There was, he said, a “grown-up way to do this kind of problem,” and he suggested that Weinberg should get onto it right away. Weinberg duly spent the next three months laboring to produce an elaborate calculation. In the end, he had to report back that he could find no trace of the empirical relationship that he had predicted from his initial and very simple-minded argument. “Now you have learned a lesson,” Oppenheimer told him. “Sometimes the elaborate, the learned method, the grown-up method is not as good as the simple and childishly naïve method.”
