News Mayim Bialik Petitions For Joint Custody of Sons By Krista Wick 4:49 PM PST, November 29, 2012 Getty Images The Big Bang Theory star Mayim Bialik has officially filed for divorce from her husband of nine years, Michael Stone.Related: Mayim Bialik Announces Divorce Bialik submitted the paperwork on Tuesday to a Los Angeles court citing "irreconcilable differences."In the documents obtained by ET, the mom of two requested joint legal and physical custody of her sons Miles, 7, and Frederick, 4, with her ex.The actress initially announced her intentions to divorce on her blog on November 21."After much consideration and soul-searching, Michael and I have arrived at the decision to divorce," she wrote. "Divorce is terribly sad, painful and incomprehensible for children. It is not something we have decided lightly."