“ Tennis balls, like a lot of objects, are made to be indestructible, which means they’re very resistant to mechanical processing, ” said Nickolas J. Themelis, director of Columbia University's Earth Engineering Center.... “ In terms of the impact, it’s a blip on the radar.... It launched a technical working group last year made up of manufacturers, officials from other tennis governing bodies and recyclers with an ambitious set of goals: Is there a way to design a fully recyclable ball?...