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.

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 so personal, subjective and fleeting, they might seem impossible to study directly and with scientific objectivity. But in recent decades, laboratories around the world have developed sophisticated techniques for getting into the minds of people while they are dreaming. In the process, they are learning more about why we need these strange nightly experiences and how our brains generate them. In this episode, Steven Strogatz speaks with sleep researcher Antonio Zadra about how new experimental methods have changed our understanding of dreams. “The Joy of Why” is a podcast from Quanta Magazine, an editorially independent publication supported by the Simons Foundation. Funding decisions by the Simons Foundation have no influence on the selection of topics, guests, or other editorial decisions in this podcast or in Quanta Magazine. “The Joy of Why” is produced by Susan Valot and Polly Stryker. Our editors are John Rennie and Thomas Lin, with support by Matt Carlstrom, Annie Melchor and Leila Sloman. Our theme music was composed by Richie Johnson. Our logo is by Jackie King, and artwork for the episodes is by Michael Driver and Samuel Velasco. Our host is Steven Strogatz. If you have any questions or comments for us, please email us at quanta@simonsfoundation.org.

Quantum field theory may be the most successful scientific theory of all time, predicting experimental results with stunning accuracy and advancing the study of higher dimensional mathematics. Yet, there’s also reason to believe that it is missing something. Steven Strogatz speaks with David Tong, a theoretical physicist at the University of Cambridge, to explore the open questions of this enigmatic theory. “The Joy of Why” is a podcast from Quanta Magazine, an editorially independent publication supported by the Simons Foundation. Funding decisions by the Simons Foundation have no influence on the selection of topics, guests, or other editorial decisions in this podcast or in Quanta Magazine. “The Joy of Why” is produced by Susan Valot and Polly Stryker. Our editors are John Rennie and Thomas Lin, with support by Matt Carlstrom, Annie Melchor and Leila Sloman. Our theme music was composed by Richie Johnson. Our logo is by Jackie King, and artwork for the episodes is by Michael Driver and Samuel Velasco. Our host is Steven Strogatz. If you have any questions or comments for us, please email us at quanta@simonsfoundation.org.

Everybody gets older, but not everyone ages in the same way. For many people, late life includes a deterioration of health brought on by age-related disease. But that’s not true for everyone, and around the world, women typically live longer than men. Why is that? 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 it works — and what scientists know about postponing or even reversing the aging process. “The Joy of Why” is a podcast from Quanta Magazine, an editorially independent publication supported by the Simons Foundation. Funding decisions by the Simons Foundation have no influence on the selection of topics, guests, or other editorial decisions in this podcast or in Quanta Magazine. “The Joy of Why” is produced by Susan Valot and Polly Stryker. Our editors are John Rennie and Thomas Lin, with support by Matt Carlstrom, Annie Melchor and Leila Sloman. Our theme music was composed by Richie Johnson. Our logo is by Jackie King, and artwork for the episodes is by Michael Driver and Samuel Velasco. Our host is Steven Strogatz. If you have any questions or comments for us, please email us at quanta@simonsfoundation.org.

How can anyone say something with certainty about infinity? What can we really know about the mysterious prime numbers without knowing all of them? Just as scientists need data to assess their hypotheses, mathematicians need evidence to prove or disprove conjectures. But what counts as evidence in the intangible realm of number theory? In this episode, Steven Strogatz speaks with Melanie Matchett Wood, a professor of mathematics at Harvard University, to learn how probability and randomness can help establish evidence for the airtight arguments demanded of mathematicians.“The Joy of Why” is a podcast from Quanta Magazine, an editorially independent publication supported by the Simons Foundation. Funding decisions by the Simons Foundation have no influence on the selection of topics, guests, or other editorial decisions in this podcast or in Quanta Magazine. “The Joy of Why” is produced by Susan Valot and Polly Stryker. Our editors are John Rennie and Thomas Lin, with support by Matt Carlstrom, Annie Melchor and Leila Sloman. Our theme music was composed by Richie Johnson. Our logo is by Jackie King, and artwork for the episodes is by Michael Driver and Samuel Velasco. Our host is Steven Strogatz. If you have any questions or comments for us, please email us at quanta@simonsfoundation.org.

How do you teach mathematics to an artificial intelligence? AI has already bested humans at various problem-solving tasks, including games like chess and Go. But before any task can be tackled by a machine, it must be reinterpreted as directions in language that computers can understand. For the last few years, researchers and amateurs all over the world have worked together to translate the essential axioms of mathematics into a programming language called Lean. Armed with this knowledge, theorem-proving programs that understand Lean have begun helping some of the world’s greatest mathematicians verify their work. Steven Strogatz speaks with Kevin Buzzard, professor of pure mathematics at Imperial College London, about the effort to “teach” math to Lean — and how projects like this one could shape the future of math. “The Joy of Why” is a podcast from Quanta Magazine, an editorially independent publication supported by the Simons Foundation. Funding decisions by the Simons Foundation have no influence on the selection of topics, guests, or other editorial decisions in this podcast or in Quanta Magazine. “The Joy of Why” is produced by Susan Valot and Polly Stryker. Our editors are John Rennie and Thomas Lin, with support by Matt Carlstrom, Annie Melchor and Leila Sloman. Our theme music was composed by Richie Johnson. Our logo is by Jackie King, and artwork for the episodes is by Michael Driver and Samuel Velasco. Our host is Steven Strogatz. If you have any questions or comments for us, please email us at quanta@simonsfoundation.org.

Scientists don’t really agree on a definition for life. We may recognize life instinctively most of the time, but any time we try to nail it down with set criteria, some stubborn counterexample spoils the effort. Still, can we really search for life on other worlds, or understand the earliest stages of life on this planet, if we don’t know what to look for? On this episode, Steven Strogatz speaks with Robert Hazen, a mineralogist, astrobiologist and senior staff scientist at the Carnegie Institution’s Earth and Planets Laboratory, along with Sheref Mansy, professor of chemistry at the University of Alberta, to learn more about how new taxonomies and a “cellular Turing test” might help us answer this essential question. “The Joy of Why” is a podcast from Quanta Magazine, an editorially independent publication supported by the Simons Foundation. Funding decisions by the Simons Foundation have no influence on the selection of topics, guests, or other editorial decisions in this podcast or in Quanta Magazine. “The Joy of Why” is produced by Susan Valot and Polly Stryker. Our editors are John Rennie and Thomas Lin, with support by Matt Carlstrom, Annie Melchor and Leila Sloman. Our theme music was composed by Richie Johnson. Our logo is by Jackie King, and artwork for the episodes is by Michael Driver and Samuel Velasco. Our host is Steven Strogatz. If you have any questions or comments for us, please email us at quanta@simonsfoundation.org.

How did life begin 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. Biologists have sometimes imagined evolutionary history as a recorded “tape of life” that might turn out differently if it were replayed again and again. In this episode, Steven Strogatz speaks with two researchers inspecting different parts of the tape. First, hear from the Nobel Prize-winning biologist Jack Szostak, who explores how a boiling pool laced with cyanide could have given rise to essential life elements like RNA and DNA. Then hear from Betül Kaçar, a paleogeneticist and astrobiologist who resurrects ancient genes to learn how they helped evolve the processes essential to modern life. “The Joy of Why” is a podcast from Quanta Magazine, an editorially independent publication supported by the Simons Foundation. Funding decisions by the Simons Foundation have no influence on the selection of topics, guests, or other editorial decisions in this podcast or in Quanta Magazine. “The Joy of Why” is produced by Susan Valot and Polly Stryker. Our editors are John Rennie and Thomas Lin, with support by Matt Carlstrom, Annie Melchor and Leila Sloman. Our theme music was composed by Richie Johnson. Our logo is by Jackie King, and artwork for the episodes is by Michael Driver and Samuel Velasco. Our host is Steven Strogatz. If you have any questions or comments for us, please email us at quanta@simonsfoundation.org.