  Proponents of Complexity Science believe that the huge variety of emergent
phenomena observed throughout nature, are generated by relatively few
microscopic mechanisms. Skeptics however point to the lack of concrete examples
in which a single mechanistic model manages to capture relevant macroscopic and
microscopic properties for two or more distinct systems operating across
radically different length and time scales. Here we show how a single
complexity model built around cluster coalescence and fragmentation, can cross
the fundamental divide between many-body quantum physics and social science. It
simultaneously (i) explains a mysterious recent finding of Fratini et al.
concerning quantum many-body effects in cuprate superconductors (i.e. scale of
10^{-9} - 10^{-4} meters and 10^{-12} - 10^{-6} seconds), (ii) explains the
apparent universality of the casualty distributions in distinct human
insurgencies and terrorism (i.e. scale of 10^3 - 10^6 meters and 10^4 - 10^8
seconds), (iii) shows consistency with various established empirical facts for
financial markets, neurons and human gangs and (iv) makes microscopic sense for
each application. Our findings also suggest that a potentially productive shift
can be made in Complexity research toward the identification of equivalent
many-body dynamics in both classical and quantum regimes.
