This American brain trust has resulted in over 400 Nobel laureates, more than any other country in the world. As of 2023, an estimated 1.2 million people around the world held a Ph.D in science, engineering or health earned at an American institution. The United States accounts for 27 percent of the world’s total research and development activity — the most of any nation — though China, at 22 percent, is closing in. This is still far ahead of the next largest players: Japan (7…