Iridescent meat and teachable moments

Behind every meal of meat is an absence: the death of the animal whose place the meat takes. The "absent referent" is that which separates the meat eater from the animal and the animal from the end product. The function of the absent referent is to keep our "meat" separated from any idea that she or he was once an animal, to keep the "moo" or "cluck" or "baa" away from the meat, to keep something from being seen as having been someone. - Carol J. Adams, The Sexual Politics of Meat, KL 186-189

WIRED just posted a series of photos illustrating various optical effects. I was intrigued by one label: “Iridescent Meat.”

[Source]

From the accompanying text:

In this picture of corned beef, the unappetizing colors come from the light waves bouncing off the sliced meat. When cut, the animal muscles of the meat protrude in a regularly spaced array, like a set of stairs, forming what is known as a diffraction grating. (Probably the most familiar diffraction grating is the back of a compact disc, which produces a rainbow pattern.) Light waves reflecting off the meat interfere with one another, giving rise to the odd prismatic colors seen in the image.

The photographer of this picture, John Flyte, was able to turn the unexpected sighting into a lesson for his fifth-grade students:

“It was St. Patrick’s Day 2011 and I wanted a traditional lunch so I ordered some freshly cut corned beef at the deli. When I got home and made a sandwich I saw green and was a little grossed out. Then I saw the reds, pinks, blues, as well as the shades of green. I recognized it as iridescence and only saw it once before at a banquet that had freshly cut roast beef. As a science teacher I was immediately fascinated and took pictures of it in natural light," Flyte wrote in an e-mail.

"When [Les Cowley] printed my picture on his website, I showed my 5th grade classes and we started a great discussion on rainbows, optics, haloes, etc. It was one of those ‘teachable moments’ that teachers dream about. Websites like Mr. Cowley’s are great, and as I try to remind my students, ‘Science is everywhere, and every where there is usually a scientific story about it.’”

In our culture, the dead bodies of nonhuman animals are traditional lunches and optics demonstrations. I’d call this a teachable moment as well, though not just about diffraction grating but about morality and the absent referent.