How many conversations start with that question? Probably more than we remember. Yet it’s an immediate pull back into the past, back to an event or shared memory that somehow binds people together, often whether they like it or not.

The biggest events in history have turned strangers into friends.

V-Day. The assassination of JFK. Martin Luther King. 911. If you lived through any of those world-changers, you can probably remember the exact moment you heard the news, where you were, what you we...