known behaviors, but our knowledge of these behaviors does not suffice to predict the behaviors of the network as a whole (Boccara, 2004). Such complex networks are said to exhibit emergent behavior if the behaviors of their components lead to unanticipated—that is, “emergent”—behavior of the network as a whole in the absence of a centralized controller that creates this behavior by design. As an example, the network of transistors on a computer chip is not normally regarded as exhibiting emergent behavior, whereas an ant colony or the World Wide Web is (Boccara, 2004).

It seems to be widely accepted that investment in basic research will be required to describe the behaviors of social and biological networks. A similar call for investment in basic research might appear counterintuitive for technologically advanced physical networks like the Internet or regional power grids. A few moments of reflection reveals, however, that these physical networks, too, exhibit emergent behaviors. The Internet is robust against expected noises but fragile against unexpected ones, like computer viruses (Doyle et al., 2005). Regional power grids fail infrequently but inevitably, under circumstances not anticipated by grid designers and not adequately dealt with by grid power control systems (IEEE Spectrum, 2004). Contrary to the efforts and hopes of the implementers of advanced technologies, the behaviors of complex physical networks are not yet completely predictable. Moreover, spending to improve the technologies in their components will not remedy this situation. Just like the development of radar awaited the basic science of electromagnetism and that of nuclear weapons awaited the discovery of nuclear fission, the ability to control the complex networks in our lives awaits as yet unforeseen discoveries in the science of networks.

Because committees are notoriously inept at developing curricula or specifying the research content of a science discipline, this committee makes no attempt to do either. It offers the analysis given in Appendix C and discussed above as a test of the proposition that network science be regarded as a coherent area of investigation worthy of investment by the Army. The committee believes that network science fully passes this test.


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