“So many things make America combustible right now: mass unemployment, a pandemic that’s laid bare murderous health and economic inequalities, teenagers with little to do, police violence, right-wingers itching for a second civil war and a president eager to pour gasoline on every fire. “I think we’re indeed in a moment where things are going to get a lot more tense before they get more peaceful,” said the University of Michigan historian Heather Ann Thompson, who won the Pulitzer Prize for her 2016 book “Blood in the Water: The Attica Prison Uprising of 1971 and Its Legacy.”