The U.S.-China relationship will be the great geopolitical rivalry of the early 21st century, and every facet of the competition will involve the two big powers' capabilities in science and technology. Figures from across the political spectrum worry about a technology race with China, and many Americans fear that China has already surpassed us in such frontier technologies as artificial intelligence and 5G broadband communications. "China has stolen a march and is now leading in 5G," then-Attorney General William Barr declared in a recent keynote speech at a Justice Department conference on China. Graham Allison of Harvard University warns that China "is currently on a trajectory to overtake the United States in the decade ahead" in artificial intelligence. The conventional wisdom about China's supposed advantages in AI and 5G shows how easy it is for incomplete understanding of technologies to lead to misjudgments and policy mistakes.