Samuel Arbesman:

Knowledge changes around us all the time. Yet we don’t always have the most up-to-date facts. This is true, I’d argue, even in an age of instant and massive information. Despite our unprecedented ability to rapidly learn new things and crowdfix mistakes, Knowledge and its sinister twin Error continue to propagate in complex and intriguing ways. Errors persist among us for far longer than they should and even when there is more accurate knowledge elsewhere. Newer knowledge does not spread as fast as it should and weaves its way unevenly throughout society.