The definition of the meter (m), which is the international unit of length, was once defined by a physical artifact - two marks inscribes on a bar of platinum-iridium. Today, the meter (m) is defined in terms of constant of nature: the length of the path traveled by the light in vacuum during a time interval of 1/299, 792, 458 of a second. The Length - Evolution from Measurement Standard to a Fundamental Constant explains the evolution of the definition of the meter.
Rainbow flag (LGBT movement) For other uses, see rainbow flag. The rainbow flag is a symbol of lesbian, gay, bisexual, and transgender (LGBT) pride and LGBT social movements in use since the 1970s. LGBT symbols. The rainbow flag, commonly the gay pride flag and LGBT pride flag, is a symbol of lesbian, gay, bisexual, and transgender (LGBT) pride and LGBT social movements.
Nazis, the KKK and other such subversive groups have long been flying the flag upside down as a symbol of their goal of overturning the current constitutional republican system. Symbols often have dual meanings, one that is told to the general public and another subversive meaning, known to a smaller group of insiders.