Early in the afternoon of Tuesday, January 28, 1986, I was walking back from lunch to my part-time job as an undergraduate academic advisor at Pace University.  It was a day like most other New York City winter days -- the air was brisk, as was the undulating throng of pedestrians moving along the city sidewalks toward a thousand different destinations.  

Until, all of a sudden,  they weren't.

For those who hadn’t been watching TV that morning, the "breaking news" had to be passed along the old-fashioned way... through a rare midday publication of a city newspaper.  Peering around the clusters of people to find out what headline had grabbed so much attention, I learned that the space shuttle Challenger had exploded just 73 seconds after takeoff.

For me, the Challenger explosion marked my first collective "before and after" moment -- a global event that cleaved time into two categories:  before it happened, and after it happened.

It also marked the end of my cultural in...