In Episode 4, we meet water engineer and environmental justice advocate Siddhartha Roy. Now a research scientist at the University of North Carolina’s Water Institute, Siddhartha was an integral part of exposing the Flint water crisis in 2015. He chats with host Ken Stern about growing up in India, the future of water equity, and his real-life fight with the Hulk.

Half of Generation Z—people who are now between 10 and 25 years old—could live to be 100. Their extended futures are shrouded by climate change, pandemics, and racial and social disparities. But according to recent polling from the Pew Research Center, Gen Z is the most optimistic generation yet. In “Century Lives: the Next 50,” host Ken Stern talks to inspirational leaders in their 20s and 30s about what they’ve learned from previous generations, how they’re working to improve the world they’ve inherited, and how they imagine their super-sized futures will unfold.