Via The New York Times, the journal PLoS One has published a map of human knowledge (if by human, you mean: academicians who read english-language journals; and if by knowledge, you mean: what that narrow subset of humans is interested in whilst journal-surfing). The researchers who put the map together combed a year's worth of user interaction data of the most popular academic journal web portals. They marked instances where a user clicked from one journal to another; every dot in the map represents a journal, and links indicate likely paths for users to click from one journal to another. The idea, then, is that this image represents the relations of the various disciplines to one another, and the extent to which they are interconnected.
The arrangement of dots - with the humanities forming a hub at the center and the natural sciences forming a perimeter around them - fell out naturally from the data. To say more than this would require that I pretend to understand terms in the PLoS One article, such as "betweenness centrality" and "first-order Markov chain," which I plainly do not. But if you're game and have a bit of calculus under your belt, then have at it. For the rest of us, here is what the pretty colors of the dots mean:
light purple - physics
blue - chemistry
green - biology
red - medicine
yellow - social sciences
white - humanities
purple - mathematics
pink - engineering
Full-size image of the map is here.
