>My favorite example is the Haber-Bosch process for fixing nitrogen and producing synthetic fertilizer (invented 1910). Surely a far more “undervalued” technology than the iPhone! It enabled us to scale up global food production to feed at least an extra 3.5 billion people who otherwise would never have been born, or would have starved.

It also kept Germany going in WW1 far longer than otherwise, by compensating for blockades on saltpeter for explosives.