The Joy of Why

It’s fair to say that enjoyment of a podcast would be severely limited without the human capacity to create and understand speech. That capacity has often been cited as a defining characteristic of our species, and one that sets us apart in the long history of life on Earth. Yet we know that other species communicate in complex ways. Studies of the neurological foundations of language suggest that birdsong, or communication among bats or elephants, originates with brain structures similar to our own. So why do some species vocalize while others don’t? In this episode, Erich Jarvis, who studies behavior and neurogenetics at the Rockefeller University, chats with Janna Levin about the surprising connections between human speech, birdsong and dance.

Scientists routinely build quantitative models — of, say, the weather or an epidemic — and then use them to make predictions, which they can then test against the real thing. This work can reveal how well we understand complex phenomena, and also dictate where research should go next. In recent years, the remarkable successes of “black box” systems such as large language models suggest that it is sometimes possible to make successful predictions without knowing how something works at all. In this episode, noted statistician Emmanuel Candès and host Steven Strogatz discuss using statistics, data science and AI in the study of everything from college admissions to election forecasting to drug discovery.

The “species” category is almost certainly the best known of all the taxonomic classifications that biologists use to organize life’s vast diversity. It’s a linchpin of both conservation policy and evolutionary theory, though in practice biologists have struggled to find a definition that works across the natural world. In this episode, Kevin de Queiroz, a zoologist and evolutionary biologist, talks with host Janna Levin about the variety of ways to conceive of a species, and ways to understand the relationships among living things.

When we think about medicine’s war on cancer, treatments such as surgery, radiation and chemotherapy spring to mind first. Now there is another potential weapon for defeating tumors: statistics and mathematical models that can optimize the selection, combination or timing of treatment. Building and feeding these models requires accounting for the complexity of the body, and recognizing that cancer cells are constantly evolving. In this episode, host Steven Strogatz hears from Franziska Michor, a computational biologist, about how our understanding of evolutionary dynamics is being used to devise new anticancer therapies.

If instruments do someday detect evidence of life beyond Earth, whether it’s in this solar system or in the farther reaches of space, astrobiologists want to be ready. One of the best ways to learn how alien life might function can be to study the organisms called extremophiles, which live in incredibly challenging environments on or in the Earth. In this episode, Penelope Boston, a microbiologist who has worked for many years with NASA, speaks with Janna Levin about the bizarre life found in habitats such as caves, how it would be possible to detect life beyond our solar system and what it would mean for humanity if we do.

The principles of thermodynamics are cornerstones of our understanding of physics. But they were discovered in the era of steam-driven technology, long before anyone dreamed of quantum mechanics. In this episode, the theoretical physicist Nicole Yunger Halpern talks to host Steven Strogatz about how physicists today are reinterpreting concepts such as work, energy and information for a quantum world.

Observations of the cosmos suggest that unseen sources of gravity — dark matter — tug at the stars in galaxies, while another mysterious force — dark energy — drives the universe to expand at an ever-increasing rate. The evidence for both of them, however, hinges on assumptions that gravity works the same way at all scales. What if that’s not true? In this episode, theoretical physicist Claudia de Rham explains her work on an alternative explanation called “massive gravity” to host Janna Levin.

Within just a few years, artificial intelligence systems that sometimes seem to display almost human characteristics have gone from science fiction to apps on your phone. But there’s another AI-influenced frontier that is developing rapidly and remains untamed: robotics. Can the technologies that have helped computers get smarter now bring similar improvements to the robots that will work alongside us? In this episode, Daniela Rus, a pioneering roboticist at the Massachusetts Institute of Technology, talks to host Steven Strogatz about the surprising inspirations from biology that may help robots rise to new levels.

Can you keep a secret? Modern techniques for maintaining the confidentiality of information are based on mathematical problems that are inherently too difficult for anyone to solve without the right hints. Yet what does that mean when quantum computers capable of solving many problems astronomically faster are on the horizon? In this episode, host Janna Levin talks with computer scientist Boaz Barak about the cryptographic techniques that keep information confidential, and why “security through mathematics” beats “security through obscurity.” Listen on Apple Podcasts, Spotify,  TuneIn or your favorite podcasting app, or you can stream it from Quanta.

Ask a question of ChatGPT and other, similar chatbots and there’s a good chance you’ll be impressed at how adeptly it comes up with a good answer — unless it spits out unrealistic nonsense instead. Part of what’s mystifying about these kinds of machine learning systems is that they are fundamentally black boxes. No one knows precisely how they arrive at the answers that they do. Given that mystery, is it possible that these systems in some way truly understand the world and the questions they answer? In this episode, the computer scientist Yejin Choi of the University of Washington and host Steven Strogatz discuss the capabilities and limitations of chatbots and the large language models, or LLMs, on which they are built.  Listen on Apple Podcasts, Spotify,  TuneIn or your favorite podcasting app, or you can stream it from Quanta.

In the tiling of wallpaper and bathroom floors, collective repeated patterns often emerge. Mathematicians have long tried to find a tiling shape that never repeats in this way. In 2023, they lauded an unexpected amateur victor. That discovery of the elusive aperiodic monotile propelled the field into new dimensions. The study of tessellation is much more than a fun thought exercise:  Peculiar, rare tiling formations can sometimes seem to tell us something about the natural world, from the structure of minerals to the organization of the cosmos. In this episode, Janna Levin speaks with mathematician Natalie Priebe Frank about these complex geometric combinations, and where they may pop up unexpectedly. Specifically, they explore her research into quasicrystals — crystals that, like aperiodic tiles, enigmatically resist structural uniformity.. Listen on Apple Podcasts, Spotify,  TuneIn or your favorite podcasting app, or you can stream it from Quanta.

The universe seems like it should be unfathomably complex. How then is science able to crack fundamental questions about nature and life? Scientists and philosophers alike have often commented on the “unreasonable” success of mathematics at describing the universe. That success has helped science probe some profound mysteries — but as the physicist Nigel Goldenfeld points out, it also helps that the “hard” physical sciences, where this progress is most evident, are in major ways simpler than the “soft” biological sciences. In this episode, Goldenfeld speaks with co-host Steven Strogatz about the scientific importance of asking the right questions at the right time. They also discuss the mysterious effects of “emergence,” the phenomenon that allows new properties to arise in systems at different scales, imposing unexpected order on cosmic complexity. Listen on Apple Podcasts, Spotify,  TuneIn or your favorite podcasting app, or you can stream it from Quanta.

During traumatic periods and their aftermath, our brains can fall into habitual ways of thinking that may be helpful in the short run but become maladaptive years later. For the brain to readjust to new situations later in life, it needs to be restored to the malleable state it was in when the habits first formed. That is exactly what Gül Dölen, a neuroscientist and psychiatric researcher at the University of California, Berkeley, is working toward in her lab. What is her surprising tool? Psychedelics. In this episode, Dölen shares with co-host Janna Levin the surprising potential of psychedelics to change the lives of those grappling with addiction, depression and post-traumatic stress. Listen on Apple Podcasts, Spotify,  TuneIn or your favorite podcasting app, or you can stream it from Quanta.

For decades, the best drug therapies for treating depression, like SSRIs, have been based on the idea that depressed brains don’t have enough of the neurotransmitter serotonin. Yet for almost as long, it’s been clear that simplistic theory is wrong. Recent research into the true causes of depression is finding clues in other neurotransmitters and the realization that the brain is much more adaptable than scientists once imagined. Treatments for depression are being reinvented by drugs like ketamine that can help regrow synapses, which can in turn restore the right brain chemistry and improve whole body health. In this episode, John Krystal, a neuropharmacologist at the Yale School of Medicine, shares the new findings in mental health research that are revolutionizing psychiatric medication. Listen on Apple Podcasts, Spotify,  TuneIn or your favorite podcasting app, or you can stream it from Quanta.

If superconductors — materials that conduct electricity without any resistance — worked at temperatures and pressures close to what we would consider normal, they would be world-changing. They could dramatically amplify power grids, levitate high-speed trains and enable more affordable medical technologies. For more than a century, physicists have tinkered with different compounds and environmental conditions in pursuit of this elusive property, but while success has sometimes been claimed, the reports were always debunked or withdrawn. What makes this challenge so tricky? In this episode, Siddharth Shanker Saxena, a condensed-matter physicist at the University of Cambridge, gives co-host Janna Levin the details about why high-temperature superconductors remain so stubbornly out of reach.. Listen on Apple Podcasts, Spotify,  TuneIn or your favorite podcasting app, or you can stream it from Quanta.

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.