Monday, April 2, 2012

Post-Move Phenomena

Back home in LA and abuzz with ideas. There are about 1,000 things I'd like to do, and even though there's no rush, I want everything right now. Patience is a virtue, but my mind has a lead foot on the accelerator. Too bad the parking break's on. 

 So in the spirit of (semi)tangible progress, lets talk physics. There is nothing like a fun fact to make everything better. 

 Question: Why are your eyes green? or blue? or brown? or hazel? 

 Well, you do have your DNA to thank, but heredity gets complicated when it comes to eye color. Lets skip the genetics and assume the eye already exists. 
 Now, when light shines through a suspension of particles in liquid, the path of that light becomes visible. This happens because particles scatter light. Intensity of the scatter depends on the frequency of light, with blue scattered most strongly (known as the Tyndall effect). Physically, this determines the color of your eyes. 
 The iris contains a thin suspension of particles, including the light-absorbing pigment melanin. Yep, that's the same pigment that dictates skin color. The less melanin you have, the more light your eyes reflect. Brown or black eyes have more melanin than blue or green eyes. As a result, more light is absorbed (less is reflected back to the observer) so the iris appears darker. Since blue light is reflected most strongly, blue is the dominant eye color perceived in individuals with little melanin in the iris. Neat!

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