Personally I think that the radio contributed far more to the world of science than the airplane. However I think that they are talking more about the way these achievements affected life in the world as a whole.
However the greatest injustice is that Agricultural Mechanization was number 7. The fact that only 100 years ago most of the country were farmers(~90%) and today it is less then 5% is amazing. Freeing those people from farm work is what allowed them to work in factories and eventually allowed for specailization like scientists.
Electricity Rules
