In 1934, professor rei, of the center for fluid mechanics, used model cars to measure the aerodynamic drag of various bodies in wind tunnels In the face of market failure, coase has given the opposite answer: external-utility problems can be solved by explicitly using the market, without government intervention. And zhang wuchang is more absolute, he said that there is no so-called external utility, there is only unclear property rights. Anyway, coase brought revolutionary innovation to market concepts. He made it clear that the key to the market was not the "price mechanism" of impersonal machinery, but the power of participants in economic activity. 304/5000