This is largely a guest post by Lads, although, given that I am somewhat less skilled than he in HTML it has been reformatted a little and shrunk a wee bit. I should also mention that I first posted it after watching the Oscars last night, and whether that befuddled me or what it was there, and then it was gone, so if it reappears as a somewhat duplicate be patient and I will delete one of the two.  Anyway, here is Lads post:

The Olduvai Gorge Theory was laid out by Richard Duncan in 1989, after seeing that world energy per capita (WEPC) has been declining since 1979. Although others had seen this, Duncan felt that they missed the point that if it kept falling, modern civilization would collapse.

Duncan defined the Electrical Civilization as the way-of-life enabled by widespread and abundant electricity, and set its limits as the period where WEPC is above 30% of its peak, i.e. the period beyond 1930.

The Olduvai Theory assumes that after peaking, WEPC will decline at a rate that mirrors its growth. This brings the Electrical Civilization to an end after 100 years. Duncan defined the idea without using a model, but his concept has been built into other models. Of these, the Meadows team's World3 is probably the most famous, giving the Electrical Civilization a lifetime between 100 and 105 years in all three reference simulations, 1969, 1989, and 1999.

And thus the Olduvai Theory evolved to:

Electrical Civilization can be described by a single pulse waveform of duration X, as measured by average energy-use per person per year. It has a life-expectancy of less than one-hundred (100) years.