From the blog: "I love how the Physics engine sorts out everything and
the movement really catches the eye."
Since the Hyperglance visualization is static, the use of the term
"physics engine" might be a bit pretentious.
It's not physics in the sense of 'Angry Birds' (i.e., time evolution
of trajectories
http://www.box2d.org/features.html), but looks more
like the algorithm used in the Graphviz variant called "neato" (i.e.,
global minimization of "energy" where the nodes are connected by
virtual "springs"
http://www.graphviz.org/About.php). In Mechanics we
would call this Statics, as opposed to Dynamics.
In other words, when an interactive change is made via the GUI level,
the otherwise static image is updated according to the results of the
minimization algorithm.