Say that you want to create an index, to quantify technological level of humanity at any time. This index puts a value on the level of today as good as the level of technological advancement year 1662 or 400 BC. It can be used in predictions of the future and so on.. What factors; quantities should the calculation be based on? Suggestions? Note that it has to be universal in time, so things like: number of transistors per dollar, or cellphones per capita wont do it. Even stuff like life expectancy is a bit complicated, since during war time it goes down but lots technological advancements are made.