Michael J. Lewis, in the New Criterion, explores its cultural legacy:
Before the sun set on September 11, it was already a commonplace that the attacks would “change everything,” as the phrase of the day went. How precisely this would happen was not entirely clear. Roger Rosenblatt, in a widely noted essay in Time, suggested that it would bring about the end of irony (an era of neo-sincerity presumably succeeding that of ironic detachment). Surely so violent a shock to the national consciousness must somehow change that consciousness itself.Read the rest of his piece. Also, The Guardian has an interactive graphic on the '9/11 Decade'.
Or so it was believed, for it was universally sensed that the events of the day represented something new in human experience. Through almost all of human history the scope of collective experience was limited by two strict physical limits, by how far the human voice could reach and by how many people could be squeezed into a given space. Plato’s ideal number of 5040 male citizens for a democracy is a realistic figure, given the acoustic properties of a Greek theater and the requirement that citizens take active part in debate—even in our lifetimes few theaters or opera houses have surpassed it.