In "The Age of Miracles", Karen Thompson Walker constructs a theme around the divide that occurs between the "clock timers" and "real timers".
Though we may often pride ourselves on our open-mindedness and acceptance of those who are different, the truth is that we are most comfortable around people who think as we do. In the novel, as the differences between the two factions become more apparent, tensions rise. Julia's neighbors are arrested, her pseudo-friend, Gabby, makes herself more of an outcast and her neighbor, Sylvia, becomes more of a loner (except, of course, when she's spending time with Joel...). Meanwhile, those living on clock time are able to lead mostly normal lives and keep up routines that resemble the ones that they lead prior to the Slowing. When confronted with the prospect of accepting someone with a radically different ideology, let's face it: most of us shy away in order to maintain our own sense of order and stability.
In the novel, the Slowing causes the different characters to respond in a myriad of ways. Some become more withdrawn, others make choices that are uncharacteristic in nature while others carry on with their lives as normal. Julia's father is the most dynamic character (at least from Julia's perspective). Prior to the Slowing, he was a stable presence who provided for his family. After it began, however, his behavior became more erratic. He began an affair with Sylvia and he lied to her mother, causing their relationship to deteriorate. Julia's friend, Gabby, transformed from a docile pre-teen into an "edgy" rebel who begins tattooing herself and joins a cult.
Though Julia blames many of the changes and conflicts on the Slowing, there are a number of forces at work in the novel. Julia, Seth, Hanna and Gabby are enduring "the age of miracles" known as middle school. Obviously, change and growth is inevitable during this time and much of what happened would have occurred regardless of the Slowing. Additionally, as the Slowing begins, there are numerous secondary effects. People are forced to deal with economic and political uncertainty. This instability leads to fallout which has consequences that resonate throughout the world.