The song includes the Anaphase of mitosis and Ascaris bivalent mitosis.
Before the show premiered in 2007, creators Chuck Lorre and Bill Prady were in the audience at a Barenaked Ladies concert when frontman Ed Robertson coincidentally improvised a freestyle rap about Simon Singh's book Big Bang: The Origin of the Universe.
Shortly after, they contacted Robertson to write the theme song.
The song is a rapid-fire history lesson about the creation of the universe that "all started with a Big Bang."
The Big Bang Theory remains one of the world's most popular TV shows. Fans can't get enough of Sheldon and his gang of geeky pals. Check out these 21 awesome facts you might not know about The Big Bang Theory shared by Digitalspy.com.