Jon gradually becomes a pawn of the U.S. government. It gives him the code name "Doctor Manhattan"—a reference to the Manhattan Project —and a costume that he begrudgingly accepts. Doctor Manhattan chooses a representation of a hydrogen atom as his emblem. He declares that its simplicity kindles his respect; accordingly, he painlessly burns the mark into his forehead. This preference for material mechanisms marks the beginning of his declining humanity. Over time, he sheds uniform bit by bit. By the end of the 1970s, he refuses to wear anything at all except during mandatory public appearances.