Author's Note: Since I first posted the article below a new scientific study was published to explain how this phenomenon operates. As I have suggested below, some mechanism similar to this might underlie the "tipping point" phenomenon we see in the sudden formation of social consensus and group awareness. I sadly lack the scientific skills to prove such a dynamic exists, but the spooky synchronicity that appears to happen spontaneously in clocks might hold a clue to understanding social trends and public awareness.
How do social problems that have exist for generations suddenly become urgent public matters subject to broad civil debate? How does public consensus suddenly coalesce around an issue that has been clouded by uncertainty for years (such as gay marriage for a recent example). No one really understands how what amounts to ambient noise in public discourse suddenly form into popular topics of public debate, or how diverse and unfocused opinions suddenly merge into a consensus.
Books like The Tipping Point, or The Wisdom of Crowds speak to the mysterious phenomenon of collective perception but don't really explain how public consciousness works When I saw this video demonstration I understood for the first time, if only in an abstract way, the mystery of the 99 monkeys, otherwise known as the 100th monkey effect where a new behavior or idea spread rapidly by unexplained means from one group to all related groups once a critical number of members of the one adopts it.
Of course the 100 monkey effect has'n been empirically confirmed, but it serves as a parable highlighting a real social phenomenon, our collective cognition. Watch this video and see if it suggests an answer as to how public consensus might appear to spontaneously form.