Olivia Newton-John, the Australian singer whose breathy voice and wholesome beauty made her one of the biggest pop stars of the '70s and charmed generations of viewers in the blockbuster movie "Grease," died on Monday, according to a statement from her husband. She was 73. "Dame Olivia Newton-John passed away peacefully at her Ranch in Southern California this morning, surrounded by family and friends. We ask that everyone please respect the family's privacy during this very difficult time," her husband, John Easterling, wrote in a statement on the singer's verified Instagram account. "Olivia has been a symbol of triumphs and...