I can think of several events in recent history where the world was not the same before as it was after the event. Of the ones that come most quickly to mind, I wish most had never, ever, ever - ever happened. The 11 September 2001 attacks are at the top of that list of terrible watersheds. The 21st century could not have had a darker debut.
The fireman in the photo below in WTC's North Tower One is Mike Kehoe. He survived the attacks and was interviewed by the Mirror 31 August 2011, here. The falling man plumetting from Tower One was likely 43-year-old Jonathan Briley, who worked in the top floor restaurant. Wiki:
Some links:Regarding the social and cultural significance of 'The Falling Man', theologian Mark D. Thompson of Moore Theological College says that "perhaps the most powerful image of despair at the beginning of the twenty-first century is not found in art, or literature, or even popular music. It is found in a single photograph."
- Pentagon survivor speaks, speculates on why he survived when others around him didn't
- Familes of September 11
- September 11 Families' Association
- Debunking 9/11 Conspiracy Theories
- National Commission on Terrorist Attacks upon the United States
- The September 11 Digital Archives