Charles A. S. Hall

Hall retired from full-time teaching in June 2012, and he now works to consolidate his life work into a format that will continue to be useful for future research.

"Energy used by the economy is a proxy of the amount of real work done in our economy," according to Charles A. Hall. In the 1980s, Hall and others hypothesised, "Over time, the Dow Jones should snake about the real amount of work." Twenty years later, a century's market and energy data shows that whenever the Dow Jones Industrial Average spikes faster than US energy consumption, it crashes: 1929, 1970s, the dot.com bubble, and now with the mortgage collapse.

Nicholas Georgescu-Roegen (a Romanian-born economist whose work in the 1970s began to define this new approach) models the economy as a living system. Like all life, it draws from its environment valuable (or “low entropy”) matter and energy, for animate life, food; for an economy, energy, ores, the raw materials provided by plants and animals. And like all life, an economy emits a high-entropy wake, it spews degraded matter and energy, that is... waste heat, waste gases, toxic byproducts, the molecules of iron lost to rust and abrasion. Low entropy emissions include trash and pollution in all their forms. Matter taken up into the economy can be recycled, using energy; but energy, used once, is forever unavailable to us at that level again. The law of entropy commands a one-way flow downward from more to less useful forms. Thus, Georgescu-Roegen, paraphrasing the economist Alfred Marshall, said: “Biology, not mechanics, is our Mecca.”

Charles A. S. Hall (born 1943) is an American systems ecologist and ESF Foundation Distinguished Professor at State University of New York in the College of Environmental Science & Forestry.