The 21st century will not be remembered for bigger and better internal combustion engines, nuclear power plants, or universities, not any more than the 20th century is noted for its advances in coal-burning trains, plantations, and razor blades. Those are things that seemed especially important at the beginning of the century but were not so impressive a few decades later. The defining qualities of this century are slow to take shape and perhaps not so easy to recognize at this point. Perhaps, for example, the Internet and electrical storage are two of them, but the technology changes so unpredictably it seems too early to say. The reason to try to get an early fix on which innovations matter and which ones don’t is so we can stop investing in things that won’t matter or aren’t what they seem to be. But the last eleven years have already given us reason enough to doubt our ability to predict.