79. Underestimating the fragility of complex systems
A person can be quickly killed by a small incision if it punctures a vital organ. A tree can be killed by removing a ring of bark, which prevents fluids from the roots from reaching the leaves, a technique called girdling. Every complex system has a weak point, sometimes several weak points. Our power grid is exactly the same way; an overload of current in one area can fry transformers in a long series, potentially shutting down power in large areas53. In a disaster situation this could lead to widespread looting, as during the New York City Blackout of 1977. Many do not appreciate how many weak points our complex society has.
There is an empirical generalization that technological systems decrease in proportion to the fourth degree of energy density. This empirical generalization (exact value varies depending on different factors) can be derived by comparing the reliability of planes and rockets54. A similar empirical generalization holds for statistics of deadly car crashes in relation to speed55. It is necessary to observe that the installed power per employee of mankind is constantly growing56.