This is what a war on knowledge looks like

A supporter of international students outside the Science Center on the Harvard University campus on May 27. (CJ Gunther, EPA-EFE/Shutterstock)

On the wall of Ulrich Mueller’s neurobiology lab at Johns Hopkins University is a map with pins that show all the different countries where his research fellows were born. It’s a visual representation of what makes American science so powerful — and why that primacy is threatened.

“The brightest minds from around the world are drawn to conduct research here,” Mueller proudly told an interviewer for a campus journal last month. The freedom and diversity of American higher education have operated like a magnet, attracting the world’s most brilliant minds and spinning off trillions of dollars in wealth.