Milk is more than just a food for babies. Breast milk has evolved to deliver thousands of diverse molecules including growth factors, hormones and antibodies, as well as microbes. Elizabeth Johnson, a molecular nutritionist at Cornell University, studies the effects of infants’ diet on the gut microbiome. These studies could hold clues to hard questions in public health for children and adults alike. In this episode of “The Joy of Why” podcast, co-host Steven Strogatz interviews Johnson about the microbial components that make breast milk one of the most wondrous biofluids found in nature. Listen on Apple Podcasts, Spotify, TuneIn or your favorite podcasting app, or you can stream it from Quanta.

Nothing escapes a black hole … or does it? In the 1970s, the physicist Stephen Hawking described a subtle process by which black holes can “evaporate,” with some particles evading gravitational oblivion. That phenomenon, now dubbed Hawking radiation, seems at odds with general relativity, and it raises an even weirder question: If particles can escape, do they preserve any information about the matter that was obliterated? Leonard Susskind, a physicist at Stanford University, found himself at odds with Hawking over the answer. In this episode, co-host Janna Levin speaks with Susskind about the “black hole war” that ensued and the powerful scientific lessons to be drawn from one of the most famous paradoxes in physics. Listen on Apple Podcasts, Spotify, TuneIn or your favorite podcasting app, or you can stream it from Quanta.

Birds flock. Locusts swarm. Fish school. Within assemblies of organisms that seem as though they could get chaotic, order somehow emerges. The collective behaviors of animals differ in their details from one species to another, but they largely adhere to principles of collective motion that physicists have worked out over centuries. Now, using technologies that only recently became available, researchers have been able to study these patterns of behavior more closely than ever before. In this episode, the evolutionary ecologist Iain Couzin talks with co-host Steven Strogatz about how and why animals exhibit collective behaviors, flocking as a form of biological computation, and some of the hidden fitness advantages of living as part of a self-organized group rather than as an individual. They also discuss how an improved understanding of swarming pests such as locusts could help to protect global food security. Listen on Apple Podcasts, Spotify, Google Podcasts, TuneIn or your favorite podcasting app, or you can stream it from Quanta.

Quantum teleportation isn’t just science fiction; it’s entirely real and happening in laboratories today. But teleporting quantum particles and information is a far cry from beaming people through space. In some ways, it’s even more astonishing. John Preskill, a theoretical physicist at the California Institute of Technology, is one of the leading theoreticians of quantum computing and information. In this episode, co-host Janna Levin interviews him about entanglement, teleporting bits from coast to coast, and the revolutionary promise of quantum technology. Listen on Apple Podcasts, Spotify, Google Podcasts, TuneIn or your favorite podcasting app, or you can stream it from Quanta.

Time seems linear to us: We remember the past, experience the present and predict the future, moving consecutively from one moment to the next. But why is it that way, and could time ultimately be a kind of illusion? In this episode, the Nobel Prize-winning physicist Frank Wilczek speaks with host Steven Strogatz about the many “arrows” of time and why most of them seem irreversible, the essence of what a clock is, how Einstein changed our definition of time, and the unexpected connection between time and our notions of what dark matter might be.

We often talk about evolution in terms of competition, as the survival of the fittest. But if it is, then where did the widespread (and widely admired) impulse to help others even at great cost to ourselves come from? In this episode, Stephanie Preston, a professor of psychology and head of the Ecological Neuroscience Lab at the University of Michigan, talks about the evolutionary, neurological and behavioral foundations for altruism with our new co-host, the astrophysicist and author Janna Levin.

We tend to think of mathematics as purely logical, but the teaching of math, its usefulness and its workings are packed with nuance. So what is “good” mathematics? In 2007, the mathematician Terence Tao wrote an essay for the “Bulletin of the American Mathematical Society” that sought to answer this question. Today, as the recipient of a Fields Medal, a Breakthrough Prize in Mathematics and a MacArthur Fellowship, Tao is among the most prolific mathematicians alive. In this episode, he joins Steven Strogatz to revisit the makings of good mathematics.

“The Joy of Why” is a Quanta Magazine podcast about curiosity and the pursuit of knowledge. The mathematician and author Steven Strogatz and the astrophysicist and author Janna Levin take turns interviewing leading researchers about the great scientific and mathematical questions of our time. New episodes are released every other Thursday.

Aristotle argued almost 2,400 years ago that a perfect vacuum could never exist. Today, the concept of nothingness figures at least implicitly into almost every theory of modern physics. In this episode closing out season 2 of “The Joy of Why,” the theoretical physicist Isabel Garcia Garcia of New York University and the Institute for Advanced Study talks with host Steven Strogatz about the impact of quantum mechanics on the definition of a “true vacuum,” the possibility of false vacuums, how the concept of vacuum energy relates to the cosmological constant, and how her studies of the vacuum could help to resolve frustrating puzzles in string theory and cosmology. “The Joy of Why” will return with new episodes in early 2024.

The heart’s electrical system keeps all its muscle cells beating in sync. A hard whack to the chest at the wrong moment, however, can set up unruly waves of abnormal electrical excitation that are potentially deadly. The resulting kind of arrhythmia may be what caused the football player Damar Hamlin of the Buffalo Bills to collapse on the field after he took a powerful hit during a 2023 National Football League game. Today, powerful defibrillators are usually used to help resynchronize hearts in distress. But Flavio Fenton, who studies the electrical dynamics of the heart, tells Steve Strogatz about a new method under development for treating arrhythmias by stimulating the heart with mild, precisely timed shocks — or possibly even with light.

The jellyfish that move through the seas by gently pulsing their saclike bodies may not seem to hold many secrets that would interest human engineers. But simple as the creatures are, jellyfish are masterful at harnessing and controlling the flow of the water around them, sometimes with surprising efficiency. As such, they embody sophisticated solutions to problems in fluid dynamics that engineers, mathematicians and other professionals can learn from. John Dabiri, an expert in mechanical and aerospace engineering at the California Institute of Technology, talk with Steven Strogatz in this episode about what jellyfish and other aquatic creatures can teach us about submarine design, the optimal placement of wind turbines, and healthy human hearts.

Sailors have spun yarns for centuries about gigantic rogue waves that could suddenly come out of nowhere to capsize the ships of unwary mariners. Scientists didn’t believe them because the stories seemed at odds with everything else known about waves. Then cameras and other instruments began to capture undeniable proof of the existence of rogue waves. Ton van den Bremer, an expert in fluid mechanics, talks with Steven Strogatz about what science has learned about how rogue waves form, whether it’s possible to predict them and how the waves can be recreated in a lab.

Neuroscience has made progress in deciphering how our brains think and perceive our surroundings, but a central feature of cognition is still deeply mysterious: namely, that many of our perceptions and thoughts are accompanied by the subjective experience of having them. Consciousness, the name we give to that experience, can’t yet be explained — but science is at least beginning to understand it. In this episode, the consciousness researcher Anil Seth and host Steven Strogatz discuss why our perceptions can be described as a “controlled hallucination,” how consciousness played into the internet sensation known as “the dress,” and how people at home can help researchers catalog the full range of ways that we experience the world.

By definition, the universe seems like it should be the totality of everything that exists. Yet a variety of arguments emerging from cosmology, particle physics and quantum mechanics hint that there could also be unobservable universes beyond our own that follow different laws of nature. While the existence of a multiverse is speculative, for many physicists it represents a plausible explanation for some of the biggest mysteries in science. In this episode, Steven Strogatz explores the idea of a multiverse with the theoretical physicist David Kaplan and learns what it might mean about our own existence.

Perpetual motion machines are impossible, at least in our everyday world. But down at the level of quantum mechanics, the laws of thermodynamics don’t always apply in quite the same way. In 2021, after years of effort, physicists successfully demonstrated the reality of a “time crystal,” a new state of matter that is both stable and ever-changing without any input of energy. In this episode, Steven Strogatz discusses time crystals and their significance with the theoretical physicist Vedika Khemani of Stanford University, who co-discovered that they were possible and then helped to create one on a quantum computing platform.

The idea of infinity is probably about as old as numbers themselves, going back to whenever people first realized that they could keep counting forever. But even though we have a sign for infinity and can refer to the concept in casual conversation, infinity remains profoundly mysterious, even to mathematicians. In this episode, Steven Strogatz chats with his fellow mathematician Justin Moore of Cornell University about how one infinity can be bigger than another (and whether we can be sure that there isn’t an intermediate infinity between them). They also discuss how physicists and mathematicians use infinity differently and the importance of infinity to the very foundation of mathematics.

Should Covid-19 vaccines be judged by how well they prevent disease or how well they prevent death? Anna Durbin, a public health expert and vaccine researcher, talks with Steven Strogatz about the science behind vaccines.

Can mathematics handle things that are essentially the same without being exactly equal? Category theorist Eugenia Cheng and host Steven Strogatz discuss the power and pleasures of abstraction.

Making living cells blink fluorescently like party lights may sound frivolous. But the demonstration that it’s possible could be a step toward someday programming our body’s immune cells to attack cancers more effectively and safely. That’s the promise of synthetic biology. While molecular biologists strip cells down to their component genes and molecules to see how they work, synthetic biologists tinker with cells to get them to perform new feats — and discover new secrets about how life works in the process. In this episode, Steven Strogatz talks with Michael Elowitz, a professor of biology and bioengineering at the California Institute of Technology and a Howard Hughes Medical Institute Investigator.

“The Joy of Why” is a podcast about curiosity and the pursuit of knowledge from Quanta Magazine. The acclaimed mathematician and author Steven Strogatz interviews leading researchers about the great scientific and mathematical questions of our time.