Thanks very much for your question.

I’ll try to give you a “short” answer here but for more info I suggest you consult some of the references/links I chat about in “A Short Intro to Long Waves.” I especially like Berry’s Long-Wave Rhythms…; Stewart’s (1989) compelling book is the first written on the 56 year energy cycle. Devezas (2006), the NATO Advanced Symposium on Kondratieff Waves, Warfare and World Security, was the book that finally convinced me that I should take long waves seriously.

There have been lots of interesting ideas about the origin of the long wave and its length, and there probably is some truth in many of them. For example, Berry mentions evidence for deterministic chaos with self-organized criticality playing a role in the financial crashes. Modis’ book Predictions was the first place I saw sunspots suggested as a possible cause; Solar activitiy has an effect on climate and weather, and thus might influence agriculture and ripple through the economy. (This idea is especially attractive if you’re an astronomer!) BTW, 5 sunspot cycles are about 56 years, the length of one energy cycle.

According to Berry, long waves are due to “innovation and diffusion of major new transportation and energy technologies, with infrastructure development, and with collective behavior marked by lag and overshoot.” So the length of the wave would include contributions from each of these effects. In the 1970s, Jay Forrester at MIT built an elaborate 15-sector model of the U.S. economy and found that it spontaneously exhibited 50-year long waves of economic activity. This was a surprise discovery to Forrester and suggests the fundamental influence of these capital-lifespan effects in determining the nature and length of the long wave.

In the 1930s, Joseph Schumpeter, a Harvard professor and formerly Austria’s Minister of Finance, emphasized the concept of periodic innovation surges as the cause of the long wave. Stewart, himself the discoverer of the 56 year energy cycle in 1989 (which is correlated with the Kondratieff Wave), noted Schumpeter proposed that “a few particularly significant innovations…have been responsible for the strong economic waves beginning roughly in 1785, 1840, and 1895.” Each of these dates is about 7 years before the opening of what we now call the Lewis and Clark Maslow Window, the Dr. Livingstone/Suez Maslow Window, and the Peary/Panama Maslow Window, respectively. (Schumpeter died in 1950, just before the Apollo Maslow Window was launched.)

It’s also interesting that long waves are correlated with major wars (see Goldstein), which apparently act to both intensify the economic boom and later its crash. And we would expect that long waves are correlated with the generational cycles of Strauss and Howe, which has been observed by Alexander.

Your comment about one long wave approximating 2-3 generations is intriguing. 55 to 60 years is also the typical time that a human influences the economy. I’m with you — it’s hard to believe these are just coincidences.

Hope this helps!