Thursday, May 9, 2013

Interference

Web of Light by Tammy Slocum

Nature is light.  Light is nature.  The two are inseparable.  When I saw the picture of this glowing spider web, it reminded me of something I had learned about light from educator Kathy Holt at Laser Interferometer Gravitational-Wave Observatory (LIGO) in Livingston, Louisiana.  I had gone down on a Math Science Partnership field experience with a group of teachers from north Louisiana.  Kathy was using bubbles to teach us about light waves and had asked us, “What causes the colors of a bubble?”  Now this was something I had never thought about and it’s great when someone pushes your brain in a new direction.

Kathy said that light waves, like ocean waves, have peaks and valleys (crest and troughs).  Red light has the longest wavelength and violet the shortest.  Remember “ROY G BIV” or the sequence of colors in the rainbow.

“All waves, including light, have a curious property:  If two waves combine, the waves can meet each other crest-to-crest, adding up and reinforcing the effect of each other, or they can meet crest-to-trough, canceling each other out so that they have no effect.  When they meet crest-to-trough, for every ‘up’ vibration in one wave, there is a corresponding ‘down’ vibration in the other wave.  This combination of equal ups and downs causes complete cancellation or interference.  Interference is responsible for the pearly luster of an abalone shell, the beautiful colors in some bird feathers and insect wings, and the flowing patches of color in an oil slick – and for the color of bubbles.”

So when I saw the picture of the spider web, I knew that interference was the cause of the colors emanating from the web.  It’s fun to merge two sciences like life science and physical science in your nature observation.  Thanks, Kathy!  I remembered!
 
                                                              
                                                                       Nature waits for you.

1 comment:

  1. It's remarkable to me that words like cancellation and interference explain such beautiful phenomena as bubble color, pearly luster of an abalone shell, and that spider web. Thank you for sharpening my eyesight and my understanding.

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