1) Life expectancy. 2) 10-year moving average of the duration of subsistence living expenses that can be funded from a fixed weight of gold. Both of these are

1) Life expectancy. 2) 10-year moving average of the duration of subsistence living expenses that can be funded from a fixed weight of gold. Both of these are very high level measures that fold in a lot of underlying technological progress. (1) is weighted towards computation and biotech, (2) against mining and expansion into space (would have to be weighted somehow there to be useful much past the next 20 years), but both encompass far more than that. Both incorporate advantages provided by fluff technologies such as networking tools, but so many levels removed that we don't have to stop arguing over whether they should be dropped in a well or not. This may or may not be a benefit from your point of view.