This book is above all a meditation on the impact of 9/11 and how it still, even know, haunts the American psyche. The story features the lives of various characters who struggle to know what to do with what they have witnessed, and fight to process their emotions. In many ways, a key thematic concern of this great novel is memory itself, and our stance towards it.
The Falling Man is a character who, unlike other characters, definitely wants to remember the tragedy he witnessed. His simulation of what he saw on that fateful day is a way of helping both himself and everybody else to remember the horror of what he saw, recreating the emotions people experienced as they saw people flinging themselves from the top floor of the World Trade Centre. In a sense, the Falling Man is like a broken record, as these memories constantly circle again and again in his consciousness. He seems to find relief from them by simulating them, and throwing himself out of buildings, but we recognise that his constant repetition of this act shows how in reality this act does not bring relief at all.