As The Joy of Why podcast returns for a second season, producer Polly Stryker and host Steven Strogatz invite listeners to join them and their brilliant new guests on another voyage of discovery.

Dreams are subjective and fleeting, but laboratories have developed ways of getting into the minds of people while they are dreaming. In this episode, Steven Strogatz speaks with sleep researcher Antonio Zadra about how new experimental methods have changed our understanding of dreams.

Quantum field theory may be the most successful scientific theory of all time, but there's reason to think it's missing something. Steven Strogatz speaks with theoretical physicist David Tong about this enigmatic theory.

Everybody gets older, but not everyone ages in the same way. In this episode, Steven Strogatz speaks with Judith Campisi and Dena Dubal, two biomedical researchers who study the causes and outcomes of aging, to understand how age works - and what scientists know about postponing or even reversing the aging process.

Just as scientists test hypotheses, mathematicians prove or disprove conjectures. But what makes a proof stronger than a guess? What does evidence look like in the world of mathematics? Hear Melanie Matchett Wood, professor of mathematics at Harvard University, explain how probability helps to guide number theorists toward certainty.

Artificial intelligence has bested humans at problem-solving tasks including games like chess and Go. Is mathematics research next? Steven Strogatz speaks with Kevin Buzzard, professor of pure mathematics at Imperial College London, to learn about the ongoing multidisciplinary effort to translate math into language that computers understand.

Without a good definition of life, how do we look for it on alien planets? Steven Strogatz speaks with Robert Hazen, a mineralogist and astrobiologist, and Sheref Mansy, a chemist, to learn more.

How did life arise on Earth? It's one of the greatest and most ancient mysteries in all of science - and the clues to solving it are all around us. Steven Strogatz speaks with Jack Szostak, a Nobel Prize-winning biologist, and Betül Kaçar, a paleogeneticist and astrobiologist, to explore our best understanding of how we all got here.

With the December 2021 launch of the James Webb Space Telescope, one of the most expensive and ambitious scientific initiatives ever attempted commenced operations. Now that the telescope has been successfully deployed in its unique position in space, its advanced instruments will be able to gather data on questions that scientists once could only dream of answering. Is there life on other planets? How do supermassive black holes mold the mass in their galaxies? JWST may soon be able to tell us. In this episode, host Steven Strogatz speaks to two researchers leading JWST's observations of our universe: Marcia Rieke, the principal investigator of the telescope's Near-Infrared Camera, and Nikole Lewis, an astrophysicist studying planets outside of our solar system. (For more on the JWST and the history of its construction and launch, read Natalie Wolchover's article, "The Webb Space Telescope Will Rewrite Cosmic History. If It Works," which was recently honored with a 2022 Pulitzer Prize for Explanatory Reporting.)

Einstein's description of gravity as a curvature in space-time doesn't easily mesh with a universe made up of quantum wavefunctions. Theoretical physicist Sean Carroll (of the "Mindscape" podcast) tells Steven Strogatz about the mind-bending implications of the quest for quantum gravity.