The Joy of Why

Evolutionary biologist Toby Kiers joins Steven Strogatz to explore how mycorrhizal fungi exchange nutrients with plants and influence soil carbon storage. The conversation examines decentralized resource allocation, partnerships between fungi and roots, and experiments using fluorescent tracers and imaging robots to observe underground networks. Kiers also describes efforts to map fungal biodiversity and protect these ecosystems.

Hosted by Steven Strogatz, Janna Levin

Mathematician Maggie Miller of the University of Texas at Austin joins Janna Levin and Steven Strogatz to explore knots, surfaces and four-dimensional topology. They discuss why loops can untangle in four spatial dimensions while two-dimensional surfaces can remain knotted, how three-dimensional snapshots help visualize 4D spaces, and Miller and collaborators’ resolution of a knotted-surface question posed by Charles Livingston in 1982. The conversation also connects visual techniques from art with mathematical reasoning.

Hosted by Janna Levin, Steven Strogatz

Theoretical physicist Jonathan Halliwell joins Steven Strogatz and Janna Levin to discuss how quantum decoherence helps explain the transition from wave-like quantum systems to the classical macroscopic world. The conversation covers quantum cosmology, decoherent histories, the measurement problem, macroscopic realism and why the quantum-to-classical transition does not require a conscious observer.

Hosted by Steven Strogatz, Janna Levin

Recorded live at the International Congress of Mathematicians in Philadelphia, this episode brings hosts Janna Levin and Steven Strogatz together with Akshay Venkatesh, Ravi Vakil and Alex Kontorovich. They examine what recent AI-generated proofs demonstrate, how machine assistance may change mathematical research, and what proof, creativity, understanding and storytelling contribute to the discipline. The recording took place on 26 July 2026; Quanta published the episode on 3 September 2026.

Hosted by Janna Levin, Steven Strogatz

Computer scientist and cognitive scientist Melanie Mitchell discusses why artificial intelligence does not think or reason like humans, how developmental and comparative psychology can improve machine-cognition experiments, and six principles for testing AI competence, robustness, and failure modes.

Ishmail Abdus-Saboor explores why touch can feel painful or pleasurable and how scientists study those experiences. The conversation connects sensory pathways to social behavior and evolution, including work with unusual animal models and the challenge of interpreting subjective experience through experiments.

Hosted by Janna Levin

Adam Riess explains how astronomers measure the universe's expansion and why different methods give conflicting results. He revisits the evidence for accelerated expansion and examines what the Hubble tension might reveal about measurement techniques or missing ingredients in cosmological models.

Hosted by Steven Strogatz

David Kipping considers how to reason about extraterrestrial life when evidence is scarce. The discussion covers promising places to search, the interpretation of possible biosignatures and the role of statistical inference, alongside questions about habitable worlds and moons beyond our solar system.

Hosted by Janna Levin

Lauren Williams introduces the positive Grassmannian and the surprising connections it creates across mathematics and physics. She explains links to waves, traffic and particle scattering, and discusses how research-level mathematical problems can help assess what artificial intelligence is capable of proving.

Hosted by Steven Strogatz

Jennifer Doudna discusses how CRISPR changed gene editing and what might come next. The conversation examines emerging applications, technical limitations and the ethical choices involved in altering genetic material, including how scientific progress can be paired with responsible use.

Hosted by Janna Levin

Yang-Hui He joins Steven Strogatz to trace geometry from ancient measurement and Euclid to curved spaces, general relativity, and string theory. They discuss why geometry provides a shared language for mathematics and physics, how rigorous proof interacts with physical intuition, and how artificial intelligence might change mathematical discovery. The conversation also contrasts broad conceptual views with concentrated work on individual problems.

Hosted by Steven Strogatz, Janna Levin

Steven Strogatz speaks with physicist Frank Wilczek about what clocks measure and why the passage of time seems directional. They discuss different arrows of time, irreversibility, and the relationship between physical time and human experience. Wilczek explains how Einstein changed the definition of time and considers whether time could be emergent or illusory. The conversation also explores connections between time, symmetry and ideas about dark matter.

Hosted by Steven Strogatz

Terence Tao and Steven Strogatz revisit Tao’s essay on what makes mathematical research valuable. Their conversation examines proof, elegance, usefulness, problem solving, and connections between fields, showing why no single criterion captures all worthwhile mathematics. They also consider how mathematical communities develop judgment and how technological tools affect research.

Hosted by Steven Strogatz

Cornell mathematician Justin Moore joins Steven Strogatz to explain different sizes of infinity and the question of whether intermediate infinities exist. They explore the role of infinity in the foundations of mathematics and contrast the ways mathematicians and physicists use infinite quantities.

Hosted by Steven Strogatz

Category theorist Eugenia Cheng and Steven Strogatz explore how mathematical objects can be equivalent without being exactly equal. Cheng explains how abstraction reveals patterns and connections across different areas of mathematics, from geometry and topology to symmetry, and how category-theoretic thinking can illuminate situations in everyday life.

Hosted by Steven Strogatz

Steven Strogatz talks with aging researchers Judith Campisi and Dena Dubal about why organisms age and why the process varies between individuals. The conversation examines cellular senescence, the influence of genes, differences in longevity between women and men, and the relationship between aging and diseases such as Alzheimer's and Parkinson's. The researchers discuss what experimental evidence can tell us about slowing or reversing aspects of aging, while distinguishing living longer from preserving health and function.

Hosted by Steven Strogatz

Steven Strogatz and Harvard mathematician Melanie Matchett Wood explore what counts as evidence in number theory before a rigorous proof is available. Their discussion examines how probability and randomness guide conjectures about prime numbers and infinite collections, and how probabilistic patterns can lead mathematicians toward certainty.

Hosted by Steven Strogatz

Kevin Buzzard of Imperial College London joins Steven Strogatz to discuss Lean, formal proof assistants and the effort to encode mathematical knowledge in a computer-readable library. They explore how computers verify difficult arguments, the distinction between Lean and its mathematical library, the formalization of work by Peter Scholze and Dustin Clausen, and the prospects and limits of computers creating new mathematics.

Hosted by Steven Strogatz

Steven Strogatz explores the origins of life with Jack Szostak and Betül Kaçar. Szostak considers how early-Earth chemistry, including cyanide-bearing environments, could give rise to precursors of RNA and DNA, and discusses competing settings for life’s beginnings. Kaçar explains how reconstructing ancient genes helps researchers investigate the evolution of essential biological processes. Together, the conversations examine what experiments can reveal about the earliest steps toward life and whether replaying evolutionary history would produce different outcomes.

Hosted by Steven Strogatz

Steven Strogatz talks with mathematicians Colin Adams and Lisa Piccirillo about knot theory and why it matters across mathematics and science. They explore how mathematicians distinguish knots, connections with the geometry of three-dimensional and higher-dimensional spaces, and applications involving DNA, materials and theoretical physics.

Hosted by Steven Strogatz