Sure.  I’d also mention that 9/11, like you said, was a pretty big tragedy.  But, you know, there have been so many terrible things that have happened to people in history, there are so many tragedies to choose from.
assistant
I don’t think so. I’m not a historian.
assistant
What are the worst tragedies of the modern day?
user
Which ones?
assistant
I was asking you. For example, 9/11.
user
Gosh. What do you mean by worst? Do you mean who suffered most or who died?
assistant
just tragedies that are considered bad
user
What sorts of tragedies are you interested in? That sounds like a bit of a vague question.  You could be talking about a specific moment in history, or several moments in history, like the Holocaust, the Vietnam War, or the 2008 housing market crash.  You could be talking about a whole series of events, like America’s involvement in the Vietnam War, or some of the events that led to it.  You could be interested in events that happened in a particular country, or events that happened on an international level.  You could even be interested in personal tragedies that you’ve personally experienced, or that have happened to people you care about.
assistant
Those are good ones. Do you have any others?
user