Why Do Mirrors Flip Left & Right (but not up & down)?

Go to https://nebula.tv/minutephysics to get access to Nebula (where you can watch MinuteBody) plus you'll get a 20% discount on an annual subscription. Support MinutePhysics on Patreon!   / minutephysics   Link to Patreon Supporters: http://www.minutephysics.com/supporters/ This video is about why words flip left & right (aka horizontally) in a mirror but not up & down (aka vertically). The answer has to do with specular reflection, mirrors being like windows into another world (alternate universes, just with in and out flipped!), and transparency of the things we write on. REFERENCES Specular Reflection https://en.wikipedia.org/wiki/Specula... PhysicsGirl video about mirrors    • Why do mirrors flip horizontally (but not ...   Fermat’s principle http://electron6.phys.utk.edu/optics4... Thomas-Fermi screening https://en.wikipedia.org/wiki/Thomas%... MinutePhysics is on twitter - @minutephysics And facebook -   / minutephysics   And Google+ (does anyone use this any more?) - http://bit.ly/qzEwc6 Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute! Created by Henry Reich