CBS News has significantly expanded its knowledge base and on-air presence with the addition of 19 new contributors, who will appear across all of the network's broadcasts and digital platforms. The new hires were announced by Bari Weiss, editor-in-chief of CBS News, during an all-hands meeting.The contributors, all experts in their fields, will begin appearing immediately. They cover the worlds of politics, national security, health, happiness, arts, food, style and more.Here are CBS News' new contributors:Elliot Ackerman – Ackerman is a veteran of the Marine Corps and CIA special operations, having served five tours of duty in Iraq and Afghanistan, where he received the Silver Star, the Bronze Star for Valor and the Purple Heart.…