The success of the Patient Protection and Affordable Care Act hinges in great part on the so-called “young invincibles.” That’s the term Atlanta attorney Richard Sanders used for young, healthy adults between ages 18 and 28 at a recent seminar in Gainesville on the new health care law and the insurance exchanges. Also known as Obamacare, the law was passed in 2010 so more uninsured people could get affordable health insurance.