The Joy of Why

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, 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.”

Common sense rules our world. This fundamental, sometimes trivial knowledge is inherent to how humans interpret language. Yet, some of these simple human truths are so obvious that they're rarely put into words. And without the data of common sense to train on, large language models such as ChatGPT have bizarre, often humorous blind spots.

Yejin Choi, professor and the chair of computer science at the University of Washington, calls common sense the “dark matter” of intelligence. In this week’s episode of “The Joy of Why,” Choi talks with co-host Steven Strogatz about decoding the interstitial glue of language and comprehension. Together, they explore the question: Should we program more humanity into the next generation of artificial intelligence?

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, co-host Janna Levin speaks with mathematician Natalie Priebe Frank on the subject of 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.

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.

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.

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, tells Steve Strogatz about the new findings in mental health research that are revolutionizing psychiatric medication.

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.

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.

You can read the transcript for this episode and see the image of the micrograph Johnson references on our website.

Nothing escapes a black hole… or does it? In the 1970s, Stephen Hawking described a subtle process by which black holes can “evaporate,” with some particles evading gravitational oblivion. This phenomenon, now dubbed “Hawking radiation,” seems inherently at odds with general relativity, but it gets weirder still: If particles can escape, do they preserve some information about the matter that was obliterated? Leonard Susskind, a physicist at Stanford University, found himself at odds with Hawking when it came to answering this question. In this episode, co-host Janna Levin speaks with Susskind about the “black hole war” that ensued and the powerful scientific lessons that have radiated from one of the most famous paradoxes in physics.

Birds flock. Locusts swarm. Fish school. In these chaotic assemblies, order somehow emerges. Collective behaviors 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 collective animal behavior more closely than ever before. These new insights are unlocking some of the secret fitness advantages of living as part of a group rather than as an individual. The improved understanding of swarming pests such as locusts could also help to protect global food security.

In this episode, co-host Steven Strogatz interviews the evolutionary ecologist Iain Couzin about  how and why animals exhibit collective behaviors, and the secret advantages that arise from them.

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.

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 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, host Janna Levin speaks with Stephanie Preston, a professor of psychology and head of the Ecological Neuroscience Lab at the University of Michigan, about the evolutionary, neurological and behavioral foundations for altruism.

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.

Tune in to the new season of ‘The Joy of Why,’ a podcast from Quanta Magazine and PRX. This season, new co-host cosmologist Janna Levin and mathematician Steven Strogatz will be joined by guests including Terence Tao, the mathematician and Fields Medalist, and Frank Wilczek, the Nobel Prize-winning physicist. New episodes premiere every other Thursday.

Even empty space bubbles with energy, according to quantum mechanics — and that fact affects almost every facet of physical reality. The theoretical physicist Isabel Garcia Garcia explains to Steven Strogatz why it’s so important in modern physics to understand what a true vacuum is.

The post Does Nothingness Exist? first appeared on Quanta Magazine

Abnormal waves of electrical activity can cause a heart’s muscle cells to beat out of sync. In this episode, Flavio Fenton, an expert in cardiac dynamics, talks with Steve Strogatz about ways to treat heart arrhythmias without resorting to painful defibrillators.

The post Can Math and Physics Save an Arrhythmic Heart? first appeared on Quanta Magazine