How to fix the world's biggest problems

We can learn a lot about improving the 21st-century world from an icon of the industrial era: the steam engine.
Harnessing steam power required many innovations, as William Rosen chronicles in the book The Most Powerful Idea in the World. Among the most important were a new way to measure the energy output of engines and a micrometer dubbed the "Lord Chancellor" that could gauge tiny distances.

Such measuring tools, Rosen writes, allowed inventors to see if their incremental design changes led to the improvements-such as higher power and less coal consumption-needed to build better engines. There's a larger lesson here: Without feedback from precise measurement, Rosen writes, invention is "doomed to be rare and erratic." With it, invention becomes "commonplace."