It's awfully hard to write effective SF about 9/11. I heard a composer say once that she wrote several songs about the event and trashed them before finally finding something that worked. In Spirit got a Hugo nomination in 2003, and it's a pretty good story. Compelling, for me, even though it didn't suck me in entirely. It has interesting speculation on time travel without paradox, and the science is laced through the story, which explains the Hugo nomination. But the real point is how that time travel is used.
The true ability to view the past would be very traumatic, as many authors from Asimov and before have explored. We don't want to know what really happened to Jesus 2000 years ago, or at several other key turning points. The stories are what matter. In the current story, the defenders of time travel have found a use for it that may make the trauma worthwhile--the development of empathy. The protagonist is one of the 9/11 co-conspirators, a fully hardened man after 30 years in jail. He is allowed to "deep project" back to carefully selected scenes in the attack. It reads somewhat tritely in places, but is in the end very convincing. Read it and remember. 3 stars