I promised some posts about H.T. Odum this year, so here goes.

First, because I’m cheap, I bought a used copy of his 1983 book Systems Ecology: An Introduction, that a library was getting rid of. This book was reissued in 1994 as Ecological and General Systems: An Introduction to Systems Ecology. My 1983 copy has some typos and endearingly quaint references like this:

The amount of memory within the computer useful for storing programs is usually between 8000 and 64,000 bytes.

He probably updated that in the 1994 version, but whatever it was updated to probably still sounds endearingly quaint today. It reminds us how far we have come.

The 1983 book has a chapter on “analog computers”. Digital computers have come so far and are so powerful that I guess we have forgotten that this sort of thing used to be useful. An analog computer is basically a circuit, and you can simulate almost any kind of system with a circuit – in a hydraulic system, water flow is analogous to electric flow and friction is analogous to electric resistance, for example. Essentially, he took the idea that energy flows through any kind of system and drew beautiful circuit diagrams of how those systems work. Almost any kind of system between the sub-atomic scale and the astronomical scale – mechanical systems, cells, organisms, ecosystems, cities, farms, economies, etc. Although the systems can get pretty complex, in both structure and behavior, they are all based on a set of surprisingly simple core building blocks, and the same set of core building blocks can describe any of these seemingly very different systems.

All the systems are concerned in some way with controlling the flow of energy and using it to do useful work. This concept is fairly obvious in electrical and mechanical systems, but it is also present in my body right now, where electrons are being passed through a series of complex chemical bonds that allow my body to operate its various organs, maintain my temperature, and repair tissues as they break down and build new tissues (hopefully not too much more, at this point.) A rainforest, a coral reef, a city, and the global economy are similarly engaged in controlling the flow of energy and using it to perform useful work. One of his key concepts was that systems try to maximize “power”, or find the right flow rate of energy that can be converted into the most useful work. Extracting the most work always involves controlling or limiting the flow in some way, which always results in some dissipation as heat. (I should mention, he doesn’t use the word “work” in exactly the same sense that I am, but I find it useful to think of work as the amount of energy that was converted into something useful.)

Another core concept was “embodied energy”, which I think of as the sum of all the useful work it took to get to a certain point in a system. For example, a fish has more embodied energy than the plants it ate, and an eagle more than the fish it ate, and a city more than the farms and mines that produced the raw materials to sustain its people and its economy.