Last October, scientists from around the world descended on Chengdu for the International Atomic Energy Agency’s 30th fusion energy conference. But one group was missing: the Americans. The quiet boycott of the event, a biennial gathering of top minds in the field, came after the U.S. Department of Energy discouraged American scientists from attending, five people told The Wire China. Researchers were warned in the summer that participating in the conference could jeopardize their ability t