Throughout your life, there will be monumentous events that will define history. These may even deeply affect you. Events such as 911 change the world in an instance. These are the events that will forever be etched in your memory. 'Where were you when" becomes the unifying question for such events. You remember exactly where you were, what you were doing, who you were with for the rest of you life.
An early event that everyone remembers happening was the assassination of Presiden John F. Kennedy. He was a young man who had captivated the world and was expected to change the world with his actions. He did begin to do this but was tragically killed before he could come close to reaching his potential. In the 47+ years since his death, those alive at the time remember well what they were doing and where they were when they heard of his passing. His death, rather than his life, defined the start of the 1960's.
Similarly remembered was the 1986 space shuttle Challenger disaster. This event suddenly made people aware that space travel was incredibly dangerous. Lives had been lost in space exploration in the past but never had so many been lost in an instant. The event was broadcast to the world as it happened. There was no doubt that millions of people had been affected at exactly the same time. No observer would ever forget the event. Space travel would never be thought the same ever again.
Of course the big event that is fixed in many millions of minds is the 911 disaster at New York city. Not only was this event remembered by many as a modern focus of history, it changed society in countless ways. In many ways, there is a pre-911 and a post-911 condition. Certainly air travel changed enormously. Security became the main concern. While many procedures and checks were rushed into place immediately, there has also been a gradual tightening of procedures and restrictions ever since. Besides air travel, shipping, commerce and documentation have all undergone extensive changes as a result of the terrorism threat that was highlighted on 911.
There have been many other events that trigger the question "Where were you when?". Each has a particular significance for many people. Those events include the death of Princess Diana, the Gulf Oil disaster, the Exxon Valdez oil spill. Each affected so many people when they happened. In many cases, a lot of resources were devoted to the event in the days, weeks and months following.
Of course, not all of the huge events have been negative. Millions of people still vividly remember Neil Armstrong walking on the moon in 1969. Millions remember when President Barrack Obama was elected. Each time a championship is won by a sports team, millions of ardent fans remember that event with the same personal significance.
Still other events have the same effect on people but they are localized to a much smaller group. A family event such as a wedding or reunion will likely be remembered by the participants for a very long time. When a family member or close friend is lost, that has a profound effect. Again, the effect of these events is on a much more limited number of people. Not that the effect is diminished by those affected but these are not events that alter all of society for millions of people.
All of the monumentous events of history affect everyone differently, but there are similarities. Grief can be shared for a life lost too young. Fear can ripple through all members of the society based on the same event. Those affected don't even have to see the event live. The hearing of the particular event brings with it much of the same profound significance as was felt by the direct observers. This fact is one of the ways that a monumentous event is defined.
The Internet has become the lightning fast delivery channel for many of the modern events. Literally seconds after something has happened, it is described on the Internet. "Breaking News" is announced on many web sites. While information is sparse at first, details stream on to the screens of millions of Internet users in short order. In the case of events such as the Indonesian Tsunami of 2004, the power of the event is realistically shown via the Internet. The stories, pictures, sounds and more are presented from every angle. The event is covered on so many Internet channels that scarsely anything else is broadcast during the days afterwards.
It has been said that history defines a civilization. Civilization may also define history. It certainly presents and archives history in many different ways. The most basic recording of history has been in the minds of the observers. That fact continues into the 21st century despite the availability of TV, radio, Internet and video recordings. Future historians can research events and begin to know the emotions that were felt at the time. They can never absorb the reality of the event into their conscious quite like a person who was alive at the time. For the future historian, the question "Where were you when?" can never have the impact that millions of people have from firsthand contact with the event.