Ask Ethan: Could You Have Two Perfectly Identical Snowflakes?

Forbes - Tech 

According to the Guinness book of world records, Nancy Knight, a scientist at the National Center for Atmosphere Research, serendipitously discovered two identical examples of snowflakes while studying snow crystals from a storm in Wisconsin in 1988, using a microscope. But when Guinness certifies two snowflakes as identical, they can only mean that it's identical to the precision of the microscope; when physics demands that two things be identical, they mean identical down to the subatomic particle!