A huge crystal of calcite is used to demonstrate birefringence, a side-effect of light's refraction through certain materials. Featuring Professor Mike Merrifield. Visit our website at http://www.sixtysymbols.com/ We're on Facebook at http://www.facebook.com/sixtysymbols And Twitter at http://twitter.com/#!/periodicvideos This project features scientists from The University of Nottingham http://www.nottingham.ac.uk/physics/index.aspx Sixty Symbols videos by Brady Haran