Why Do Mirrors Flip Horizontally (but not Vertically)?

Fascinating and very informative video asking a question that I hadn’t thought of before: Why do mirrors flip images horizontally but not vertically?

“See” for yourself…

I found this video in Slate.com.  You should check it out:

http://www.slate.com/blogs/bad_astronomy/2015/02/17/physics-girl-mirrors-flipping-images.html

And, totally gratuitously and incredibly tangentially, the song “Ghost In You” by the Psychedelic furs, from their album Mirror Moves…