“It’s some sort of technological signal. The question is whether it’s Earth technology or technology from somewhere out yonder,” said Sofia Sheikh, a graduate student at Pennsylvania State University leading a team studying the signal and trying to decipher its origin. She is part of Breakthrough Listen, a $100 million effort funded by Yuri Milner, a Russian billionaire investor, to find alien radio waves. The project has now stumbled on its most intriguing pay dirt yet.