This chart is an immensely complex map of the interconnections between the different scientific disciplines. It was made by comparing the citations of nearly a million articles and assigning a little dot to each distinct area of research. It is basically the same as the sort of continuum I always imagined between them, (though the one I always saw wasn't 2-dimensional). I am surprised that earth science/ecology leads into biology instead of organic chemistry, and did not expect computer science to bridge a gap between physics and social science of all things. I suppose though that there is a difference between the way the different subjects are related content-wise and citation-wise. Even so, it is interesting that the latter almost gives you the former.
They certainly got one thing right: putting astrophysics on top.