This is the Red Flag of the Soviet Union (1922-1991) – with variants in existence prior to 1917 and 1922. The Red Flag is not necessarily limited to the Soviet Union, but is in fact the flag that represents the International Working Class. It is thought to have originated during the Paris Commune of 1871, where the shirt of an ordinary working man killed by the French military, was raised high on a wooden pole. The shirt was originally made of ‘white’ cotton, but was now soaked in ‘red blood’. Therefore, the flag of the International Working Class represents the ‘blood of the workers’. The Soviet Union added the ‘golden’ hammer (which represents all industrialised workers) and the sickle (which represents all the agricultural workers). The Red Flag in the Soviet Union was the same on both sides until 1980, when the Soviet Authorities brought-in a ‘new’ version whereby one-side contained the hammer and sickle, with the other-side kept plain (minus the hammer and sickle). Despite this change, this did not legally negate or abolish the older version(s), which main use and existence. During the Great Patriotic War (1941-1945), Soviet Red Army men and women often went into battle against Nazi German forces carry this flag whilst ‘unarmed’. Such excellent individuals were considered armed with (and ‘protected’) by ‘Socialism’.Needless to say, Nazi German soldiers were ordered to particularly target the Red Flag bearers. When Soviet Red Flag bearers fell, other Soviet Red Army soldiers would pick-up the Red Flag and continue.
In 1991, the dissolution of the Soviet Union was symbolised with the lowering of the Red Flag over the Kremlin. Today, this Red Flag (and many versions of it) continue to represent the International Working Class, and it is considered a great honour to carry this flag during protest marches and commemorations, etc. Today, this Red Flag is still carried by the Russian military representing the ‘battle honours’ related to WWII. This flag is also used by the various breakaway ‘Socialist’ republics of Eastern Ukraine that reject the current neo-Nazi regime operating out of Kiev (Western Ukraine). All existing Communist Parties throughout the world (including Communist China Vietnam, Laos and North Korea), use this flag (and its many variants) to represent the Revolutionary ideology of Marxist-Leninism.
(Dr Sheldon Cooper does not cover any of this history, but it is significant that the producers of the Big Bang Theory allowed this flag to be shown and identified on air.)