May  2010
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Billie Silvey
Light
Optics
'Let There Be. . .'
Sources of Light
An eclectic website about Women, Christianity, History,
Culture  and the Arts--and anything else that comes to mind.
Most mornings I wake up around 6:00 a.m.— that point when the
darkness of night begins to give way to the light of day.  The birds
wake up about the same time and start chirping.  The squirrels as
well, and they chase each other around the yard, tumbling and
cheeping.  I waken to the happy sounds of nature awakening in the
treetops and on our back lawn.

I seem to be particularly sensitive to light.  I don’t know when I
might wake up if our bedroom had heavy drapes, but it doesnâ
€™t.  Frank, on the other hand, can sleep hours longer than I can,
even on the brightest day. I guess he isn’t so light sensitive.

Light is electromagnetic radiation of a wavelength that is visible to
our eyes.  It has a dual nature, with qualities both of a wave and of a
particle.  Light travels in a straight line until it encounters an object
that bends or absorbs it.  Light is fast, traveling at 186,000 miles a
second.  It takes about one and a half seconds for light to reach us
from the moon.

Light is made up of particles of pure energy called photons.  
Photons have no mass and differing amounts of energy.  The energy
of light gives
color to our world.

When I see an object, the lenses on the front of  my
eyes focus light
onto my
retina.  My retina is made up of light-sensitive material
including cones, which are sensitive to color and contribute to my
daylight vision, and rods, which are not, and give me night vision.  
The optic nerve connects my retina to my brain, where the visual
image is composed.

What would the world be without light to reflect, eyes to channel
and brains to interpret?

Other articles in this website include
Optics, Sources of Light, and
"Let There Be Light" on light in scripture.

I'd love to hear from you about your reactions to light--either
scientific or otherwise.  Just write me at
b.silvey@sbcglobal.net.

Next month's website will discuss the Gilded Age in America, from
the late 1800s till the end of World War I.