“Unweaving The Rainbow”

Skip the BS

by Skip Eisiminger

“To light, the gods themselves kneel.”
—Anonymous

CLEMSON, SC—(Weekly Hubris)—3/29/10—One of my favorite buildings on the Clemson University campus is Sikes Hall, which has a cornerstone that I often invite my Humanities students to decipher. In part the inscription reads, “5904 A[nno] L[ucis]” which, freely translated, means that the building was begun 5,904 years after the light came on or, more conventionally, 1904 AD.

Apparently, the local Masons rounded off 4004 BC, Bishop Ussher’s date for Jehovah’s creation, and added it to 1904. A century later, the Clemson physics department would surely deny that pitiful but quaint number because it’s much more likely the lamp was lit 13.7 billion years ago, give or take a few million. Yet, as long as that light has been travelling, the more remote areas of the universe are still waiting for its arrival.  Though no one was around to witness it, the Big Bang surely was a dazzling and deafening display. The Hubble telescope has photographed “embers” on the leading edge of the ur-blast, and one can still hear it at 160.4 GHz.

Ever since life evolved into consciousness, priests of all stripes have been quick to associate the gods they worship with light and the forces of evil with dark. Jesus of Nazareth claimed to be the light, figuratively speaking of course, and Mephistopheles’ name means “one who does not love the light.” Counterintuitive to many, the Quakers close their eyes to see the light and wait for the spirit to provide the fireworks. Indeed, the Quaker “Inner Light” is God, but it is not to be found outside the body where most of us would normally seek it. Theological history records the contentious conflict between proponents of immanent light and the transcendent.

Before 1704, most people thought light was a generic-brand tube sock—white and not very interesting. The alchemist-mathematician Isaac Newton, on the other hand, found it irresistible. He aimed sunlight through a prism and promptly named seven colors, where an infinite number reside, and virtually single-handedly created orange and indigo. But why seven? Jehovah created the universe in seven days; there are seven conspicuous heavenly bodies visible to the naked eye, and there are seven tones in an octave. You didn’t think science leapt fully armed like Athena from the head of Zeus, did you?

In 2009, most of the myth and pseudoscience associated with light is behind us, though as late as 1915, light bulbs came in packages warning consumers not to light them with a match. We laugh, but we have not lit a hundred thousand fires, striking matches on our taut rumps, either.  Regardless of whether light emanates from star fire, foxfire, or firefly, the stuff that quivers on the rods and cones of our retinas is fascinating, and I hope to see a lot more of it before facing Shelley’s “white radiance of eternity.”

In no particular order, let’s consider the transparent quintessence that is making the pixels dance on your screen.

Ultraviolet light is known to be one cause of cataracts, which are commonly removed with blinding beams of light.

Blue-to-violet light may cause a headache that is often cured by wearing yellow-tinted glasses.

Visible light shares about one-twentieth of the electromagnetic spectrum between the microwaves that cook food and the x-rays that locate broken bones.

Sunlight staves off rickets with tiny carcinogens. The same light striking the skin stimulates the production of Vitamin D, but too much sun leads to a greenhouse of skin cancers. A hundred years ago, tanned skin meant that one could not afford to avoid the sun; today, it’s a sign one has rented a tanning bed at the nearest strip mall.

Too little light causes a rise in suicide, depression, alcoholism, and seasonal affective disorder rates. The cure? “Give them some light,” as Hamlet’s uncle might have exclaimed.

New York’s World Trade Center was once an icon of profligate consumption: to illuminate a single cubicle required switching on a quarter-acre of fluorescent tubes. Yet when the fabled towers fell, the most suitable monument anyone could think of was two towering shafts of light aimed up into the night sky.

The temperature of a tungsten filament as it sublimes from a solid metal to a gas is about 4,500 degrees F, or about half that of Earth’s closest star, which means that man has difficulty producing light as white as sunlight except in a nuclear explosion.

It has been estimated that if you could coax fourteen billion fireflies to fly together in a ball, the luminescence would be as bright as the sun but cold to the touch.

Light waves travel through a vacuum that sound waves cannot penetrate.

To make actors on a stage more visible to the audience, light is used to make the audience invisible to the actors.

Light is bent by gravity but has no mass. Nevertheless, one day its mass-less momentum will billow the spinnakers of star ships (if we’re not still dependent on foreign oil). The closer these ships approach warp speed, the less they can see where they’re going. It should not matter, however, because at the speed of light, time stops, and matter turns to energy. Light emanating from the ships’ headlamps will travel no faster or slower than 186,000 miles per second. Approaching a black hole, light’s speed will remain constant until it stops therein forever.

The smallest unit of light, the photon, is its own antiparticle. Moreover, it has no plus or minus electrical charge—but an electric short produces, you guessed it, light.

Though they exist in theory only, tachyons (“swift ones”) may fly faster than photons, which amble about the Earth’s equator seven times in less than a second.

Long known to be slowed by translucent materials, a light beam was frozen by scientists at Harvard in 2004. When thawed, the photons resumed their original speed without any visible annoyance.

Light travels as a wave but behaves as a particle when expelled from a lantern or “dies” on striking a flat-black sweater. Burn the sweater and release the latent photons. Others say light is neither particle nor wave, but both at the same time.

In the interest of full disclosure, I do not pretend to understand the last five paragraphs, but I accept much of what I do not comprehend if I have it on good authority.

As a retired English professor, the following is closer to the realm of my understanding: if I sit on a screened porch at night with the lights turned off, I can see the stars. Turn the porch lights on, and the stars vanish. Lights on or off, my wife and I enjoy discussing such ponderables as why the love light goes off when the electric bill arrives. Or why the hero shines more brightly when he places his light under a bushel.

In his poem, “Lamia,” published 1819, John Keats worried that Newton and other scientists of the Enlightenment did “unweave a rainbow.” He also mourned the loss of gnomes (but that’s another blog). It’s true, Newton did tease apart the light visible above red and below violet, but the rainbow’s components are as mysterious and compelling as ever. What a great privilege it is to count oneself a member of the species that has given us such delicious profundities. “Unweave a rainbow” indeed! Like bullet-proof textiles and a text by Annie Dillard, light has never been more securely woven!