There is a community of bloggers interested in any topic that appears in postings. On any given day, some of the bloggers express new thoughts on the topic, or react to topical postings by other bloggers. This constitutes the *chatter* on that topic.
Occasionally, an event occurring in the real world induces a reaction from bloggers, and we see a *spike* in the number of postings on a topic. Spikes do not typically propagate through blogspace, in the sense that bloggers typically learn about spikes not from other blogs, but instead from a broad range of channels including mainstream media. Thus, we can assume all informed authors are aware of the topical event and have an opportunity to write about it.
On rare occasions, the chatter reaches *resonance*, i.e., someone makes a posting to which everyone reacts sharply, thereby causing a spike. The main characteristic of resonance is that a spike arises from either no external input or a very small external input. The formation of order (a spike) out of chaos (chatter) has been observed in a variety of situations [26], though observation of our data reveals that this happens very rarely in blogspace.